JP2007258900A

JP2007258900A - Unwanted-wave detector

Info

Publication number: JP2007258900A
Application number: JP2006078675A
Authority: JP
Inventors: Miki Kagano; 未来加賀野; Takamori Terada; 孝守寺田
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2006-03-22
Filing date: 2006-03-22
Publication date: 2007-10-04
Anticipated expiration: 2026-03-22
Also published as: JP4693667B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an unwanted-wave detector that is capable of expanding a range of a receivable input signal level while detecting an unwanted wave even when a signal level of the unwanted wave is not suppressed below a reception sensitivity level. <P>SOLUTION: The unwanted-wave detector includes first-third frequency converters 4-6, which respectively convert first-third RF signals RF1-RF3 having the same frequency interval between reception signals adjacent to each other to first-third IF signals IF1-IF3; first-third frequency wave-filters 7-9, which limit each of the converted IF signals to a frequency band of each corresponding IF signal so as to output it; and an intermodulation distortion-wave detector 10 which detects the presence of an intermodulation wave, by applying arithmetic processing to voltage values respectively corresponding to each electric field strength of the first-third RF signals obtained from an output signal of each frequency wave-filter, so as to output a detection signal for turning off operation of a reception system when detecting the presence of the intermodulation wave. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、周波数が等間隔のＲＦ信号を３波以上受信する受信システムにおいて、受信した信号が所望波の信号か不要波（混変調歪波）であるかを判定し、不要波を受信しないようにする不要波検出装置に関するものである。 The present invention determines whether a received signal is a desired wave signal or an unnecessary wave (intermodulation distortion wave) in a receiving system that receives three or more RF signals with equal frequency intervals, and does not receive an unnecessary wave. The present invention relates to an unnecessary wave detection device.

周波数が等間隔のＲＦ信号を３波以上受信する受信システム（例えば、駅構内で電車の乗客の乗降状態を複数映像で監視するシステム等）では、自身の信号（注目している受信信号）以外の受信信号２波による３次混変調歪波が自身の周波数と同じになるので、周波数ろ波器（ｆｉｌｔｅｒ）を通しても不要波である３次混変調歪波を抑圧することができない。
つまり、注目している受信信号が無い場合でも、３次混変調歪波が受信感度レベル以上になると、受信すべきでないものを受信してしまう。 Other than its own signal (received signal of interest) in a receiving system that receives three or more RF signals with equal frequency intervals (for example, a system that monitors the on-boarding status of train passengers in a station using multiple images) Since the third-order intermodulation distorted wave due to the two received signals becomes the same as its own frequency, the third-order intermodulation distorted wave that is an unnecessary wave cannot be suppressed even through the frequency filter.
That is, even when there is no reception signal of interest, if the third-order intermodulation distortion wave exceeds the reception sensitivity level, the signal that should not be received is received.

例えば、特許文献１（特開平１０−０４１８３４号公報）には、近接周波数の不要波による相互変調を改善し、呼出信号の受信率を向上させる無線選択呼出受信機において、受信した無線信号を中間周波数に変換する周波数変換回路のトランジスタのバイアスを切り換えて所望波（即ち、注目している受信信号）に対する不要波（３次混変調歪波）の受信レベルを抑制・除去することが記載されている。
特開平１０−０４１８３４号公報（図１、要約） For example, in Patent Document 1 (Japanese Patent Laid-Open No. 10-041834), a radio selective call receiver that improves intermodulation due to unnecessary waves of adjacent frequencies and improves the reception rate of a paging signal is received by the received radio signal in the middle. It describes that the reception level of an unnecessary wave (third-order intermodulation distortion wave) with respect to a desired wave (that is, a received signal of interest) is suppressed / removed by switching the bias of a transistor of a frequency conversion circuit that converts the frequency. Yes.
Japanese Patent Laid-Open No. 10-041834 (FIG. 1, summary)

前記特許文献1では、電源電圧を上げて周波数変換回路のトランジスタのバイアスを変化させて飽和特性を改善することによって、不要波（３次混変調歪波）を抑圧・除去し、不要波の受信を回避している。
しかし、回路上（仕様上）の制限により、その受信入力レベルには上限がある。 In Patent Document 1, unnecessary waves (third-order intermodulation distortion waves) are suppressed / removed by raising the power supply voltage and changing the bias of the transistor of the frequency conversion circuit to improve saturation characteristics, and receiving unnecessary waves. Is avoiding.
However, there is an upper limit to the received input level due to circuit (specification) limitations.

