Relay device and its control method

Abstract

To provide a relay device which realizes a stable operation with a simple configuration.SOLUTION: In a relay device, a switcher 39 which performs output by switching between an IF and an IF 2 (RF) to the output side is provided, a portion of the IF, IF 2 branched by a coupler 40 is subjected to logarithmic detection by a common logarithmic detector (detector) 44, and its detection output is recognized as an analog value, an FPGA 43 may recognize the intensity when the detection output is digitized by an AD converter 45, VAGC11 being the control voltage of a VATT 22 is subjected to feedback control by the FPGA 43 when the IF is selected by the switcher 39, and VAGC21 being the control voltage of a VATT 26, VAGC22 being the control voltage of a VATT 29 and VAGC23 being the control voltage of a VATT 35 are subjected to feedback control by the FPGA 43 when the IF 2 is selected by the switcher 39.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a relay device that receives a transmission signal received from a higher-level station side in wireless communication, amplifies it after reception by a relay station, and re-transmits it to other relay stations or lower-level stations, and a control method therefor.

Background Art

[0002] In terrestrial television broadcasting and the like, a relay station receives a UHF-band transmission signal from a higher-level station (such as a broadcasting station), performs signal processing such as equalization processing and amplification on this, and then re-transmits it to other relay stations, receivers, etc. Thus, a method of performing stable broadcasting over a wide area is adopted. In this case, the reception level (intensity) at the relay station of the broadcast wave is not necessarily constant, and it is required that the above processing can be stably performed even when the reception level fluctuates greatly. For this reason, the intensity of the received signal is brought within a certain range and then the above signal processing is performed on the digital signal obtained by AD conversion. Further, as the signal to which the above signal processing is applied, an IF (Intermediate Frequency) signal having a lower frequency than the UHF band is preferable. Therefore, the received signal is converted into an IF signal having a constant intensity and then digitized, and the above signal processing is performed on this.

[0003] Patent Document 1 describes the configuration of such a relay device. Here, AGC (Auto Gain Control) control is performed so that the intensity of the signal immediately before AD conversion becomes constant regardless of the reception level. For this reason, the broadcast wave received by the relay device passes through a BPF (band-pass filter) and an amplifier corresponding to the channel, and also passes through an attenuator whose attenuation amount is variable. For AGC control, a part of the signal before AD conversion is distributed and detected, and the attenuation amount of the attenuator is controlled so that this detection voltage becomes constant.

[0004] However, when the reception level is extremely low, appropriate signals may not be obtained even when the above processing is performed. Therefore, in this case, it is preferable not to retransmit (relay) this signal. For this reason, in the relay device described in Patent Document 1, a switch is provided before the output after AD conversion, and the signal strength is monitored separately from the above AGC control. When this strength is lower than a certain value (threshold), control is performed to turn off this switch. Since the signal strength after AGC control becomes constant regardless of the reception level as described above, such monitoring of the reception level is performed at a stage before AGC control is performed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0006] The relay method is not fixed to one. For example, depending on the purpose or the like, the broadcast wave relay method and the IF relay method may be switched and used. What the above receiver receives is, for example, a microwave of 470 MHz to 710 MHz (UHF band) in the broadcast wave relay method, and the above IF signal in the case of the IF relay method (IF-TTL method), and its frequency is, for example, 37.15 MHz. For this reason, in the relay device, these signals are switched and received, and after the above AGC control and reception level monitoring are performed for each dedicated system, the above signal processing is performed and then a new broadcast wave is retransmitted.

[0007] When performing AGC control and monitoring the reception level as described above independently for broadcast wave relay and IF relay respectively, components necessary for these operations are required for each system, resulting in a complex configuration of the relay device (reception converter). In particular, redundancy is required for the broadcast relay device to prevent broadcast interruption due to failures, and in many cases, multiple independent configurations as described above are provided. In this case, the configuration of the entire relay device becomes particularly complex.

[0008] For this reason, a relay device that realizes stable operation with a simple configuration has been demanded.

[0009] The present invention has been made in view of such circumstances, and an object thereof is to solve the above problems.

