JPH09271005A - Catv transmission equipment for multi-directional reception - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to continue cable broadcasting even when a fault is generated in one of two mutually relational receiving systems. SOLUTION: A resending device 2 reproduces a video carrier from a received VHF broadcasting signal and supplies the reproduced video carrier to a modulator 4 in the device 1. A resending device 1 receives rebroadcasting program by a microwave, demodulates the received program, removes ghosts by a ghost canceler circuit 3, and inputs the ghost-removed signal to the modulator 4. A composit signal outputted from the modulator 4 is converted into a prescribed channel by a mixer 5 based upon a local oscillation signal oscillated from a local oscillator 21. After demodulating and processing the received VHF broadcasting signal, the device 2 converts the processed signal into a composit signal by a modulator 18. Even when a fault is generated in a receiving system of the device 1, the device 1 can execute television broadcasting through a cable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CATV transmission device for multidirectional reception, which transmits a television broadcast signal using a cable to an area where the received electric field strength is low.

[0002]

2. Description of the Related Art In common TV reception such as CATV (cable television), a UHF channel television broadcast radio wave is received and the received UHF channel is converted into a VHF channel or a VHF channel television broadcast radio wave. Is converted to a different VHF channel and transmitted using a cable. In particular, when the electric field strength is weak in a region where there is a VHF television broadcast wave and the image quality of the broadcast wave is deteriorated due to the influence of noise from the outside world or the reflected wave, it is necessary to provide the broadcast service of the same program. There is.

This broadcasting service receives a VHF television broadcast program through a UHF satellite station, a microwave line or the like, and the received television broadcast program is VHF.
This is done by converting to a band and transmitting with a cable. In the case of transmitting television broadcasting by cable, if the shielding performance of the TV receiver is not sufficient, beat transmission interference due to the difference in the image carrier frequency between the television broadcast radio wave and the television signal transmitted by the cable occurs.
The image receiving screen becomes unsightly.

In order to solve this, conventionally, (1) only one of VHF and UHF is received and retransmitted. (2) When receiving only UHF, converting it to VHF, and transmitting it, the same channel is not used. (3) The converted VHF channel is given a frequency offset of about 10 kHz to make the same-channel beat inconspicuous. (4) Increase the input level of the television and increase the DU ratio with the interfering wave. (5) Change the television installation method so that the television broadcast radio waves do not directly enter the television. (6) Satellite stations such as VHF and UHF are received at the same time, and the one with the better image quality is always selected and retransmitted on the same channel. Although measures such as these have been taken, they were not reliable.

Therefore, as a countermeasure against this, there is a method conventionally described in Japanese Utility Model Publication No. 57-1493. Hereinafter, this method will be described with reference to FIG. FIG.
At, the television broadcast radio wave is transmitted through the first antenna 12
1 and is supplied to the mixer 122. The mixer 122 frequency-converts the local oscillation signal from the local oscillator 123 and selects the selected television broadcast signal as a video intermediate frequency signal. The video intermediate frequency signal is input to the filter 124, the video carrier is extracted, and is supplied to the limiter 125. The video carrier is input to one input terminal of the phase comparator 130 after the AM component is suppressed by the limiter 125.

The second antenna 126 receives a television broadcast wave to be rebroadcast, and the received signal is generated by a mixer 127 in a local oscillator signal from a voltage controlled oscillator (VCO) 131. The frequency is converted into a video intermediate frequency signal. The video intermediate frequency signal is input to the filter 128, the video carrier is extracted, and is supplied to the limiter 129. This video carrier wave is input to the other input terminal of the phase comparator 130 after the AM component is suppressed by the limiter 129.

In this way, the video carrier signal is input to the two input terminals of the phase comparator 130,
An error signal corresponding to the phase difference between both video carrier signals is output. By supplying this error signal to the VCO 131, the oscillation frequency of the VCO 131 is controlled, and the frequency of the image carrier input from the limiter 125 to the phase comparator 130 is adjusted to the frequency of the video carrier input from the limiter 129 to the phase comparator 1.
The frequencies of the video carrier waves input to 30 come to match.