この発明は、このような問題点を解決するために成されたものであり、周波数が等間隔の３波以上の受信ＲＦ信号の電界強度差を利用して不要波（即ち、混変調波）と所望波とを見分けることによって、使用されている回路（例えば、周波数変換回路）のトランジスタ特性などの制限のために不要波の信号レベルを受信システムの受信感度レベル以下に抑圧しきれない状態の場合でも、不要波の有無を検出することを可能とし、受信システムが受信可能な入力信号レベルの範囲を広げることができる不要波検出装置を提供することを目的とする。 The present invention has been made to solve such a problem, and an unnecessary wave (that is, a cross-modulated wave) is obtained by using a difference in electric field strength between three or more received RF signals with equal frequency. By distinguishing the desired signal from the desired wave, the signal level of the unwanted wave cannot be suppressed below the reception sensitivity level of the receiving system due to limitations on the transistor characteristics of the circuit used (for example, the frequency conversion circuit). Even in such a case, it is an object to provide an unnecessary wave detection device that can detect the presence or absence of unnecessary waves and can widen the range of input signal levels that can be received by a receiving system.

周波数が低い方から第１、第２、第３のＲＦ信号であり、上記第１と第２のＲＦ信号の周波数間隔と上記第２と第３のＲＦ信号の周波数間隔が同じである第１、第２および第３のＲＦ信号を受信し、各受信ＲＦ信号間の信号レベル差が所定値以内である受信システムに用いられる不要波検出装置であって、
上記受信した第１、第２および第３のＲＦ信号を、周波数が等間隔の第１、第２および第３のＩＦ信号にそれぞれ変換する第１、第２および第３の周波数変換器と、変換された上記第１、第２および第３のＩＦ信号をそれぞれ対応するＩＦ信号の周波数帯域に制限して出力する第１、第２および第３の周波数ろ波器と、上記第１、第２および第３の周波数ろ波器の出力信号から得る上記第１、第２および第３のＲＦ信号の電界強度にそれぞれ対応する電圧値を演算処理することにより混変調波の有無を検出し、混変調波が有りと検出された場合は、上記受信システムの動作をオフとする検出信号を出力する混変調歪波検出器とを備えたものである。 First, second, and third RF signals from the lowest frequency, and the frequency interval between the first and second RF signals is the same as the frequency interval between the second and third RF signals. , An unnecessary wave detection device used in a reception system that receives the second and third RF signals and that has a signal level difference between the received RF signals within a predetermined value,
First, second, and third frequency converters for converting the received first, second, and third RF signals into first, second, and third IF signals having equally spaced frequencies, respectively; First, second, and third frequency filters that output the converted first, second, and third IF signals by limiting to the corresponding IF signal frequency bands, and the first, second, Detecting the presence or absence of intermodulation waves by calculating the voltage values respectively corresponding to the electric field strengths of the first, second and third RF signals obtained from the output signals of the second and third frequency filters; When it is detected that there is a cross modulation wave, a cross modulation distortion wave detector that outputs a detection signal for turning off the operation of the reception system is provided.

また、本発明に係わる不要波検出装置の上記混変調歪波検出器は、上記第１、第２および第３の周波数ろ波器の出力信号がそれぞれ入力され、上記第１、第２および第３のＲＦ信号の電界強度に対応する電圧値を出力する第１、第２および第３のＲＳＳＩ(Receiving Signal Strength Indicator)回路と、上記第１と第３のＲＳＳＩ回路の出力電圧値の電位差を出力する第１の減算器と、上記第１と第３のＲＳＳＩ回路の出力電圧値の電位差を出力する第２の減算器と、上記第１の減算器の出力と基準信号とを比較する第１の比較器と、上記第２の減算器の出力と上記基準信号とを比較する第２の比較器とで構成され、
上記第１の比較器と上記第２の比較器の比較結果に基づいて混変調波の有無を検出し、混変調波が有りと検出された場合は受信システムの動作をオフとする検出信号を出力するものである。 Further, the intermodulation distortion wave detector of the unwanted wave detection apparatus according to the present invention receives the output signals of the first, second and third frequency filters, respectively, and the first, second and second The potential difference between the output voltage values of the first, second and third RSSI (Receiving Signal Strength Indicator) circuits that output a voltage value corresponding to the electric field strength of the third RF signal, and the first and third RSSI circuits. A first subtractor for output; a second subtractor for outputting a potential difference between the output voltage values of the first and third RSSI circuits; and a first subtractor for comparing the output of the first subtractor with a reference signal. 1 comparator, and a second comparator for comparing the output of the second subtractor with the reference signal,
Based on the comparison result of the first comparator and the second comparator, the presence / absence of an intermodulation wave is detected, and when the presence of the intermodulation wave is detected, a detection signal for turning off the operation of the receiving system is generated. Output.

