JP2019068354A - Diversity microphone receiving system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiving system of a diversity type microphone which can reduce the number of antenna cables and is free from noise and interference. A frequency converter 3 converts a frequency of a radio wave received by an antenna B into a value different from the frequency of a radio wave received by another antenna A. The multiplexing circuit 4 multiplexes the radio wave from the antenna A that has not undergone frequency conversion and the radio wave from another antenna B that has undergone frequency conversion by the frequency converter 3. One cable transmits the multiplexing signal output from the multiplexing circuit 4 to the receiver side. The frequency inverse converter returns the frequency of the radio wave frequency-converted by the frequency converter 3 to the frequency before conversion. The local oscillator 70 outputs the same local signal to the frequency converter 3 and the frequency inverse converter. [Selection diagram] Fig. 1

Description

  The present invention relates to a wireless microphone (hereinafter referred to as a WL microphone) receiving system using a diversity scheme.

  In wireless communication using the diversity scheme, radio waves transmitted from one transmitter are received by two or more antennas, and an antenna with good reception quality (for example, received electric field strength) is selected. Such a diversity scheme is also used as a reception system of a WL microphone as described in, for example, Patent Document 1 or Patent Document 2.

  In the conventional system, it was necessary to connect each signal from the receiving antenna of the WL microphone to the receiver with a cable. When the input signal from two or more antennas is supplied to the receiver, the input signal is usually supplied to the receiver using the same number of cables as the antenna input. However, antennas forming diversity (for example, two antennas A and B) are usually installed at a distance from one wavelength to about three wavelengths. Therefore, a plurality of cables will be laid in almost the same place.

  Further, as a receiving system for digital terrestrial broadcasting, for example, a technology for multiplexing and transmitting a plurality of antenna inputs using one cable is described in, for example, Patent Document 3. However, since this prior art uses different local signals when performing frequency inverse conversion, different frequency components are included when switching audio signals in an analog system and in real time like a WL microphone. And noise will be generated.

JP, 2006-319624, A JP, 2006-287709, A Patent No. 4719229 gazette

  As described above, in the prior art, it is necessary to lay out cables for the number of antennas, and there is a problem that the construction work of the system becomes complicated. In addition, the multiplex transmission technology adopted for terrestrial digital broadcasting has disadvantages such as noise, and can not be adopted for the reduction of the antenna cable of the analog WL microphone.

  In the case of an FM modulation signal, a signal transmitted directly and a signal subjected to frequency conversion are used after demodulation, and then switched for use. However, since a frequency shift occurs between the signal subjected to frequency conversion and the direct signal, Deviation occurs and appears as noise. Although frequency conversion requires a local signal indicating the amount of conversion for each channel, in order to avoid interference with other signals, the frequency of this local signal may be devised to fall within the unused frequency band as well. desired.

  The present invention is proposed to solve the problems of the prior art as described above. An object of the present invention is to provide a diversity microphone reception system that can reduce antenna cables and does not have noise or interference.

The diversity microphone reception system of the present invention is characterized by having the following configuration.
(1) A plurality of antennas for receiving radio waves from the transmitter.
(2) A frequency converter which converts the frequency of the radio wave received by the plurality of antennas into a frequency of a value different from the frequency of the radio wave received by another antenna.
(3) A circuit for multiplexing radio waves from an antenna not subjected to frequency conversion among the plurality of antennas and radio waves from other antennas subjected to frequency conversion by the frequency converter.
(4) One cable for transmitting the multiplexed signal output from the circuit that multiplexes the radio waves of the plurality of antennas to the receiver side.
(5) A splitter that is connected to the receiver end of the single cable and separates radio waves from each antenna from the multiplexed signal.
(6) Among the radio waves separated from among the signals multiplexed by the branching filter, a frequency inverse converter that returns the frequency of the radio wave frequency-converted by the frequency converter to the frequency before conversion;
A local oscillator that outputs the same local signal to the frequency converter and the frequency inverse converter.

The present invention also includes the following embodiments.
(7) The local oscillator is provided on the receiver side of the cable, and the local signal output from the local oscillator is input to the frequency inverter, and the frequency conversion is performed via the cable. Input to the

(8) A DC power supply is provided on the receiver side of the cable, and a DC current output from the DC power supply passes through the cable to the radio wave from the frequency converter, the frequency inverter and the antenna. Are supplied to a circuit that multiplexes

  According to the present invention, it is possible to reduce the number of cables to be wired to one by performing frequency conversion of one signal of two antenna inputs and performing multiplex transmission with one cable. In addition, using the same local signal can prevent noise and interference with other signals.

