JP5799896B2 - RF signal transmission device, RF signal transmission system, and reception device - Google Patents

Description

  The present invention relates to an RF signal transmission device, an RF signal transmission system, and a reception device.

  A broadcasting facility for television broadcasting or radio broadcasting radiates an RF (Radio Frequency) signal in which a video signal, an audio signal or the like is carried on a carrier wave as a radio wave from a transmission antenna. A radio broadcast receiver for viewing a broadcast such as a television receiver or a radio receiver receives an RF signal emitted from a broadcast facility.

Takao Wabo and Akira Yasuda (original author Richard Schreier, Gabor C. Temes) Introduction to ΔΣ analog / digital converters (Understanding Delta-Sigma Data Converters), Maruzen Co., Ltd., 2007

  When an RF signal of content provided by TV broadcasting is received by a receiving antenna and then transmitted to a network, the RF signal received by the receiver is demodulated, and the video signal or audio signal constituting the content is digitally converted. It is necessary to perform various conversion processes such as conversion.

However, since a receiver such as a television receiver is an RF signal receiver, it cannot receive a content signal after various conversion processes are performed on the RF signal.
Therefore, for example, it is difficult to view the content of the television broadcast transmitted to the network as it is with a television receiver.

  Accordingly, an object of the present invention is to enable content to be transmitted to a network in a format that can be easily received by a receiver of an RF signal.

(1) The present invention includes an input unit to which an RF signal is input from the outside, a ΔΣ modulator that performs ΔΣ modulation on the RF signal input to the input unit and outputs a quantized signal, and the ΔΣ modulation A transmission unit that transmits the quantized signal output from the transmitter to the outside.

The quantized signal (ΔΣ modulated signal) obtained by ΔΣ modulation of the RF signal is a digital signal, but also represents an analog waveform of the RF signal.
Therefore, the quantized signal transmitted from the RF signal transmission apparatus can be transmitted as a digital signal to an external network. In addition, the receiver that has received the quantized signal can receive the quantized signal as an RF signal.

(2) The input unit preferably includes an input system for supplying an RF signal received via an antenna to the ΔΣ modulator. In this case, the RF signal received via the antenna can be converted into a quantized signal by the ΔΣ modulator.

(3) It is preferable that the input unit includes an input system that applies the quantized signal received from another RF signal transmission device to the ΔΣ modulator as an RF signal. In this case, the quantized signal received from another RF signal transmission apparatus can be acquired as an RF signal, and the RF signal can be converted again into a quantized signal by the ΔΣ modulator.

(4) An input switching unit that switches an RF signal applied to the ΔΣ modulator is further provided, and the input unit transmits a first input system to which the RF signal is input via an antenna and another RF signal transmission device. A second input system in which the quantized signal is input as an RF signal, and the input switching unit includes an RF signal input to the first input system and an RF signal input to the second input system. Preferably, a signal is selectively applied to the ΔΣ modulator. The RF signal from the first input system and the RF signal from the second input system can be selectively supplied to the ΔΣ modulator.

(5) It is preferable to further include an output terminal that outputs the RF signal input to the input unit to a receiver that receives the RF signal. In this case, the input RF signal can be output to the receiver.

(6) An output switching unit that switches an RF signal output from the output terminal is further provided, and the input unit transmits a first input system to which the RF signal is input via an antenna and another RF signal transmission device. A second input system in which the quantized signal is input as an RF signal, and the output switching unit includes an RF signal input to the first input system and an RF signal input to the second input system. Preferably, a signal is selectively applied to the output terminal. In this case, the RF signal from the first input system and the RF signal from the second input system can be selectively applied to the output terminal.

(7) It is preferable to further include an AD converter that AD converts the RF signal input to the input unit, and the ΔΣ modulator is supplied with the digital RF signal output from the AD converter. In this case, a digital RF signal is given to the ΔΣ modulator.

(8) It is preferable that a frequency conversion unit that performs frequency conversion of the RF signal input to the input unit is further provided, and the frequency conversion unit preferably supplies the frequency-converted RF signal to the ΔΣ modulator. In this case, the frequency of the input RF signal can be converted.

(9) The apparatus further includes a control unit that controls the ΔΣ modulator, the ΔΣ modulator being configured to change a quantization noise stop band, and the control unit configured to change a quantization noise stop band of the ΔΣ modulator. It is preferable to perform control for changing. In this case, even if there are a plurality of RF signal frequencies input to the ΔΣ modulator, ΔΣ modulation can be performed.

(10) The control unit can acquire transmission request information including information that can identify content, and performs ΔΣ modulation on the RF signal of the content indicated by the acquired transmission request information. It is preferable to perform control for changing the quantization noise stop band of the ΔΣ modulator according to the frequency band of the RF signal of the content. In this case, the quantization noise stop band of the ΔΣ modulator is changed in accordance with the frequency band of the RF signal of the content indicated by the transmission request information.

(11) The information processing apparatus further includes a storage unit that holds a list of contents that can be input as RF signals in the input unit, and the ΔΣ modulator includes the content indicated by the acquired transmission request information in the list. The ΔΣ modulation is preferably performed. In this case, if the content indicated by the transmission request information is included in the content list, ΔΣ modulation is executed.

(12) The control unit can acquire stop request information, and preferably performs control to stop transmission of the quantized signal by the transmitter based on the acquisition of stop request information. In this case, when stop request information is acquired, the transmission of the quantized signal by the transmitter is stopped.

(13) The present invention viewed from another viewpoint includes the RF signal transmission device according to (1), and a reception device that receives the quantized signal transmitted from the RF signal transmission device. This is an RF signal transmission system.

(14) It is preferable that the receiving device includes a receiver that receives the quantized signal transmitted from the RF signal transmission device as an RF signal.

(15) The present invention from another viewpoint includes the RF signal transmission device according to (5) or (6), and a receiver that receives the RF signal output from the output terminal. This is a featured receiving apparatus.

(16) According to another aspect of the present invention, there is provided a control unit that performs processing for transmitting transmission request information including information for specifying content to be transmitted to the RF signal transmission device according to (10), And a receiver that receives the quantized signal transmitted from the RF signal transmission device as an RF signal of the content requested to be transmitted.

(17) From another viewpoint, the present invention provides a receiver for receiving the quantized signal transmitted from the RF signal transmission device according to (12) as an RF signal, and the RF signal transmission device. And a control unit that performs processing for transmitting stop request information for requesting stop of transmission of the quantized signal.

  According to the present invention, the quantized signal transmitted from the RF signal transmission device can be transmitted to the outside as a digital signal.

1 is a configuration diagram of an RF signal transmission system according to an embodiment. It is a functional block diagram which shows RF signal transmission apparatus. It is a figure which shows a program information list. It is a sequence diagram which shows operation | movement of RF signal transmission system. It is a figure which shows the state of RF signal transmission apparatus. It is a functional block diagram of the RF signal transmission apparatus comprised as a relay apparatus. It is a functional block diagram of the RF signal transmission apparatus specialized for the reception function. It is a block diagram of a ΔΣ modulator. This is a primary low-pass type ΔΣ modulator. (A) is an output spectrum of the low pass type ΔΣ modulator, and (b) is an output spectrum of the band pass type ΔΣ modulator. (A) is an output spectrum of the low pass type ΔΣ modulator, and (b) is an output spectrum of the band pass type ΔΣ modulator. (A) is an output spectrum of the low pass type ΔΣ modulator, and (b) is an output spectrum of the band pass type ΔΣ modulator. (A) is a polar coordinate indicating the operation of the low-pass ΔΣ modulator, and (b) is a polar coordinate indicating the operation of the bandpass ΔΣ modulator. This is a secondary band-pass ΔΣ modulator obtained by converting from a primary low-pass ΔΣ modulator. This is a low-pass ΔΣ modulator having a CRFB structure. This is a bandpass type ΔΣ modulator obtained by conversion from a low pass type ΔΣ modulator having a CRFB structure. FIG. 6 is an output spectrum waveform diagram of a bandpass ΔΣ modulator for θ0 = π / 4. FIG. 6 is an output spectrum waveform diagram of a bandpass ΔΣ modulator for θ0 = 3π / 4. FIG. 6 is an output spectrum waveform diagram of a bandpass ΔΣ modulator for θ0 = 5π / 4. FIG. 6 is an output spectrum waveform diagram of a bandpass ΔΣ modulator for θ0 = 7π / 4. It is a block diagram of RF signal transmission apparatus which has a zone | band extension part. It is explanatory drawing of the extended signal band. It is a figure which shows the pass characteristic of the extended signal band and a band pass filter. It is a figure which shows a main signal component and a harmonic component.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[1. RF signal transmission system]
FIG. 1 is a diagram showing an overall configuration of the RF signal transmission system 1. The RF signal transmission system 1 according to the embodiment includes a plurality of transmission / reception devices 9 and 9. Each of the transmission / reception devices 9 and 9 has an RF signal transmission device 300. The plurality of RF signal transmission apparatuses 300 are connected to each other via a signal transmission path (Internet) 4.

