JP2012015814A - High frequency circuit and high frequency signal conversion method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency circuit and a high frequency signal conversion method which comply with an electric field strength specified by the Radio Law and adaptively convert to a signal of a desired frequency.SOLUTION: The high frequency circuit includes frequency conversion parts 4 and 6, a gain control part 5, and a level detecting part 9. The frequency conversion part 4 selects a signal of a desired channel from a plurality of RF signals in channel arrangement, and converts the RF signal, in frequency, to an IF signal whose frequency is lower than that of the RF signal, having a band width corresponding to a band width equivalent to almost one channel of the frequency of the RF signal. The frequency conversion part 6 converts, in frequency, the IF signal to the signal of an RF frequency which is higher than the frequency of the IF signal. The gain control part 5 adjusts a gain of at least one of the RF signal and the IF signal. The level detecting part 9 detects intensity of an output signal of the frequency conversion part 6, and controls the gain control part 5 so that the intensity of the output signal of the frequency conversion part 6 is adjusted to be almost constant.

Description

  Embodiments described herein relate generally to a high-frequency signal conversion technique for adaptively converting an input signal into a signal of another frequency.

  In recent years, the number of mobile terminals to which a one-segment TV function is added is increasing. Such a portable terminal directly receives a broadcast signal for terrestrial digital broadcasting wirelessly. In addition to such portable terminals, there are an increasing number of cases in which a plurality of liquid crystal televisions that receive broadcast signals wirelessly are used in the home.

  For example, a broadcast signal for terrestrial digital broadcasting has a high frequency and thus is easily attenuated. The frequency range of the broadcast signal for terrestrial digital broadcasting is 470 MHz to 770 MHz in the UHF (Ultra High Frequency) band. Therefore, when a user tries to receive a broadcast signal directly using a portable terminal at home, it may be difficult to receive the signal due to deterioration of radio wave intensity. For this reason, high-frequency signal transmission apparatuses that amplify and retransmit received broadcast signals have become widespread.

JP 2002-252790 A

  In the radio wave law, when a broadcast signal is retransmitted using a high-frequency signal transmission device without a license, an upper limit of the electric field strength of the broadcast signal is determined according to the frequency. Therefore, the high-frequency signal transmission device needs to amplify and retransmit the broadcast signal in compliance with the Radio Law. In addition, the intensity of a broadcast signal received by a receiving antenna for terrestrial digital broadcasting may vary depending on the channel. Therefore, when the high-frequency signal transmission device amplifies or frequency-converts the broadcast signals of a plurality of channels having a difference in intensity, a difference also occurs in the intensity of the output signal.

  For this reason, when the electric field strength of the output signal based on the broadcast signal of the strongest channel is set as the upper limit of regulation of the Radio Law, the high-frequency signal transmission device has a relative electrolysis strength of the output signal based on the broadcast signal of other channels. It will be set low. As a result, the mobile terminal that receives the output signal from the high-frequency signal transmission device impairs the reception quality of the received signal in wireless transmission. Therefore, the high-frequency signal transmission device needs to appropriately adjust the strength of the final output signal regardless of the channel. When a broadcast signal for digital broadcast and a broadcast signal for analog broadcast are mixed, the intensity of the broadcast signal for digital broadcast and the intensity of the broadcast signal for analog broadcast are different. Therefore, it is necessary for the high-frequency signal transmission device to adjust its strength appropriately regardless of whether the broadcast signal is digital or analog. At the same time, the high-frequency signal transmission device needs to set the local oscillation frequency when the frequency of the broadcast signal is converted so as to comply with the Radio Law.

  Accordingly, an object of the present invention is to provide a high-frequency circuit and a high-frequency signal conversion method that adaptively convert a signal having a desired frequency while observing the electric field strength defined by the Radio Law.

