JP2022032360A - Level adjustment device - Google Patents

Abstract

To provide a level adjustment device capable of adjusting a signal level of a received signal of a plurality of channels with easier structure.SOLUTION: A level adjustment device 100 comprises: a mixer 105 that performs a frequency conversion of a received signal of a plurality of channels by using a local oscillation signal; a separation part 118 that separates a signal after the frequency conversion by the mixer 105 into a signal of a first band and a signal of a second band; mixers 109 and 110 that perform the conversion of the signal of the first band and the frequency of the second band by using the local oscillation signal; AGC amplifiers 113 and 114 that adjust a level of the signal after the conversion of the frequency by the mixers 109 and 110; a mixer 115 that mixes the signal after the adjustment of the level and outputs them; and a control part 117 that controls a frequency Lo of the local oscillation signal so that the received signal of the plurality of channels is separated into the first band and the second band in accordance with a second channel which has a correlation with the first channel lower than a predetermined threshold value in a plurality of channels.SELECTED DRAWING: Figure 1

Description

Application for application of Article 30, Paragraph 2 of the Patent Law has been submitted. Masato Kawagoe published in the proceedings of the 73rd Hokkaido Broadcasting Technology Report Meeting on April 17, 2020.

The present invention relates to a level adjusting device.

As shown in FIG. 10, for the purpose of eliminating the difficulty of television broadcasting, broadcast waves of a plurality of channels transmitted from the transmission station 1 are received by a reception antenna 2 provided at a predetermined reception point, and the reception antenna 2 is used. A facility (co-listening facility) for transmitting a received signal to an optical receiver 4 installed in each home or the like by a transmitter 3 is installed. Conventionally, the transmitter 3 and the receiver 4 have been connected via a coaxial cable, but in recent years, the coaxial cable has been replaced with an optical cable.

In the above-mentioned common listening facility, the signal level of the received signal may decrease due to the influence of fading due to marine propagation, long-distance propagation, topography, natural phenomenon, or the like of the broadcast wave. When a coaxial cable is used, a unit for adjusting the signal level is provided for each channel, and the signal level is adjusted by the unit before being transmitted to the receiver. However, since the above-mentioned unit has been removed due to the repair from the coaxial cable to the optical cable, reception failure due to a decrease in the signal level of the received signal has become a problem.

Patent Document 1 describes a retransmission device including a retransmission unit that retransmits a received signal of terrestrial digital broadcasting. The retransmission unit down-converts the signal of the band for up to three consecutive channels by the local oscillation signal and converts it into the intermediate frequency band signal, and the intermediate frequency band signal is converted into the intermediate frequency band signal by three SAWs having different passing bands of 6 MHz each. Input to each filter to extract the signal of each channel. The retransmission unit adjusts the level of the extracted channel signal, mixes the level-adjusted signal, and outputs the signal.

Japanese Unexamined Patent Publication No. 2009-30312

It is known that an amplifier (AGC amplifier) having an AGC (Auto Gain Control) function is effective as a countermeasure against reception failure due to fading. The AGC function is a function that adjusts the gain with respect to the level fluctuation of the input signal and controls the level of the output signal to be constant. By using the AGC amplifier, the level of the output signal can be kept constant even when the signal level of the received signal fluctuates.

Depending on the frequency characteristics of each channel that receives the signal in the common listening facility, only the signal level of the received signal of some channels may behave differently from the signal level of the received signal of another channel. The AGC amplifier adjusts the gain based on the sum of the signal levels of all the input channels (total power detection method), so it works effectively when the signal levels of all channels fluctuate with the same behavior. .. However, when only the signal level of the received signal of some channels differs from the signal level of the received signal of other channels, even if an AGC amplifier is used, it cannot follow the fluctuation of the signal level of some channels. Reception failure may occur.

In the retransmission device described in Patent Document 1, a plurality of retransmission units having different numbers and arrangements of channels that can be processed are prepared, and a plurality (three or four depending on the region) are prepared according to the channel arrangement for each region. It is necessary to combine the retransmission units of (1), which increases the cost and complicates the configuration. Therefore, there is a demand for a technique for adjusting the signal levels of received signals of a plurality of channels with a simpler configuration.