In this RF signal transmission system 1, each RF signal transmission device 300 transmits an RF signal for wireless broadcasting service to another arbitrary RF signal transmission device 300 via the signal transmission path 4. be able to.
In FIG. 1, only two transmission / reception devices 9, 9 are shown, but a large number of transmission / reception devices 9, 9 are installed.

The RF signal input to the RF signal transmission device 300 is, for example, a wireless RF signal transmitted from the antenna 2c included in the broadcasting facility 2. The broadcast facility 2 is, for example, a broadcast facility that transmits a broadcast RF signal for digital terrestrial television broadcasting. The wireless RF signal transmitted from the broadcasting facility 2 is received by the antenna 320 provided in the RF signal transmission device 300.
The RF signal transmission device 300 can transmit the RF signal received by the antenna 320 to another RF signal transmission device 300.

The broadcast facility 2 converts a signal including a video signal, an audio signal, and program information of broadcast content into an RF signal by modulating the signal with a carrier wave.
Here, the program information is various information (program information) related to the broadcast program. For example, the program information includes an ID (program ID) for identifying a program (content), a program channel, a program title, a broadcast date and time of the program, text describing the program content, and the like.

  The RF signal transmission device 300 has a function of generating a quantized signal by applying ΔΣ modulation to an externally input RF signal. The generated quantized signal is transmitted from the source RF signal transmission device 300 to the other RF signal transmission device 300 via the signal transmission path 4 (including the optical transmission paths 4e and 4f).

  Each of the plurality of RF signal transmission devices 300 outputs the RF signal received by the antenna 320 and the quantized signal received from the other RF signal transmission device 300 to an external receiver 7B such as the television receiver 7B. It has a function.

  The quantized signal is a digital signal, but represents an analog waveform of an analog RF signal. For this reason, even if a quantized signal is given from the RF signal transmission apparatus 300 to the television receiver 7B, the receiver 7B performs reception processing in the same manner as when the RF signal received by the antenna 320 is given. Yes.

That is, the transmission of the quantized signal from the transmission / reception device (transmission device) 9 on the transmission side to the transmission / reception device (reception device) 9 on the reception side is substantially performed from the transmission / reception device (transmission device) 9 on the transmission side. Transmission of the RF signal of the broadcast content to the transmission / reception device (reception device) 9 is performed.
Each RF signal transmission device 300 has a function of transmitting a quantized signal to another RF signal transmission device 300 via the signal transmission path 4 and a quantized signal from the other RF signal transmission device 300 via the signal transmission path 4. Both functions are provided.

For example, in one area B1, the RF signal transmitted from the broadcasting facility 2 can be received by the antenna 320 connected to the RF signal transmission device 300, but in another area B2, the RF signal In some cases, the transmission apparatus 300 cannot receive the RF signal by the antenna 320.
The RF signal transmission system 1 according to the present embodiment is effective in such a case. That is, the RF signal transmission device 300 can acquire an RF signal that cannot be received by its own antenna 320 via another RF signal transmission device 300.

  The RF signal transmission system 1 may be used, for example, for providing broadcasting content to a user who is out of a range where radio waves from the broadcasting facility 2 reach, in addition to measures against radio wave interference.

[2. RF signal transmission device]
As shown in FIG. 2, the RF signal transmission apparatus 300 includes a control unit 301, an antenna terminal (input terminal) 302 to which an antenna is connected, a first frequency converter 303, and a first switching unit (input switching unit) 304. An AD converter 305, a second frequency converter 306, a ΔΣ modulator 307, a transmission / reception unit 308, an optical link (E / O, O / E) 309, a buffer 311, an output unit 312, An output terminal 313 for TV output, a second switching unit (output switching unit) 314, a remote control receiving unit 315, and an analog filter 316 are provided. The optical link 309 may be provided as a device different from the RF signal transmission device 300.

  The control unit 301 is for controlling each unit constituting the RF signal transmission apparatus 300. The function of the control unit 301 will be described later.

  The antenna terminal 302 is an RF signal external input terminal, and is configured as, for example, a terminal to which a coaxial cable is connected. The antenna terminal 302 inputs the RF signal received by the antenna 320 into the RF signal transmission device 300. The antenna terminal 302 constitutes (a part of) an input unit to which an RF signal is input from the outside.

The first frequency converter 303 and the second frequency converter 306 perform frequency conversion of the input signal. The first frequency converter 303 converts (down-converts) the frequency f1 of the RF signal into a signal (IF signal) having a predetermined intermediate frequency f3.
The signal output from the first frequency converter 303 is given to the AD converter 305. The AD converter 305 AD-converts the signal output from the first frequency converter 303 and outputs a digital signal.
The second frequency converter 306 converts (up-converts) the frequency f3 of the digital signal output from the AD converter 305 into a signal of the target frequency f2. The signal (digital RF signal) output from the second frequency converter 306 is given to the ΔΣ modulator 307.

  When the frequency f2 of the signal output from the second frequency converter 306 is equal to the frequency f1 of the signal input to the first frequency converter 303, the externally input RF signal remains at the same frequency and ΔΣ Input to the modulator 307.

  The frequency f2 of the signal output from the second frequency converter 306 may be different from the frequency f2 of the signal input to the first frequency converter 303. When f1 and f2 are different, the first frequency converter 303 and the second frequency converter 306 function as a frequency conversion unit (channel conversion unit) for an RF signal input from the outside.

  The first frequency converter 303 and the second frequency converter 306 are controlled by the control unit 301. The control unit 301 can provide the ΔΣ modulator 307 without changing the frequency f1 of the RF signal input from the outside, or can change the frequency f1 to an arbitrary frequency f2 and give it to the ΔΣ modulator 307.

  The control unit 301 controls the first frequency converter 303 according to the frequency (desired input frequency) f1 of the RF signal input from the outside, and converts the frequency f1 into a predetermined intermediate frequency f3. Further, the control unit 301 controls the second frequency converter 306 in accordance with the frequency (desired output frequency) f2 of the RF signal to be input to the ΔΣ modulator 307, and changes the predetermined intermediate frequency f3 to the desired frequency f2. Convert it.

The AD converter 305 is used to convert an input analog signal into a digital signal. The AD converter 305 includes a first frequency converter 303 that performs down-conversion and a second frequency conversion that performs up-conversion. By providing it between the devices 306, the operation speed of the AD converter 305 can be kept low.
If it is not necessary to keep the operating speed of the AD converter 305 low, the frequency conversion unit for the RF signal may be composed of one frequency conversion unit 303 or 306.

The first switching unit (input switching unit) 304 is for switching an RF signal (input RF signal) given to the ΔΣ modulator 307 side.
In addition to the first input system to which the RF signal is input from the above-described antenna terminal 302, the input unit as the RF signal transmission device 300 receives a quantized signal transmitted from another RF signal transmission device 300 as an RF signal. The second input system is included.

  The second input system reaches the first switching unit 304 via the buffer 311, the output unit 312, and the analog filter 316 from the transmission / reception unit 308 that receives the quantized signal transmitted from the other RF signal transmission device 300. It is an input system.

The first switching unit (input switching unit) 304 selectively selects one of the RF signal input from the first input system and the RF signal input from the second input system (first frequency converter 303). The signal is supplied to the ΔΣ modulator 307 via the AD converter 305 and the second frequency converter 306.
Switching of the input system by the first switching unit 304 is controlled by the control unit 301.

  The RF signal input from the first input system or the second input system is supplied to the ΔΣ modulator 307. The ΔΣ modulator 307 of the present embodiment is configured as a bandpass type ΔΣ modulator, but may be a low pass type ΔΣ modulator.

The ΔΣ modulator 307 performs ΔΣ modulation on the input RF signal and outputs a 1-bit quantized signal (pulse signal).
The bandpass type ΔΣ modulator 307 is configured to be able to change the quantization noise stop band (the center frequency of the bandpass type ΔΣ modulator 307). The quantization noise stop band of the ΔΣ modulator 307 is controlled by the control unit 301. The quantization noise stop band of the bandpass type ΔΣ modulator 307 is adjusted by the control unit 301 so as to be a frequency band including the frequency band of the RF signal input to the bandpass type ΔΣ modulator 307 (details will be described later). ).
Note that the quantized signal output from the ΔΣ modulator 25 does not have to be 1 bit. The quantized signal output from the ΔΣ modulator 25 may be smaller than the number of bits of digital data input to the ΔΣ modulator 25.