  According to the embodiment, the high-frequency circuit includes a first frequency conversion unit, a second frequency conversion unit, a gain control unit, and a level detection unit. The first frequency converter is an analog-modulated or digital-modulated RF signal, selects a signal of a desired channel from the RF signals arranged in a plurality of channels, and converts the RF signal into the RF signal. The frequency of the RF signal is converted to an IF signal having a bandwidth corresponding to a bandwidth per channel of the frequency of the RF signal and output. The second frequency converter converts the input IF signal into a signal having an RF frequency higher than the frequency of the IF signal and outputs the signal. The gain control unit adjusts the gain of at least one of the RF signal and the IF signal. The level detection unit detects the intensity of the signal corresponding to the intensity of the output signal from the second frequency conversion unit, and substantially reduces the intensity of the output signal from the second frequency conversion unit based on the detection result. The gain control unit is controlled so as to be adjusted to be constant.

The block diagram which shows the high frequency signal transmission apparatus which concerns on 1st embodiment. The graph which shows the electric field strength of the weak radio station made into the license unnecessary according to the Radio Law. The block diagram which shows the high frequency signal transmission apparatus which concerns on 2nd embodiment. The block diagram which shows the high frequency signal transmission device which concerns on 3rd embodiment. The block diagram which shows the high frequency signal transmission apparatus which concerns on 4th embodiment. The block diagram which shows the other example of the high frequency signal transmission apparatus which concerns on 4th embodiment. The block diagram which shows the high frequency signal transmission apparatus which concerns on 5th embodiment. The block diagram which shows the other example of the high frequency signal transmission apparatus which concerns on 5th embodiment.

  Hereinafter, this embodiment will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the high-frequency signal transmission device according to the first embodiment. The high-frequency signal transmission device includes a high-frequency circuit unit 1 and a transmission antenna 18. The high-frequency circuit unit 1 is an RF (Radio Frequency) signal that is analog-modulated or digital-modulated like a TV (television) broadcast signal, and inputs RF signals of RF 90 to 770 MHz arranged in a plurality of channels. Input from part 2. The gain control unit 3 amplifies or attenuates the RF signal and then inputs it to the first frequency conversion unit 4.

  The first frequency converter 4 mixes the input RF signal and the signal of the first local oscillator 10. The first frequency converting unit 4 converts only the RF signal of the desired channel by appropriately setting the frequency of the first local oscillating unit 10. The first frequency converter 4 passes the RF signal through an IF (Intermediate Frequency) filter (not shown) having a center frequency of 44 MHz and a bandwidth of 6 MHz corresponding to the bandwidth per channel, for example. And suppress other channels. That is, the first frequency conversion unit 4 performs frequency conversion so that the RF signal of the desired channel is always a constant frequency IF signal.

  The IF signal output from the first frequency conversion unit 4 is amplified or attenuated by a gain control unit 5 such as a variable gain amplifier and then input to the second frequency conversion unit 6. The second frequency converter 6 mixes the input IF signal and the signal of the second local oscillator 11. The second frequency converting unit 6 converts the IF signal into a signal having a desired frequency by appropriately setting the frequency of the second local oscillating unit 11. Then, the second frequency converter 6 outputs the output signal to the output unit 8. The output unit 8 outputs the output signal frequency-converted by the second frequency conversion unit 6 to the transmission antenna 18.

  Here, the frequency of the output signal frequency-converted by the second frequency converter 6 and the frequency of the second local oscillator 11 are designed to be 332 MHz or less. The reason for this design will be described. FIG. 2 is a graph showing the electric field strength of a weak radio station whose license is not required under the Radio Law. If the electric field strength of the transmission signal at a distance of 3 meters from the transmission antenna 18 is lower than the strength shown in the graph, a license for the radio station (high-frequency signal transmission device according to the first embodiment) is unnecessary in the Radio Law. Has been. When the frequency of the transmission signal from the transmission antenna 18 is 322 MHz or less, the electric field strength is as high as 500 μV / m 2 or less. On the other hand, when the frequency of the transmission signal is higher than 322 MHz and close to 10 GHz, the electric field strength is as low as 35 μV / m 2 or less.