本発明の不要波検出装置によれば、周波数が等間隔の３波以上の受信ＲＦ信号の電界強度差を利用して不要波（混変調波）と所望波とを見分けることによって、使用されている回路のトランジスタ特性などの制限のために不要波の信号レベルを受信システムの受信感度レベル以下に抑圧しきれない状態の場合でも、不要波の有無を検出することが可能であり、受信可能な入力信号レベルの範囲を広げることができる。 According to the unwanted wave detection device of the present invention, the unwanted wave (cross-modulation wave) and the desired wave are distinguished from each other by using a difference in electric field strength between three or more received RF signals with equal frequency. Even if the signal level of the unwanted wave cannot be suppressed below the reception sensitivity level of the receiving system due to limitations on the transistor characteristics of the circuit being used, it is possible to detect the presence of the unwanted wave and receive it. The range of the input signal level can be expanded.

以下、図面に基づいて、本発明の一実施の形態について説明する。
なお、各図間において、同一符合は、同一あるいは相当のものであることを表す。
実施の形態１．
図１は、本実施の形態による不要波検出装置の全体構成を示すブロック図である。
本実施の形態による不要波検出装置は、例えば、駅構内で電車の乗降状態を複数の映像で受信して監視するシステムのような「無線で複数のＲＦ信号を受信する受信システム」への適用に好適なものである。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the drawings, the same reference sign indicates the same or equivalent.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing the overall configuration of the unwanted wave detection device according to this embodiment.
The unnecessary wave detection apparatus according to the present embodiment is applied to, for example, a “reception system that receives a plurality of RF signals wirelessly” such as a system that receives and monitors a boarding / alighting state of a train with a plurality of images in a station premises. It is suitable for.

図に示すように、本実施の形態による不要波検出装置は、第１の受信信号入力端子ＣＨ１〜第３の受信信号入力端子ＣＨ３の３つの受信信号入力端子を有している。
そして、各受信信号入力端子（ＣＨ１〜ＣＨ３）にて同時に受信された３つの受信信号（ＲＦ１＋ＲＦ２＋ＲＦ３）は、それぞれ第１の増幅器１〜第３の増幅器３、第１のダウンミキサー４〜第３のダウンミキサー６、第１の周波数ろ波器７〜第３の周波数ろ波器９を通る。
そして、第１の周波数ろ波器７〜第３の周波数ろ波器９のそれぞれの出力は、混変調歪波検出器１０と後段回路（図示なし）に接続される。 As shown in the figure, the unnecessary wave detection device according to the present embodiment has three reception signal input terminals, a first reception signal input terminal CH1 to a third reception signal input terminal CH3.
The three received signals (RF1 + RF2 + RF3) received simultaneously at the received signal input terminals (CH1 to CH3) are respectively the first amplifier 1 to the third amplifier 3, the first down mixer 4 to the third The downmixer 6 passes through the first frequency filter 7 to the third frequency filter 9.
The outputs of the first to third frequency filters 7 to 9 are connected to the intermodulation distortion wave detector 10 and a subsequent circuit (not shown).

