JPS5854544B2 - tv reception system - Google Patents

Description

[Detailed Description of the Invention] This invention transmits a UHF band broadcast signal and a VHF band broadcast signal received by separate antennas to an output terminal for receiving television broadcasting through a single transmission line. A television receiving system, specifically, the frequency of the broadcast signal in the UHF band is once converted to the frequency in the VHF band and then transmitted through the transmission line, so that the transmission can be performed with less loss,
Furthermore, it relates to a television receiving system that returns the frequency of the signal to the original UHF band frequency near the output terminal, so that the television receiver can receive the image in the same way as normal UHF broadcasting. It is.

And the purpose is that both the above signals are VHF.
Even if the signal is sent at a frequency in the VHF band, it is possible to obtain a back screen by eliminating the adjacent channel beat, and even if the signal sent at a frequency in the VHF band is returned to the frequency in the UHF band mentioned above. To provide a television reception system that can keep costs low.

The drawings showing the embodiments of the present application will be described below.

In FIG. 1, reference numeral 1 denotes an antenna for receiving broadcast signals in the VHF band, which is capable of receiving low band television broadcast signals from channels 1 to 3 and biband television broadcast signals from channels 4 to 12.

Reference numeral 2 denotes an amplifier, which is used to amplify the signal received by the antenna 1 when the level of the signal is low.

Reference numeral 3 designates an antenna for receiving broadcast signals in the UHF band, which is capable of receiving television broadcast signals in the UHF band from channel 13 to channel 62.

A first frequency converter 4 converts the frequency of the broadcast signal received by the antenna 3 to a mid-band channel in the VHF band.

5 is a mixer, and 6 is a transmission line, for example, a coaxial cable is used.

7 is a pilot signal generator, and a stable oscillation circuit such as a crystal oscillation circuit is used, for example.

Further, the frequency is selected to a value as described below.

Reference numeral 8 designates a branching device used to superimpose the pilot signal from the pilot signal generator 7 onto the transmission line 6, and is generally used by connecting its input end 8as, output end 8b1, and branch end 8c as shown in the figure.

Incidentally, this superposition of the pilot signal may be performed using a resistor as shown in FIG. 1.

Next, 10 shows a trunk branch amplifier connected to the output end of the transmission line 6.

In this trunk branch amplifier 10, 11 is an input terminal;
Reference numeral 2 indicates an output terminal, and reference numeral 13 indicates a distribution terminal, which is exemplified as an output terminal for receiving television broadcasting.

14 is an AGC amplifier circuit, which operates in the VHF band (90~222M
A well-known or well-known circuit configuration capable of AGC amplifying the broadcast signal of H2) is used.

Reference numeral 15 denotes a second frequency converter, which converts the mid-band frequency signal sent via the transmission line 6 into the original UHF band frequency signal.

Also, in this frequency converter 15, the frequency conversion signal (
A pilot signal is used as a local oscillation signal (generally called a local oscillation signal).

16 indicates a well-known distribution circuit.

Next, reference numeral 17 indicates a television receiver connected to the output terminal 13 for receiving television broadcasting.

Incidentally, this television receiver 17 is generally installed at each subscriber's home in a communal reception facility.

In the above configuration, the V received by antenna 1
The broadcast signal in the HF band is amplified by the amplifier 2.

On the other hand, the UHF band broadcast signal received by the antenna 3 is converted to a mid-band frequency by the first frequency converter 4.

These signals are sent to a transmission line 6 via a mixer 5.

The pilot signal generated by the pilot signal generator 7 is also transmitted along the transmission line 6 together with the broadcast signal.

Next, the signal sent via the transmission line 6 is input to the main branch amplifier 10 from its input terminal 11.

This input signal is processed by AGC amplifier circuit 14.
The signal is amplified and output from the output terminal 12, and a portion thereof reaches the distribution circuit 16.

The mid-band frequency signal input to the first input terminal 11 is converted back to the original UHF band frequency signal by the frequency converter 15, and the signal reaches the distribution circuit 16.

The signals entering these distribution circuits 16 are
The signals are distributed and output from the plurality of distribution terminals 13 to the television receiver 17.

Next, the frequency of the pilot signal generated by the pilot signal generator 7 will be explained.

As the frequency of this pilot signal, the difference value between the frequency of the UHF band broadcasting signal input to the frequency converter 4 and the mid-band frequency output from the frequency converter 4 after converting the frequency of that signal is determined as an integer. The value divided by is used.

Moreover, the value is a frequency (generally 90 to 222 MHz) that can be amplified by the AGC amplifier circuit 14.
Furthermore, a frequency that does not interfere with television signals in the VHF band is used.

In this example, the frequencies shown in Table 1 below are selected.