  The high-frequency signal transmission device according to the first embodiment needs to transmit a transmission signal with as high an electric field strength as possible so that a reception device such as a terminal (not shown) located far away can receive the transmission signal. . Therefore, the high-frequency signal transmission device according to the first embodiment needs to set the frequency of the transmission signal so that the electric field strength of the transmission signal is 500 μV / m 2 or less at a distance of 3 meters. Therefore, the frequency of the signal of the second local oscillation unit 11 needs to be realized at 332 MHz or less. For example, when the IF frequency is 44 MHz and the transmission frequency is set to 303.143 MHz, the frequency of the second local oscillation unit 11 can be set to 303.143-44 = 259.143 MHz.

  The level detection unit 9 controls the gain control unit 3 and the gain control unit 5 so that the electric field strength of the transmission signal transmitted from the transmission antenna 18 is 500 μV / m 2 or less at a distance of 3 meters. In other words, the level detection unit 9 is information set so that the intensity of the output signal output from the output unit 8 is 3 μm from the transmission antenna 18 and the electric field intensity of the transmission signal is 500 μV / m 2 or less. Information). The level detection unit 9 monitors the intensity (signal level) of the output signal at the output unit 8. The level detection unit 9 controls the gain control unit 3 and the gain control unit 5 so that the intensity of the output signal in the output unit 8 is the same value as the setting intensity information. Therefore, the level detection unit 9 does not depend on the intensity of the RF signal input from the input unit 2, and sets the intensity of the output signal to an appropriate substantially constant value (the electric field intensity of the transmission signal is 500 μV at a distance of 3 meters from the antenna 18). Can be automatically controlled to be a value that is less than / m). The level detection unit 9 may mainly control either the gain control unit 3 or the gain control unit 5 in order to adjust the intensity of the output signal from the high frequency circuit unit 1.

  Here, the first frequency converter 4 will be further described. The high-frequency circuit unit 1 shown in FIG. 1 is a super heterodyne system that combines one first frequency conversion unit 4 and one first local oscillation unit 10 to convert to a constant frequency. The high-frequency circuit unit 1 may be frequency-converted by the double super heterodyne method without being bound by this method, or may generate an IF signal by a digital circuit even if the RF signal is directly subjected to quadrature detection and then frequency-converted. Also good.

  In the above, an example in which IF is 44 MHz is shown, but the present invention is not limited to this. The high frequency circuit unit 1 may use an IF of about 30 to 60 MHz, which is an IF of a television receiver for receiving analog broadcasts. Further, the high-frequency circuit unit 1 may use an IF of about 4 MHz to 10 MHz called Low-IF. Further, the high-frequency circuit unit 1 may use a Zero-IF by performing orthogonal detection.

  Further, the gain control unit 3 and the gain control unit 5 will be further described. One of the purposes of the gain control is to keep the electric field strength of the transmission signal at an appropriate substantially constant value below a specified value at a distance of 3 meters from the transmission antenna 18 as described above. Another object is to apply each stage to suppress nonlinear distortion in circuits such as the gain controller 3, the first frequency converter 4, the gain controller 5, and the second frequency converter 6 shown in FIG. It is to avoid excessive signal input. Therefore, the level detection unit 9 may use a method of detecting the signal strength at a plurality of stages and optimizing the signal strength for each stage. Further, the level detection unit 9 may use a method of detecting the intensity of the output signal from the output unit 8 and comprehensively optimizing the signal intensity. Furthermore, the level detection unit 9 may use a method of applying both in combination.