The quantized signal (ΔΣ modulation signal) output from the ΔΣ modulator 307 is transmitted to the signal transmission path 4 by the transmission / reception unit (transmission unit) 308.
The transmission / reception unit 308 packetizes the quantized signal (ΔΣ modulation signal) as a digitized RF signal, and transmits it as packet data. The transmission / reception unit 308 performs processing necessary for packet communication such as packet retransmission.

  In addition, the transmission / reception unit 308 also transmits necessary information included in the packet data to the quantized signal reception side (another RF signal transmission device). The information transmitted by the transmission / reception unit 308 includes the quantization signal received by the reception side (other RF signal transmission device) of the quantized signal, and the quantized signal (pulse-shaped ΔΣ modulation signal) output by the ΔΣ modulator 307. ) Includes information (reproduction information) for reproduction as a signal having the same waveform (pulse waveform).

  The ΔΣ modulator 307 outputs a pulsed quantized signal (ΔΣ modulation signal) at a rate corresponding to the sampling frequency fs. If only the quantized value indicated by such a quantized signal is simply converted into packet data, the bit data indicating the quantized value is only included in the packet data, and information regarding the rate of the quantized signal is lost. Therefore, the transmission / reception unit 308 outputs, from the bit string indicating the quantized value, the Σ modulator 307 of the transmission-side RF signal transmission device 300 on the reception side (other RF signal transmission device) of the packetized quantized signal. The packet data including the reproduction information is transmitted so that the pulsed ΔΣ modulation signal can be reproduced.

The reproduction information includes, for example, information (sampling rate information) indicating a sampling rate (sampling frequency) in the ΔΣ modulator 25. If the quantized value indicated by the quantized signal is pulsed at a rate corresponding to the sampling rate, the pulsed ΔΣ modulated signal output from the ΔΣ modulator 307 can be reproduced.
When the quantized signal is multi-bit, the reproduction information may include information indicating the number of bits of the quantized signal.

When the reproduction information is known in the receiving apparatus, the transmission / reception unit 308 does not need to transmit the reproduction information.
When the quantized signal as the digitized RF signal is not packetized and is transmitted to the signal transmission line 4e while maintaining the signal waveform as a 1-bit or multi-bit pulse signal, Thus, there is no need to reproduce the signal, so transmission of reproduction information is not required.

  The packet data output from the transmission / reception unit 308 is converted into an optical signal by the optical link 309 and transmitted to the signal transmission paths 4e and 4f. The optical transmission lines 4e and 4f are connected to the Internet 4. That is, the packet data is transmitted via the Internet 4 that is a signal transmission path.

  In the RF signal transmission system 1 of the present embodiment, the quantized signal as a digitized RF signal is packetized, so that a communication network that performs packet communication such as the Internet 4 can be used as a signal transmission path.

The digitized RF signal may be transmitted by a signal transmission path configured as a dedicated line or by a circuit switching type signal transmission path. Occupying communication is performed, so it tends to be expensive.
On the other hand, a communication network that performs packet communication such as the Internet 4 can be used as a signal transmission path, and the cost can be reduced.
In addition, since the RF signal is digitized by ΔΣ modulation (particularly, band-pass ΔΣ modulation), the amount of information is relatively small, so that it is suitable for packet communication.
Note that when a signal transmission path (such as a dedicated line) that does not require packetization is used, the packetization function in the transmission / reception unit 308 can be omitted.

  In the case of packet communication, since the transmission speed of the signal transmission path 4 is not guaranteed, it is not possible to transmit the quantized signal output from the ΔΣ modulator 307 to the signal transmission path 4 while maintaining the signal waveform as a pulse signal. However, the RF signal transmission device (reception device) 300 on the reception side can perform pulse-shaped ΔΣ modulation output from the Σ modulator 307 on the transmission side even from a packetized quantized signal by exchanging the reproduction information described above. It is easy to reproduce the signal.

  In addition, even in communication that occupies a signal transmission path instead of packet communication, the transmission speed of the signal transmission path 4 is not sufficient to transmit the quantized signal output from the ΔΣ modulator 307 on the transmission side as it is. In this case (when the transmission speed of the signal transmission path 4 is lower than the sampling speed (1 / fs) of the ΔΣ modulator 307), it is necessary to convert the quantized signal into a signal that is low enough to be transmitted through the signal transmission path 4. is there. Even in this case, the RF signal transmission apparatus 300 on the reception side can perform the quantization that is output from the Σ modulator 307 on the transmission side even from the quantized signal converted to low speed by exchanging the reproduction information described above. It is easy to reproduce the signal.

The quantized signal transmitted from the other RF signal transmission apparatus 300 is received by the transmission / reception unit (reception unit) 308 (via the optical link 309).
The optical link 309 converts an optical signal (packet data; packetized quantized signal) transmitted from the optical transmission lines 4 e and 4 f connected to the signal transmission path 4 into an electrical signal, and sends it to the transmission / reception unit 308. Output.

  The transmission / reception unit 308 performs depacketization of the packet data converted into an electrical signal, and extracts a quantized signal (quantized value of the quantized signal) and other information (reproduction information) from the packet data.

  The quantized signal received by the transmission / reception unit 308 is temporarily stored in a FIFO (First In First Out) type buffer 311. The reproduction information (sampling speed information) received by the receiving unit 32 is given to the output unit 312.

  By temporarily storing the received quantized signal in the buffer 311 and outputting it, even if the transmission speed of the signal transmission path is not constant or there is a packet loss, the quantized signal is It is possible to output continuously at a predetermined rate (a rate corresponding to the sampling speed indicated by the reproduction information) without any breaks. In other words, the provision of the buffer 311 can cope with a case where a quantized signal is transmitted by packet communication or a case where the signal transmission path 4 has no speed guarantee. If the transmission speed of the signal transmission path 4 is sufficiently high, the buffer 311 can be omitted.

The output unit 312 outputs the quantized signal (quantized value of the quantized signal) stored in the buffer 311 as a pulse signal at a predetermined rate (a rate corresponding to the sampling rate indicated by the reproduction information).
That is, the quantized signal output from the output unit 312 reproduces the signal waveform of the quantized signal output from the ΔΣ modulator 307 of another RF signal transmission device 300.
Note that it is not necessary to use the reproduction information received by the transmission / reception unit 308, and the reproduction information may be set in advance in the RF signal transmission apparatus 300.

  The quantized signal output from the ΔΣ modulator 307 of another RF signal transmission apparatus 300 holds information as an RF signal at a frequency near the carrier frequency of the RF signal. Therefore, the quantized signal output from the output unit 312 also holds information as an RF signal.

  The quantized signal (ΔΣ modulation signal) has quantization noise that is noise-shaped in the ΔΣ modulator 307, and when it is desired to extract the RF signal by removing this quantization noise, the carrier frequency of the RF signal An analog filter (bandpass filter) 316 that passes nearby frequencies is used. However, the analog filter 316 can be omitted when quantization noise is not a problem.

As described above, the quantized signal output from the output unit 312 can be applied to the ΔΣ modulator 307 side as an externally input RF signal (an RF signal input from the second input system), as well as the second switching. The signal can be output from the output terminal 313 via the unit 314.
The output terminal 313 is configured as a terminal to which a coaxial cable is connected, for example. The output terminal 313 is connected to a television receiver (receiver that receives an RF signal) 7B.

  The television receiver 7B can receive a normal RF signal received via the antenna 320, and can also receive a quantized signal output from the output unit 312 as an RF signal. That is, the television receiver 7B can receive the quantized signal (RF signal) transmitted from the other RF signal transmission device 300 via the RF signal transmission system 1 in the same manner as the RF signal transmitted as the wireless broadcast.

The RF signal (output RF signal) output from the output terminal 313 is switched by the second switching unit (output switching unit) 314.
The second switching unit 314 receives the RF signal received by the antenna 320 (RF signal input from the first input system) and the quantized signal output from the output unit 312 (RF signal; input from the second input system). RF signal) is selectively applied to the output terminal 313.
Switching of the output RF signal by the second switching unit 314 is controlled by the control unit 301.

The control unit 301 controls the second switching unit 314 so as to switch a signal output from the output terminal 313 according to an operation by the user.
Further, when there is no fear of interference, both the RF signal from the antenna 320 and the RF signal (quantized signal) from the output unit 312 may be provided to the television receiver 7B.

  Note that the RF signal transmission device 300 can be used only for the transmission (transmission or reception) of an RF signal with another RF signal transmission device 300, or the function of inputting the RF signal received from the antenna 320 or the input The function of outputting the RF signal from the output terminal may not be provided. In these cases, the first switching unit 304 and the second switching unit 314 can be omitted.