It is a systematic diagram showing an embodiment of a receiving system of the present invention. It is a systematic diagram showing an example of a frequency converter in an embodiment of the present invention. FIG. 7 is a system diagram showing an example of a frequency divider and a frequency inverter provided in an antenna divider in the embodiment of the present invention. It is a systematic diagram at the time of applying the present invention to the receiving system of WL microphone used at the platform of a station.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The number of WL microphones and antennas in this embodiment is merely an example, and is not limited.

[1. First embodiment]
(1) Configuration As shown in FIG. 1, the receiving system of the present embodiment is provided with a pair of diversity antennas (hereinafter referred to as antennas) A and B for receiving radio waves from the transmitter 1. A high frequency amplifier 2 is connected to the antenna A, and a frequency converter 3 is connected to the antenna B. The output sides of the high frequency amplifier 2 and the frequency converter 3 are connected to the input end of one cable 5 via the splitter 4. An antenna divider 6 is connected to the output end of the cable 5. The antenna divider 6 incorporates a frequency divider and a frequency inverter, and a plurality of diversity receivers 7 are connected to the output side thereof.

  Two pairs of antennas A ′ and B ′ having the same configuration as the antennas A and B are connected to the antenna divider 6 via one cable 5 respectively. The plurality of sets of antennas A and B and A 'and B' are disposed at appropriate intervals along the movement range of the transmitter 1, and similarly, the high frequency amplifier 2, the frequency converter 3 and the A wave 4 is provided.

  FIG. 2 is a system diagram showing an example of the frequency converter 3. The frequency converter 3 includes a band pass filter 31 for separating a necessary frequency band (ft) from radio waves received by the antenna B, an amplifier 32 for the separated ft signal, and a mixer circuit 33 for frequency conversion. . The mixer circuit 33 converts the signal ft from the antenna B into a superimposed signal fi (fi = ft ± fl) different in frequency from the signal ft from the antenna B by multiplying the signal ft from the antenna by the local signal fl from the antenna divider 6.

  A splitter 37 and a DC separator 38 are connected to the output side of the mixer circuit 33 via the band pass filter 34 of the superimposed signal, the amplifier 35 and the band pass filter 36. The splitter 37 separates the local signal fl transmitted from the antenna divider 6 via the cable 5, and the separated local signal fl is routed through the band pass filter 39, the amplifier 40 and the band pass filter 41. Are supplied to the mixer circuit 33. The DC separator 38 separates the DC component supplied from the antenna divider 6 via the cable 5 and supplies power to each circuit provided between the antenna and the cable 5.

  FIG. 3 is a system diagram showing an example of the frequency divider and the frequency inverse converter provided in the antenna divider 6. At the output end of the cable 5, a duplexer 62 on the antenna A side is connected via a DC mixer 61. The DC mixer 61 superimposes the output of the DC power supply of the antenna divider 6 on the local signal fl flowing toward the antenna side of the cable 5 and sends it to the demultiplexer 4. The splitter 62 separates the signal ft on the antenna A side which has not been frequency-converted from the superimposed signal fi transmitted via the cable 5.

  A splitter 65 is connected to the first output side of the splitter 62 on the antenna A side via a band pass filter 63 and an amplifier 64, and the output terminal of the splitter 65 is connected to the diversity receiver 7 .

  A splitter 66 on the antenna B side, a band pass filter 67, and a mixer circuit 68 are sequentially connected to the second output side of the splitter 62 on the antenna A side. The local signal fl is supplied to the branching filter 66 and the mixer circuit 68. That is, the antenna divider 6 is provided with a local oscillator 70, and after the local signal fl generated by the local oscillator 70 is amplified by the amplifier 71, a splitter 72 and a bandpass filter 73 or 74 are used to provide a splitter. 66 and the mixer circuit 68. The local signal fl supplied to the branching filter 66 is superimposed on the DC power supply in the DC mixer 61, and is sent to the frequency converter 3 via the cable 5.