  According to the first embodiment, since the high-frequency circuit unit 1 performs frequency conversion in two stages, it is possible to transmit the RF signals of all channels from 90 MHz to 770 MH with the same configuration. Since the high frequency circuit unit 1 controls the intensity of the output signal from the high frequency circuit unit 1 for each channel, even if there is a difference in the intensity of the RF signal depending on the channel, the output signal is substantially constant for all channels. Can be output. Therefore, the high-frequency signal transmission device can improve the reception quality of wireless transmission. The high-frequency circuit unit 1 can be controlled to an appropriate constant value without depending on the strength of the RF signal input from the input unit 2 while observing the intensity of the output signal from the high-frequency circuit unit 1 in accordance with the Radio Law. The frequency of the two local oscillations 11 can also be set to 322 MHz or less.

  FIG. 3 is a block diagram showing the configuration of the high-frequency signal transmission device according to the second embodiment. The same components as those described above are denoted by the same reference numerals and description thereof is omitted. The high-frequency signal transmission device includes a high-frequency circuit unit 1 and a transmission antenna 18. The high-frequency circuit unit 1 further includes an output signal distributor 7.

  An output signal from the second frequency converter 6 is input to the output signal distributor 7. The output signal distributor 7 distributes the output signal from the second frequency converter 6 into a first output signal and a second output signal, and outputs them. The first output signal is input to the transmission antenna 18 via the output unit 8. The transmission antenna 18 transmits a transmission signal based on the first output signal. The second output signal is input to the level detection unit 9.

  The level detector 9 detects the intensity (level) of the input second output signal. The level detection unit 9 outputs a control voltage or a control signal corresponding to the strength of the second output signal to the gain control unit 3 and the gain control unit 5. The gain control unit 3 and the gain control unit 5 adjust the intensity of the second output signal to an appropriate substantially constant value based on the control voltage or control signal output from the level detector 9. At the same time, the gain control unit 3 and the gain control unit 5 adjust the first output signal, that is, the output signal of the output unit 8 to an appropriate constant value. According to the second embodiment, there are the same effects as in the first embodiment.

  FIG. 4 is a block diagram illustrating a configuration of the high-frequency signal transmission device according to the third embodiment. The same components as those described above are denoted by the same reference numerals and description thereof is omitted. The high-frequency signal transmission device includes a high-frequency circuit unit 1, an input unit 12, a wide-band high-frequency amplification unit 13, a wide-band distribution unit 15, a transmission antenna 18, a high-frequency circuit unit 101, and a transmission antenna 118.

  The high-frequency circuit unit 1 and the transmission antenna 18 are as described in the second embodiment shown in FIG. The high-frequency circuit unit 101 includes an input unit 102, a gain control unit 103, a first frequency conversion unit 104, a gain control unit 105, a second frequency conversion unit 106, an output signal distributor 107, an output unit 108, and a level detection unit 109. The first local oscillator 110 and the second local oscillator 111 are provided. Input unit 102, gain control unit 103, first frequency conversion unit 104, gain control unit 105, second frequency conversion unit 106, output signal distributor 107, output unit 108, level detection unit 109, first local oscillation Each of the unit 110 and the second local oscillation unit 111 includes an input unit 2, a gain control unit 3, a first frequency conversion unit 4, a gain control unit 5, a second frequency conversion unit 6, an output signal distributor 7, an output The configuration is the same as that of the unit 8, the level detection unit 9, the first local oscillation unit 10, and the second local oscillation unit 11. The transmission antenna 118 has the same configuration as the transmission antenna 18.

  The broadband high frequency amplification unit 13 amplifies the RF signal input from the input unit 12 and then outputs the amplified RF signal to the broadband distribution unit 15. The broadband distributor 15 distributes the RF signal amplified by the broadband high-frequency amplifier 13 into two. The broadband distribution unit 5 inputs one distributed signal from the input unit 2 to the first high-frequency circuit unit 1. The broadband distribution unit 15 inputs the other distributed signal from the input unit 102 to the high-frequency circuit unit 101.