An object of the present invention is to solve the above-mentioned problems and to provide a level adjusting device capable of adjusting the signal levels of received signals of a plurality of channels with a simpler configuration.

In order to solve the above problems, the level adjusting device according to the present invention is a level adjusting device that adjusts and outputs the signal levels of the received signals of a plurality of channels in the first frequency band, and outputs a locally oscillated signal. A first frequency conversion unit that performs frequency conversion of received signals of the plurality of channels into a second frequency band lower than the first frequency band by using the local oscillator and the local oscillation signal, and the first frequency conversion unit. A separation unit that separates the signal after frequency conversion by the frequency conversion unit 1 into a signal in the first band and a signal in the second band higher than the first band in the second frequency band. Using the local oscillation signal, a second frequency conversion unit that performs frequency conversion of the signal of the first band from the second frequency band to the first frequency band, and the local oscillation signal are used. A third frequency conversion unit that performs frequency conversion of the signal in the second band from the second frequency band to the first frequency band, and a signal after frequency conversion by the second frequency conversion unit. After level adjustment by the first level adjustment unit, the second level adjustment unit that adjusts the level of the signal after frequency conversion by the third frequency conversion unit, and the first level adjustment unit that adjusts the level of the above. The correlation between the mixer, which mixes and outputs the signal of the above and the signal after the level adjustment by the second level adjustment unit, and the first channel as a reference among the plurality of channels is more than a predetermined threshold value. A control unit that controls the frequency of the locally oscillated signal so that the received signals of the plurality of channels are separated into the first band and the second band according to the lower second channel. , Equipped with.

Further, in the level adjusting device according to the present invention, the input destinations of the received signals of the plurality of channels in the first frequency band can be switched between the first frequency conversion unit and the first level adjusting unit. The control unit further includes a switching unit, and the control unit is used when the correlation between the first channel and all the channels other than the first channel among the plurality of channels is equal to or higher than the predetermined threshold value. It is preferable to control the switching unit so that the received signal of the channel is input to the first level adjusting unit.

According to the level adjusting device according to the present invention, it is possible to adjust the signal level of the received signal of a plurality of channels with a simpler configuration.

It is a figure which shows the structural example of the level adjustment apparatus which concerns on one Embodiment of this invention. It is a figure which shows the process on the Low side in the level adjustment apparatus shown in FIG. It is a figure which shows the processing on the High side in the level adjustment apparatus shown in FIG. It is a figure which shows the specific example of the processing on the Low side in the level adjustment apparatus shown in FIG. It is a figure which shows the specific example of the processing on the High side in the level adjustment apparatus shown in FIG. It is a flowchart which shows an example of the operation of the control part shown in FIG. It is a figure which shows an example of the signal level fluctuation of the received signal of a plurality of channels before the signal level adjustment by the level adjustment apparatus shown in FIG. 1. It is a figure which shows an example of the signal level fluctuation of the received signal of a plurality of channels after the signal level adjustment by the level adjustment apparatus shown in FIG. 1. It is a figure which shows an example of the presence / absence of signal separation by the level adjustment apparatus shown in FIG. It is a figure for demonstrating the common listening facility of a broadcast wave.

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

FIG. 1 is a diagram showing a configuration example of a level adjusting device 100 according to an embodiment of the present invention. The level adjusting device 100 according to the present embodiment adjusts the signal levels of the received signals of a plurality of channels received by the receiving antenna 2 shown in FIG. 10, and outputs the signal levels to the transmitter 3.

As shown in FIG. 1, the level adjusting device 100 according to the present embodiment includes a local oscillator 101, distributors 102, 103, 106, a switching unit 104, mixers 105, 109, 110, and a bandpass filter (BPF). ) 107, 108, 111, 112, AGC amplifiers 113, 114, a mixer 115, a storage unit 116, and a control unit 117.

