JPH0145794B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention combines an image signal and a first digital signal such as an audio signal or a control signal in a narrower band than the image signal from the own station A to the other station B. Then, the radio frequency local carrier wave is FM modulated and multiplexed transmitted, and in the reverse direction from the other station B to the own station A, only the second digital signal in the same narrow band as the first digital signal is transmitted, and the radio frequency local carrier wave is ASKed. It is transmitted through digital modulation such as modulation. The reception is related to a so-called heterodyne reception bidirectional radio communication system in which both stations A and B mix the radio signal with a local carrier wave, convert it into an intermediate frequency signal, and demodulate it.

(b) Conventional technology and problems Conventionally, from local station A to partner station B, image signal a,
In a two-way wireless communication system in which a narrowband signal c with a narrower bandwidth than the image signal a is simultaneously transmitted, and only a similar narrowband signal g is transmitted from the other station B to the own station A, the image signal a and Since the narrowband signal c, which is transmitted simultaneously, is placed outside the predetermined transmission frequency band of the image signal a and transmitted by frequency division multiplexing, there is a drawback that the overall transmission bandwidth used becomes wider. Furthermore, apart from the frequency allocation problem mentioned above,
Both stations have a carrier wave oscillator for transmitting and a receiving local oscillator for communication, and a carrier wave modulated by the frequency of the transmitting local oscillator of both stations is added to the mixer of each station and demodulated to the baseband frequency band. There is a method that eliminates the need for a receiving local oscillator by adding the signal transmitted in the baseband frequency band of the own station as an opposite phase and canceling out the signal contained in the carrier wave leaking to the output side of the demodulator. The former method requires a reception local oscillator, which is particularly expensive in the millimeter wave band, while the latter method has the disadvantage of making reverse compensation to cancel unnecessary signals difficult, and therefore requires a receiver local oscillator.
There is a drawback that N deteriorates.

(c) Purpose of the Invention The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to ensure that the total frequency bandwidth used when simultaneously transmitting the narrowband signal c exceeds the predetermined frequency bandwidth required to transmit only the image signal a. To provide a wireless communication system in which the output of a carrier wave oscillator for transmission is branched and used as a local carrier wave for heterodyne reception, thereby eliminating the need for an independent local carrier wave oscillator for reception and not deteriorating the S/N of the reception system. be.

(d) Structure of the Invention In order to achieve the above object, the present invention combines an image signal a and a first digital signal c from a local station A to a remote station B, as shown in FIG. Modulator 3 performs FM modulation on the carrier wave for radio frequency transmission and multiplex transmission.
Only the digital signal g is digitally modulated on the radio frequency local carrier wave 33 by the modulator 18 and transmitted to own station A. For reception, both stations A and B mix the radio signal with the local carrier wave, convert it into an intermediate frequency signal, and demodulate it. In a two-way wireless communication system with heterodyne reception, the first digital signal c from the own station A to the other station B is converted into a burst wave narrower than the pulse width of the horizontal synchronization signal of the image signal a, and the first digital signal c is transmitted from the local station A to the opposite station B. The second digital signal g from the other station B to the local station A is transmitted on one or more horizontal sync signals allocated in advance to one or more of the horizontal sync signals of the image signal a. A horizontal synchronization signal f whose speed is converted to a burst wave narrower than the pulse width of the horizontal synchronization signal and on which the burst wave of the first digital signal c does not ride among the horizontal synchronization signals of the image signal e' that the other station B receives from its own station A. It transmits to its own station A during the time period. Then, for heterodyne reception of own station A, the output of the modulator 3 during the time period when no burst wave is added to the horizontal synchronization signal of the image signal for transmission is branched and shared, and for heterodyne reception of opposite station B, the output of the modulator 3 is divided and shared. Radio frequency local carrier wave 33 for transmission of digital signal g
It is characterized by branching and sharing.

(e) Embodiment of the invention An embodiment of the invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a wireless communication system according to an embodiment of the present invention, FIG. 2 is a block diagram of a pulse generating circuit that is slightly narrower than the pulse width of the horizontal synchronizing signal in the synchronizing signal extracting circuit of FIG. 1, and FIG. The figure is a time chart of waveforms at various parts in FIG. 2, and A, B, and C correspond to points a, b, and c in FIG. 2. Figure 4 is a waveform diagram mainly consisting of synchronizing pulses of the video signal, Figure 5 is a time chart of the waveforms of each part in Figure 1, and A to H are a, a', b, b', and c in Figure 1. ,c′,d,e,e′,e″,f
，
Corresponding to points f', g, g', h, and h'.

In the figure, 1 is an emphasis circuit, 2 is a synthesizer, and 3 is a
FM modulator, 4, 14, 34 are branch circuits, 5, 1
0, 19, 20 are band pass filters (hereinafter referred to as BPF), 6, 9 are duplexers, 7, 8 are antennas,
11 and 21 are mixers, 12 and 22 are intermediate frequency amplifiers, 13 is an FM modulator, 15 is a synchronization signal line regeneration circuit, 16 is a de-emphasis circuit, 17, 24,
25 and 32 are speed conversion circuits, 18 is a modulator,
23 is a demodulator, 26 and 27 are synchronous signal extraction circuits,
28 and 29 are clock extraction circuits, 30 and 31 are frequency dividers, 33 is a transmitting local oscillator, 35 is a phase synchronization circuit, 36 is a delay circuit, 37 is an inverter circuit, 3
8 indicates a NAND circuit.