Means for Solving the Problems

[0010] The present invention is a relay device that, when receiving and relaying a transmission signal, adjusts the intensity of the received transmission signal using a variable attenuator whose attenuation rate is adjusted by a control voltage, and performs relaying. A first relay method in which a first transmission signal is used as the transmission signal, and a second relay method in which a second transmission signal having a carrier frequency different from that of the first transmission signal is used as the transmission signal are switched and used. A variable attenuator is provided in each of a first signal path that adjusts and outputs the intensity of the received first transmission signal and a second signal path that adjusts and outputs the intensity of the received second transmission signal. In the first signal path, the first transmission signal is frequency-converted so as to approach the carrier frequency of the second transmission signal. It includes a common detector that selects and inputs the first transmission signal after passing through the first signal path and the second transmission signal after passing through the second signal path. The control voltage of the variable attenuator in the first signal path and the control voltage of the variable attenuator in the second signal path are feedback-adjusted so that the detection output of the detector becomes constant. At this time, when the reception level of the received transmission signal is low, an operation of not performing relaying may be performed, and an arithmetic unit that calculates the reception level based on the detection output and the corresponding control voltage may be provided.。 Further, the first relay method is a broadcast wave relay method, the second relay method is an IF relay method, and it may be used for terrestrial digital broadcasting. Further, the present invention is a control method for a relay device that adjusts the intensity of a received transmission signal and performs relay when receiving and relaying the transmission signal. A first relay method in which a first transmission signal is used as the transmission signal, and a second relay method in which a second transmission signal having a carrier frequency different from that of the first transmission signal is used as the transmission signal are switched and used. A first signal path for adjusting and outputting the intensity of the received first transmission signal, and a second signal path for adjusting and outputting the intensity of the received second transmission signal are provided. In the first signal path, frequency-convert the first transmission signal so as to approach the carrier frequency of the second transmission signal. Either the first transmission signal after passing through the first signal path or the second transmission signal after passing through the second signal path is selected and detected to detect a detection output. Based on the detection output, the adjustment of the intensity of the first transmission signal in the first signal path and the adjustment of the intensity of the second transmission signal in the second signal path are performed by feedback of the detection output. At this time, the adjustment of the intensity of the first transmission signal in the first signal path and the adjustment of the intensity of the second transmission signal in the second signal path are performed by adjusting a control voltage according to the detection output. Based on the detection output and the corresponding control voltage, the reception level of the transmission signal is calculated. When the calculated reception level is low, an operation of not performing relay may be performed.

Effect of the Invention

[0011] According to the present invention, a relay device that realizes stable operation with a simple configuration can be obtained.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] Next, embodiments for carrying out the present invention will be specifically described with reference to the drawings. The relay device according to the embodiment of the present invention is used, for example, for terrestrial digital television broadcasting, and receives a signal (OFDM carrier wave, hereinafter referred to as RF) in the UHF band (for example, 470 MHz to 710 MHz), performs signal processing such as equalization processing on it, and then amplifies and retransmits it as a similar broadcast wave (first relay method), or receives an IF (Intermediate Frequency: for example, 37.15 MHz) signal (hereinafter referred to as IF) with a frequency lower than that of RF, performs various processes on it, and then amplifies and retransmits it as a similar broadcast wave (second relay method). Either one is selected and operates. The data transmitted by the broadcast wave and the IF signal is the same broadcast data.

[0014] FIG. 1 is a diagram showing a simplified configuration of this relay device 1. Here, this component is divided into a reception unit 10, a reception conversion unit 20, a signal processing unit 50, and a transmission unit 60.

[0015] The reception unit 10 receives the above-mentioned RF and IF. Here, each signal is extracted by providing frequency filters corresponding to the frequencies of RF and IF. At this time, actually, a plurality of channels are set for RF, and each channel has a different frequency, and the selection is also performed.

[0016] The RF and IF received by the receiving unit 10 are both input to the reception conversion unit 20 as analog signals. However, since their reception levels (signal intensities) vary according to the reception status and the like, they are not constant. If this reception level is too low, appropriate broadcast waves may not be retransmitted even when various processes as described later are performed. Therefore, here, this reception level is recognized, and when this reception level is below a certain threshold, control is performed so that the output from the reception conversion unit 20 to the signal processing unit 50 is not performed.

[0017] On the other hand, when this reception level is higher than this threshold, the reception conversion unit 20 outputs the above two types of signals to the next-stage signal processing unit 50. At this time, when performing the processes carried out in the signal processing unit 50, since the RF and IF need to be converted into digital signals suitable for processing instead of analog signals, an AD converter is provided on the output side of the reception conversion unit 20. In the reception conversion unit 20, by performing AGC (Auto Gain Control) control, the above signal intensity immediately before AD conversion is set to a constant value. At this time, the processes carried out in the signal processing unit 50 are appropriately performed for the IF digitized in this way, but are not appropriate for the RF in the UHF band. Therefore, for the RF, after converting it into an IF2 with a frequency close to that of the IF, the same processes as for the IF are performed.