As a result, the video intermediate frequency signal output from the mixer 122 and the video intermediate frequency signal output from the mixer 127 are synchronized in frequency. Then, the video intermediate frequency signal output from the mixer 127 is up-converted by the local oscillator signal from the local oscillator 123 in the mixer 132 and output from the output terminal 133 to the cable. Note that the video carrier of the television signal output to the cable is equal to the video carrier of the television broadcast radio wave received by the first antenna 121, and the transmitted video signal is the second carrier.
It becomes a video signal of a television broadcast radio wave received by the antenna 126. As a result, the rebroadcast program transmitted via the cable can be received without causing beat interference.

[0009]

However, in the above-mentioned method for preventing beat interference, there may be a failure in the receiving system of the television broadcast radio wave for synchronizing with the image carrier of the television signal transmitted by the cable. . Then, the reference image carrier wave is not input to the phase comparator, so that the predetermined oscillation frequency signal cannot be obtained from the VCO. Therefore, there is a problem that the television transmission signal is not output from the CATV transmission device. In addition, when a receiving system for obtaining a rebroadcast program fails, a video signal cannot be obtained, and rebroadcast cannot be performed.

Therefore, according to the present invention, even if a failure occurs in the receiving system for obtaining the rebroadcast program or the receiving system of the television broadcast radio wave for obtaining the synchronized video carrier,
It is an object of the present invention to provide a CATV transmission device for multidirectional reception, which can send a video signal of a rebroadcast program to a cable. Further, in this case, it is another object of the present invention to provide a CATV transmission device for multidirectional reception in which co-channel beat interference does not occur.

[0011]

In order to achieve the above object, a multi-directional receiving CATV transmission apparatus of the present invention uses a cable for transmitting a television signal whose carrier is a frequency signal assigned to a channel of a television broadcast radio wave. In the CATV transmission device for transmitting by the above, the reproducing means for reproducing a video carrier from the television broadcasting signal received by the antenna for receiving the first frequency band, and the video signal by demodulating the received television broadcasting signal into a baseband signal. After performing the processing of 1), the original video signal frequency band is restored again.
After processing the video signal by demodulating the television broadcast signal received via the video signal processing unit and a specific wireless line in a frequency band different from the first frequency band into a baseband signal, A second video signal processing unit for returning the video frequency band to the video frequency band, a video carrier oscillator oscillating at a frequency substantially equal to the video carrier, and a detection unit for detecting whether or not the video carrier is reproduced by the reproducing unit.
When the video carrier is detected by the detecting means, the video carrier reproduced by the reproducing means is supplied to the second video signal processing section to restore the original video signal frequency band.

[0012] In the CATV transmission apparatus for multi-directional reception, the television signal normally output from the second video signal processing unit is converted into a frequency band of a predetermined channel and output, and the wireless signal is output from the wireless line. When the received signal of No. 1 deteriorates, the television signal output from the first video signal processing unit is converted into a frequency band of a predetermined channel and output.

Further, in the CATV transmission apparatus for multidirectional reception, a local oscillation signal for converting a television broadcast signal received by an antenna for receiving the first frequency band into a video intermediate frequency, and the second video. A local oscillation signal for converting the television signal output from the signal processing unit or the television signal output from the first video signal processing unit into a frequency band of a predetermined channel is commonly supplied from a local oscillator. It is a thing.

According to the present invention as described above, by utilizing the video carrier from the built-in video carrier oscillator when a failure occurs in the receiving system of the television broadcasting radio wave for obtaining the video carrier to be synchronized, The rebroadcast program can be broadcast on a cable. In addition, when the receiving system of the wireless line for obtaining the rebroadcast program is deteriorated or fails, the video signal obtained from the receiving system of the television broadcast wave to obtain the synchronized video carrier is sent to the cable. By doing so, it is possible to rebroadcast without interruption.