  The splitter 66 extracts only the superimposed signal fi from the local signal fl and the superimposed signal fi input thereto, and outputs the superimposed signal fi to the mixer circuit 68 via the band pass filter 67. In the mixer circuit 68, based on the local signal fl from the local oscillator 70, frequency inverse conversion processing of the superimposed signal fi sent from the demultiplexer 66 is performed. A splitter 77 is connected to the output side of the mixer circuit 68 via a band pass filter 75 and an amplifier 76, and an output terminal of the splitter 77 is connected to the diversity receiver 7.

(2) Operation The operation of the present embodiment is as follows.
In the present embodiment, the radio wave ft emitted from the transmitter 1 is received by the antenna A and the antenna B. The radio wave ft received by the antenna A is amplified by the high frequency amplifier 2 and input to the duplexer 4.

  The radio wave ft received by the antenna B is subjected to high frequency amplification and frequency conversion in the frequency converter 3 and converted to the superimposed signal fi (fi = ft ± fl), and then input to the duplexer 4. That is, as shown in FIG. 2, the local signal fl from the antenna divider 6 is input to the frequency converter 3. Therefore, in the mixer circuit 33 of the frequency converter 3, the radio wave ft received by the antenna B and the local Based on the signal fl, a superimposed signal fi of a frequency different from that of the received radio wave ft is created.

  The signal ft from the antenna A (the path of (1) in FIG. 1) and the superimposed signal fi (the path of (2) in FIG. 1) frequency-converted based on the signal ft from the antenna B After being multiplexed at step (d), the signal is sent as a multiplexed signal to one cable 5 (the path (3) in FIG. 1), and transmitted to the antenna divider 6 via the cable 5.

  In the antenna divider 6, the signal ft from the antenna A in the multiplexed signal is separated from the multiplexed signal by the demultiplexer 62 on the antenna A side, and passes through the band pass filter 63, the amplifier 64 and the divider 65. The signal is output to the diversity receiver 7 (path (4) in FIG. 1).

  The superimposed signal fi in the multiplexed signal is separated from the multiplexed signal by the demultiplexer 66 on the antenna B side, and output to the mixer circuit 68 via the band pass filter 67. In mixer circuit 68, frequency inverse conversion processing of superimposed signal fi is performed by arithmetic processing of local signal fl supplied from local oscillator 70 and superimposed signal fi, and the same signal ft as that received by antenna B is obtained. It is generated.

  The signal fi from the antenna B generated by the mixer circuit 68 is output to the diversity receiver 7 via the band pass filter 75, the amplifier 76 and the distributor 77 (the path (5) in FIG. 1).

(3) Frequency Conversion and Frequency Inversion In this embodiment, the same local signal fl is used to perform frequency conversion and frequency inverse conversion of the reception signal ft of the antenna B, thereby receiving the reception signal from the superimposed signal fi. It is possible to reproduce ft.

In this embodiment, assuming that the received signal is Asin α and the local signal is B sin β, in frequency conversion,

Thus, only one term of the equation (1) is taken out by the band pass filter, and (AB / 2) cos (α-β) is transmitted as the superimposed signal fi.

In re-frequency conversion, assuming that the transmission signal is (AB / 2) cos (α-β) and the local signal is C sin β, the arithmetic processing by the mixer circuit 68 is

Thus, when only one term of the equation (2) is extracted by the band pass filter 75 from this calculation result, the signal ft after the re-frequency conversion is (ABC / 4) · sin α. In the case of the FM modulation wave, since the amplitude has no information, it is possible to take out a signal having the same frequency information as the reception signal ft by the frequency inverter.

For example, the frequency of the WL microphone which is often used in the station yard is a radio equipment C type (300 MHz band) for a specific low power radio station radio microphone. In this type of wireless microphone, settings are as follows.
(1) Asin α: 322.025 MHz to 322.400 MHz
(2) Bsin β: 109.500 MHz
(3) (AB / 2) cos (.alpha .-. Beta.): 212.525 MHz to 212.900 MHz

  In this case, the duplexer 4 of FIG. 1 has a frequency of 300 MHz or more (ft passing the path (1) in the figure) and less than 250 MHz (fi and fl passing the path (2) in the figure). The wave device 37 can be configured by simple low pass filters and high pass filters of 200 MHz or more (fi) and less than 150 MHz (fl). Moreover, since Bsinβ can be changed in the range of about 70 MHz to 120 MHz, interference avoidance from a nearby wireless system can be easily realized.