That is, to explain example 1 in Table 1, the channel number of the input broadcast signal in the UHF band is 13 (frequency is 470 to 476 MHz),
Moreover, when the channel number of the converted output signal in the mid-band is A (frequency is 110 to 116 MHz), 110 MHz is subtracted from 470 MHz to obtain 360 MHz as the difference value.

Next, by dividing this 360 MHz by an arbitrary integer, for example 3, 120 h is obtained.

This 120 MHz is a frequency in the VHF band that can be amplified by the AGC amplifier circuit 14 and does not interfere with television signals, so this 120 MHz may be used as a pilot signal.

In the frequency converter 15 of the second option, frequency conversion is performed as follows.

For example, referring to Example 1 above, the frequency converter 15
First, the 120 MHz pilot signal is multiplied by 3 to obtain 360 MHz.

Next, by using this 360MHz as a signal for frequency conversion, the broadcast signal of channel A in the mid-band is converted back to the original 13 channels in the UHF band (its frequency is 470 to 476 h). I can do it.

The pilot signal shown above is the example 1 (1
) In addition to 120 MHz, values such as those shown in Examples 2 to 7 or other various values can be used.

Next, FIG. 2, which shows the circuit configuration of the main branch amplifier 10 in more detailed block form, will be described.

First, the AGC amplifier circuit 14 is composed of well-known or well-known blocks, and 21 is a front-stage amplifier, 22 is a variable attenuator, 23 is a rear-stage amplifier, and 24 is a pilot signal extractor, which extracts only the pilot signal. It is constructed using a bandpass filter that allows the light to pass through.

25 is a high frequency amplification section, 26 is a detection circuit, and 27 is a DC amplification section, which can control the amount of attenuation of the variable attenuator 22 according to the output thereof.

Next, in the frequency converter 15, 28 is a band pass filter, which has a pass band that allows only mid-band frequency signals to pass through.

29 is a high frequency amplification section, 30 is a band pass filter,
A filter similar to the filter 28 described above is used.

31 is a mixing section, 32 is a high frequency amplification circuit, and 33 is a pilot signal selection section, which is configured using a bandpass filter so as to be able to extract the pilot signal.

34 is a multiplier circuit, which is a circuit designed to multiply the pilot signal as described above.

35 indicates an amplifier circuit. Reference numeral 36 denotes a television signal distribution circuit which distributes the signal input to the input terminal 11 into two.

Further, 37 is a mixing circuit configured to mix the output signals from the AGC amplifier circuit 14 and the frequency converter 15 and send the mixed signal to the distribution circuit 16.

38 and 39 are power source separation filters that are designed to extract only the AC power sent by superimposing the transmission line on the television signal, and are equipped with a low-pass filter.

40 indicates a power supply circuit. In the configuration described above, the signal input to the input terminal 11 is divided into two by the distribution circuit 36, one of which is amplified by the AGC amplifier circuit 14.

On the other hand, the other one is input to the frequency converter 15.

In this frequency converter 15, the broadcast signal of the mid-band frequency is passed through a band pass filter 28 and an amplifying section 29.
, passes through a bandpass filter 30 and reaches a mixing section 31.

On the other hand, the pilot signal extracted by the pilot signal selection section 33 is multiplied by a multiplier circuit 34, and further amplified by an amplifier circuit 35, and then reaches the mixing section 31.

In the mixing section 31, the mid-band frequency signal is frequency-converted by a frequency-converting signal from the amplifier circuit 35, as is well known.

The converted signal is outputted from the terminal 13 via the amplifier circuit 32, the mixing circuit 37, and the distribution circuit 16.

Next, FIG. 3 shows a different embodiment of the present application, in which the AGC
A divider 41 is provided on the output side of the amplifier circuit 14e, and one of the divided outputs is inputted to the pilot signal selection section 33e.

Further, in the circuit shown in FIG. 3, only one output terminal 13e for receiving television broadcasting is used.

It should be noted that parts that are considered to have the same or equivalent configuration as those in the previous figure in terms of function are given the same reference numerals as in the previous figure with the alphabet e, and redundant explanations are omitted.

(Furthermore, the same idea will be applied to the next editions as well, and the alphabet 19g will be added in order to omit repeated explanations.

) Next, FIG. 4 shows a further different embodiment of the present invention, and shows a circuit in which all signals to the frequency converter 15f are obtained from the distributor 41f.

Also, in the circuit shown in FIG. 4, the distributor 41f
Since the level of the signal obtained is relatively high, the amplifier 29 as in the previous embodiment is not used.

Further, two output terminals 13f for receiving television broadcasting are used as shown in the figure.

Therefore, the distributor 16f also has two distributions.

Next, FIG. 5 shows a different embodiment of the first frequency converter, and shows an example in which the first converter also uses a pilot signal from a pilot signal generator. be.

In FIG. 5, 45 is an input terminal, which is a terminal to which a signal from a UHF antenna is input.