[0015]

1 is a block diagram showing the configuration of a first embodiment of a CATV transmission apparatus for multidirectional reception of the present invention. In FIG. 1, 1 is a microwave antenna for receiving a television program to be rebroadcast, 2 is a microwave demodulator for demodulating the received microwave and outputting a video signal and an audio signal of the television program to be rebroadcast, Reference numeral 3 is a ghost canceller circuit for removing a ghost component from the demodulated video signal, 4 is a modulator for modulating a carrier wave with the ghost-removed video signal and audio signal, and 5 is a modulator 4 A mixer (MIX) for frequency-converting the composite signal output from the TV into a predetermined channel of television broadcasting for rebroadcasting.
3) and 6 are bandpass filters (BPF) that remove unnecessary wave components.

Further, 13 is a VHF antenna for receiving VHF television broadcasting, 14 is a band-pass filter (BPF) for extracting a desired frequency band, and 15 is a channel for re-broadcasting television broadcasting. A mixer (MIX1) for converting into an intermediate frequency signal, 16 is a demodulator for demodulating the intermediate frequency signal output from the mixer 15 to obtain a baseband video signal and an audio signal, and 17 is a ghost component from the demodulated video signal. Is a ghost canceller circuit for removing the signal, 18 is a modulator for generating a composite signal by modulating a carrier wave with the ghost-removed video signal and audio signal, and 19 is for rebroadcasting the composite signal output from the modulator 18. Mixer (MI) for frequency conversion to a predetermined channel of television broadcasting
X2) and 20 are bandpass filters (BPF) that remove unnecessary wave components.

Further, 21 is a mixer 15 and a mixer 1.
9 is a local oscillator that supplies a local oscillation signal in common, 22 is a synchronous carrier regenerator that regenerates a carrier from the intermediate frequency signal output from the mixer 15, and 23 is the microwave antenna 1
It is an antenna switching device that selects and outputs either a television signal of the system or a television signal of the VHF antenna 13 system. In the first embodiment of the CATV transmission apparatus for multidirectional reception of the present invention, the retransmission apparatus 1 is configured by the configurations of the microwave demodulator 2 to the BPF 6, and the configurations of the BPF 14 to the BPF 20 are configured. The retransmitting device 2 is configured by the above. The regenerated carrier wave output from the synchronous carrier regenerator 22 is the modulator 4 of the retransmitting apparatus 1 and the modulator 18 of the retransmitting apparatus 2.
Is commonly supplied to.

Next, the CATV device for multi-directional reception configured as described above is installed in an area where the electric field of the VHF broadcast wave is weak, and the CATV device for multi-directional reception is directed toward the VHF for multi-directional reception.
The broadcast program is transmitted by a micro line. Therefore, the VHF television broadcast radio wave is received by the antenna 13, the BPF 14 extracts only a predetermined frequency band, and is input to the mixer 15. A local oscillator signal from the local oscillator 21 is supplied to the mixer 15, and a signal of a predetermined channel of VHF television broadcasting input to the mixer 15 is converted into an intermediate frequency signal. The converted intermediate frequency signal is input to the demodulator 16 and the synchronous carrier regenerator 22.

The synchronous carrier regenerator 22 regenerates the image carrier and supplies the regenerated carrier to the modulator 18. Further, the demodulator 16 demodulates the video signal and audio signal of the program to be rebroadcast to baseband. in this case,
The demodulator 16 may perform synchronous detection by using the video carrier from the synchronous carrier regenerator 22. Then, the video signal is input to the modulator 18 via the ghost canceller circuit 17, and the audio signal is directly input to the modulator 18. The ghost canceller circuit 18 uses a reference signal (GCR signal: Ghost Canc) for removing the ghost component.
(el Reference) is detected and the ghost component contained in the video signal is removed by the GCR signal.

In this modulator 18, the synchronous carrier regenerator 2
The composite video signal is generated by modulating the video carrier reproduced in 2 with the video signal and the audio signal from which the ghost has been removed. In the mixer 19, the generated composite signal is frequency-converted into a predetermined channel by the local oscillation signal from the local oscillator 21, the unnecessary wave component is removed by the BPF 20, and the signal is output toward the antenna switch 23. In this case, the modulator 18
In Fig. 1, the reproduced video carrier is modulated and the local oscillator 21 supplies the local oscillator signal common to the mixer 15 and the mixer 19, so that the television broadcast signal input to the retransmission device 2 is , And becomes synchronized with the television broadcast signal output from the retransmission device 2.

