JP3156972B2 - FM rebroadcast system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FM rebroadcasting system for rebroadcasting FM broadcasts, for example, in a car tunnel.

[0002]

2. Description of the Related Art Conventionally, this type of system has been developed with the F
The M radio wave is received by the receiving antenna and the FM receiver, and FM demodulation is performed to obtain an audio signal. This audio signal is provided to the rebroadcasting apparatus, and FM-modulated by the rebroadcasting apparatus. Then, an FM signal obtained by FM-modulating the audio signal is supplied to a transmission antenna installed at a rebroadcasting target such as a tunnel, and emitted from the transmission antenna into the air as FM radio waves.

FIG. 2 is a block diagram showing a configuration example of a conventional rebroadcasting apparatus. In the drawing, IN1, IN2,..., INn are input terminals of audio signals, respectively, and receive audio signals of respective channels to be rebroadcast are supplied from the FM receiver. The audio signals input from the input terminals IN1, IN2,..., INn are relay contacts k1-1, k1-2,.
Through each of the stereo modulators 20-1, 20-2 ..., 20-n
Is input to each of.

The stereo modulators 20-1 to 20-n perform FM stereo modulation of carrier waves having frequencies f1, f2,..., Fn of the corresponding channels with the input audio signal. The stereo modulators 20-1 to 20-n perform FM stereo modulation.
The M signal is given to the power amplifier 21. The power amplifier 21 amplifies the given FM signal to a level necessary to emit the signal as a radio wave, mixes each of the channels f1 to fn, and supplies it to the transmitting antenna.

By the way, for example, in FM rebroadcasting in a car tunnel or the like, an emergency broadcast such as accident information is provided. That is, in FIG. 2, an interrupt sound for an emergency broadcast is input from a terminal 22, and the interrupt sound is amplified by an interrupt sound amplifier 23. Then, the interrupt sound amplified by the interrupt sound amplifier 23 is transferred to the relay contacts k1-1 to k1-1.
Input to each of the stereo modulators 20-1 to 20-n via each of k1-n. Thereafter, as in the case of the above-described normal voice, FM stereo modulation, power amplification, and the like are performed, and the resultant is provided to the transmission antenna. The relay contacts k1-1 to k
The switching of 1-n is performed by driving the relay K1 under interrupt control externally performed via the terminal 24.

As described above, the conventional rebroadcasting apparatus has the stereo modulators 20-1 to 20-n. Here, the stereo modulators 20-1 to 20-n are very expensive and complicated because various characteristics such as frequency characteristics have to be matched with the modulators installed in the broadcasting stations of the corresponding channels. Configuration.

[0007]

As described above, the conventional F
In the M rebroadcast system, an incoming FM radio wave is received by a receiving antenna and a receiving device, demodulated into an audio signal, and then input to a retransmitting device. Then, in the retransmission device, F
Rebroadcasting is performed by performing M stereo modulation. For this reason, a large-sized and expensive demodulator and a complicated and expensive stereo modulator are required for the receiving device and the re-transmitting device, so that the system becomes expensive and maintenance is troublesome and costly. There was such a problem.

The present invention has been made in view of such circumstances, and an object of the present invention is to simplify the system configuration, thereby reducing the cost of the system, the time and effort for maintenance, and the cost. It is to provide a possible FM rebroadcast system.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a receiving means for receiving incoming FM radio waves of a plurality of channels, converting them into high-frequency FM signals, and transmitting them without demodulation; A plurality of FM monaural modulation means provided to correspond to each of the plurality of channels to generate an FM monaural signal corresponding to each channel frequency by performing FM monaural modulation on an audio signal input from the outside in correspondence with each of the plurality of channels; Selecting means for selectively selecting the high-frequency FM signal obtained by the receiving means and the FM monaural signal generated by the FM monaural modulating means in accordance with an instruction from the outside; Transmitting means for emitting the high-frequency FM signal or the FM monaural signal into the air as FM radio waves.

[0010]

According to the present invention, a high frequency FM signal obtained by converting an incoming FM radio wave is transmitted to the retransmitting device without being demodulated into a voice signal. Then, the retransmitting device switches between a high frequency FM signal separated for each channel and a monaurally modulated external signal corresponding to each channel, which is provided to the transmitting means, and sends out to the air as FM radio waves. For this reason, although the number of inexpensive monaural modulators having a relatively simple configuration is increased, an expensive demodulation means and a stereo demodulation means having a complicated configuration are not required, and the FM can be easily maintained at low cost.
A rebroadcast system can be provided.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of the FM rebroadcast system according to the present embodiment. The same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, reference numeral 1 denotes a high-frequency F
This is a receiving antenna for converting into an M signal. The FM signal obtained by the receiving antenna 1 is provided to the tuner 2.
The tuner 2 extracts signals of the respective channels f1 to fn from the applied FM signal, and supplies these signals to the FM rebroadcasting apparatus 3 in parallel.