The control unit 301 is connected to the television receiver 7B so as to be able to transmit information, and can exchange necessary information other than the RF signal with the television receiver 7B.
For example, the control unit 301 acquires a list of program information extracted from the RF signal received by the television receiver 7B from the television receiver 7B. The control unit 301 stores the acquired program information list in the storage unit 301b. The program information does not need to be acquired from the external television receiver 7B, and the function of the receiver 7B is provided in the RF signal transmission apparatus 300, and the program information is extracted directly from the input RF signal. May be.

The control unit 301 can execute processing for transmitting the program information list stored in the storage unit 301 b to another RF signal transmission device 300 via the transmission / reception unit 308 and the signal transmission path 4.
In addition, the control unit 301 executes a process of acquiring from the other RF signal transmission device 300 a list of program information that can be transmitted by the other RF signal transmission device 300 from the other RF signal transmission device 300. Can do.
The control unit 301 can store the program information list acquired from the other RF signal transmission device 300 in the storage unit 301b.

  The control unit 301 can generate a program list screen for displaying the program information list stored in the storage unit 301b on the television receiver 7B connected to the RF signal transmission device 300. The user can perform an operation of selecting a program that can be received by the RF signal transmission apparatus 300 via the signal transmission path 4 by viewing the program list screen displayed on the television receiver 7B. When a program is selected by the user, the control unit 301 performs processing for generating transmission request information of an RF signal of the selected program and transmitting the information via the transmission / reception unit 308.

  The remote control receiving unit 315 is for receiving an operation signal from the user, and includes an infrared sensor that receives infrared rays. The remote control receiving unit 315 receives an operation signal (infrared communication signal) output from the remote control for operating the RF signal transmission device, and outputs the received signal to the control unit 301. The remote control receiving unit 315 may be configured to receive a signal by visible light or electromagnetic waves in addition to infrared rays.

  In the present embodiment, the RF signal transmission device 300 and the television receiver 7B are configured as separate devices. The output terminal 313 for television output and the antenna terminal 7B-1 are connected by a cable such as a coaxial cable, so that one receiving device 9 is configured. Note that the RF signal transmission device 300 may be built in the television receiver 7B, and the reception device 9 may be configured as an integrated device. By configuring as the integrated receiver 9, high functionality can be achieved with the same handling as a conventional television.

FIG. 3 shows the program information list described above.
The program information indicates a program (content) that each RF signal transmission device 300 can receive by the antenna 320, that is, a program (content) that the RF signal transmission device 300 can output the RF signal as a quantized signal. .
The program information includes a program ID, a program channel (frequency channel), a program title, a program broadcast date and time, and a device ID.

  The program information list (content list) illustrated in FIG. 3 includes, for example, program ID = “100”, program channel = “3”, program title = “9 o'clock news”, and date = “21: 0”. 21:59 "is included. That is, according to this program information, the title of the program corresponding to the program ID “100” is “9 o'clock news”, its channel is “3”, and its broadcast time is “21: 0 to 21: 59 ". The device ID is an ID that identifies the RF signal transmission device 300 that can receive the program with the corresponding program ID through the antenna 320.

  Note that the program information may include other information such as program content, broadcast area of the program, and information related to secondary usage restrictions.

[3. RF signal transmission processing]
FIG. 4 shows a processing procedure of RF signal transmission by the RF signal transmission system 1. In FIG. 4, an RF signal transmission device 300 that receives an RF signal (quantized signal) is referred to as an “RF signal transmission device 300a”, and an RF signal transmission device 300 that transmits an RF signal (quantized signal) is referred to as an “RF signal transmission device”. 300b "and the other RF signal transmission device 300 is" RF signal transmission device 300c ".

  Prior to the processing procedure of FIG. 4, the control unit 301 of each RF signal transmission device 300 (300a, 300b, 300c) acquires or generates program information that can be received by the device 300 periodically or as needed. To do. When program information is newly acquired or generated by the RF signal transmission device 300, the program information is stored in the storage unit 301b of the RF signal transmission device 300.

  When a user of the RF signal transmission device 300a performs an operation for viewing program information by using an operation device such as a remote controller, the control unit 301 of the RF signal transmission device 300a outputs a signal input from the remote control reception unit 315. Based on this, request information of the program information list is generated, and the request information is transmitted to the other RF signal transmission apparatuses 300b and 300c (step S1).

  Receiving the request for the program information list, the control unit 301 of the RF signal transmission devices 300b and 300c transmits the program information list stored in the storage unit 301b to the requesting RF signal transmission device 300a (step S2-1). , S2-2).

  The control unit 301 of the RF signal transmission device 300a that has received the program information list displays a program list screen that displays the contents of the program information list so that the user can select a program that the user wants to view from the received program information list. Generate. The generated program list screen is displayed on the television receiver 7B or an operating device (remote controller) (not shown).

The control unit 301 of the RF signal transmission device 300a accepts an operation (operation by a remote controller) for selecting a program ID and a desired channel to be transmitted while the program list screen is displayed.
After receiving the selection of the program ID and the desired channel from the user, the control unit 301 of the RF signal transmission device 300a generates transmission request information.
The transmission request information is for the RF signal transmission device 300a to request the other RF signal transmission device 300b to transmit a program (content). The transmission request information includes a program ID (information for specifying a program (content)), a desired channel at transmission (desired frequency f2 at transmission), and a request source ID.

The program ID included in the transmission request information is an ID of a program that is requested to be transmitted to the requesting RF signal transmission apparatus 300.
The desired channel (desired frequency f2) included in the transmission request information is the channel (frequency) of the RF signal when the RF signal (quantized signal) is transmitted from the RF signal transmitting device 300b on the RF signal transmitting side to the RF signal transmitting device 300a. Band).
The desired channel (frequency f2) may be different from the channel (frequency f1) of the RF signal input to the input unit of the transmission-side RF signal transmission device 300b, and an arbitrary channel can be set.
The request source ID included in the transmission request information is an ID (MAC address, IP address, etc.) for specifying the RF signal transmission device 300a of the request source (reception side).

  The control unit 301 of the RF signal transmission device 300a that has transmitted the transmission request information connects the second switching unit 314 to the output unit 312 side (see FIG. 5). That is, the RF signal is input from the second input system. As a result, the RF signal transmission device 300a that has transmitted the transmission request information receives the quantized signal transmitted from the other RF signal transmission device 300b as shown in FIG. 5, and uses the quantized signal as an RF signal. Then, it can be output to the television receiver 7B.

  The transmission request information transmitted by the RF signal transmission device 300a is received by the other RF signal transmission devices 300b and 300c. The RF signal transmission apparatuses 300b and 300c that have received the transmission request information determine whether or not the program indicated by the program ID included in the transmission request information is included in a program that can be received by the antenna 320 of the own apparatuses 300b and 300c. (Steps S4-1 and S4-2). This determination can be made based on whether or not the program ID included in the received transmission request information is included in the program list stored in the storage unit 301b.

Here, in the RF signal transmission device 300b, the received program ID is included in the program list stored in the storage unit 301b, and the program indicated by the received program ID is transmitted to the antenna 320 of the own device 300b. Can be received. On the other hand, in the RF signal transmission device 300c, the received program ID is not included in the program list stored in the storage unit 301b, and the program indicated by the received program ID is transmitted to the antenna 320 of the own device 300c. And cannot be received.
Therefore, here, the RF signal transmission device 300b is a device for transmitting a program (step S4-1).

  Note that the RF signal transmission device 300b that transmits the program may be determined by the RF signal transmission device 300a on the receiving side, and the transmission request information may be transmitted only to the RF signal transmission device 300b that transmits the program.

  The RF signal transmission device 300b that has become the transmission side device connects the first switching unit 304 to the antenna 320 side so that ΔΣ modulation can be applied to the RF signal received by the antenna 320 (see FIG. 2).

After the first switching unit 304 is connected to the antenna 320 side, the control unit 301 of the RF signal transmission device 300b starts ΔΣ modulation so as to generate a quantized signal corresponding to the transmission request information (step S5).
That is, the control unit 301 controls each of the frequency converters 303 and 306 and the ΔΣ modulator 307 according to the program ID and the desired channel included in the transmission request information.

Specifically, the process in step S5 is executed as follows.
The control unit 301 of the RF signal transmission device 300b extracts a program ID, a desired channel (frequency f2), and a request source ID from the received transmission request information.

The control unit 301 specifies the frequency band (center frequency f1) of the RF signal when the program indicated by the extracted program ID is transmitted from the broadcast facility 2. The control unit 301 controls the frequency conversion units 303 and 306 so that the analog RF signal (center frequency f1) received by the antenna 320 is frequency-converted to the RF signal of the desired channel (center frequency f2).
For example, if the channel (frequency band) when the program indicated by the extracted program ID is received by the antenna 320 is “3” (center frequency f1), the desired channel is “1” (center frequency f2). For example, the frequency converters 303 and 306 convert the frequency band of the RF signal from channel = 3 (center frequency f1) to desired channel = 1 (center frequency f2).