Further, the television broadcast program transmitted through the microwave line is received by the microwave antenna 1 and input to the microwave demodulator 2. The microwave demodulator 2 demodulates the video signal and audio signal of the rebroadcast program into baseband. Of these, the video signal is input to the modulator 4 via the ghost canceller circuit 3, and the audio signal is directly input to the modulator 4. The ghost canceller circuit 3 removes the ghost component contained in the video signal by the GCR signal.

The video carrier reproduced by the synchronous carrier reproducer 22 is supplied to the modulator 4 via terminals b1 and a1 and is modulated by the ghost-removed video signal and audio signal to produce a composite. A signal is generated. The generated composite signal is the mixer 5
At, the frequency is converted into a predetermined channel by the local oscillation signal from the local oscillator 21 supplied through the terminals b2 and a2, the unnecessary wave component is removed by the BPF 6, and the signal is output to the antenna switch 23. In this case, since the modulator 4 modulates the video carrier reproduced by the retransmission device 2 and the local oscillator signal common to the mixers 5 and 15 is supplied from the local oscillator 21, the retransmission is performed. The television broadcast signal input to the device 2 and the television broadcast signal output from the retransmission device 1 are synchronized.

The antenna switching device 23 is used as the retransmitting device 1.
Then, the reception power of the radio wave received by the retransmitting device 2 is detected, and the television broadcast signal output from the receiving system having the larger reception power is output and sent to the cable. Normally, the received power on the side of the retransmitting device 1 receiving the microwave is higher, so that the television broadcast signal of the rebroadcast program output from the retransmitting device 1 is selected by the antenna switch 23. It will be sent to the cable.

In this case, as described above, the retransmission device 1
The television broadcast signal output from the retransmitting device 2
Since it is synchronized with the television broadcast signal received at, even if the rebroadcast program transmitted by cable is received, the same channel beat interference does not occur. Further, when the microwave line is deteriorated or a failure occurs due to rain or snow, the antenna switching device 23 selects and outputs the television broadcast signal output from the retransmission device 2. It can be prevented that the television broadcast is not transmitted to the cable.

FIG. 2 is a block diagram showing a modified example of the first embodiment of the CATV transmission apparatus for multidirectional reception of the present invention. The CATV transmission device for multi-directional reception shown in FIG. 2 is designed to enable the re-transmission device 1 to perform television broadcasting of rebroadcast programs even if a failure occurs in the reception system of the re-transmission device 2. is there. In FIG. 2, the same reference numerals as those in FIG. 1 are the same, and the description thereof will be omitted. Reference numeral 7 in FIG. 2 is a carrier switching device for selecting either the video carrier from the synchronous carrier regenerator 22 or the video carrier from the video carrier oscillator 8 of the retransmitting device 2 and supplying it to the modulator 4. Reference numeral 8 is a video carrier oscillator that oscillates a frequency substantially equal to the frequency of the video carrier, and 9 is a signal detector that detects the presence or absence of the video carrier from the synchronous carrier regenerator 22 supplied to the retransmission device 1.

Further, 10 is a local oscillator that oscillates at a frequency substantially equal to the frequency of the local oscillator signal output from the local oscillator 21, and 11 is the presence or absence of the local oscillator signal from the local oscillator 21 supplied from the retransmitting device 2. Signal detector for detecting, 12
Is a local switch that selects either the local oscillator signal from the local oscillator 21 or the local oscillator signal of the local oscillator 10 of the retransmitting device 2 and supplies it to the mixer 5.

Next, the operation of the CATV transmission apparatus for multidirectional reception configured as described above will be described, but only the operation different from FIG. 1 will be described. Since the CATV transmission device for multi-directional reception is installed in a weak electric field region of VHF television broadcast waves, the VHF antenna 13 is installed by searching for a point that can receive as well as possible. Then, the VHF antenna 13 and the CAT for multidirectional reception
Since the V transmission device may be connected via a high frequency cable of several km, an accident such as disconnection of the high frequency cable may occur.