[0018] The above signals digitized and output from the reception conversion unit 20 are made into broadcast waves that are again analogized after being subjected to well-known multipath equalization processing, IF delay processing, etc. in the signal processing unit 50. Here, the IF and IF2 are frequency-converted again to become broadcast waves. As a result, the deterioration of the above signals during the period until they are received by the relay device 1 is compensated, and it becomes possible to retransmit broadcast waves in a non-deteriorated state from this relay device 1.

[0019] This broadcast wave is input to the transmission unit 60, amplified to an appropriate output here, and output after passing through the corresponding BPF. As a result, the broadcast wave emitted from the upper-level station is relayed by this relay device 1 and emitted toward the recipient.

[0020] The operation and functions of the relay device 1 as described above are the same as those of the relay device described in Patent Document 1. However, in this relay device 1, such an operation is realized with a simpler configuration.

[0021] The reception conversion unit 20 in this relay device 1 has signal paths corresponding to the broadcast wave relay method and the IF relay method respectively, and can correspond to either relay method. At this time, the components related to the recognition of the reception level and AGC control are shared in these signal paths. For this reason, the structure of the reception conversion unit 20 can be simplified and the number of its components can be reduced.

[0022] FIG. 2 is a diagram showing the configuration of this reception conversion unit 20. As shown in FIG. 1, since RF and IF are input to the reception conversion unit 20, a switch 21 which is a switch for selecting the side to be used among them is provided. As a result, when RF is selected, the lower signal path (first signal path) L1 in FIG. 2 is selected, and when IF is selected, the upper signal path (second signal path) L2 in FIG. 2 is selected respectively. The operation of the switch 21 is performed by the user.

[0023] In the upper signal path L2, a variable attenuator (VATT) 22, a LPF (Low Pass Filter) 23, and an attenuator (ATT) 24 are provided in sequence from the upstream side. The LPF 23 is set to transmit only the 37.15 MHz IF without transmitting RF. Both the VATT 22 and the ATT 24 are used to make the intensity suitable for the subsequent processing of the IF. However, among these, the attenuation rate of the VATT 22 in particular is variable, and the VATT 22 is used for the AGC control of the IF, and its attenuation rate is determined by the value of the input AGC control voltage (control voltage).

[0024] The intensity of the RF flowing through the lower signal path L1 is generally smaller than that of the IF. Therefore, amplification is performed in multiple stages in the lower signal path L1, and accordingly, a plurality of attenuators (variable attenuators VATT) are also provided. First, in the lower signal path L1, an amplifier 25, a variable attenuator (VATT) 26, an HPF (High Pass Filter) 27, an amplifier 28, a VATT 29, and an amplifier 30 are sequentially provided. The HPF 27 is set to pass only the RF of the selected channel that is 470 MHz or higher without transmitting the IF. The VATTs 26 and 29 are used for AGC control for the RF in the same manner as the AGC control of the VATT 22 for the IF.

[0025] The RF after passing through the VATT 29 is input to a mixer 31 and mixed with a local signal R-Lo oscillated by a local oscillator 32, thereby being frequency-converted into an IF2 close to the IF, for example, 40 MHz. As described above, the frequency of the RF actually varies according to the channel, but the frequency of the R-Lo is set so that the frequency of the IF2 is constant (40 MHz) regardless of the channel.

[0026] This IF2 passes through an LPF 33 that transmits only the IF2, and then passes through an amplifier 34, a VATT 35, an LPF 36, an amplifier 37, and a BPF (Band Pass Filter) 38. The VATT 35 is also used for AGC control for the IF2 in the same manner as the VATTs 26 and 29.

[0027] Corresponding to the switch 1 on the input side, a switch 39 for switching and outputting the IF and the IF2 (RF) is provided on the output side. The switch 39 is set to be interlocked with the switch 21, and either the IF or the IF2 selected by the switch 39 is amplified by an amplifier 41 via a coupler 40, digitized by an AD converter 42, and then input to an FPGA (Field Programmable Gate Array: arithmetic unit) 43. As a result, the FPGA 43 can recognize the IF and the IF2 and output them to the signal processing unit 50 in the next stage.