次に、図１に示した本実施の形態による不要波検出装置の動作について説明する。
第１の信号入力端子ＣＨ１に入力した受信信号（ＲＦ１＋ＲＦ２＋ＲＦ３）は、第１の増幅器１により増幅され、増幅された第１の受信信号ＲＦ１は第１のダウンミキサー（第１の周波数変換器）４により第１のローカル発振信号ＬＯ１と混合されて第１の中間周波数の信号（第１のＩＦ信号）ＩＦ１にダウンコンバートされる。
第１のダウンミキサー（第１の周波数変換器）４から出力される第１のＩＦ信号ＩＦ１は、第１のＩＦ信号ＩＦ１の周波数帯域のみを通過させる第１の周波数ろ波器７に入力される。
第１の周波数ろ波器７を通過した信号は混変調歪波検出器１０の第１の入力端子ＩＮ１へ入力されると共に、後段回路（図示なし）へも送られる。 Next, the operation of the unnecessary wave detection device according to the present embodiment shown in FIG. 1 will be described.
The reception signal (RF1 + RF2 + RF3) input to the first signal input terminal CH1 is amplified by the first amplifier 1, and the amplified first reception signal RF1 is a first downmixer (first frequency converter) 4. Is mixed with the first local oscillation signal LO1 and down-converted to a first intermediate frequency signal (first IF signal) IF1.
The first IF signal IF1 output from the first downmixer (first frequency converter) 4 is input to the first frequency filter 7 that passes only the frequency band of the first IF signal IF1. The
The signal that has passed through the first frequency filter 7 is input to the first input terminal IN1 of the intermodulation distortion detector 10 and is also sent to a subsequent circuit (not shown).

また、第２の信号入力端子ＣＨ２に入力した受信信号（ＲＦ１＋ＲＦ２＋ＲＦ３）は、第２の増幅器２により増幅され、増幅された第２の受信信号ＲＦ２は第２のダウンミキサー（第２の周波数変換器）５により第２のローカル発振信号ＬＯ２と混合されて第２の中間周波数の信号（第２のＩＦ信号）ＩＦ２にダウンコンバートされる。
第２のダウンミキサー（第２の周波数変換器）５から出力される第２のＩＦ信号ＩＦ２は、第２のＩＦ信号ＩＦ２の周波数帯域のみを通過させる第２の周波数ろ波器８に入力される。
第２の周波数ろ波器８を通過した信号は混変調歪波検出器１０の第２の入力端子ＩＮ２へ入力されると共に、後段回路（図示なし）へも送られる。 The received signal (RF1 + RF2 + RF3) input to the second signal input terminal CH2 is amplified by the second amplifier 2, and the amplified second received signal RF2 is supplied to the second downmixer (second frequency converter). 5) is mixed with the second local oscillation signal LO2 and down-converted to a second intermediate frequency signal (second IF signal) IF2.
The second IF signal IF2 output from the second downmixer (second frequency converter) 5 is input to the second frequency filter 8 that passes only the frequency band of the second IF signal IF2. The
The signal that has passed through the second frequency filter 8 is input to the second input terminal IN2 of the intermodulation distortion detector 10 and is also sent to a subsequent circuit (not shown).

また、第３の信号入力端子ＣＨ３に入力した受信信号（ＲＦ１＋ＲＦ２＋ＲＦ３）は、第３の増幅器３により増幅され、増幅された第３の受信信号ＲＦ３は第３のダウンミキサー（第３の周波数変換器）６により第３のローカル発振信号ＬＯ３と混合されて第３の中間周波数の信号（第３のＩＦ信号）ＩＦ３にダウンコンバートされる。
第３のダウンミキサー（第３の周波数変換器）６から出力される第３のＩＦ信号ＩＦ３は、第３のＩＦ信号ＩＦ３の周波数帯域のみを通過させる第３の周波数ろ波器９に入力される。
第３の周波数ろ波器９を通過した信号は混変調歪波検出器１０の第３の入力端子ＩＮ３へ入力されると共に、後段回路（図示なし）へも送られる。 The received signal (RF1 + RF2 + RF3) input to the third signal input terminal CH3 is amplified by the third amplifier 3, and the amplified third received signal RF3 is supplied to the third down mixer (third frequency converter). ) 6 is mixed with the third local oscillation signal LO3 and down-converted to a third intermediate frequency signal (third IF signal) IF3.
The third IF signal IF3 output from the third downmixer (third frequency converter) 6 is input to the third frequency filter 9 that passes only the frequency band of the third IF signal IF3. The
The signal that has passed through the third frequency filter 9 is input to the third input terminal IN3 of the intermodulation distortion wave detector 10, and is also sent to a subsequent circuit (not shown).