Here, when the VHF antenna 13 and the retransmitting device 2 are disconnected from each other, since the television broadcasting signal is not input to the retransmitting device 2, the synchronous carrier regenerator 2
No. 2 cannot reproduce the video carrier.
Then, since the video carrier wave is not supplied to the re-transmitting device 1, the modulator 4 does not output the composite signal, and the re-broadcast program cannot be broadcast on the television. Therefore, the signal detector 9 detects whether or not the video carrier is being supplied from the retransmitting device 2, and if it is determined that the video carrier is not being supplied, the carrier switch 7 is switched from the synchronous carrier regenerator 22 side to the video carrier. Switch to the carrier oscillator 8 side.

As a result, the image carrier wave from the image carrier oscillator 8 is supplied to the modulator 4, so that the composite signal is generated and output. in this case,
The frequency of the image carrier oscillated by the image carrier oscillator 8 is ideally the same as the frequency of the image carrier of the television broadcast, but in reality, it may be substantially the same. Also, the local oscillator 2 of the retransmission device 2
When the oscillation of the local oscillator 21 is stopped, the mixer 15 and the mixer 1 may be stopped.
9 and the mixer 5 cannot perform frequency conversion. In this case, the television broadcasting signal is not output from the retransmitting apparatus 1 and the retransmitting apparatus 2, and the cable broadcasting cannot be performed.

Therefore, the signal detector 1 determines whether or not the local oscillator signal from the local oscillator 21 is supplied to the retransmission device 1.
When it is detected in 1 and it is determined that the power is not supplied, the local switching unit 12 is switched from the local oscillator 21 side to the local oscillator 10 side. As a result, the local oscillation signal from the local oscillator 10 is supplied to the mixer 5,
The television signal converted into a predetermined channel can be output from the mixer 5. In this case, the frequency of the video carrier oscillated by the local oscillator 10 is
Ideally, the same frequency as the frequency of the local oscillator signal is desirable, but in reality, it may be almost equal.

As described above, the CA for multidirectional reception shown in FIG.
In the TV transmission device, even if a failure occurs in the reception system of the re-transmission device 2 and the re-transmission device 2 does not operate, the re-transmission program of the VHF television broadcast is used from the re-transmission device 1 by using a cable. You will be able to broadcast.

Next, FIG. 3 is a block diagram showing the configuration of the second embodiment of the CATV transmission apparatus for multidirectional reception of the present invention.
Shown in The CATV transmission device for multidirectional reception shown in FIG.
This is an example in which a rebroadcast program is transmitted on a UHF broadcast channel, and the configuration of the retransmitting device 1 is different from that of the CATV transmitting device for multidirectional reception shown in FIG. 1 will be described. In FIG. 3, 3
0 is a UHF antenna for receiving UHF television broadcasting, 31 is a band pass filter (BPF) for extracting a desired frequency band, 32 is a predetermined channel of television broadcasting to be rebroadcast, and is converted into an intermediate frequency signal Mixer (MIX3) 33, a local oscillator that oscillates a local oscillation signal supplied to the mixer 32, and a demodulator 34 that demodulates the intermediate frequency signal output from the mixer 32 to obtain a baseband video signal and an audio signal. , 35 is a ghost canceller circuit for removing ghost components from the demodulated video signal, 36 is a modulator for generating a composite signal by modulating a carrier wave with the ghost-free video signal and audio signal, and 37 is a modulator 36 Re-broadcast the composite signal output from the Mixer for (MIX4), 3
8 is a band pass filter (BP) for removing unnecessary wave components.
F).

CAT for multi-directional reception configured as described above
The V device is installed in an area where the electric field of the VHF broadcast wave is weak, and the VHF broadcast program is transmitted to the multidirectional reception CATV device by the UHF broadcast channel. Therefore, the UHF television broadcast radio wave is received by the antenna 30, the BPF 31 extracts only a predetermined frequency band, and is input to the mixer 32. A local oscillator signal from the local oscillator 33 is supplied to the mixer 32, and a signal of a predetermined channel of UHF television broadcasting input to the mixer 32 is converted into an intermediate frequency signal. The converted intermediate frequency signal is input to the demodulator 34.