  The first frequency conversion unit 4 in the high frequency circuit unit 1 and the first frequency conversion unit 104 in the high frequency circuit unit 101 selectively convert different RF signal channels into IF signals. The second frequency conversion unit 6 in the high-frequency circuit unit 1 and the second frequency conversion unit 106 in the high-frequency circuit unit 101 frequency-convert IF signals to different frequencies (322 MHz or less) and output them. The first high-frequency circuit unit 1 transmits the output signal to the transmission antenna 18 via the output unit 8. Similarly, the second high-frequency circuit unit 101 transmits an output signal to the transmission antenna 118 via the output unit 108.

  According to the third embodiment, since the high-frequency signal transmission device includes a plurality of high-frequency circuit units, it is possible to frequency-convert the RF signals of the channels corresponding to the number. That is, the high-frequency signal transmission device can transmit transmission signals having different frequencies according to the number of high-frequency circuit units. FIG. 4 shows an example of two systems of high-frequency circuit units and transmission antennas, but the number may be increased.

  FIG. 5 is a block diagram showing a configuration of the high-frequency signal transmission device according to the fourth embodiment. The same components as those described above are denoted by the same reference numerals and description thereof is omitted. The high-frequency signal transmission device includes a high-frequency circuit unit 1, an input unit 12, a wide-band high-frequency amplification unit 13, a wide-band distribution unit 14, and a transmission antenna 18.

  The broadband high-frequency amplifier 13 amplifies the RF signal input from the input unit 12 and then outputs the amplified RF signal to the broadband distributor 14. The broadband distributor 14 distributes the RF signal amplified by the broadband high-frequency amplifier 13 into two. The wideband distribution unit 14 inputs one distributed wideband distribution output signal from the input unit 2 to the high frequency circuit unit 1. The broadband distribution unit 14 inputs the other distributed broadband output signal to the TV receiver 16. The TV receiver 16 performs normal television reception based on the wideband distribution output signal. Furthermore, the user can confirm the reception quality of the RF signal by using the function of checking the level of the RF signal of the TV receiver 16.

  The reason for confirming the reception quality of the RF signal by the TV receiver 16 is as follows. In order for a receiving device such as a television (not shown) located far away from the high-frequency signal transmission device to stably receive the transmission signal from the transmission antenna 18, the quality of the RF signal itself input to the input unit 12 is important. is there. This is because, when the quality of the RF signal itself cannot be ensured, there is a possibility that a sufficient distance from the transmission antenna 18 to the receiving device cannot be ensured.

  Therefore, the user confirms the quality of the RF signal input to the input unit 12 using the TV receiver 16. If the quality of the RF signal is poor, the user can switch the gain of the broadband high-frequency amplifier 13 to ensure sufficient signal quality. The gain of the broadband high-frequency amplifier 13 is switched, for example, by switching the switch.

  FIG. 6 is a block diagram illustrating another example of the configuration of the high-frequency signal transmission device according to the fourth embodiment. The same components as those described above are denoted by the same reference numerals and description thereof is omitted. The high-frequency signal transmission device includes a high-frequency circuit unit 1, an input unit 12, a wide-band high-frequency amplification unit 13, a wide-band distribution unit 14, a wide-band distribution unit 15, a transmission antenna 18, and a high-frequency circuit unit 101.

  The broadband high-frequency amplifier 13 amplifies the RF signal input from the input unit 12 and then outputs the amplified RF signal to the broadband distributor 14. The broadband distributor 14 distributes the RF signal amplified by the broadband high-frequency amplifier 13 into two. The broadband distribution unit 14 inputs one distributed broadband distribution output signal to the broadband distribution unit 15. The broadband distribution unit 15 further distributes the broadband distribution output signal into two. The broadband distribution unit 15 inputs one broadband distribution output signal from the input unit 2 to the high frequency circuit unit 1. The other broadband distribution output signal is input from the input unit 102 to the high-frequency circuit unit 101. The broadband distribution unit 14 inputs the other distributed broadband output signal to the TV receiver 16.