The local oscillator 101 outputs a local oscillation signal having a predetermined frequency lower than the frequency of the received signal of the receiving antenna 2 to the distributor 102. The received signal of the receiving antenna 2 is, for example, a signal in the UHF (Ultra High Frequency) band (first frequency band) of 470 to 710 MHz. The local oscillator 101 can control the frequency Lo of the local oscillation signal, for example, between 368 MHz and 440 MHz.

The distributor 102 outputs the local oscillation signal output from the local oscillator 101 to the mixer 105, the mixer 109, and the mixer 110.

The distributor 103 receives input signals of a plurality of channels received by the receiving antenna 2. The distributor 103 outputs the received signals of the plurality of input channels to the mixer 105 or the AGC amplifier 113 via the switching unit 104. Further, the distributor 103 outputs the received signals of a plurality of channels to the storage unit 116.

The switching unit 104 switches the output destination of the signal from the distributor 103 between the mixer 105 and the AGC amplifier 113 according to the control of the control unit 117. The switching unit 104 makes it possible to switch the input destinations of the received signals of a plurality of channels between the mixer 105 and the AGC amplifier 113.

The mixer 105 as the first frequency conversion unit uses the local oscillation signal output from the distributor 102, and uses a frequency band lower than the frequency band of the output signal (received signals of a plurality of channels) of the distributor 103 (first frequency band). The frequency of the output signal of the distributor 103 is converted into the frequency band (2). For example, the mixer 105 performs frequency conversion of received signals of a plurality of channels from the UHF band to the VHF (Very High Frequency) band of 30 to 300 MHz. The mixer 105 outputs the frequency-converted signal to the distributor 106.

The distributor 106 outputs the output signal of the mixer 105 (the signal after frequency conversion by the mixer 105) to the BPF 107 and the BPF 108.

The BPF 107 outputs (passes) a signal in a predetermined band (first band) among the signals output from the distributor 106 after frequency conversion by the mixer 105 to the mixer 109. The BPF 107 passes, for example, a signal from 30 MHz to 108 MHz.

The BPF 108 is a signal in a predetermined band (second band) output from the distributor 106 after frequency conversion by the mixer 105, which is higher than the band through which the BPF 107 passes the signal (first band). , Output (pass) to the mixer 110. The BPF 108 passes, for example, a signal from 114 MHz to 342 MHz.

In general, it is easier to create a separation filter that is cheaper and has better characteristics in the VHF band than in the UHF band. Therefore, as in the present embodiment, the reception signals of a plurality of channels in the UHF band are frequency-converted to the VHF band and then input to the BPF 107 and 108, whereby the cost can be reduced and the characteristics can be improved.

The distributor 106, BPF 107 and BPF 108 constitute the separation unit 118. The separation unit 118 converts the signal after frequency conversion by the mixer 105 into a signal in the first band (for example, 30 MHz to 108 MHz) and a signal in the second band (114 MHz to 342 MHz) higher than the first band. To separate.

The mixer 109 as the second frequency conversion unit uses the local oscillation signal to perform frequency conversion of the output signal of the BPF 107 to the original frequency band (first frequency band). The mixer 109 outputs the frequency-converted signal to the BPF 111.

The mixer 110 as the third frequency conversion unit performs frequency conversion of the output signal of the BPF 108 to the original frequency band (first frequency band) by using the local oscillation signal. The mixer 110 outputs the frequency-converted signal to the BPF 112.

The BPF 111 outputs (passes) a signal in a predetermined band to the AGC amplifier 113 among the signals after frequency conversion by the mixer 109. The BPF 111 passes signals from, for example, 470 MHz to 548 MHz.

The BPF 112 outputs (passes) a signal in a predetermined band to the AGC amplifier 114 among the signals after frequency conversion by the mixer 110. The BPF 112 passes, for example, a signal from 482 MHz to 710 MHz.

The AGC amplifier 113 as the first level adjustment unit adjusts the level of the output signal of the distributor 103 or the BPF 111, and outputs the level-adjusted signal to the mixer 115.