ここで、第１の受信信号ＲＦ１と第２の受信信号ＲＦ２の周波数間隔と第２の受信信号ＲＦ２と第３の受信信号ＲＦ３の周波数間隔は同じであり、周波数の低い方から、第１の受信信号ＲＦ１、第２の受信信号ＲＦ２、第３の受信信号ＲＦ３であるとする。
具体的には、ＲＦ１＝１６８０ＭＨｚ、ＲＦ２＝１７２０ＭＨｚ、ＲＦ３＝１７６０ＭＨｚであるとする。この場合、ＲＦ１とＲＦ２の周波数間隔およびＲＦ２とＲＦ３の周波数間隔は、いずれも同じ４０ＭＨｚである。
そして、ＬＯ１＝２０８０ＭＨｚ、ＬＯ２＝２１２０ＭＨｚ、ＬＯ３＝２１６０ＭＨｚと設定すると、第１のダウンミキサー４〜第３のダウンミキサー６からは４００ＭＨｚにダウンコンバートされたＩＦ１〜ＩＦ３がそれぞれ出力される。
なお、各周波数ろ波器７〜９は、受信システムが注目している受信信号に対応するＩＦ信号の帯域である３０ＭＨｚに帯域制限をかけるので、注目している受信信号がＲＦ２の場合、第２の周波数ろ波器８からは注目する受信信号ＲＦ２の中間周波数の信号ＩＦ２のみが出力する。 Here, the frequency interval between the first reception signal RF1 and the second reception signal RF2 and the frequency interval between the second reception signal RF2 and the third reception signal RF3 are the same. Assume that the received signal RF1, the second received signal RF2, and the third received signal RF3.
Specifically, it is assumed that RF1 = 1680 MHz, RF2 = 1720 MHz, and RF3 = 1760 MHz. In this case, the frequency interval between RF1 and RF2 and the frequency interval between RF2 and RF3 are both 40 MHz.
If LO1 = 2080 MHz, LO2 = 2120 MHz, and LO3 = 2160 MHz, IF1 to IF3 downconverted to 400 MHz are output from the first downmixer 4 to the third downmixer 6, respectively.
Each frequency filter 7-9 limits the bandwidth to 30 MHz, which is the bandwidth of the IF signal corresponding to the received signal focused on by the receiving system, so that when the focused received signal is RF2, The second frequency filter 8 outputs only the signal IF2 having an intermediate frequency of the reception signal RF2 of interest.

図１に示すように、第１の信号入力端子ＣＨ１〜第３の信号入力端子ＣＨ３のそれぞれに３波（第１の受信信号ＲＦ１、第２の受信信号ＲＦ２および第３の受信信号ＲＦ３）が同時に入力される（ＲＦ１＋ＲＦ２＋ＲＦ３）場合、この３波が入力された時点で回路が有する相互変調歪みより、“２＊ＲＦ２−ＲＦ１”および“２＊ＲＦ２−ＲＦ３”の周波数成分が発生する。
ＲＦ１＝１６８０ＭＨｚ、ＲＦ２＝１７２０ＭＨｚ、ＲＦ３＝１７６０ＭＨｚであるとすると、“ＲＦ３＝２＊ＲＦ２−ＲＦ１”となり、相互変調歪みと信号ＲＦ３は同じ周波数になる。信号ＲＦ１についても同様である。
従って、第１の中間周波数信号ＩＦ１と第３の中間周波数信号ＩＦ３の周波数帯域には周波数が同じである混変調による３次歪成分“２＊ＩＦ２−ＩＦ３”、“２＊ＩＦ２−ＩＦ１”がそれぞれ存在する。 As shown in FIG. 1, three waves (a first reception signal RF1, a second reception signal RF2, and a third reception signal RF3) are transmitted to each of the first signal input terminal CH1 to the third signal input terminal CH3. When simultaneously input (RF1 + RF2 + RF3), frequency components of “2 * RF2−RF1” and “2 * RF2−RF3” are generated from the intermodulation distortion of the circuit when these three waves are input.
Assuming that RF1 = 1680 MHz, RF2 = 1720 MHz, and RF3 = 1760 MHz, “RF3 = 2 * RF2−RF1”, and the intermodulation distortion and the signal RF3 have the same frequency. The same applies to the signal RF1.
Accordingly, the third-order distortion components “2 * IF2-IF3” and “2 * IF2-IF1” due to intermodulation having the same frequency are present in the frequency bands of the first intermediate frequency signal IF1 and the third intermediate frequency signal IF3. Each exists.