The frequency of the transmission signal transmitted from the transmission antenna 18 and the frequency of the transmission signal transmitted from the transmission antenna 118 are different from each other as in the third embodiment shown in FIG. Further, the reason for connecting the TV receiver 16 to the high-frequency signal transmission device is as described above. When it is desirable that the strengths of the broadband distribution signals input to the input unit 2, the input unit 102, and the TV receiver 16 are the same, the broadband distribution unit 14 is designed by appropriately changing the distribution ratio of the signals. You may do it.
According to the fourth embodiment, since the quality of the RF signal itself input to the high-frequency signal transmission device can be confirmed, the quality of the transmission signal transmitted from the transmission antenna 18 can be ensured.

  FIG. 7 is a block diagram showing the configuration of the high-frequency signal transmission device according to the fifth embodiment. The same components as those described above are denoted by the same reference numerals and description thereof is omitted. The high-frequency signal transmission device includes a high-frequency circuit unit 1, an input unit 12, a wide-band high-frequency amplification unit 13, a wide-band distribution unit 15, a transmission signal mixing unit 17, a transmission antenna 18, and a high-frequency circuit unit 101.

  The transmission signal mixing unit 17 has one input terminal connected to the output unit 8 of the high frequency circuit unit 1 and the other input terminal connected to the output unit 108 of the high frequency circuit unit 101. The transmission signal mixing unit 17 is further connected to the transmission antenna 18. The transmission signal mixing unit 17 mixes the output signal from the high-frequency circuit unit 1 and the output signal having different frequencies from the high-frequency circuit unit 101. The transmission antenna 18 transmits a transmission signal in which a plurality of output signals are mixed.

  FIG. 8 is a block diagram showing another example of the configuration of the high-frequency signal transmission device according to the fifth embodiment. The same components as those described above are denoted by the same reference numerals and description thereof is omitted. The high-frequency signal transmission device includes a high-frequency circuit unit 1, an input unit 12, a wide-band high-frequency amplification unit 13, a wide-band distribution unit 14, a wide-band distribution unit 15, a transmission signal mixing unit 17, a transmission antenna 18, and a high-frequency circuit unit 101.

  The broadband high-frequency amplifier 13 amplifies the RF signal input from the input unit 12 and then outputs the amplified RF signal to the broadband distributor 14. The broadband distributor 14 distributes the RF signal amplified by the broadband high-frequency amplifier 13 into two. The broadband distribution unit 14 inputs one distributed broadband distribution output signal to the broadband distribution unit 15. The broadband distribution unit 15 further distributes the broadband distribution output signal into two. The broadband distribution unit 15 inputs one broadband distribution output signal from the input unit 2 to the high frequency circuit unit 1. The other broadband distribution output signal is input from the input unit 102 to the high-frequency circuit unit 101. The broadband distribution unit 14 inputs the other distributed broadband output signal to the TV receiver 16. The reason for connecting the TV receiver 16 to the high-frequency signal transmission device is as described above.

  The transmission signal mixing unit 17 has one input terminal connected to the output unit 8 of the high frequency circuit unit 1 and the other input terminal connected to the output unit 108 of the high frequency circuit unit 101. The transmission signal mixing unit 17 is further connected to the transmission antenna 18. The transmission signal mixing unit 17 mixes the output signal from the high-frequency circuit unit 1 and the output signal having different frequencies from the high-frequency circuit unit 101. The transmission antenna 18 transmits a transmission signal in which a plurality of output signals are mixed.