The ΔΣ modulator 307 of the RF signal transmission device 300b performs ΔΣ modulation on the digital RF signal (frequency f2) output from the second frequency converter 306, and outputs a quantized signal.
Further, the control unit 301 of the RF signal transmission device 300b controls the ΔΣ modulator 307 so that the center frequency of the quantization noise stop band becomes the frequency f2. A method of changing the center frequency of the quantization noise stop band will be described later.

The quantized signal output from the ΔΣ modulator 307 is packetized and transmitted to the receiving-side RF signal transmission device 300a specified by the extracted requester ID.
In this way, the process of step S5 is executed.

  The control unit 301 of the transmitting-side RF signal transmission device 300b waits for stop request information while the quantized signal is output from the RF signal transmission device 300b, and whether the broadcast time of the program being transmitted has ended. Determine whether.

  The reception-side RF signal transmission device 300 a receives the quantized signal transmitted from the transmission-side RF signal transmission device 300 b by the transmission / reception unit 308. The transmission / reception unit 308 depackets the received quantized signal. As shown in FIG. 5, the received quantized signal is output to the television receiver 7B as an RF signal via the buffer 311, the output unit 312, the analog filter 316, the second switching unit 314, and the output terminal 313. . The television receiver 7B reproduces a video signal and an audio signal from the input RF signal. As a result, a video signal and an audio signal based on the quantized signal received from the requested RF signal transmission device 300b are reproduced by the television receiver 7B.

  When the receiving side user performs a predetermined operation for stopping viewing while the receiving side RF signal transmission device 300a is receiving the quantized signal, the control unit 301 of the RF signal transmission device 300a stops. Request information is transmitted (step S7). This stop request information is transmitted to the RF signal transmission device 300b on the transmission side.

When receiving the stop request information during transmission of the quantized signal of the program, the RF signal transmission device 300b on the transmitting side stops the quantization of the RF signal and the transmission of the quantized signal even during the program.
The RF signal transmission device 300b on the transmission side determines whether or not the broadcast time of the program being transmitted has ended, and also stops the quantization of the RF signal and the transmission of the quantized signal even when the broadcast time has ended. May be.

When stopping the transmission of the quantized signal, the control unit 301 of the transmission-side RF signal transmission device 300b transmits stop notification information to the reception-side RF signal transmission device 300a (step S8).
When receiving the stop notification signal, the reception-side RF signal transmission device 300a stops receiving the quantized signal.

  Thus, according to the present embodiment, an RF signal received by one of the RF signal transmission devices 300b is transmitted to another RF signal transmission device 300b via the signal transmission path 4 (Internet or the like). Therefore, a wireless broadcast program that can be received in the area B1 can be viewed in another area B2 without providing a wireless broadcast relay device.

  In addition, since the RF signal is digitized by ΔΣ modulation (particularly, band-pass ΔΣ modulation), the amount of information is relatively small, so that it is suitable for packet communication.

  Moreover, according to the configuration of the present embodiment, the transmitting-side RF signal transmission device 300b changes the channel (frequency band) of the RF signal received by the antenna 320 and transmits the RF signal (quantized signal). Can do. Therefore, the user on the receiving side can view the program requested to be transmitted on the channel desired by the user.

For example, it is assumed that the channel of the RF signal input from the antenna 320 of the RF signal transmission device 300b on the transmission side is “3”.
On the other hand, in the receiving-side RF signal transmission device 300a, the channel “3” is a channel for receiving by the antenna 320, but the channel “1” is an empty channel (a channel not used for broadcasting). Suppose that
In this case, when the receiving side sets the desired channel as channel “1” and transmits the transmission request information to the RF signal transmission device 300b on the transmission side, the RF signal transmission device 300b on the transmission side transmits the program received by the antenna 320. The channel is converted from channel “3” to channel “1” and transmitted.
As a result, the receiving-side RF signal transmission device 300a can receive a desired program on an empty channel.

[4. Modified example]
The RF signal transmission device 300 shown in FIG. 6 is obtained by omitting the input system (first input system) from the antenna 320 and the output system to the television receiver 7B in the RF signal transmission device 300 shown in FIG. is there. An RF signal transmission device 300 illustrated in FIG. 6 functions exclusively as a relay device that transmits an RF signal (quantized signal) received from another RF signal transmission device 300 to another RF signal transmission device 300. When relaying, the channel of the RF signal can also be converted.
Note that the RF signal transmission device 300 shown in FIG. 2 can also be used as a relay device.

  The RF signal transmission device 300 illustrated in FIG. 7 is configured to omit the function of transmitting the quantized signal to the other RF signal transmission device 300 and receive the RF signal from the antenna 320 and the other RF signal transmission device 300. Is. Note that the input system from the antenna 320 may be omitted in the RF signal transmission device 300 shown in FIG.

[5. Bandpass ΔΣ modulation]
[5.1 Basic Configuration of ΔΣ Modulator]
As shown in FIG. 8, the ΔΣ modulator 307 includes a loop filter 27 and a quantizer 28 (see Non-Patent Document 1).
In the ΔΣ modulator 307 shown in FIG. 8, an input (in this embodiment, an RF signal) U is given to the loop filter 27. The output Y of the loop filter 27 is supplied to a quantizer (for example, 1-bit quantizer) 28. The output (quantized signal) V of the quantizer 28 is given as another input to the loop filter 27.

The characteristic of the ΔΣ modulator 307 can be expressed by a signal transfer function (STF) and a noise transfer function (NTF).
That is, when the input of the ΔΣ modulator 307 is U, the output of the ΔΣ modulator 307 is V, and the quantization noise is E, the characteristics of the ΔΣ modulator 307 are expressed in the z region as follows. is there.

  Therefore, given the desired NTF and STF, the transfer function of the loop filter 27 can be obtained.

Such ΔΣ modulation is a kind of oversampling modulation, and is generally a technique used for AD conversion or DA conversion.
In ΔΣ modulation, noise shaping (Noise Shaping) is performed in which the quantization noise in the signal band is moved outside the signal band to greatly reduce the quantization noise in the signal band.

FIG. 9 shows a block diagram of a linear z-domain model of the first-order low-pass type ΔΣ modulator 125. Reference numeral 127 represents a loop filter portion, and reference numeral 128 represents a quantizer. When the input to the ΔΣ modulator 125 is U (z), the output is V (z), and the quantization noise is E (z), the characteristics of the ΔΣ modulator 125 are expressed in the z region. It is as follows.
V (z) = U (z) + (1-z ⁻¹ ) E (z)

That is, in the primary low-pass ΔΣ modulator 125 shown in FIG. 9, a signal transfer function STF (z) = 1, the noise transfer function ^{NTF (z) = 1-z} -1.

[5.2 Low-pass ΔΣ modulation and bandpass ΔΣ modulation]
In general, the term “ΔΣ modulation” refers to low-pass ΔΣ modulation.
In the low-pass ΔΣ modulation, as shown in FIG. 10A, noise shaping is performed such that the low-frequency quantization noise moves to a higher frequency side and the low-frequency quantization noise is attenuated. That is, in the low-pass type Δ modulation, the noise transfer function (NTF) has a characteristic of blocking passing noise at a low frequency (near 0 Hz).

  In order to perform oversampling, the frequency of the signal subjected to ΔΣ modulation needs to be sufficiently smaller than the sampling frequency fs of the low-pass ΔΣ modulator. In other words, a sufficiently high sampling frequency fs is required for the signal frequency. For example, a sampling frequency fs of about 128 times the signal frequency is required.

  On the other hand, in the band-pass type ΔΣ modulation, as shown in FIG. 10B, the noise transfer function (NTF) blocks passing noise at a frequency higher than 0 Hz.

In the band-pass ΔΣ modulation, not the signal frequency f ₀ but the signal bandwidth f _B should be sufficiently smaller than the sampling frequency fs.
Therefore, in the bandpass type ΔΣ modulation, the frequency (center frequency) f ₀ of the signal subjected to ΔΣ modulation may be equal to or lower than the sampling frequency fs.
In other words, in the band-pass ΔΣ modulation, the sampling frequency fs may be sufficiently larger than the signal bandwidth f _B. For example, a sufficiently large sampling frequency fs of about 64 times the signal bandwidth f _B is sufficient.