これらの３次歪成分は、第１の中間周波数信号ＩＦ１および第３の中間周波数信号ＩＦ３に対しては十分に低くなる（即ち、Ｃ（carrier）／Ｎ（noise）を確保できる）ように回路を設計しているため、問題にならない。
しかし、第１の受信信号ＲＦ１と第２の受信信号ＲＦ２の２つの受信信号波のみが入力される場合、第３の受信信号入力端子ＣＨ３に対応する第３の周波数ろ波器９の出力には第３の中間周波数信号ＩＦ３と周波数が同じであるＲＦ１（ＩＦ１）とＲＦ２（ＩＦ２）の混変調により発生する３次の歪成分“２＊ＲＦ２−ＲＦ１（２＊ＩＦ２−ＩＦ１）”のみが出力され、この３次の歪成分のレベルが受信感度レベルに対して低いときには問題ないが、それ以上になると誤受信が発生する。 These third order distortion components are sufficiently low for the first intermediate frequency signal IF1 and the third intermediate frequency signal IF3 (that is, C (carrier) / N (noise) can be ensured). Because it is designed, it will not be a problem.
However, when only two reception signal waves of the first reception signal RF1 and the second reception signal RF2 are input, the output of the third frequency filter 9 corresponding to the third reception signal input terminal CH3 is used. Is only the third-order distortion component “2 * RF2-RF1 (2 * IF2-IF1)” generated by the cross modulation of RF1 (IF1) and RF2 (IF2) having the same frequency as the third intermediate frequency signal IF3. There is no problem when the level of the output third order distortion component is lower than the reception sensitivity level, but erroneous reception occurs when the level is higher.

図２は、このとき（即ち、第１の受信信号ＲＦ１と第２の受信信号ＲＦ２の２つの受信信号波のみが入力されるとき）の“ＩＦ周波数−受信電力特性”であり、受信信号と歪成分のレベル差を示している。
なお、図２において、縦軸の「電力」は、後述する図５の縦軸の「ＲＳＳＩ出力電圧」に相当するものである。
図３は、本実施の形態による混変調歪波検出器１０の構成を示すブロック図である。 FIG. 2 shows “IF frequency-received power characteristics” at this time (that is, when only two received signal waves of the first received signal RF1 and the second received signal RF2 are input). The level difference of the distortion component is shown.
In FIG. 2, “power” on the vertical axis corresponds to “RSSI output voltage” on the vertical axis in FIG.
FIG. 3 is a block diagram showing a configuration of the intermodulation distortion detector 10 according to the present embodiment.

図３を参照しながら混変調歪波検出器１０の動作について説明する。
第１のＲＳＳＩ（Receiving Signal Strength Indicator）回路１１は、第１の入力端子ＩＮ１に入力された第１の周波数ろ波器７を通過した信号をＤＣ電圧値ＲＳ１に変換して出力する。
即ち、第１のＲＳＳＩ回路１１は、第１の受信信号ＲＦ１の電界強度に対応する電圧値ＲＳ２を出力する。
第２のＲＳＳＩ（Receiving Signal Strength Indicator）回路１２は、第２の入力端子ＩＮ２に入力された第２の周波数ろ波器８を通過した信号をＤＣ電圧値ＲＳ２に変換して出力する。
即ち、第２のＲＳＳＩ回路１２は、第２の受信信号ＲＦ２の電界強度に対応する電圧値ＲＳ２を出力する。 The operation of the intermodulation distortion wave detector 10 will be described with reference to FIG.
A first RSSI (Receiving Signal Strength Indicator) circuit 11 converts a signal passing through the first frequency filter 7 input to the first input terminal IN1 into a DC voltage value RS1 and outputs the DC voltage value RS1.
That is, the first RSSI circuit 11 outputs the voltage value RS2 corresponding to the electric field strength of the first reception signal RF1.
A second RSSI (Receiving Signal Strength Indicator) circuit 12 converts the signal passing through the second frequency filter 8 input to the second input terminal IN2 into a DC voltage value RS2 and outputs the DC voltage value RS2.
That is, the second RSSI circuit 12 outputs the voltage value RS2 corresponding to the electric field strength of the second reception signal RF2.

