KR200346362Y1 - AM broadcasting repeater with band remove circuit - Google Patents

Abstract

The present invention relates to an AM broadcast re-relay device having a band cancellation circuit, wherein the AM broadcast re-relay device includes an AM LS, a main repeater, and a plurality of sub-relays for receiving an antenna signal. Eight series resonant trap circuits can be arranged in parallel between the transmission line and ground to reduce the high signal in some of the AM signal bands input to the repeater, and the output of the serial resonant trap circuit is common. And a band elimination circuit for outputting through the attenuator, and install an optical transmitter in the AM LA, and install an optical receiver in the main repeater to transmit a broadcast signal as an optical signal using an optical cable therebetween. In addition, a splitter is installed in front of the power amplifier of the main repeater and the divided signal is transmitted by an optical transmitter. Through the cable it is characterized by being configured to transmit to the sub relay.

Description

AM broadcasting repeater with band remove circuit

The present invention relates to an AM underground broadcasting apparatus using a band cancellation circuit. In particular, the present invention provides a band cancellation circuit including eight series resonant circuits and an amplifier circuit for suppressing noise levels, thereby reducing the burden of the power amplifier and being inputted. The present invention relates to an AM underground re-broadcaster using a band-rejection circuit that allows signals to be uniformly relayed at high output.

In general, the underground broadcast apparatus is a device that relays a broadcast so that the radio broadcast can be heard in an underground environment where radio waves cannot reach due to the grounding effect of the ground such as a tunnel, a subway, or a basement of a building.

The existing AM radio repeater amplifies the input signal to a proper level without any signal processing and then amplifies the signal to a high level in the power amplifier. In this method, the gain of the power amplifier is constant within a certain band regardless of the frequency. When the large and small signals are simultaneously received by the saturation point of the power amplifier, only the large signal is relayed and the small signal is not well relayed. There is a case. That is, it is greatly affected by the state of the input signal.

Another conventional repeater system selects and relays channels to separately amplify AM signals for each frequency. This is because a device for relaying one channel must exist for each channel to receive multiple channels. Add sorting device as many channels as you want.

This makes the device complex, expensive and cannot broadcast additional broadcasts. Therefore, additional costs are required to relay additional broadcasts.

The present invention aims to provide an AM broadcast repeater that compensates for the problems of the existing AM broadcast repeater, thereby reducing the burden of the power amplifier and equalizing the input signal so that all channels can be relayed at high output. .

The present invention can compensate for some of the disadvantages of the conventional schemes by lowering the signal band of the high level (535KHz ~ 1605KHz) of the AM signals received by the antenna by using a resonance circuit to reduce the low level signal and its level. Make the same adjustments. To this end, it has a band elimination circuit including eight series resonant circuits and an attenuator for suppressing noise levels.

In addition, the present invention can be well relayed by transmitting a signal to the light even in a relatively long distance that is difficult to relay due to the existing loss, and by using a low-loss optical cable, it is easy to expand even if other systems are combined later. It is intended to have extensibility to do so.

Figure 1 is a block diagram showing an overview of the AM broadcast relay system according to the present invention.

2 is a schematic view of the AM LS of the AM broadcast relay system according to the present invention;

3 is a block diagram of the main repeater of the AM broadcast re-relay device having a band cancellation circuit according to the present invention.

4 is a block diagram of a band cancellation circuit according to the present invention.

5 is a configuration diagram of a sub repeater according to the present invention.

<Description of the symbols for the main parts of the drawings>

1: external AM antenna 2, 3: optical cable

100: AM L 110: high voltage capacitor

120, 220, 250, 320: AM bandpass filter

130: low noise amplifier (MMIC) 140, 242: attenuator

150, 292, 293: optical transmitter 160, 291, 360: power supply

200: main repeater 201, 301. 301 ': leaky coaxial cable

210, 310: optical receiver 230, 260: amplifier

240: band elimination circuit 241, 241-1, 241-8: series resonant trap circuit

270: divider 280, 340: power amplifier

290, 350: Low pass filter 300, 300 ': Sub repeater

330: Delive Amplifier

In the AM broadcasting re-relay device having the band elimination circuit according to the present invention, the AM broadcasting signal received from an external antenna through AM LN is amplified by the main repeater and broadcasted through the leakage coaxial cable. In the repeater,