Here, for example, it is assumed that the carrier frequency f ₀ of the RF signal is 1 GHz and the signal band f _B is 20 MHz. When low-pass ΔΣ modulation is performed on a modulation wave (RF signal) of such a radio frequency, the maximum frequency of the modulation wave is about 1 GHz, so that the maximum frequency of the modulation wave is 1 GHz. A sufficiently large (about 128 times) sampling frequency fs (= about 128 GHz) is required. As described above, low-pass ΔΣ modulation is suitable for an RF signal having a relatively low carrier frequency (for example, an RF signal for radio broadcasting), but an RF signal having an extremely high carrier frequency (for example, a television signal) For the broadcast RF signal), the sampling frequency (sampling speed) is too high.

On the other hand, in the band-pass ΔΣ modulation, the sampling frequency fs may be sufficiently larger than the signal bandwidth f _B , so that if the signal band is an RF signal of 20 MHz, 20 MHz × 64 = 1. A sampling frequency fs of about 28 GHz (sampling rate = 1.28 GS / S) may be used. If the signal band is 5 MHz, a sampling frequency of 320 MHz (sampling speed = 320 MS / s) may be used.
Thus, the band-pass type ΔΣ modulation is advantageous because the sampling frequency (sampling speed) can be reduced.

[5.3 Design of bandpass type ΔΣ modulator]
[5.3.1 Conversion formula]
According to Non-Patent Document 1, a low pass type ΔΣ modulator can be converted into a band pass type ΔΣ modulator by performing the following conversion on the low pass type ΔΣ modulator.

  A bandpass ΔΣ modulator is obtained by replacing z in the z region model of the low-pass ΔΣ modulator 125 with z ′ = − z2 in accordance with the above conversion equation.

Using the above conversion equation, an n-order low-pass ΔΣ modulator (n is an integer of 1 or more) can be converted to a 2n-order band-pass Σ modulator.
For example, the frequency characteristic of the first-order low-pass type ΔΣ modulator 125 is as shown in FIG. The frequency characteristics of the secondary bandpass ΔΣ modulator obtained by converting the primary lowpass ΔΣ modulator 125 with the above conversion formula are as shown in FIG. In FIG. 11, the horizontal axis θ is the normalized frequency.

  Although the signal transfer function and noise transfer function of the bandpass ΔΣ modulator obtained by the above conversion equation have the same gain as the low-pass ΔΣ modulator 125 before conversion, the frequency characteristics shown in FIG. The frequency characteristic shown in FIG. 11A is compressed by half and folded.

  The bandpass ΔΣ modulator obtained by the above conversion formula has the same stability characteristics and SNR characteristics as the low-pass ΔΣ modulator 125 before conversion operating at the same oversampling ratio.

However, in the above conversion formula, as shown in FIG. 11B, only a bandpass ΔΣ modulator for a quarter of the sampling frequency fs (normalized frequency θ = ± π / 2) can be obtained. That is, in the above conversion formula, only a bandpass ΔΣ modulator having a quarter frequency (normalized frequency θ = ± π / 2) of the sampling frequency fs and the center frequency f ₀ of the quantization noise stop band can be obtained.

The inventor has obtained a conversion equation for obtaining a bandpass ΔΣ modulator having a desired frequency f ₀ (θ = θ ₀ ) as a center frequency f ₀ of the quantization noise stop band from the low pass ΔΣ modulator. I found it. The conversion formula is as shown in the following formula (3), for example.

here,
θ ₀ = 2π × (f ₀ / fs)

The conversion formula of Formula (2) relates to a specific frequency θ ₀ = π / 2, but the conversion formula of Formula (3) is generalized to an arbitrary frequency (θ ₀ ).

[5.3.2 Concept of conversion formula]
In the low-pass type ΔΣ modulator, assuming that z = e ^jωT = 1, the absolute value of z ′ for conversion to the band-pass type ΔΣ modulator should be 1 while maintaining the characteristics of the low-pass type modulator. It is.
If | z ′ | = 1, the magnitude (amplitude) of the signal that has passed through the element z changes, and the characteristics are deteriorated compared to the low-pass ΔΣ modulator before conversion.
Note that z ′ may be 1 or −1. This is because z ′ = 1 and z ′ = − 1 are merely a relationship in which the phases are reversed, and the signal magnitude is not changed.

Therefore, z ′ for obtaining the bandpass ΔΣ modulator while maintaining the characteristics of the lowpass ΔΣ modulator without deteriorating is a function fcnv (z, θ ₀ ) including z and θ ₀ , For any z, θ ₀ , any function f _cnv (z, θ ₀ ) in which the absolute value of f _cnv (z, θ ₀ ) is always 1 may be used.

If such a function fcnv (z, θ ₀ ) is found, a low-pass ΔΣ modulator and a band-pass ΔΣ modulator for a desired frequency f ₀ (θ ₀ ) can be obtained.

The present inventor _finds such a function z ′ = f _cnv (z, θ ₀ ) as follows and generalizes a conversion formula z → z ′ (formula (3)) obtained by generalizing formula (2). Obtained.

First, conversion from a low pass type ΔΣ modulator to a band pass type ΔΣ modulator having a desired frequency f ₀ (θ = θ ₀ ) as a center frequency f ₀ is considered in terms of frequency characteristics as shown in FIG. Become. FIG. 12 is a generalization of FIG. 11 at an arbitrary frequency f ₀ (θ = θ ₀ ).
As shown in FIG. 12B, the center frequency of the noise stop band of the band-pass ΔΣ modulator is f ₀ (θ ₀ = 2π × (f ₀ / fs)).

here,

Therefore, we consider in the frequency domain. T is a sampling period.

In addition, ωT in Equation (4) is

It is.

Then, as shown in FIG. 12A, the low-pass ΔΣ modulator operates at f0 = 0 (θ = 0). Therefore, the present inventor considered that the following equation (6) holds in the low-pass type ΔΣ modulator with respect to the equation (4).

That is, it can be considered that the low-pass type ΔΣ modulator operates at ^{ej0 as} shown in FIG.

From the equation (6), the following equation (7) is obtained.

On the other hand, the bandpass ΔΣ modulator operates as a complex conjugate pair at θ ₀ and −θ ₀ as shown in FIGS. 12B and 13B.
Therefore, considering the fact that the bandpass type ΔΣ modulator has a complex conjugate pair based on the formula (7) in the low-pass type Δ modulator, the following formula (8) is obtained.

The present inventor obtained z ′ = f _cnv (z, θ ₀ ) using the formula (8).
That is, first, the above equation (8) is modified as follows to obtain equation (10) in which the value of the right side (one side) is 1.

Equation (10), the value of the expression of the left-hand (the other side) is, any z, the theta _0, it is clear that it is always identity as the left-hand side value = 1.
Therefore, the left side of the equation (10) is a function f _cnv (z, θ ₀ ) _whose value is always 1 for any z and θ ₀ .

From Expression (10), z ′ in the conversion expression z → z ′ for converting from the low pass type to the band pass type is as follows.

From the above equation (11), the conversion equation of equation (3) is obtained.
In the above equation (3), when θ ₀ = π / 2 (when f ₀ = fs / 4) is set, it can be seen that it is equivalent to the conversion equation of equation (2).
Further, the low-pass ΔΣ converter has θ ₀ = 0. When θ ₀ = 0, the conversion equation of Equation (3) becomes z → z, and it can be seen that Equation (3) does not deform the low-pass ΔΣ converter.

Since z ′ = f _cnv (z, θ ₀ ) may be −1 (because the absolute value is 1), z ′ may be in the following format.

Moreover, even if the denominator and the numerator of z ′ = f _cnv (z, θ ₀ ) are interchanged, it becomes 1 or −1.

Of course, the expression format of the expression z ′ = f _cnv (z, θ ₀ ) whose absolute value is always 1 for any z, θ ₀ is not limited to that illustrated. Regarding f _cnv (z, θ ₀ ), there are various expression formats. This means that the equation can be transformed from the equation (8) in order to obtain an identity with a value of one side of 1 or −1. It is clear that this is not the case.

[5.4 Example of Bandpass ΔΣ Modulator]
[5.4.1 First example]
FIG. 14 shows a second-order bandpass ΔΣ modulator 307 obtained by converting the first-order lowpass ΔΣ modulator 125 shown in FIG. 9 using the conversion equation (3).
In the conversion from FIG. 9 to FIG. 14, for the convenience of notation, the following conversion equation with a = cos θ ₀ in Equation (3) was used.

[5.4.2 Second example]
FIG. 15 shows a low-pass ΔΣ modulator 125 having a CRFB structure loop filter 127 described in Non-Patent Document 1. In FIG. 15, reference numeral 128 denotes a quantizer.

  When the low-pass type ΔΣ modulator 125 shown in FIG. 15 is converted by the conversion formula (3), a bandpass type ΔΣ modulator 307 shown in FIG. 16 is obtained. Also here, for convenience of description, in equation (3), a = cos θ0.