(3) Effects According to the present embodiment, the following effects are exhibited.
(1) A plurality of diversity signals can be transmitted by one cable, and by performing frequency conversion and frequency inverse conversion at the same local frequency, the reception signal can be regenerated at the receiver end and transmitted by a plurality of cables The same diversity effect as in the case can be obtained.

(2) By making the local frequency the same, the frequency can be easily changed, and the interference from the proximity system can be avoided. In particular, since the same local frequency is used, it is possible to easily change the conversion frequency, the local frequency, and the converted frequency by changing the local frequency within the pass frequency range of each device. Can be avoided.

[2. Other embodiments]
The present invention is not limited to the above embodiment, and includes, for example, the following other embodiments.

(1) As shown in FIG. 4, transmitters 1-1 to 1-4 having transmission frequencies of different channels for the upstream and downstream homes of the station, and a plurality of corresponding diversity antennas A and B Provide In such a configuration, the signals ft1 to ft4 received by the antennas A and B of each set are amplified or frequency-converted by the high frequency amplifier 2 and the frequency converter 3, respectively, and then multiplexed by the demultiplexer 4 The signal is transmitted to the antenna divider 6 via the cable 5 of

  In antenna divider 6, after the signal of antenna A and the signal of antenna B are separated from the multiplexed signal input from each cable 5, frequency reverse conversion is performed on the signal of antenna B, and then diversity reception of each channel is performed. Output to the machine. By doing this, it is possible to transmit received signals from a plurality of transmitters of different channels to the receiver side via the dedicated cables 5, respectively.

(2) As power supplies for the high frequency amplifier 2 and the frequency converter 3 connected to the antennas A and B, instead of supplying DC power from the antenna divider 6 via the cable 5, an independent power supply is provided on the antenna side. It can also be provided.

(3) The local oscillator 70 for outputting a local signal need not be provided inside the antenna divider 6 as long as it can supply the same local signal to the frequency converter 3 and the frequency inverter. It may be provided on the antenna side of the cable 5 or may be provided on the receiver side.

(4) The above embodiment uses the splitter 4 as a circuit for multiplexing radio waves from a plurality of antennas, but it separates the direct current supplied via the cable 5 in the splitter 4 In the case where the DC current is separated by another circuit, or when the antenna side of the cable 5 has an independent power supply, the multiplexer 4 may be replaced with another multiplexing circuit. . The same applies to other duplexers and DC separators, and dedicated circuits can be used when local signals and DC power are not transmitted overlapping radio waves from an antenna.

DESCRIPTION OF SYMBOLS 1 ... Transmitter 2 ... High frequency amplifier 3 ... Frequency converter 4 ... Splitter 5 ... Cable 6 ... Antenna divider 7 ... Diversity receiver 31, 34, 36, 39, 41, 63, 67, 73, 74, 75 ... Band-pass filters 32, 35, 40, 64, 71, 76 ... Amplifiers 33, 68 ... Mixer circuits 37, 62, 66 ... Splitters 38 ... DC splitters 61 ... DC mixers 65, 72, 77 ... Splitters 70 ... Local oscillator

Claims (3)

A plurality of antennas each for receiving radio waves from the transmitter;
A frequency converter for converting the frequency of the radio wave received by the plurality of antennas into a frequency different from the frequency of the radio wave received by another antenna;
A circuit for multiplexing radio waves from an antenna not subjected to frequency conversion among the plurality of antennas and radio waves from other antennas subjected to frequency conversion by the frequency converter;
One cable for transmitting the multiplexed signal output from the circuit for multiplexing the radio waves of the plurality of antennas to the receiver side;
A splitter connected to the receiver end of the single cable for separating radio waves from each antenna from the multiplexed signal;
Among the radio waves separated from among the signals multiplexed by the branching filter, a frequency inverse converter that returns the frequency of the radio wave frequency-converted by the frequency converter to the frequency before conversion;
A reception system of a diversity type microphone comprising a local oscillator that outputs the same local signal to the frequency converter and the frequency inverse converter. The local oscillator is provided at the receiver side of the cable,
2. The diversity microphone receiving system according to claim 1, wherein the local signal output from the local oscillator is input to the frequency inverter and to the frequency converter via the cable. . A DC power supply is provided on the receiver side of the cable,
The direct current output from the said DC power supply is supplied to the circuit which multiplexes the electromagnetic wave from the said frequency converter, the said frequency inverter, and the said antenna via the said cable. The reception system of the diversity type microphone as described.

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