The demodulator 34 demodulates the video and audio signals of the rebroadcast program into baseband. In this case, the demodulator 34 may perform synchronous detection using a video carrier reproduced by a synchronous carrier reproducer (not shown). Then, the video signal is input to the modulator 36 via the ghost canceller circuit 35, and the audio signal is directly input to the modulator 36. The ghost canceller circuit 35 removes the ghost component contained in the video signal by the GCR signal.

In this modulator 36, the video carrier reproduced by the synchronous carrier reproducer 22 of the retransmitting device 2 is modulated by the ghost-removed video signal and audio signal to generate a composite signal. In the mixer 37, the generated composite signal is frequency-converted into a predetermined channel by the local oscillation signal from the local oscillator 21 of the retransmission device 2, the unnecessary wave component is removed by the BPF 38, and the signal is output toward the antenna switch 23. To be done. In this case, the modulator 36 modulates the video carrier reproduced by the retransmitting device 2 and the mixer 15
Since a local oscillator signal common to the mixer 37 and the mixer 37 is supplied from the local oscillator 21, the television broadcast signal input to the retransmission device 2 and the television broadcast signal output from the retransmission device 1 are synchronized. Come to do. Therefore,
Even if a rebroadcast program transmitted by cable is received, co-channel beat interference does not occur.

Further, the VHF antenna 13 and the retransmitting device 2
When a failure occurs in the receiving system of the retransmitting device 2 such as disconnection between the sync carrier regenerator 22 and the receiver, a VHF television broadcast signal is not input to the retransmitting device 2.
Will not be able to reproduce the video carrier. Then, since the video carrier is not supplied to the re-transmitting device 1, the composite signal is not output from the modulator 36, and the re-broadcast program cannot be broadcast on television. Therefore, the signal detector 39 detects whether or not the video carrier is supplied from the retransmitting device 2, and if it is determined that the carrier is not supplied, the carrier switching device 40 is operated from the synchronous carrier regenerator 22 side. Carrier oscillator 41
Switch to the side.

As a result, the modulator 36 is supplied with the video carrier from the video carrier oscillator 41, so that the composite signal is generated and output. In this case, the frequency of the image carrier oscillated by the image carrier oscillator 41 is ideally the same frequency as the frequency of the image carrier of the television broadcast, but in reality, it may be substantially equal. Further, there is a possibility that an accident may occur in which the oscillation of the local oscillator 21 of the retransmission device 2 is stopped, and when the oscillation of the local oscillator 21 is stopped, frequency conversion cannot be performed in the mixer 15, the mixer 19, and the mixer 37. In this case, the television broadcasting signal is not output from the retransmitting apparatus 1 and the retransmitting apparatus 2, and the cable broadcasting cannot be performed.

Therefore, the signal detector 4 determines whether or not the local oscillator signal from the local oscillator 21 is supplied to the retransmission device 1.
When it is detected in 2 and it is determined that the power is not supplied, the local switching unit 43 is switched from the local oscillator 21 side to the local oscillator 44 side. As a result, the mixer 37 is supplied with the local oscillation signal from the local oscillator 44, and the television signal converted into a predetermined channel can be output from the mixer 37. In this case, the frequency of the image carrier oscillated by the local oscillator 44 is ideally the same frequency as the frequency of the local oscillation signal of the local oscillator 21, but it may be practically substantially the same frequency.

When the electric field strength of the UHF television broadcast is deteriorated or a failure occurs due to rain or snow, the antenna switch 23 selects the television broadcast signal output from the retransmitting device 2. Since the output is performed, it is possible to prevent the television broadcast from being stopped from being transmitted to the cable. As described above, in the CATV transmission apparatus for multidirectional reception shown in FIG.
Even if the receiving system fails and the retransmitting device 2 does not operate, the retransmitting device 1 can broadcast a rebroadcast program of VHF television broadcasting using a cable.