As shown in Figure 4, the frequency of the synchronization signal of the image signal is 15.76KHz, and the equivalent pulse is 2 during this one cycle.
One pulse is generated for the vertical synchronization signal (however, a cutting pulse is inserted and the pulse width is wide), and two pulses are generated for the horizontal synchronization signal.

In the embodiment of the present invention, in one direction, the first digital signal is placed in a burst on top of the horizontal synchronization signal skipped once with the pulse width of the horizontal synchronization signal, and transmitted in the opposite direction. The second digital signal is transmitted in a high-speed burst during the time when the first digital signal is not included in the horizontal synchronization signal of the received image signal. Therefore, in the synchronization signal extraction circuits 26 and 27, as shown in FIG.
A pulse signal with a duty ratio of 50% as shown in FIG. 3A is generated in synchronization with a frequency of Hz, and this pulse signal is used in a delay circuit 36 to generate a pulse with a width slightly narrower than that of the horizontal synchronizing signal. The delayed signal is inverted by an inverter circuit 37, and a signal as shown in FIG. 3B is added to a NAND circuit 38 to generate a signal as shown in FIG. 3C. This signal shown in C is synchronized with the horizontal synchronizing signal and has a pulse width slightly narrower than that of the horizontal synchronizing signal. For example, if a digital signal for one direction is placed in a burst pattern at every sync signal, and a digital signal for the opposite direction is placed in a burst at every other time when it is not placed, then the signal shown in C is frequency-divided. A signal as shown in FIG. 5B and F is created by dividing the frequency by 1/2 and emitting pulses alternately. Of course, by changing this frequency division ratio, it is possible to carry a digital signal in one direction every two or three times, and to carry a digital signal in one direction in the opposite direction when it is not carried.

The necessary pulses among the pulses thus obtained are added to the speed converters 24 and 25 on the A station side in FIG. 1, and the speed converters 17 and 3 on the B station side in FIG.
2 and the clock signal extraction circuit 28.

Next, using Fig. 1 and Fig. 5, stations A and B in Fig. 1 are
The transmitting side of the station will be explained.

An image signal as shown in FIG. 5A is sent to a synthesizer 2 via an emphasis circuit 1 for improving characteristics. On the other hand, the digital signal shown at C is input to the speed signal conversion circuit 25, and is sequentially shifted and stored in a shift register (not shown) using an external clock. When the pulse signal shown in B is applied using a clock with a frequency N times that of the external clock, which can accommodate about 10 bits in the pulse width described above, the output gate of the speed conversion circuit 26 is opened. Read it then. This read out signal as shown in D is sent to the synthesizer 2 in a burst form, and is placed on top of the horizontal synchronization signal of the image signal sent to the synthesizer 2 one by one, and is sent out as a waveform as shown in E. .

The signal as shown in E is sent to FM modulator 3.
Modulate, branch circuit 4, block unwanted frequencies
It is transmitted to the B station via the BPF 5, duplexer 6, and antenna 7. At this time, the FM modulated signal branched by the branch circuit 4 is applied to the mixer 21 on the receiving side. Next, to transmit the digital signal from the B station side, the digital signal as shown in FIG. Then, this stored digital signal is
When the pulse signal shown in F is applied using a clock with a frequency N times that of the external clock, which can accommodate about 10 bits in the pulse width explained above, the gate of the output of the speed conversion circuit 17 is applied. It will be opened, so read it at that time. This read out signal as indicated by H is applied to the modulator 18 in a burst form.

This modulator 18 is not frequency modulated, e.g.
Transmitting local oscillator 33 with modulators such as ASK and PSK
A branched signal is added to the mixer 11 and modulator 18 side by the branch circuit 34, and this signal is modulated with a burst signal shown by H, and the BPF 19, which removes unnecessary frequencies, and the transmitter/receiver duplexer 9. Transmit to station A via antenna 8.

Next, the receiving side of station B and station A will be explained with reference to FIG. The signal transmitted from station A passes through the antenna 8, the duplexer 9, and the BPF 10, which passes the necessary frequencies, and is added to the mixer 11 to become an intermediate frequency band signal.The signal is amplified by the intermediate frequency amplifier 12, and then sent to the FM The signal is demodulated by a demodulator 13, branched by a branch circuit 14, and sent to a synchronizing signal line reproducing circuit 15, a clock signal extracting circuit 28, and a speed converting circuit 32. The synchronizing signal line reproducing circuit 15 samples and holds the image signal during the pulse shown in FIG. 5B from the synchronizing signal extracting circuit 27 (not shown).
The de-emphasis circuit 16 removes the characteristics added by the emphasis circuit 1 and sends out the original image signal {FIG. 5A}. In addition, the clock signal extraction circuit 28 extracts a clock with a frequency N times that of the external clock from the digital signal carried on the transmitting side between the pulses shown in FIG. At 30, it is applied to the speed conversion circuit 32 together with the external clock on the transmitting side. The speed conversion circuit 32 reads the digital signal superimposed on the image signal during the pulse width shown in FIG. stored in a register (not shown);
The digital signal stored in the shift register is read and transmitted using a clock equal to the external clock on the transmitting side.