In the FM rebroadcasting apparatus 3, the signals of the respective channels f1 to fn given from the tuner 2 are input to the power amplifier (mixer) 21 via the relay contacts k1-1 to k1-n. I do.

Each channel f1 provided by the tuner 2
Signal input terminals IN1 to INn are connected to a relay contact k1-
1 to k1-n are connected to normally closed contacts, while the normally open contacts of relay contacts k1-1 to k1-n are connected to monaural modulators 31-1, 31-2 ..., 31-n, respectively. Have been. Each of the monaural modulators 31-1 to 31-n receives the interrupt audio amplified by the interrupt audio amplifier 23, respectively. Monaural modulator 31-1 ~
31-n are the frequencies f1 and f2 of the corresponding channels, respectively.
.., Fn and generate F.
M monaural modulation. The FM signals obtained by the monaural modulators 31-1 to 31-n are also supplied to the power amplifier 21 via relay contacts k1-1 to k1-n.

The FM signal output from the power amplifier 21 is transmitted via an output terminal OUT to a leaky-coaxial-cable (LCX) laid in the tunnel TN.
4 is supplied. The LCX 4 has a terminating resistor 5 connected to its end, and functions as a transmitting antenna.

Thus, the present FM rebroadcasting system receives the arriving FM radio wave and gives the FM signal to the power amplifier 21 without demodulation, to provide it for rebroadcasting. The interrupted voice is FM-monaural-modulated by the monaural modulators 31-1 to 31-n. Then, the FM signals obtained by the monaural modulators 31-1 to 31-n are supplied to the power amplifier 21 and used for broadcasting. Therefore, the retransmitting device 3 does not need a stereo modulator, and it is sufficient that the retransmitting device 3 includes a monaural modulator that is simpler in configuration than the stereo modulator and is inexpensive. Also, since the FM signal obtained by receiving the arriving FM radio wave is not demodulated, a demodulator is not required, and in this regard, the system configuration is simple and inexpensive.

By the way, if demodulation is performed once, then re-modulated and then re-broadcasted, processing such as fading compensation can be performed after demodulation. However, if the received electric field is strong, such processing is not possible. The present invention is not always necessary, and the present invention is extremely effective in a place where conditions are satisfied, such as a strong reception electric field.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the FM rebroadcasting system for rebroadcasting in a car tunnel is described. However, the target for rebroadcasting is not limited to a car tunnel, and may be any target.

In the above embodiment, the FM signal is separated by the tuner 2 for each channel. However, the FM signal obtained by the receiving antenna 1 may be directly input to the rebroadcasting apparatus 3 without separation. In addition, various modifications can be made without departing from the spirit of the present invention.

[0020]

According to the present invention, an incoming FM radio wave is
A receiving means for converting the signal into an M signal, for example, a receiving antenna and a tuner;
FM monaural modulation means such as a monaural modulator for generating an FM monaural signal by monaural modulation, and the FM signal obtained by the reception means and the FM monaural signal generated by the FM monaural modulation means are externally transmitted. a selection means such as alternatively selecting for example a relay in accordance with the instructions, to release the pre-Symbol FM signal or the FM monaural signal selected by the selection means in the air as an FM radio wave,
For example , since the system is constituted by the power amplifier and the transmission means including the leaky coaxial cable , there is no need to provide a stereo modulator in the system as in the conventional case, and the system configuration is simplified. As a result, the cost of the system, the time and effort for maintenance, and the cost can be reduced.
M rebroadcast system.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an FM rebroadcast system according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Receiving antenna, 2 ... Tuner, 3 ... Rebroadcasting apparatus, 2
1: Power amplifier, 23: Interrupt audio amplifier, 31-1 to 31-n ...
Monaural modulator, K1 relay, k1-1 to k1-n relay contacts, 4 leaky coaxial cable (LCX), 5 termination resistor.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04H 1/00 H04B 5/00

Claims (1)

(57) [Claims] A receiving means for receiving incoming FM radio waves of a plurality of channels, converting the received FM radio waves into high-frequency FM signals and transmitting the demodulated FM signals without demodulation, and provided for each of the plurality of channels; A plurality of FM monaural modulation means for FM-modulating an input audio signal in correspondence with each of the plurality of channels to generate an FM monaural signal corresponding to each channel frequency; and the high-frequency wave obtained by the receiving means. Selecting means for selectively selecting the FM signal and the FM monaural signal generated by the FM monaural modulating means in accordance with an instruction from the outside; and the high-frequency FM signal selected by the selecting means or A retransmission system for transmitting an FM monaural signal into the air as FM radio waves.