Z in (1 / (z−1)) and (z / (z−1)) in FIG. 15 is converted by a conversion formula. Expressions after conversion of (1 / (z-1)) and (z / (z-1)) are as follows, respectively.

[5.4.3 Others]
The conversion to the band-pass type ΔΣ modulator can be applied to other high-order low-pass type ΔΣ modulators (for example, the CIFB structure, the CRFF structure, the CIFF structure, etc. described in Non-Patent Document 1).

[5.5 Output results]
FIGS. 17 to 20 show a case where θ ₀ = π / 4 (FIG. 17), θ ₀ = 3π / 4 (FIG. 18) in the bandpass type ΔΣ modulator of the second example (FIG. 16), The output spectrum waveform is shown when θ ₀ = 5π / 4 (FIG. 19) and when θ ₀ = 7π / 4 (FIG. 20).

As shown in FIGS. 17 to 20, at each frequency of θ ₀ = π / 4, 3π / 4, 5π / 4, 7π / 4, a signal appears at a desired θ ₀ , and θ ₀ = ± π It can be seen that bandpass ΔΣ modulators for frequencies other than / 2 are obtained.

Conventionally, a design method for a bandpass ΔΣ modulator that performs bandpass ΔΣ modulation on an arbitrary frequency f ₀ has not been established. However, by using a conversion equation such as Equation (3), the desired carrier frequency f ₀ can be set as the noise rejection band of the noise transfer function (NTF), and the bandpass ΔΣ with respect to the desired carrier frequency f ₀ . A bandpass ΔΣ modulator that performs modulation can be designed.

[5.6 Change Control of Noise Stop Band of ΔΣ Modulator]
The ΔΣ modulator 307 of the RF signal transmission device 300 can convert the value of z based on the above-described equation (3). That is, the ΔΣ modulator 307 can change the center frequency of the quantization noise stop band. In other words, the quantization noise stop band can be changed.

The control unit 301 of the RF signal transmission device 300 determines the ΔΣ modulator 307 based on the above-described equation (3) according to the center frequency f2 (the above-described carrier frequency f ₀ ) of the RF signal input to the ΔΣ modulator 307. ΔΣ modulation can be performed on an RF signal of an arbitrary channel by converting z.
In this way, by changing cos θ ₀ (coefficient a) in the conversion equation (3) according to the center frequency f2 of the RF signal (the carrier frequency f ₀ described above), the sampling frequency fs is not changed, Bandpass ΔΣ modulation corresponding to an arbitrary frequency f2 (f ₀ ) can be performed. When cos θ ₀ is changed, the coefficient of NTF shown in Expression (1) is changed, but the order of the expression is maintained. For this reason, even if the configuration of the bandpass ΔΣ modulator 307 is changed according to the carrier frequency f2 (f ₀ ) of the RF signal, the complexity (order) of the equation does not change, and therefore the bandpass ΔΣ The signal processing load in the modulator 307 does not change. This is described in [7. The same applies to the use of harmonics.

As described above, this embodiment is advantageous because the signal processing load in the bandpass ΔΣ modulator 307 does not change even when the carrier frequency f2 (f ₀ ) is changed. In the present embodiment, the signal processing load in the band-pass ΔΣ modulator 307 depends on the sampling frequency fs determined by the signal bandwidth according to the Nyquist theorem, but even if the carrier frequency f2 (f ₀ ) is changed. Since the signal bandwidth does not change, there is no need to change the sampling frequency fs. When the ΔΣ modulator is a low-pass type, it is necessary to change the sampling frequency fs in order to cope with a change in the carrier frequency f ₀ , and in this respect, the band-pass type is advantageous.

Further, by using the expression (3), the ΔΣ modulator 307 can be used not only as a band pass type ΔΣ modulator that can cope with an arbitrary frequency f2 (f ₀ ) but also as a low pass type ΔΣ modulator. That is, the ΔΣ modulator 307 can be switched between a low pass type and a band pass type.

[6. Bandwidth expansion]
FIG. 21 shows a modification of the configuration between the AD converter 305 and the ΔΣ modulator 307 of the RF signal transmission apparatus 300 of FIG. In FIG. 21, an orthogonal demodulator 325, a baseband unit 326, a band extension unit 29, and an orthogonal modulator 327 are added. In the RF signal transmission apparatus 300 of FIG. 21, the description and illustration are omitted, which is the same as that of FIG.

As described above, in the band-pass ΔΣ modulation, the signal band f _B only needs to be sufficiently small with respect to the sampling frequency fs. For example, if the signal band is an RF signal having a frequency of 20 MHz, the sampling frequency fs (sampling speed = 1.28 GS / S) may be 20 MHz × 64 = 1.28 GHz.

Here, when the above-described sampling frequency fs (1.28 GHz) can be further increased, the signal band f _B can be afforded. Therefore, as shown in FIG. 21, a band extending unit 29 is provided to reduce the signal band f _B. It is preferable to expand.
Here, the quadrature demodulator 325 performs quadrature demodulation on the signal output from the AD converter 305 and outputs a baseband signal. The baseband unit 326 outputs IQ baseband signals (I signal and Q signal) as digital data. In the quadrature modulator 327, quadrature modulation is applied to the IQ baseband signal.
By performing upsampling, the band extension unit 29 inserts zero signals on both sides of the original signal band fB (= 20 MHz) and doubles the signal band (f _B ′ = 40 MHz) as shown in FIG. ). As the signal band fB ′ is expanded, the sampling frequency fs of the bandpass ΣΔ modulator 25 is also doubled to 2.56 GHz.

Thus, when the band f _B is expanded, the sampling frequency fs increases. Here, the carrier frequency f _0, it is possible to select the following values sampling frequency fs, the sampling frequency fs increases, also increases the range of selection of the carrier frequency f _0.

Here, for example, it is assumed that the signal band f _B = 20 MHz and the carrier frequency f ₀ is 2 GHz. In this case, if the sampling frequency fs is determined based on only the signal band f _B = 20 MHz for the band-pass ΔΣ modulation, the sampling frequency fs = 1.28 GHz = 20 MHz × 64. However, since the sampling frequency fs = 1.28 GHz is smaller than the carrier frequency f0 = 2 GHz, it is inappropriate.

However, when the sampling frequency fs is determined based on the expanded signal band f _B ′ = 40 MHz, the sampling frequency fs = 2.56 GHz = 40 MHz × 64. In this case, the sampling frequency fs = 2.56 MHz is appropriate because it is higher than the carrier frequency f0 = 2 GHz.

Further, the signal band portions f _B1 and f _B2 expanded by the band extending unit 29 are substantially portions where no signal exists. Therefore, as shown in FIG. 23, the band-pass filter 316 of the RF signal transmission apparatus 300 on the RF signal receiving side may use the signal band f _B before expansion as the pass band, and the expanded signal band f _B 'The whole may not be a passband.
In addition, since the band-pass filter roll-off can be widened using the expanded signal band portions f _B1 and f _B2 , the design of the band-pass filter is facilitated.

[7. Use of harmonics]
Since the output of the ΔΣ modulator 307 is a quantized signal (pulse signal), a harmonic component due to aliasing exists in addition to the main signal component.
By using this harmonic component, in the RF signal transmission device 300 on the transmission side, the quantized signal (received by the RF signal transmission device 300 on the reception side is suppressed while keeping the carrier frequency f ₀ ′ and the sampling frequency fs low. RF signal) frequency can be increased.

For example, it is assumed that the frequency (reception frequency) f _{0 of the} RF signal desired to be received by the receiving-side RF signal transmission device 300 is 2 GHz. When harmonics are not used, the transmission-side RF signal transmission device 300 needs to set the carrier frequency (frequency of unmodulated wave) f ₀ to 2 GHz and the sampling frequency fs to a value larger than 2 GHz.

However, as shown in FIG. 24, when a modulated wave having a carrier frequency f ₀ ′ is input to the bandpass type ΔΣ modulator 307, the output (quantized signal) of the bandpass type ΔΣ modulator 307 becomes the carrier frequency. In addition to having a main signal component centered on f ₀ ′, it also has a harmonic component of f ₀ = n × fs + f ₀ ′ (n is an integer having an absolute value of 1 or more) by folding.
This harmonic component is actively received by the RF signal transmission device 300 on the reception side, so that the RF signal transmission device 300 on the transmission side receives the signal while performing processing for a relatively low frequency f ₀ ′. The RF signal transmission device 300 on the side can receive a modulated wave having a high frequency having a carrier frequency f ₀ = n × fs + f ₀ ′.