46 is a high frequency amplifier, which is capable of amplifying broadcast signals in the UHF band.

47 is a mixer, and 48 is a high frequency amplifier, which is capable of amplifying signals in the vHF midband frequency.

Reference numeral 49 denotes a band-elimination filter, which is a filter designed to block only the frequency of the pilot signal in the vHF midband frequency band.

Reference numeral 50 indicates an output terminal, which is a terminal connected to the mixer 5.

Reference numeral 51 denotes a band pass filter, which is a filter that allows only the pilot signal to pass.

52 is a multiplier circuit, which has the same multiplier as the multiplier circuit 34.

53 is a power supply separation filter, 54 is a power supply circuit, and each amplifier 4
6.48 or a multiplier circuit 52 or the like is operated.

In such a configuration, when a signal from the pilot signal generator enters the output terminal 50, the pilot signal is separated by the bandpass filter 51, further multiplied by the multiplier circuit 52, and sent to the mixer. Sent to 47.

On the other hand, the UHF band broadcast signal inputted to the input terminal 45 is amplified by the high frequency amplifier 46, and then frequency-converted by the mixer 47 based on the signal from the multiplier circuit 52, resulting in a mid-band frequency signal.

This signal is amplified by an amplifier circuit 48, and a band-stop filter 4
9 and then sent out from the output terminal 50.

As described above, in the present invention, a broadcast signal in the UHF band and a broadcast signal in the VHF band are transmitted to the output terminal 13 for receiving television broadcasting via one transmission line 6. (Broadcasting signals in the F band have a frequency of VH
Even if the signal is transmitted with less loss by converting it to a frequency in the F band, the broadcasting signal in the UHF band is transmitted by converting the frequency to a mid-band frequency in the VHF band. from,
It has the advantage that broadcast signals in both of the above bands can be transmitted without worrying about adjacent channel beats.

This has the effect that when a signal is received from the output terminal 13 to the television receiver to receive broadcasting in the UHF or VHF band, either broadcasting can be received on a high-quality screen.

In addition, a pilot signal is passed through the transmission line 6 from its input side to its output side in addition to the above-mentioned transmission signals, and the broadcast signal in the VHF band transmitted through the transmission line is transmitted along with the pilot signal itself. The output terminal 13 is output at an extremely stable level by AGC amplification based on the signal.
Therefore, when the receiver 7 receives a broadcast signal in the VHF band, an extremely good and stable screen can be obtained.

Furthermore, the T transmitted at the above-mentioned mid-band frequency
The second frequency converter 15 is used to convert the original U
Even if the signal is returned to a signal with a frequency in the HF band, the frequency of the pilot signal is selected to a specific value as described above, and the pilot signal sent via the transmission line is sent to the frequency converter 15. Since the frequency converter 15 is designed to be used as a frequency conversion signal in ) can be made unnecessary.

This has the economical effect of reducing the cost of the frequency converter extremely low (30% or 50% reduction) by selecting the frequency of the pilot signal to a specific value, which is an inexpensive configuration. .

[Brief explanation of the drawing]

The drawings show an embodiment of the present application. Fig. 1 is a system diagram of a television receiving system, Fig. 1 shows a different example of a pilot signal superimposition method, and Fig. 2 is a block diagram of a main branch amplifier. , FIG. 3 and FIG. 4 are block diagrams showing different embodiments of the main branch amplifier, respectively, and FIG. 5 is a block diagram showing a different embodiment of the first frequency converter. 1.3... Antenna, 4... First frequency converter, 7... Pilot signal generator, 6
...Transmission line, 14...AGC amplifier circuit, 15...Second frequency converter, 13...
...Output terminal for receiving television broadcasting, 17...TV receiver.

Claims (1)

[Claims] I A first antenna for receiving broadcast signals in the VHF band, a second antenna for receiving broadcast signals in the UHF band, connected to the second antenna, and transmitting the frequency of the received broadcast signal in the UHF band to VHF. a first frequency converter configured to convert to a mid-band frequency in a band; a transmission line having an input end connected to the first antenna and the frequency converter; and a transmission line connected to the output end of the transmission line and an AGC amplification circuit that performs AGC amplification of a VHF band broadcast signal sent via a transmission line based on a pilot signal described later; and a second frequency converter configured to convert the signal at the mid-band frequency to the signal at the original UHF band frequency. In the television receiving system, the pilot signal generator is connected to the pilot signal generator, and the output terminal of the AGC amplifier circuit and the output terminal of the second frequency converter are both connected to an output terminal for receiving television broadcasting. The frequency of the pilot signal is the UH received by the second antenna.
Among the values obtained by dividing the difference value between the frequency of the F-band broadcast signal and the frequency of the above-mentioned mid-band by an integer, and the above-mentioned AGC
The second frequency converter is configured to use the pilot signal input via the transmission line as a frequency conversion signal. TV reception system.