The CATV transmission apparatus for multidirectional reception shown in FIG. 3 is provided with terminals b3 and b4 for connecting a video signal processing apparatus for removing interference such as pulse noise received by VHF broadcasting in the retransmission apparatus 2. Has been. Therefore, if a video signal processing device is connected between the terminals b3 and b4, the video signal from the terminal b3 is input to the video signal processing device, and processing such as pulse noise removal, SN improvement, and contour correction is performed. . Then, the processed video signal is returned to the retransmitting device 2 from the terminal b4 and becomes a high quality video signal. Further, since this video signal processing device is expensive, if not connected, the terminals b3 and b4 are directly connected as shown in the drawing.

[0041]

Since the present invention is configured as described above, when a failure occurs in the receiving system of the television broadcast radio wave for obtaining the video carrier wave to be synchronized, the video carrier wave from the built-in video carrier wave oscillator. By using
The rebroadcast program can be broadcast on a cable. Also, when the receiving system of the wireless line for obtaining the rebroadcast program is deteriorated, it is interrupted by sending the video signal obtained from the receiving system of the television broadcast radio wave for obtaining the synchronized video carrier wave to the cable. It is possible to rebroadcast without any.

[Brief description of drawings]

FIG. 1 shows a first CATV transmission device for multidirectional reception according to the present invention.
3 is a block diagram showing the configuration of the embodiment of FIG.

FIG. 2 shows a first CATV transmission device for multidirectional reception according to the present invention.
FIG. 13 is a block diagram showing a configuration of a modified example of the embodiment of FIG.

FIG. 3 is a second CATV transmission device for multidirectional reception according to the present invention.
3 is a block diagram showing the configuration of the embodiment of FIG.

FIG. 4 is a block diagram showing a configuration of a conventional CATV transmission device for multidirectional reception.

[Explanation of symbols]

1 Microwave Antenna 2 Microwave Demodulator 3,17,35 Ghost Canceller Circuit (GC) 4,18,36 Modulator 5,15,19,32,37 Mixer (MIX) 6,14,20,31,38 Band Pass filter (B
PF) 7,40 Carrier switcher 8,41 Video carrier oscillator 9, 11, 39, 42 Signal detector 10, 21, 33, 44 Local oscillator 12,43 Local switcher 13 VHF antenna 16, 34 Demodulator 22 Synchronous carrier Regenerator 23 Antenna selector 30 UHF antenna

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukihisa Kimura 1-4-24 Fujimi, Kofu-shi, Yamanashi Japan Network Service Co., Ltd.

Claims (3)

[Claims] 1. A CATV transmission device for transmitting a television signal using a frequency signal assigned to a channel of a television broadcasting radio wave as a carrier, by a cable, the television broadcasting signal received by an antenna for receiving a first frequency band. A reproduction means for reproducing a video carrier from the base station, a first video signal processing section for demodulating the received television broadcast signal into a baseband signal to process the video signal, and then returning it to the original video signal frequency band again. After demodulating the television broadcast signal received via a specific wireless line in a frequency band different from the first frequency band into a baseband signal and processing a video signal,
A second video signal processing unit for returning to the original video frequency band, a video carrier oscillator that oscillates at a frequency substantially equal to the video carrier, and a detection unit that detects whether or not the video carrier is reproduced by the reproduction unit. When the video carrier is detected by the detecting means, the video carrier reproduced by the reproducing means is supplied to the second video signal processing section to restore the original video signal frequency band. C for multi-directional reception characterized by
ATV transmission device. 2. A television signal normally output from the second video signal processing unit is converted into a frequency band of a predetermined channel and output, and when a received signal from the wireless line is deteriorated, 2. The multi-directional receiving CATV transmission device according to claim 1, wherein the television signal output from the first video signal processing unit is converted into a frequency band of a predetermined channel and output. 3. A local oscillator signal for converting a television broadcast signal received by an antenna for receiving the first frequency band into a video intermediate frequency, and a television signal output from the second video signal processing section. , Or the first
2. The CATV transmission device for multidirectional reception according to claim 1, wherein a local oscillator signal for converting a television signal output from the video signal processing unit into a frequency band of a predetermined channel is commonly supplied from a local oscillator. .