The AGC amplifier 114 as the second level adjustment unit adjusts the level of the output signal of the BPF 112, and outputs the signal after the level adjustment to the mixer 115.

The mixer 115 mixes the signal after level adjustment by the AGC amplifier 113 and the signal after level adjustment by the AGC amplifier 114, and outputs the signal to the transmitter 3.

The storage unit 116 stores the signal level data of the output signal (received signal of a plurality of channels) of the distributor 103 for a predetermined time (for example, 24 hours).

The control unit 117 controls the frequency of the local oscillation signal output by the local oscillator 101. Specifically, the control unit 117 responds to a channel (second channel) whose correlation with the reference channel (first channel) is lower than a predetermined threshold among the plurality of channels of the received signal. The frequency Lo of the local oscillation signal is controlled so that the received signals of the plurality of channels are separated into a first band through which the BPF 107 passes the signal and a second band through which the BPF 108 passes the signal. Further, when the above-mentioned reception signal is separated, the control unit 117 controls the switching unit 104 so that the output destination of the signal from the distributor 103 is the mixer 105. Further, when the above-mentioned separation of the received signal is unnecessary, the control unit 117 controls the switching unit 104 so that the output destination of the signal from the distributor 103 is the AGC amplifier 113.

Next, the operation of the level adjusting device 100 according to the present embodiment will be described. First, the separation of the received signals of a plurality of channels by the level adjusting device 100 according to the present embodiment will be described. As described above, in the level adjusting device 100 according to the present embodiment, the frequency of the signal that processes the received signals of a plurality of channels is higher than that of the system including the BPF 107, the mixer 109, and the BPF 111, BPF 108, It is separated into a system consisting of a mixer 110 and a BPF 112. Hereinafter, the system processed by the BPF 107, the mixer 109 and the BPF 111 is referred to as the Low side, and the system processed by the BPF 108, the mixer 110 and the BPF 112 is referred to as the High side. Further, it is assumed that the frequency band of the received signals of the plurality of channels is 470 MHz to 710 MHz. Further, it is assumed that the frequency of the locally oscillated signal can be controlled in the range of 368 MHz to 440 MHz. Further, it is assumed that the BPF 107 passes a signal from 30 MHz to 108 MHz and the BPF 108 passes a signal from 114 MHz to 342 MHz. Further, it is assumed that the BPF 111 passes a signal of 470 MHz to 548 MHz and the BPF 112 passes a signal of 482 MHz to 710 MHz.

First, the processing on the Low side will be described with reference to FIG.

The mixer 105 uses the locally oscillated signal to perform frequency conversion of received signals of a plurality of channels. The frequency of the signal after frequency conversion by the mixer 105 differs depending on the frequency Lo of the locally oscillated signal. For example, when the frequency Lo of the locally oscillated signal is 368 MHz, the frequency of the signal after frequency conversion by the mixer 105 is 102 MHz to 342 MHz. When the frequency Lo of the locally oscillated signal is 440 MHz, the frequency of the signal after frequency conversion by the mixer 105 is from 30 MHz to 270 MHz.

The BPF 107 passes a signal from 30 MHz to 108 MHz. Therefore, when the frequency Lo of the locally oscillated signal is 368 MHz, the BPF 107 outputs a signal of 102 MHz to 108 MHz to the mixer 109. Further, when the frequency Lo of the locally oscillated signal is 440 MHz, the BPF 107 outputs a signal of 30 MHz to 108 MHz to the mixer 109.

The mixer 109 uses the local oscillation signal to perform frequency conversion of the output signal of the BPF 107. When the frequency Lo of the locally oscillated signal is 368 MHz, the mixer 109 frequency-converts the output signal of the BPF 107 (the signal of 102 MHz to 108 MHz) into the signal of 470 MHz to 476 MHz and outputs the output signal to the BPF 111. When the frequency Lo of the locally oscillated signal is 440 MHz, the mixer 109 frequency-converts the output signal of the BPF 107 (the signal of 30 MHz to 108 MHz) into the signal of 470 MHz to 548 MHz and outputs the output signal to the BPF 111.