The main repeater,

A first bandpass filter for receiving and band-passing the broadcast signal from the AM LS, a first amplifier for amplifying the first bandpass filtered signal, and a high level of the signal amplified in the first amplifier. A band cancellation circuit for lowering the signal band by using a resonant circuit to reduce signal levels of arbitrary bands to be at a level comparable to a low level signal, and a second band for bandpassing the output signal of the band cancellation circuit. A pass filter, a second amplifier for amplifying the filtered signal, a power amplifier for power amplifying the signal of the second amplifier, a low pass for removing noise from the output signal of the power amplifier and radiating it with a leaky coaxial cable Characterized in that it comprises a filter.

The present invention is to install the optical transmitter in the AM LAN and to install the optical receiver in the main repeater is configured to transmit a broadcast signal as an optical signal by using an optical cable between them, the divider in front of the power amplifier of the main repeater It is characterized in that it is configured to transmit the distributed signal to the sub-relay through the optical cable by the optical transmitter.

In the band removing circuit according to the present invention, eight series resonant trap circuits capable of adjusting the frequency in parallel between the transmission line and the ground are arranged so as to reduce a high signal of some bands of the input AM signal band. It characterized in that the output of the series resonant trap circuit in common to the output through the attenuator to the second band pass filter.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing the outline of the AM broadcast re-relay apparatus to which the present invention is applied.

An external AM antenna (1) for receiving AM broadcast over the airwaves, an AM L & A (LNA) 100 for receiving AM broadcast signals received through the external AM antenna 1 and converting them into optical signals; The AM signal is received from the AM LS 100 through the optical cable 2 and amplified to have a different gain according to the band, and the power amplified to have a substantially uniform output. The leaky coaxial cable 201 The main repeater (MAIN REPEATER) to emit through and the sub-relay radiator receives the AM broadcast signal from the main repeater 200 through the optical cable (3) to convert into RF signal to radiate through the leaky coaxial cable (301) (SUB REPEATER) (300).

As described above, the AM repeater to which the present invention is applied is largely composed of the AM LS 100, the main repeater 200, and the sub repeater 300, and further serve according to the number of tunnels or the expansion of the broadcasting area. Repeater 300 'can be added.

The AM LS 100 receives an external AM signal and amplifies it into a signal having an appropriate size with a low noise amplifier, converts it into light, and transmits it to the main repeater 200. Because it transmits by light, it is easy to construct without being restricted by distance. The signal coming into the main repeater 200 has different gains depending on the band, and thus has a substantially uniform output, which is amplified by power and radiated through the leaky coaxial cable 201. In addition, the signal is converted to light and sent to the sub repeater 300 so as to emit the signal at a higher distance. The signal sent to the sub repeater 300 is converted back to RF and amplified in the place where necessary, and radiated through the leaky coaxial cable 301. In addition, these sub repeaters can be expanded according to the number of places required.

2 is a block diagram of an AM LNA of an AM broadcast relay device to which the present invention is applied.

As shown in the drawing, there is a high voltage capacitor 110 that prevents the input of high voltage DC power into the input circuit, and there is a band pass filter (BPF) 120 which prevents the input signal other than the AM signal from being input. . Signals other than the input signal AM are removed by the band pass filter 120. The AM signal thus input is amplified by an amplifier (MMIC) 130 having a low noise figure and transmitted to the optical transmitter 150. A 2dB attenuator 140 is inserted between the optical transmitter 150 and the amplifier 130 to ensure impedance matching. Reference numeral 160 in the drawing is a power supply.

3 is a configuration diagram of a main repeater according to the present invention.

Amplification unit 230 after converting the signal transmitted to the light from the AM LS 100 to the RF signal through the optical receiver 210, and removes other signals generated in the conversion process by the band pass filter (BPF) (220) Enters the band removing circuit 240 through. The configuration of the band removing circuit 240 is as shown in FIG.

