JPS6379427A - Auxiliary signal transmission system of radio transmission system - Google Patents

Abstract

PURPOSE:To contrive to simplify the device constitution and the effective utilization of the frequency by using an auxiliary signal so as to apply frequency modulation to a pilot signal and sending the result thereby eliminating the need for a subcarrier exclusive for the auxiliary signal. CONSTITUTION:When the operator of a transmission side equipment 10 inputs a voice from a microphone to discuss the maintenance with the operator of a receiving side equipment 20, the voice signal is led to a frequency modulation circuit 40 as an auxiliary signal OS. The modulation circuit 40 uses the pilot signal PS as a carrier to frequency-modulate the auxiliary signal OS and the result is sent while being synthesized with a TV signal VS by a synthesizer 12. The pilot signal PS separated and extracted by a band pass filter 27 is led to a detector 28 at a synthesizer 12 and also led to a frequency demodulator circuit 41. The demodulation circuit 41 demodulates the auxiliary signal OS and outputs the result as a voice signal via a speaker or the like.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a wireless transmission system used for example in television signal transmission, and in particular to a method for transmitting auxiliary signals between transmitting and receiving devices. Regarding.

<Conventional technology> When transmitting television (TV) signals over long distances, SH
F-band wireless transmission systems may be used. Third
The figure shows an example of its configuration, where 1 is the transmitting side device, 2
indicate receiving side devices, respectively. First, the sending device 1
First, the VSB-AM modulated TV signal vS of a plurality of channels in the VHF or UHF band is introduced into the input conversion circuit 11, and this circuit 11 rearranges it into, for example, 6 Mth intervals, and then the synthesizer 12 converts it to a constant level. is combined with the pilot signal PS. This synthesized signal is then introduced into the frequency conversion circuit 13, where it is mixed with the signal generated from the local oscillator 14, frequency-converted into an SHF band signal, and then amplified by the high-frequency amplifier 15. It is transmitted from the antenna 16 toward the receiving device 2. On the other hand, the receiving side device @ 2 receives the SHF band signal coming from the transmitting side device 1 with an antenna 21 and first introduces it into a frequency conversion circuit 22, where it is generated from a local oscillator 23. It is mixed with the signal and frequency-converted to a VHF or UHF band signal. After the output signal is amplified by the AGC amplifier 24, the TV signal is outputted via the output conversion circuit 25.

At this time, a pilot signal PS is separated from the output signal of the AGC amplifier 24 by a divider 26 and a bandpass filter 27, and this pilot signal PS is sent to a detector 2.
8, and the level of the TV signal is made constant by variably controlling the amplification factor of the AGC amplifier 24 using the detected output. Therefore, in such a system,
For example, even if the condition of the wireless transmission path changes due to weather, TV signals can always be transmitted stably.

By the way, in this type of system, an auxiliary signal is generally transmitted in addition to the TV signal between the transmitting device 1 and the receiving device 2 for maintenance meetings, remote control, etc. Conventionally, the transmission of the information has been carried out as follows, for example. That is, apart from each transmission channel of the TV signal and the transmission frequency of the pilot signal PS, a subcarrier dedicated to the auxiliary signal O8 is set as shown in FIG. 4, for example. As shown in FIG. 3, an auxiliary signal modulation circuit 19 consisting of a frequency modulation circuit 17 and a synthesizer 18 is provided in the transmitting device 1, and the frequency modulation circuit 17 modulates the frequency of the subcarrier with the auxiliary signal to generate this signal. Synthesizer 18
The signal is combined with the TV signal and sent to the receiving side. On the other hand, the receiving side equipment @2 includes a distributor 29 and a band pass filter 30.
Auxiliary signal regeneration circuit 3 consisting of a frequency demodulation circuit 31 and a frequency demodulation circuit 31
2 is provided, and the above amount is obtained from the output signal of the AGC amplifier 24! !
Il! 29 and a bandpass filter 30 to extract a subcarrier component, and convert this subcarrier into a frequency IB and a demodulation circuit 3.
1 to reproduce the auxiliary signal O8. Therefore, the auxiliary signal O8 can be reliably transmitted together with the TV signal vS.

However, in such a conventional auxiliary signal transmission method, a subcarrier dedicated to the auxiliary signal O8 is set and transmitted, so as mentioned earlier, the auxiliary signal is transmitted to the transmitting side device 1 and the receiving side device 2. A dedicated modulation circuit 19 and demodulation circuit 32 must be provided, which has the disadvantage of complicating the configuration of each device. Furthermore, this was not preferable in terms of effective use of frequencies.

(Problems to be Solved by the Invention) As described above, the conventional system has the problems of complicating the configuration of the device and not being able to utilize frequencies effectively.The present invention focuses on these points, and The present invention aims to provide an auxiliary signal transmission method for a wireless transmission system that eliminates the need for subcarriers dedicated to auxiliary signals, simplifies the configuration of the device, and makes effective use of frequencies.

[Structure of the Invention] (Means for Solving the Problems) As shown in FIG. The pilot signal is frequency-modulated with an auxiliary signal and sent out, and the pilot signal frequency demodulation circuit B1 is provided to the receiving side device! i: Provide this circuit B
The auxiliary signal is reproduced by frequency demodulating the pilot signal received by the auxiliary signal.

(Function) As a result, the auxiliary signal is apparently transmitted as an upper pilot signal, so there is no need to set up a subcarrier dedicated to the auxiliary signal as in the past, and the effective use of frequency is improved accordingly. It will be done.