  According to the fifth embodiment, even if the high-frequency signal transmission device includes a plurality of high-frequency circuit units, one transmission signal obtained by mixing a plurality of output signals having different frequencies is output from the transmission signal. It can be transmitted from the transmitting antenna 18. Therefore, the high-frequency signal transmission device does not need to have the same number of transmission antennas as the number of high-frequency circuit units.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... High frequency circuit part, 2 ... Input part, 3 ... Gain control part, 4 ... 1st frequency conversion part, 5 ... Gain control part, 6 ... 2nd frequency conversion part, 7 ... Output signal distribution part, 8 ... Output unit, 9 ... level detection unit, 10 ... first local oscillation unit, 11 ... second local oscillation unit, 12 ... input unit, 13 ... wideband high frequency amplification unit, 14 ... wideband distribution unit, 15 ... wideband distribution unit , 16 ... TV receiver, 17 ... transmission signal mixing unit, 18 ... transmission antenna, 101 ... high frequency circuit unit, 102 ... input unit, 103 ... gain control unit, 104 ... first frequency conversion unit, 105 ... gain control unit , 106 ... second frequency converter, 107 ... output signal distributor, 108 ... output unit, 109 ... level detector, 110 ... first local oscillator, 111 ... second local oscillator, 118 ... transmitting antenna .

Claims (7)

An analog-modulated or digital-modulated RF signal, a signal of a desired channel is selected from the RF signals arranged in a plurality of channels, and the RF signal is lower than the frequency of the RF signal and the RF signal A first frequency converter that converts the frequency into an IF signal having a bandwidth equivalent to the bandwidth per channel of the frequency of
A second frequency converter that converts the input IF signal to a signal having an RF frequency higher than the frequency of the IF signal and outputs the signal;
A gain controller that adjusts the gain of at least one of the RF signal and the IF signal;
The intensity of the output signal from the second frequency conversion unit is detected, and the gain control unit is controlled to adjust the intensity of the output signal from the second frequency conversion unit to be substantially constant based on the detection result. A level detector to perform,
A high-frequency circuit comprising: The signal input from the second frequency conversion unit is distributed to first and second output signals, the first output signal is input to a transmission antenna, and the second output signal is input to the level detection unit. An output signal distributor for input;
The level detection unit detects the intensity of the second output signal, and controls the gain control unit based on the detection result,
The gain control unit adjusts the intensity of the second output signal to be substantially constant based on the control by the level detector, and also adjusts the intensity of the first output signal to be substantially constant.
The high-frequency circuit according to claim 1. A broadband high-frequency amplifier for amplifying the input RF signal;
A first broadband distributor that distributes the output signal of the broadband high-frequency amplifier and inputs a plurality of broadband distributed output signals to each of the plurality of first frequency converters;
Each of the plurality of first frequency converters converts the RF signals of different channels into the IF signals,
Each of the plurality of second frequency converters converts the IF signal into signals having different frequencies and outputs the signals.
The high frequency circuit according to claim 1 or 2. A second wideband distribution unit that distributes the RF signal and inputs a wideband distribution output signal to the first frequency converter and the television receiver;
The high-frequency circuit according to claim 1. A transmission signal mixing unit that mixes and outputs signals having different frequencies from the plurality of second frequency conversion units,
The high-frequency circuit according to claim 3 or 4. 6. The high-frequency circuit according to claim 1, wherein a frequency of the RF signal is a television signal of 90 MHz to 770 MHz, and a frequency of an output signal from the second frequency conversion unit is 322 MHz or less. An analog-modulated or digital-modulated RF signal, the RF signal arranged in a plurality of channels is input,
A signal of a desired channel is selected from the input RF signals, and the RF signal is lower than the frequency of the RF signal, and a bandwidth corresponding to a bandwidth per channel of the frequency of the RF signal. The IF signal of the first frequency conversion and output,
The IF signal is output with a second frequency conversion to a signal having an RF frequency higher than the frequency of the IF signal,
Detecting the intensity of the second frequency converted signal;
Based on this detection result, the intensity of the second frequency converted signal is adjusted to be substantially constant,
High-frequency signal conversion method.

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