The BPF 111 passes a signal from 470 MHz to 548 MHz. When the frequency Lo of the locally oscillated signal is 368 MHz, the BPF 111 outputs a signal of 470 MHz to 476 MHz to the AGC amplifier 113. When the frequency Lo of the locally oscillated signal is 440 MHz, the BPF 111 outputs a signal of 470 MHz to 548 MHz to the AGC amplifier 113.

Next, the processing on the High side will be described with reference to FIG.

The BPF 108 passes signals from 114 MHz to 342 MHz. Therefore, when the frequency Lo of the locally oscillated signal is 368 MHz, the BPF 108 outputs a signal of 114 MHz to 342 MHz to the mixer 110. Further, when the frequency Lo of the locally oscillated signal is 440 MHz, the BPF 108 outputs a signal of 114 MHz to 270 MHz to the mixer 110.

The mixer 110 uses the local oscillation signal to perform frequency conversion of the output signal of the BPF 108. When the frequency Lo of the locally oscillated signal is 368 MHz, the mixer 110 frequency-converts the output signal of the BPF 108 (a signal of 114 MHz to 342 MHz) into a signal of 482 MHz to 710 MHz and outputs the output signal to the BPF 112. When the frequency Lo of the locally oscillated signal is 440 MHz, the mixer 110 frequency-converts the output signal of the BPF 108 (a signal of 114 MHz to 270 MHz) into a signal of 554 MHz to 710 MHz and outputs the output signal to the BPF 112.

The BPF 112 passes a signal from 482 MHz to 710 MHz. When the frequency Lo of the locally oscillated signal is 368 MHz, the BPF 112 outputs a signal of 482 MHz to 710 MHz to the AGC amplifier 114. When the frequency Lo of the locally oscillated signal is 440 MHz, the BPF 112 outputs a signal of 554 MHz to 710 MHz to the AGC amplifier 114.

As described with reference to FIGS. 2 and 3, when the frequency Lo of the locally oscillated signal is 368 MHz, the received signal is separated into two systems with 476 MHz as a boundary and input to the AGC amplifiers 113 and 114. When the frequency Lo of the locally oscillated signal is 440 MHz, the received signal is separated into two systems with 548 MHz as a boundary and input to the AGC amplifiers 113 and 114. As described above, in the level adjusting device 100 according to the present embodiment, the boundary between the signal separated on the Low side and the signal separated on the High side is adjusted by adjusting the frequency Lo of the locally oscillated signal. be able to.

Separation of received signals of a plurality of channels by the level adjusting device 100 according to the present embodiment will be described more specifically with reference to FIGS. 4 and 5. In FIGS. 4 and 5, received signals of 16ch and 20ch to 33ch will be described as an example. The received signal of 16ch is a signal of 488 MHz to 494 MHz. The received signals of 20ch to 30ch are signals having a bandwidth of 6 MHz between 500 MHz and 600 MHz, respectively. Hereinafter, an example of separating the 16ch signal and other channels (20ch to 33ch) will be described.

First, the processing on the Low side will be described with reference to FIG.

The control unit 117 controls the frequency Lo of the local oscillation signal to, for example, 386 MHz. When the frequency Lo of the locally oscillated signal is 386 MHz, the received signal of 16ch is frequency-converted from 102 MHz to a signal of 108 MHz. Therefore, the BPF 107 passes the received signal of 16ch and cuts the signal of 20ch to 33ch. The mixer 109 frequency-converts the output signal of the BPF 107 into a signal of the original frequency band (488 MHz to 494 MHz). Therefore, the 16ch reception signal is input to the AGC amplifier 113.

Next, the processing on the High side will be described with reference to FIG.

When the frequency Lo of the locally oscillated signal is 386 MHz, the received signal of 16ch is frequency-converted from 102 MHz to a signal of 108 MHz. Further, the received signals of 20ch to 33ch are frequency-converted in the range of 126 MHz to 210 MHz. Therefore, the BPF 108 passes the received signals of 20ch to 33ch and cuts the received signals of 16ch. The mixer 110 frequency-converts the output signal of the BPF 108 into a signal in the original frequency band (between 512 MHz and 596 MHz). Therefore, the received signals of 20ch to 33ch are input to the AGC amplifier 114.