Also, most of the circuit for transmitting the auxiliary signal is also used as the circuit for transmitting the pilot signal, so
The construction of the valve device is simplified.

(Embodiment) FIG. 2 shows the configuration of a wireless transmission system to which an auxiliary signal transmission system is applied in an embodiment of the present invention.

In this figure, the same parts as those in FIG. 3 are given the same reference numerals and detailed explanations will be omitted.

The transmitting device 10 is provided with a frequency modulation circuit 40 that uses the pilot signal PS as a carrier wave and frequency-modulates the pilot signal PS with the auxiliary signal O8. Here, the modulation degree of this frequency modulation circuit 40 is set to be shallow to the extent that it does not affect the level of the pilot signal PS. On the other hand, the receiving side device 2o is provided with a frequency demodulation circuit 41 that introduces the pilot signal PS output from the bandpass filter 27 of the AGC loop and demodulates the frequency of this pilot signal PS to reproduce an auxiliary signal.

With such a configuration, when the operator of the transmitting side @1a10 inputs voice from the microphone to have a maintenance meeting with the operator of the receiving side device 2o, for example, the voice signal is sent to the frequency modulation circuit 40 as the auxiliary signal O8. will be introduced in Then this frequency modulation circuit 40
uses the pilot signal PS as a carrier wave, shallowly frequency modulates the pilot signal PS with the auxiliary signal O8, and outputs it to the synthesizer 12. Therefore, the auxiliary signal O8 is combined with the TV signal S while being carried on the pilot signal PS, and is sent out to the receiving side signal fi120. On the other hand, in the receiving side bag @20, the pilot signal PS separated and extracted by the band pass filter 27 forming a part of the AGC loop is introduced to the detector 28 and also to the frequency demodulation circuit 41. And this frequency demodulation circuit 4
1, frequency demodulation of the pilot signal PS is performed.

Therefore, in this state, the auxiliary signal O is sent from the transmitting device 10.
When the pilot signal PS frequency-modulated by 8 arrives, the frequency demodulation circuit 41 outputs an auxiliary signal O8 obtained by frequency demodulating the pilot signal PS, and this auxiliary signal O8 is amplified by, for example, a low frequency amplifier. It is supplied to a speaker and output as audio. Therefore, the operator of the receiving device 20 can learn instructions etc. from the operator of the transmitting device 10 by listening to the audio output from this speaker.

In this embodiment, since the auxiliary signal O8 is transmitted on the pilot signal PS, the dedicated subcarrier can be used as a subcarrier, and as a result, the frequency of the subcarrier can be used for other signal transmission. Since it becomes possible to divert the frequency, it is possible to use the frequency effectively. Further, since a part of the circuit required for transmitting the auxiliary signal O8 can be used also as a circuit for transmitting the pilot signal PS, the circuit configuration of the transmitting side device 10 and the receiving side device 20 can be simplified. .

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the circuit configurations of the transmitting side device and the receiving side device, the types of transmission signals, etc. may be modified in various ways without departing from the gist of the present invention. can.

[Effects of the Invention 1] As detailed above, according to the present invention, a frequency modulation circuit for auxiliary signals using a pilot signal as a carrier wave is provided in the transmitting side device, and the pilot signal is frequency-modulated with the auxiliary signal by this circuit and transmitted. In addition, by providing a pilot signal frequency demodulation circuit in the receiving side device and frequency demodulating the pilot signal received by this circuit to reproduce the auxiliary signal, a subcarrier dedicated to the auxiliary signal can be used. It is possible to provide an auxiliary signal transmission method for a wireless transmission system that eliminates the need for simplification of device configuration and effective use of frequencies.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a circuit block diagram showing the configuration of a wireless transmission system to which an auxiliary signal transmission system according to an embodiment of the present invention is applied, and FIG. 3 is a functional block diagram showing the configuration of a conventional auxiliary signal transmission system. FIG. 4 is a circuit block diagram of a wireless transmission system to which the signal transmission method is applied, and is a frequency distribution diagram for explaining the conventional auxiliary signal transmission method. 10... Transmission side device, 11... Input conversion circuit, 12
...Synthesizer, 13.22...Frequency conversion circuit, 14
．． 23...Local oscillator, 15...High frequency amplifier, 1
6.21... Antenna, 20... Receiving side device, 24
... AGC amplifier, 25... Output conversion circuit, 26.
...Distributor, 27... Bandpass filter, 28...
Detector, 40... Frequency modulation circuit, 41... Frequency demodulation circuit, VS... Television (TV) signal, PS
...Pilot signal, O8...Auxiliary signal. Applicant's representative Patent attorney Takehiko Suzue +ch 2ch 3ch 4ch 5
ch figure 4

Claims (1)

[Claims] The transmission side device converts the transmission signal into a predetermined transmission frequency band together with a pilot signal of a certain level, and then sends it to the reception side device, which receives the transmission signal and extracts the pilot signal from the transmission signal. In a wireless transmission system in which the level of the transmitted signal is controlled based on the reception level of the pilot signal after separation, the transmitting side device is provided with frequency modulation of the pilot signal by an auxiliary signal used for making a meeting between the transmitter and the receiver. 1. An auxiliary signal transmission method for a wireless transmission system, characterized in that a receiving side device is provided with a demodulation circuit that frequency-demodulates a received pilot signal and reproduces the auxiliary signal.