[0028] On one hand, a part of the IF and IF2 branched by the coupler 40 is logarithmically detected by a common logarithmic detector (detector) 44, and its detection output is recognized as an analog value. By digitizing this detection output with the AD converter 45, the FPGA 43 can recognize this intensity. The FPGA 43 performs AGC control so that this intensity becomes a certain set value, that is, adjusts the attenuation rate of the above-mentioned VATT(s). This adjustment is performed by the FPGA 43 outputting an AGC control voltage input to each of the above-mentioned VATTs, and the AGC control voltage output in digital form from the FPGA 43 is output to each VATT side via the DA converter 46. Although it is described in FIG. 2 for convenience that a single DA converter 46 is provided, actually, a DA converter is provided for each AGC control voltage (four types in FIG. 2).

[0029] For example, when the IF is selected by the switch 39, VAGC, which is the control voltage of VATT22, 11 is feedback-controlled by the FPGA 43. At this time, for example, when the recognized detection output is smaller than the set value, the FPGA 43 changes VAGC 11 by a fixed value ΔV in the direction of decreasing the attenuation rate, and when the recognized detection output is larger than the set value, the FPGA 43 changes VAGC 11 by ΔV in the direction of increasing the attenuation rate (the opposite direction to the above case), and when the detection output is within a certain narrow region including the set value, this VAGC 11 is maintained. By this, the attenuation rate of VATT22 is automatically adjusted.

[0030] When the IF2 is selected by the switch 39, VAGC, which is the control voltage of VATT26, 21 VAGC, which is the control voltage of VATT29, 22 VAGC, which is the control voltage of VATT35, 23is feedback - controlled by the FPGA 43. At this time, for example, when two of the attenuation rates (control voltages) of VATT 26, 29, and 35 are fixed, only one control voltage can be controlled in the same manner as described above. Also, when two or more of the attenuation rates of VATT 26, 29, and 35 are variable, ΔV can be set as described above for the control voltages of each VATT with variable attenuation rate, and the same operation can be performed.

[0031] In this way, the FPGA 43 adjusts the increase and decrease of the control voltage of VATT, so as to perform an adjustment such that the detection output of the logarithmic detector 44 becomes approximately equal to the set value. As a result, the intensities of IF and IF2 input to the signal processing unit 50 are also controlled to be constant. The operation of this AGC control itself is performed in the same manner as the technique described in Patent Document 1.

[0032] Also, in the reception conversion unit 20, when the reception level of the IF or RF selected by the switch 39 is lower than a certain threshold value, a switch 47 whose on - off is controlled according to the recognized reception level is provided so as not to output IF and IF2. The FPGA 43 controls the on - off operation of the switch 47 according to the reception level. This operation is also the same as the technique described in Patent Document 1.

[0033] With the above configuration, in this relay device 1 (reception conversion unit 20), for AGC control of IF and RF (IF2), a common logarithmic detector 44, DA converter 46, FPGA 43, etc. are used. Therefore, although two signal paths are provided, the structure of this reception conversion unit 20 can be simplified.

[0034] Next, the relationship between AGC control and reception level recognition in this reception conversion unit 20 will be described. This reception level can be defined as, for example, the signal strength of IF and RF when input to the switch 21 in FIG. 2. In this case, it is necessary to recognize the reception level individually for each of IF and RF. Usually, for this purpose, components for recognizing the signal strength are required in each of the upper signal path L2 and the lower signal path L1 in FIG. 2. On the other hand, since the intensity at least at the stage when IF and IF2 (RF) reach the switch 39 is constantly adjusted by the above AGC control, it is difficult to recognize this reception level using IF and IF2 at this stage.

[0035] On the other hand, the FPGA 43 performs control such that the detection output of the logarithmic detector 44 becomes a predetermined value by adjusting the AGC control voltage as described above. Therefore, the reception level can be estimated from the current state of AGC control. Specifically, this reception level can be estimated from the current detection output and the current state of AGC control (AGC control voltage with respect to VATT). In the configuration of FIG. 2, since the FPGA 43 can recognize both the current detection output and the current AGC control voltage, this reception level can be estimated.