Next, the operation of the control unit 117 will be described with reference to FIG. FIG. 6 is a flowchart showing an example of the operation of the control unit 117.

The control unit 117 sets an initial value (step S101). Specifically, the control unit 117 sets A as the minimum channel number among all the channels received at the reception point of the common listening facility. Further, the control unit 117 sets the channel numbers of the other channels as B [m] (m = 0, 1, ...) In ascending order. The channel having the channel number B [m] (chB [m]) is a channel whose signal is compared with the channel (chA) having the channel number A, as will be described later. Hereinafter, chB [m] may be referred to as a comparison channel. Further, the control unit 117 sets the maximum channel number as MAXch among all the channels in the area. Further, the control unit 117 sets MAXfreq as the maximum channel number that can be separated on the Low side. MAXfreq is determined according to the range in which the frequency Lo of the local oscillation signal output by the local oscillator 101 can be adjusted. Further, the control unit 117 sets a predetermined threshold value of the correlation coefficient as CORval. Further, the control unit 117 sets the maximum channel number as SEPch among the channels separated on the Low side. Hereinafter, the channel whose channel number is SEPch is referred to as a separated channel.

The control unit 117 sets m = 0 and SEPch = MAXfeq + 1 (step S102), and initializes the comparison channel and the separation channel.

The control unit 117 determines whether or not A ≦ MAXfreq (step S103). That is, the control unit 117 determines whether or not chA is a channel in a range separable to the Low side.

When it is determined that A≤MAXfreq (step S103: Yes), the control unit 117 uses the signal level data of the received signals of chA and chB [m] stored in the storage unit 116 for a predetermined time (step S103: Yes). For example, only the past 24 hours, 12 hours, 6 hours, 1 hour, etc.) are acquired. The control unit 117 calculates the correlation coefficient C between the received signal of chA and the received signal of chB [m] (step S104). In this way, the control unit 117 uses chA as a reference channel (first channel) to correlate the received signal of chA with the received signal of chB [m] (second channel) which is a comparison channel. calculate. When the received signal of chA and the received signal of chB [m] fluctuate with the same tendency, the correlation coefficient C becomes large. On the other hand, when the received signal of chA and the received signal of chB [m] fluctuate with different tendencies, that is, when the behavior of the signals is different, the correlation coefficient C becomes small.

The control unit 117 determines whether or not the calculated correlation coefficient C is equal to or greater than the threshold value CORval (C ≧ CORval) (step S105).

When it is determined that C ≧ CORval (step S105: Yes), the control unit 117 determines whether or not B [m] = MAXch (step S106).

When it is determined that B [m] is not MAXch (step S106: No), the control unit 117 adds 1 to m (step S107), and returns to the process of step S104.

When it is determined that C ≧ CORval (C <CORval) (step S105: No), the control unit 117 determines whether or not B [m] -1 ≦ MAXfreq (step S108). That is, the control unit 117 sets the received signal of the channel having the channel number B [m] or more to the High side and the received signal of the channel having the channel number B [m] -1 or less to the Low side with chB [m] as a delimiter. Determine if it is separable to the side.

When it is determined that B [m] -1≤MAXfreq (step S108: Yes), the control unit 117 sets SEPch = B [m] -1 (step S109).

When it is determined that B [m] -1≤MAXfreq is not (B [m] -1> MAXfreq) (step S108: No), the control unit 117 sets SEPch = MAXfreq (step S110).

After the processing of step S109 or step S110, or when it is determined that B [m] = MAXch (step S106: Yes), the control unit 117 determines whether or not SEPch ≦ MAXfreq (step S111). ).