Specifically, when the reception frequency f ₀ of the reception-side RF signal transmission device 300 is 2 GHz, the center frequency fc of the passband of the analog bandpass filter for restoring the quantized signal to the RF signal is also set to 2 GHz. Is done. That is, the receiving-side RF signal transmission device 300 receives a modulated wave (RF signal) having a center frequency f ₀ of 2 GHz.
In this case, assuming that the sampling speed fs of the bandpass type Δ modulator 307 of the RF signal transmission device 300 on the transmission side is 1.5 GHz (<f ₀ ), the frequency f ₀ ′ of the carrier wave output from the frequency converter 306 is ,
f ₀ ′ = f ₀ −fs = 2 GHz−1.5 GHz = 500 MHz
It's okay.

Accordingly, as the RF signal transmission device 300 on the transmission side, the transmission side is actually viewed from the RF signal transmission device 300 on the reception side while handling a modulated wave having a center frequency (carrier frequency) f ₀ ′ of 500 MHz. The RF signal transmission device 300 can be regarded as transmitting a modulated wave having a center frequency (carrier frequency) f ₀ of 2 GHz. As a result, it is possible to transmit a modulated wave having a frequency higher than the sampling frequency in the RF signal transmission device 300 on the transmission side.

When the main signal component shown in FIG. 24 is transmitted as an RF signal having a frequency (reception frequency) desired by the reception-side RF signal transmission device 300, and the harmonic component shown in FIG. 24 is transmitted by the reception-side RF signal transmission device 300. Summarizing both cases of transmission as a signal of a desired frequency (reception frequency), the frequency f ₀ ′ of the carrier wave output from the frequency converter 306 of the RF signal transmission device 300 on the transmission side satisfies the following equation: It becomes.
f ₀ ′ = f ₀ −n × fs
However,
f ₀ : reception frequency on the receiving side fs: sampling frequency of the bandpass type ΔΣ modulator 307 f ₀ ′: frequency of the modulated wave output from the frequency converter 306 n: integer

In the above equation, when n = 0, the main signal component shown in FIG. 24 is transmitted as a signal having a frequency (reception frequency) desired by the reception-side RF signal transmission device 300, and other cases are illustrated in FIG. In this case, the harmonic component indicated by 24 is transmitted as a signal of a desired frequency (reception frequency) by the receiving-side RF signal transmission device 300.
As n increases, the harmonic component gradually decreases, so n = ± 1 (particularly n = 1) is preferable.

In addition, the center frequency fc of the passband of the analog bandpass filter for restoring the quantized signal to the RF signal satisfies the following expression.
fc = f ₀ '+ n × fs
However,
fc: center frequency of passband of analog bandpass filter fs: sampling frequency of bandpass ΔΣ modulator 307 f ₀ ′: frequency of modulated wave output from frequency converter 306 n: integer

Also in the above formula, when n = 0, the main signal component shown in FIG. 24 is transmitted as a signal of the frequency (reception frequency) desired by the reception-side RF signal transmission device 300, and the other cases are as follows. This is a case where the harmonic component shown in FIG. 24 is transmitted as a signal of a desired frequency (reception frequency) by the reception-side RF signal transmission device 300.
As n increases, the harmonic component gradually decreases, so n = ± 1 (particularly n = 1) is preferable.

[8. Addendum]
[8.1 Appendix 1]
In the above description, the terrestrial digital television broadcast has been described as an example of the broadcast service, but the digital television broadcast may be a satellite digital television broadcast. Also, the analog television broadcast may be used as the television broadcast. The broadcast may be a radio broadcast.

[8.2 Appendix 2]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 RF signal transmission system 2 Broadcasting equipment 2c Antenna 4 Signal transmission path 4e Optical transmission path 4f Optical transmission path 4g Optical transmission path 7B Television receiver 9 Transmission / reception apparatus (transmission apparatus; reception apparatus)
300 RF signal transmission device 301 Control unit 302 Antenna terminal (input terminal)
303 1st frequency converter (frequency conversion part)
304 1st switching part 305 AD converter 306 2nd frequency converter (frequency conversion part)
307 ΔΣ modulator 308 Transmission / reception unit 309 Optical link 311 Buffer 312 Output unit 313 Output terminal 314 Second switching unit 316 Analog filter 320 Antenna

Claims (16)

An input unit through which an RF signal is input from the outside;
An AD converter that performs AD conversion on the RF signal input to the input unit ;
A ΔΣ modulator that performs ΔΣ modulation on a digital signal output from the AD converter and outputs a quantized signal;
A transmission unit for transmitting the quantized signal output from the ΔΣ modulator to the outside;
An RF signal transmission device comprising:   The RF signal transmission apparatus according to claim 1, wherein the input unit includes an input system that supplies an RF signal received via an antenna to the ΔΣ modulator. An input unit through which an RF signal is input from the outside;
A ΔΣ modulator that performs ΔΣ modulation on the RF signal input to the input unit and outputs a quantized signal;
A transmission unit for transmitting the quantized signal output from the ΔΣ modulator to the outside;
With
The input unit includes an input system that supplies the quantized signal received from another RF signal transmission device to the ΔΣ modulator as an RF signal.
R F signal transmission device. An input unit through which an RF signal is input from the outside;
A ΔΣ modulator that performs ΔΣ modulation on the RF signal input to the input unit and outputs a quantized signal;
A transmission unit for transmitting the quantized signal output from the ΔΣ modulator to the outside;
With
An input switching unit for switching an RF signal applied to the ΔΣ modulator;
The input unit is
A first input system through which an RF signal is input via an antenna;
A second input system in which the quantized signal transmitted from another RF signal transmission device is input as an RF signal;
The input switching unit selectively supplies the RF signal input to the first input system and the RF signal input to the second input system to the ΔΣ modulator.
R F signal transmission device. An input unit through which an RF signal is input from the outside;
A ΔΣ modulator that performs ΔΣ modulation on the RF signal input to the input unit and outputs a quantized signal;
A transmission unit for transmitting the quantized signal output from the ΔΣ modulator to the outside;
With
The apparatus further includes an output terminal that outputs the RF signal input to the input unit to a receiver that receives the RF signal.
R F signal transmission device. An output switching unit that switches an RF signal output from the output terminal;
The input unit is
A first input system through which an RF signal is input via an antenna;
A second input system in which the quantized signal transmitted from another RF signal transmission device is input as an RF signal,
The RF signal transmission device according to claim 5, wherein the output switching unit selectively supplies an RF signal input to the first input system and an RF signal input to the second input system to the output terminal. A frequency conversion unit that performs frequency conversion of the RF signal input to the input unit;
The RF signal transmission device according to claim 1, wherein the frequency conversion unit supplies the frequency-converted RF signal to the ΔΣ modulator. An input unit through which an RF signal is input from the outside;
A ΔΣ modulator that performs ΔΣ modulation on the RF signal input to the input unit and outputs a quantized signal;
A transmission unit for transmitting the quantized signal output from the ΔΣ modulator to the outside;
With
A controller for controlling the ΔΣ modulator;
The ΔΣ modulator is configured to change a quantization noise stop band,
The control unit performs control for changing a quantization noise stop band of the ΔΣ modulator.
R F signal transmission device. The control unit is capable of acquiring transmission request information including information that can identify the content, and performs ΔΣ modulation on the RF signal of the content indicated by the acquired transmission request information. The RF signal transmission device according to claim 8 , wherein control for changing a quantization noise stop band of the ΔΣ modulator is performed according to a frequency band of a signal. A storage unit that holds a list of contents that can be input as an RF signal to the input unit;
The RF signal transmission device according to claim 9 , wherein the ΔΣ modulator performs the ΔΣ modulation when a content indicated by the acquired transmission request information is included in the list. Wherein the control unit is capable of acquiring a stop request information, based on acquiring the stop request information, any one of claims 8-10 to perform a control of stopping the transmission of the quantized signal by the transmission unit The RF signal transmission device according to Item. The RF signal transmission device according to any one of claims 1 , 3, 4, 5, and 8 ,
A receiving device for receiving the quantized signal transmitted from the RF signal transmission device;
An RF signal transmission system comprising: The RF signal transmission system according to claim 12 , wherein the reception device includes a receiver that receives the quantized signal transmitted from the RF signal transmission device as an RF signal. An RF signal transmission device according to claim 5 or 6,
A receiver for receiving an RF signal output from the output terminal;
A receiving apparatus comprising: A control unit that performs processing for transmitting transmission request information including information for specifying content to be transmitted to the RF signal transmission device according to claim 9 ;
A receiver that receives the quantized signal transmitted from the RF signal transmission device as an RF signal of the content requested to be transmitted;
A receiving apparatus comprising: A receiver that receives the quantized signal transmitted from the RF signal transmission device according to claim 11 as an RF signal;
And a control unit that performs processing for transmitting stop request information for requesting the RF signal transmission device to stop transmission of the quantized signal.