[0036] FIG. 3 schematically shows this principle. In FIG. 2, in the upper signal path L2, only VATT22 (AGC control voltage VAGC 11 ) is used, while in the lower signal path L1, VATT26, 29, 35 (AGC control voltage VAGC 21 , VAGC 22 , VAGC 23 ) are used. Here, for simplicity, it is assumed that in the signal path L2 as well, the attenuation amount is adjusted only by one of these (for example, VATT35 (VAGC 23 )) and the other AGC control voltages are set to be constant.

[0037] In FIG. 3(a), the relationship between the reception level and the detected voltage is schematically shown. If the attenuation amount is constant, the higher the reception level, the higher the detected voltage. Here, for simplicity, it is assumed that they have a linear relationship. This relationship is the same even when the attenuation amount changes. However, the larger the attenuation amount, the higher the actual reception level even for the same detected voltage. Therefore, the relationship between the reception level and the detected voltage when the attenuation amount is divided into three types (large, medium, and small) is as shown in FIG. 3(a).

[0038] However, as described above, in this reception conversion unit 20, since the detected voltage of the logarithmic detector 44 is determined to be constant, it is preferable to use the relationship in FIG. 3(b) obtained by rewriting the relationship in FIG. 3(a) as the relationship between the reception level and the attenuation amount when the detected voltage is constant. This relationship can be stored in a non-volatile memory or the like as a data table for each detected voltage and can be used by the FPGA 43. However, since the attenuation amount corresponds one-to-one with the AGC control voltage of VATT (VAGC when IF is selected, VAGC 11 when IF2 is selected, VAGC 23 ), actually, this data table determines the correspondence relationship between the reception level and the AGC control voltage for each detected voltage. In the example of FIG. 3, this correspondence relationship is simplified to be a linear relationship, but actually, it does not have to be a linear relationship as long as the attenuation amount (AGC control voltage) and the reception level correspond one-to-one. That is, when the set value of the detected voltage (detected output) is determined as described above from the above data table, the FPGA 43 can calculate the reception level from this detected voltage (detected output) and the current attenuation amount (AGC control voltage).

[0039] If the received level recognized in this way by the FPGA 43 is lower than the threshold value set by the user, the switch 47 is turned off regardless of the AGC control. As a result, no output is generated from this relay device 1 (reception conversion unit 20). On the other hand, since the AGC control and the recognition of the received level as described above are continuously performed even in this case, when the received level becomes equal to or higher than the above-mentioned threshold value, the FPGA 43 can turn on the switch 47. As a result, an output is generated from this relay device 1 (reception conversion unit 20).

[0040] In the second signal path L2 (IF), since only the VATT 22 is provided as described above, when the second signal path L2 (IF) is selected, the reception level of the IF is recognized by the above operation. On the other hand, in the first signal path L1 (RF), actually, the VATTs 26, 29, 35 (AGC control voltages VAGC 21 、VAGC 22 、VAGC 23 ) are used, and these can be individually controlled so that the above-mentioned detection voltage becomes constant. In this case, the FPGA 43 determines in advance the distribution of the attenuation amounts by the VATT 26, the attenuation amount by the VATT 29, and the attenuation amount by the VATT 35, and then can adjust the AGC control voltages VAGC 21 、VAGC 22 、VAGC 23 .

[0041] In this case, if the AGC control voltage VAGC 21 dependency (positive or negative of the coefficient of variation) of the attenuation amount in the VATT 26, the AGC control voltage VAGC 22 dependency of the attenuation amount in the VATT 29, and the AGC control voltage VAGC 23 dependency of the attenuation amount in the VATT 35 are set to be in the same direction, the VAGC 2 =VAGC 21 +VAGC 22 +VAGC 23 , which is the sum of the respective AGC control voltages, can be defined as a temporary AGC control voltage. In this case, the temporary AGC control voltage VAGC 2If the sum of the attenuation amounts in the first signal path L1 is defined as a provisional attenuation amount, they can be made to correspond one-to-one. That is, with such a provisional AGC control voltage VAGC 2 by using this, even when the first signal path L1 is selected, control similar to that of the second signal path can be performed.

[0042] In this case, one of the attenuation amounts of VATT26, 29, 35 may be fixed and the other two attenuation amounts may be adjusted. For example, the attenuation amount of VATT26 (AGC control voltage VAGC 21 ) may be fixed, and with the above-mentioned provisional AGC control voltage VAGC 2 =VAGC 22 +VAGC 23 as described above, the reception level can also be estimated in the same manner. The conversion data table used by the FPGA43 as described above can be appropriately prepared according to such a method of adjusting the attenuation amount.