When it is determined that SEPch ≦ MAXfreq (step S111: Yes), the control unit 117 controls the switching unit 104 so that the reception signals of a plurality of channels are input from the distributor 103 to the mixer 105. Further, the control unit 117 is a local oscillation signal so that the received signal of the channel whose channel number is SEPch or less passes through the BPF 107 on the Low side, and the received signal of the channel whose channel number is larger than SEPch passes through the BPF 108 on the High side. The frequency Lo of is controlled (step S112).

When it is determined that SEPch ≤ MAX freak (SEPch> MAX freak) (step S111: No), the control unit 117 distributes the received signals of a plurality of channels because the separated channels are not in the range separable to the Low side. The switching unit 104 is controlled so as to be input from the device 103 to the AGC amplifier 113.

As described with reference to FIG. 6, in the control unit 117, the correlation coefficient C between the received signal of chA and the received signal of chB [m] is smaller than the threshold value CORval, and B [m] -1≤MAXfreq. In this case, the received signals of a plurality of channels are separated into two systems with chB [m] as a delimiter. Specifically, in the control unit 117, the frequency of the local oscillation signal is separated so that the channel of channel number B [m] -1 or less is separated on the Low side and the channel of channel number B [m] or more is separated on the High side. Control Lo.

Further, when the correlation coefficient C between the received signal of chA and the received signal of chB [m] is smaller than the threshold value CORval and B [m] -1> MAXfreq, the control unit 117 selects the channel whose channel number is MAXfreq. As a delimiter, the received signals of a plurality of channels are separated into two systems. Specifically, the control unit 117 controls the frequency Lo of the local oscillation signal so that the channel having a channel number of MAXfreq or less is separated on the Low side and the channel having a channel number greater than MAXfreq is separated on the High side.

As described above, in the control unit 117, the reception signals of the plurality of channels are received by the BPF 107 according to the chB [m] whose correlation with the reference chA (first channel) is smaller than the predetermined threshold value CORval. The frequency Lo of the local oscillation signal is controlled so that the passing band (first band) and the BPF 108 are separated into a signal and a passing band (second band).

FIG. 7 is a diagram showing an example of signal level fluctuations of received signals of a plurality of channels (16ch, 20ch, 22ch, 26ch, 29ch, 31ch and 33ch) before the signal level adjustment by the level adjusting device 100 according to the present embodiment. Is.

As shown in FIG. 7, the signal level of the received signal of the channel other than 16ch changes from about 70 dBμV to about 85 dBμV, and the method of increase or decrease is generally uniform. On the other hand, the signal level of the received signal of 16ch is different from the behavior of the signal level of the received signal of other channels, and there is a time zone in which the signal level is lowered to about 50 dBμV. As described above, the behavior of the signal level of the received signal is significantly different between 16ch and other channels. Therefore, the level adjusting device 100 according to the present embodiment separates the received signals of 16 channels into the Low side and the received signals of other channels into the High side to adjust the signal level.

FIG. 8 is a diagram showing signal level fluctuations of the received signals of each channel after the level adjusting device 100 adjusts the signal levels of the received signals of the plurality of channels shown in FIG. 7.

As shown in FIG. 8, by adjusting the signal level by the level adjusting device 100 according to the present embodiment, the signal levels of the received signals of all channels can be kept substantially constant.

As described above, according to the level adjusting device 100 according to the present embodiment, the necessity of controlling the frequency Lo of the locally oscillated signal and the frequency of the locally oscillated signal are determined automatically from the correlation of the signals between the channels without human intervention. Lo can be controlled. Normally, the behavior of the level fluctuation of each channel varies with time. For example, only 16ch may behave differently, or only 16ch and 20ch may behave differently from other channels. In such a case, if automatic determination / control is not performed, the setting in either case will be fixed, and a time zone in which the AGC function does not work well will occur. On the other hand, by performing automatic determination and control as in the level adjusting device 100 according to the present embodiment, it is possible to perform appropriate channel separation according to the time change and to make the AGC function.