The signal transmitted from station B passes through the antenna 7, the duplexer 6, and the BPF 20 that passes the necessary frequencies, and then is added to the mixer 21 to become an intermediate frequency band.The signal is amplified by the intermediate frequency amplifier 22, and then sent to the demodulator 23. The signal is demodulated at , and becomes a signal as shown in FIG. 5H, which is applied to the speed conversion circuit 24. At this time, the clock extraction circuit 29 extracts a clock with a frequency N times that of the external clock on the transmitting side from the signal shown in FIG. Add to circuit 24. The speed conversion circuit 24 reads the input signal shown in FIG. 5H during the pulse width shown in FIG. The digital signal is stored in a shift register (not shown), and the digital signal stored in the shift register is read and transmitted using a clock equal to the external clock on the transmitting side. If the data capacity of the digital signals on the A-station side and the B-station side are different, the ratio of the number of data bursts may be changed, or the frequency of the clock N times that of the external clock may be changed. In addition, the modulators 3 and 18 are configured to use modulators other than FM modulators, such as ASK and PSK.
etc., and the modulator 3 may be an FM modulator.

As described above, it is possible to share the horizontal synchronization time zone of the image signal, to transmit narrowband digital signals in both directions within the predetermined transmission frequency band of the image signal, and also to eliminate the need for a reception local oscillator and to use the S/I of the reception system. N also does not get worse. Particularly when used in the millimeter wave band, the reception local oscillator is expensive, and eliminating it allows the system to be configured at a lower cost.

(f) Effects of the Invention As explained in detail above, according to the present invention, when transmitting narrowband digital signals such as audio signals and control signals simultaneously with image signals, the overall frequency bandwidth used is equal to that required for only the image signals. The transmission bandwidth is sufficient, which is narrower than in the past, and since a receiving local oscillator is not required, the wireless communication system has the effect of becoming cheaper.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a wireless communication system according to an embodiment of the present invention, FIG. 2 is a block diagram of a pulse generation circuit whose pulse width is slightly narrower than the horizontal synchronization signal pulse width in the synchronization signal extraction circuit of FIG. 1, and FIG. The figure shows a time chart of the waveforms of each part in FIG. 2, FIG. 4 shows a waveform diagram mainly consisting of synchronizing pulses of the video signal, and FIG. 5 shows a time chart of the waveforms of each part in FIG. 1. In the figure, 1 is an emphasis circuit, 2 is a synthesizer, and 3 is a
FM modulator, 4, 14, 34 are branch circuits, 5, 1
0, 19, 20 are bandpass wavers, 6, 9 are duplexers, 7, 8 are antennas, 11, 21 are mixers, 12, 22 are intermediate frequency amplifiers, 13 is FM modulator, 15 is synchronization Signal line regeneration circuit, 16 is a de-emphasis circuit, 17, 24, 25, 32 are speed conversion circuits, 18 is a modulator, 23 is a demodulator,
26 and 27 are synchronized signal extraction circuits, 28 and 29 are clock extraction circuits, 30 and 31 are frequency dividers, 33 is a transmitting local oscillator, 35 is a phase synchronization circuit, 36 is a delay circuit, 37 is an inverter circuit, and 38 is a NAND circuit. Shows the circuit.

Claims (1)

[Claims] 1 From the local station A to the remote station B, the image signal a and the first digital signal c are combined, the modulator 3 modulates the carrier wave for radio frequency transmission, multiplex transmission is performed, and the signal is transmitted from the remote station B to the local station A. In the reverse direction, only the second digital signal g is transmitted to the radio frequency local carrier wave 33 by the modulator 18.
In a two-way wireless communication system with heterodyne reception, the radio signal is digitally modulated and transmitted to own station A, and both stations A and B mix the radio signal with a local carrier wave, convert it to an intermediate frequency signal, and demodulate it. The first digital signal c from to the partner station B is converted into a burst wave having a width narrower than the pulse width of the horizontal synchronizing signal of the image signal a, and is pre-allocated to one or more of the horizontal synchronizing signals of the image signal a. The second digital signal g from the other station B to the local station A is converted into a burst wave whose pulse width is narrower than the horizontal synchronization signal of the image signal a and transmitted to the other station B. Image signal received by station B from own station A
Among the horizontal synchronizing signals of e', the horizontal synchronizing signal f is transmitted to the own station A during the time period when the burst wave of the first digital signal c is not carried, and the image signal for transmitting is transmitted to the own station A for heterodyne reception. The output of the modulator 3 during the time period when no burst wave is riding on the horizontal synchronization signal of the second digital signal g is branched and shared, and the local carrier wave 33 of the radio frequency for transmitting the second digital signal g is used for heterodyne reception by the opposite station B. A wireless communication method characterized by branching and sharing.