The signals passing through the band elimination circuit 240 are again inputted through the AM band pass filter 250 and the amplifier 260 to the divider 270, and may be passed from the divider 270 to the sub relays 300. One of the divided signals is amplified by the power amplifier 280, and then spurious is removed through the power LPF 290 and radiated to the underground environment through the leaky coaxial cable 201. do.

In addition, the remaining signals are converted to light through the optical transmitters 292 and 293 and then transmitted to each sub-relay 300. Reference numeral 291 in the drawing is a power supply.

4 is a block diagram of the band cancellation circuit of the AM broadcast retransmission apparatus according to the present invention.

As shown therein, the band removing circuit 240 includes eight series resonant trap circuits 241: 241-1 to 241-8 that can adjust a frequency in parallel between a transmission line input from the amplifier 230 and a ground. ) Are arranged and configured to output the output of the series resonant trap circuits 241: 241-1 to 241-8 to the AM band pass filter 250 through the attenuator 242 in common. This uses a signal level reduction scheme commonly known as traps. In other words, it is a circuit that can remove (reduce) high signal of some band among AM signal bands by connecting 8 traps in parallel and adjusts level of signals that are not accurate but relatively uniformly through 8 band adjustment. By adjusting it, you can improve the quality of broadcast.

Through the band elimination circuit 240, the input signal may be uniformly adjusted by differently adjusting the amplification degree of some bands in the AM band.

5 is a configuration diagram of a sub repeater applied to the present invention.

The input optical signals are converted into RF signals through the optical receiver 310, and other signals generated during the conversion are removed while passing through the band pass filter (BPF) 320. This signal is amplified by a suitable signal in the drive amplifier 330 and amplified in the power amplifier (HPA) 340 and then spurious is removed through the low pass filter (LPF) 350 is radiated to the leaky coaxial cable 301 Lose. Reference numeral 360 in the drawing is a power supply.

In the present invention, in relaying AM broadcasting, a signal transmission is carried out between the LS and the main repeater, the main repeater, and each of the sub repeaters by using an optical cable. By constructing a fixed module, the input signal can be made uniform by adjusting the amplification degree differently by removing signals of some bands of AM broadcasting.

The present invention configured as described above has the effect of lowering the high level signal band through the band elimination circuit so that the low level signal and its level can be equally adjusted. This reduces the burden on the power amplifier and allows multiple channels to be relayed at high outputs. In addition, there is an effect that can be relayed well by transmitting a relatively long distance through the optical cable, there is an effect that the scalability is improved.

Claims (3)

In the AM broadcast relay system configured to receive AM broadcast signal received from an external antenna through AM LNA and then amplify the power in the main repeater to radiate through the leaky coaxial cable. The main repeater, A first bandpass filter for receiving and band-passing the broadcast signal from the AM LS, a first amplifier for amplifying the first bandpass filtered signal, and a high level of the signal amplified in the first amplifier. A band cancellation circuit for lowering the signal band by using a resonant circuit to reduce signal levels of arbitrary bands to be at a level comparable to a low level signal, and a second band for bandpassing the output signal of the band cancellation circuit. A pass filter, a second amplifier for amplifying the filtered signal, a power amplifier for power amplifying the signal of the second amplifier, a low pass for removing noise from the output signal of the power amplifier and radiating it with a leaky coaxial cable AM broadcast repeater having a band cancellation circuit characterized in that it comprises a filter. The method of claim 1, wherein the AM broadcast retransmission device, The optical transmitter is installed in the AM LA and the optical receiver is installed in the main repeater, and the broadcast signal is transmitted as an optical signal by using an optical cable therebetween, and the distributor is installed in front of the power amplifier of the main repeater. And a band elimination circuit, characterized in that configured to transmit the received signal to the sub repeater through the optical cable by the optical transmitter. The method of claim 1, wherein the band removing circuit, Eight series resonant trap circuits can be arranged in parallel between the transmission line and ground to reduce high signals in some of the input AM signal bands, and the output of the serial resonant trap circuit is commonly attenuated. AM broadcast relay having a band cancellation circuit, characterized in that configured to output to the second band pass filter through.