As described with reference to FIG. 6, the control unit 117 sets SEPch = MAXfreq + 1 when the correlation coefficient C between chA and all the comparison channels is CORval or less. In this case, since SEPch> MAXfreq, the control unit 117 does not control the frequency Lo of the local oscillation signal, but controls the switching unit 104 so that the output signal of the distributor 103 is input to the AGC amplifier 113. Therefore, as shown in FIG. 9, the control unit 117 switches the presence / absence of signal separation according to the degree of correlation of each channel. By doing so, it is possible to eliminate unnecessary frequency conversion and the like.

As described above, in the present embodiment, the level adjusting device 100 is used among the plurality of channels.
Depending on the channel (second channel) whose correlation with the reference channel (first channel) is lower than a predetermined threshold, the received signals of a plurality of channels are in the band through which the BPF 107 passes the signal (first channel). The frequency Lo of the locally oscillated signal is controlled so as to be separated into a band (band) and a band (second band) through which the BPF 108 transmits the signal.

Therefore, a channel whose correlation between the reference channel and the reference channel is lower than a predetermined threshold value is input to different AGC amplifiers 113 and 114, respectively. Therefore, the AGC function enables the signal level of the channel having a low correlation. Improvements can be made. Further, by controlling the frequency Lo of the locally oscillated signal, it is possible to adjust the boundary for separating the received signals of a plurality of channels, so that the signal can be adjusted without using a dedicated configuration according to the channel arrangement for each region. You can adjust the level. Therefore, the signal level of the received signals of a plurality of channels can be adjusted with a simpler configuration.

Although the above embodiments have been described as representative examples, it will be apparent to those skilled in the art that many modifications and substitutions are possible within the spirit and scope of the invention. Therefore, the invention should not be construed as limiting by the embodiments described above, and various modifications and modifications can be made without departing from the claims. For example, it is possible to combine a plurality of the constituent blocks described in the configuration diagram of the embodiment into one, or to divide one constituent block into one.

1 Transmitter 2 Receiver antenna 3 Transmitter 4 Receiver 100 Level adjuster 101 Local oscillator 102, 103, 106 Distributor 104 Switching unit 105 Mixer (first frequency converter)
107, 108, 111, 112 Bandpass filter 109 mixer (second frequency converter)
110 Mixer (3rd frequency converter)
113 AGC amplifier (first level adjustment unit)
114 AGC amplifier (second level adjustment unit)
115 Mixer 116 Storage unit 117 Control unit 118 Separation unit

Claims (2)

It is a level adjusting device that adjusts and outputs the signal levels of the received signals of a plurality of channels in the first frequency band.
A local oscillator that outputs a local oscillation signal,
A first frequency conversion unit that performs frequency conversion of received signals of the plurality of channels into a second frequency band lower than the first frequency band by using the locally oscillated signal.
Separation of the signal after frequency conversion by the first frequency conversion unit into a signal in the first band and a signal in the second band higher than the first band in the second frequency band. Department and
A second frequency conversion unit that performs frequency conversion of the signal in the first band from the second frequency band to the first frequency band using the locally oscillated signal.
A third frequency conversion unit that performs frequency conversion of the signal in the second band from the second frequency band to the first frequency band using the locally oscillated signal.
The first level adjusting unit that adjusts the level of the signal after frequency conversion by the second frequency conversion unit, and
A second level adjusting unit that adjusts the level of the signal after frequency conversion by the third frequency conversion unit, and
A mixer that mixes and outputs the signal after level adjustment by the first level adjustment unit and the signal after level adjustment by the second level adjustment unit, and
Among the plurality of channels, the received signals of the plurality of channels are the first band and the second channel according to the second channel whose correlation with the reference first channel is lower than a predetermined threshold. A level adjusting device including a control unit that controls the frequency of the locally oscillated signal so as to be separated into the band of the above. In the level adjusting device according to claim 1,
Further, a switching unit capable of switching the input destinations of the received signals of the plurality of channels in the first frequency band between the first frequency conversion unit and the first level adjusting unit is provided.
When the correlation between the first channel and all the channels other than the first channel among the plurality of channels is equal to or higher than the predetermined threshold value, the control unit receives signals from the plurality of channels. A level adjusting device that controls the switching unit so as to be input to the first level adjusting unit.

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