[0043] Note that in the above example, the operation for making the intensities (detected outputs) of IF and IF2 input to the signal processing unit constant during steady operation was described. However, other operations, for example, transient operations at the time of equipment startup can be set as appropriate. For example, at startup, by setting the attenuation amount of the variable attenuator to be large, it is possible to suppress the signal intensity from becoming excessive, and then the above-described feedback control may be performed. In this case, the operation of stopping the output to the signal processing unit according to the reception level as described above is performed after such feedback control is started.

[0044] Also, in the above example, two signal paths were provided according to two types of relay methods, but it is obvious that the same operation is possible even if these are three or more. Also, in a relay device having redundancy, a plurality of the configurations of FIGS. 1 and 2 are provided. In such a case, the above-described configuration in which the configuration is simplified is particularly effective.

[0045] The above description has been based on embodiments of the present invention. It should be understood by those skilled in the art that these embodiments are illustrative, and various modifications are possible for combinations of their respective components, and such modifications are also within the scope of the present invention.

Explanation of Reference Numerals

[0046] 1 Relay device 10 Receiver 20 Receiver conversion unit 21, 39 Switch 22, 26, 29, 35 Variable attenuator (VATT) 23, 33, 36 Low Pass Filter (LPF) 24 Attenuator (ATT) 25, 28, 30, 34, 37, 41 Amplifier 27 High Pass Filter (HPF) 31 Mixer 32 Local oscillator 38 Band Pass Filter (BPF) 40 Coupler 42, 45 AD converter 43 Field Programmable Gate Array (Arithmetic unit: FPGA) 44 Logarithmic detector 46 DA converter 47 Switch 50 Signal processing unit 60 Transmitter L1 First signal path L2 Second signal path

Claims

1. A relay device that, when receiving and relaying a transmission signal, adjusts the intensity of the received transmission signal using a variable attenuator whose attenuation rate is adjusted by a control voltage, and performs relaying, wherein: A first relaying method in which a first transmission signal is used as the transmission signal, and a second relaying method in which a second transmission signal having a carrier frequency different from that of the first transmission signal is used as the transmission signal are switched and used; The variable attenuator is provided in each of a first signal path that adjusts and outputs the intensity of the received first transmission signal, and a second signal path that adjusts and outputs the intensity of the received second transmission signal; In the first signal path, the first transmission signal is frequency-converted so as to approach the carrier frequency of the second transmission signal; A common detector that selects and inputs the first transmission signal after passing through the first signal path and the second transmission signal after passing through the second signal path; Comprising; The control voltage of the variable attenuator in the first signal path and the control voltage of the variable attenuator in the second signal path are feedback-adjusted so that the detection output of the detector is constant. A relay device characterized by this.

2. When the reception level of the received transmission signal is low, an operation of not performing relaying is performed, The relay device according to claim 1, further comprising an arithmetic unit that calculates the reception level based on the detection output and the corresponding control voltage.

3. The relay device according to claim 1 or 2, wherein the first relaying method is a broadcast wave relaying method, the second relaying method is an IF relaying method, and it is used for terrestrial digital broadcasting.

4. A control method for a relay device that, when receiving and relaying a transmission signal, adjusts the intensity of the received transmission signal and performs relaying, wherein: A first relaying method in which a first transmission signal is used as the transmission signal, and a second relaying method in which a second transmission signal having a carrier frequency different from that of the first transmission signal is used as the transmission signal are switched and used; A first signal path for adjusting and outputting the intensity of the received first transmission signal and a second signal path for adjusting and outputting the intensity of the received second transmission signal are provided; In the first signal path, the first transmission signal is frequency-converted so as to approach the carrier frequency of the second transmission signal; Select and detect either the first transmission signal after passing through the first signal path or the second transmission signal after passing through the second signal path to detect a detection output. A control method for a relay device, characterized in that adjustment of the intensity of the first transmission signal in the first signal path and adjustment of the intensity of the second transmission signal in the second signal path are performed by feeding back the detection output so that the detection output becomes constant.

5. The adjustment of the intensity of the first transmission signal in the first signal path and the adjustment of the intensity of the second transmission signal in the second signal path are performed by adjusting a control voltage according to the detection output. Calculate the reception level of the transmission signal based on the detection output and the corresponding control voltage. The control method for a relay device according to claim 4, characterized in that when the calculated reception level is low, an operation of not performing relaying is performed.

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