第３のＲＳＳＩ（Receiving Signal Strength Indicator）回路１３は、第３の入力端子ＩＮ３に入力された第３の周波数ろ波器９を通過した信号をＤＣ電圧値ＲＳ３に変換して出力する。
即ち、第３のＲＳＳＩ回路１３は、第３の受信信号ＲＦ３の電界強度に対応する電圧値ＲＳ３を出力する。
また、第１の減算器１４は、第１のＲＳＳＩ回路１４の出力電圧値ＲＳ１と第３のＲＳＳＩ回路１３の出力電圧値ＲＳ３の電位差Ｓ１を求めて出力する。
第２の減算器１５は、第２のＲＳＳＩ回路１２の出力電圧値ＲＳ２と第３のＲＳＳＩ回路１３の出力電圧値ＲＳ３の電位差Ｓ２を求めて出力する。 A third RSSI (Receiving Signal Strength Indicator) circuit 13 converts the signal that has passed through the third frequency filter 9 input to the third input terminal IN3 into a DC voltage value RS3 and outputs it.
That is, the third RSSI circuit 13 outputs the voltage value RS3 corresponding to the electric field strength of the third reception signal RF3.
Further, the first subtractor 14 obtains and outputs a potential difference S1 between the output voltage value RS1 of the first RSSI circuit 14 and the output voltage value RS3 of the third RSSI circuit 13.
The second subtracter 15 calculates and outputs a potential difference S2 between the output voltage value RS2 of the second RSSI circuit 12 and the output voltage value RS3 of the third RSSI circuit 13.

次に、第１の比較器１６および第２の比較器１７の動作について説明する。
基準信号Ｖｒｅｆは、各受信ＲＦ信号間（即ち、第１の受信信号ＲＦ１、第２の受信信号ＲＦ２、第３の受信信号ＲＦ３の受信信号間）の信号レベル差よりも所定レベル大きい電界強度差を表すＤＣ電圧に設定されているものとする。
例えば、基準信号Ｖｒｅｆは、ＲＳＳＩ回路の特性を考慮して、受信する３波の最大電力弾力レベル差の１０ｄＢに幾らか（ｅｘ．１０ｄＢ）を加えた電力レベル差となるように電位差を設定する。 Next, operations of the first comparator 16 and the second comparator 17 will be described.
The reference signal Vref is an electric field strength difference that is a predetermined level larger than the signal level difference between the respective reception RF signals (that is, between the reception signals of the first reception signal RF1, the second reception signal RF2, and the third reception signal RF3). It is assumed that the DC voltage is set.
For example, in consideration of the characteristics of the RSSI circuit, the reference signal Vref sets a potential difference so as to be a power level difference obtained by adding some (ex.10 dB) to 10 dB of the maximum power elasticity level difference of three waves to be received. .

第１の比較器１６は、第１の減算器１４の出力Ｓ１と基準信号Ｖｒｅｆとを比較して、比較結果Ｃ１を出力する。
なお、比較結果Ｃ１は、第１の減算器１４の出力Ｓ１の方が基準信号Ｖｒｅｆより高ければ“Ｈ”であり、第１の減算器１４の出力Ｓ１の方が基準信号Ｖｒｅｆより低ければ高ければ“Ｌ”である。
即ち、第１の比較器１６は、第１の減算器１４の出力Ｓ１の方が基準信号Ｖｒｅｆより高ければ“Ｈ”を出力し、第１の減算器１４の出力Ｓ１の方が基準信号Ｖｒｅｆより低ければ“Ｌ”を出力する。 The first comparator 16 compares the output S1 of the first subtracter 14 with the reference signal Vref and outputs a comparison result C1.
The comparison result C1 is “H” if the output S1 of the first subtractor 14 is higher than the reference signal Vref, and is higher if the output S1 of the first subtracter 14 is lower than the reference signal Vref. “L”.
That is, the first comparator 16 outputs “H” if the output S1 of the first subtractor 14 is higher than the reference signal Vref, and the output S1 of the first subtractor 14 outputs the reference signal Vref. If it is lower, “L” is output.

第２の比較器１７は、第２の減算器１５の出力Ｓ２と基準信号Ｖｒｅｆとを比較して、比較結果Ｃ２を出力する。
なお、比較結果Ｃ２は、第２の減算器１５の出力Ｓ２の方が基準信号Ｖｒｅｆより高ければ“Ｈ”であり、第２の減算器１５の出力Ｓ２の方が基準信号Ｖｒｅｆより低ければ高ければ“Ｌ”である。
即ち、第２の比較器１７は、第２の減算器１５の出力Ｓ２の方が基準信号Ｖｒｅｆより高ければ“Ｈ”を出力し、第２の減算器１５の出力Ｓ２の方が基準信号Ｖｒｅｆより低ければ“Ｌ”を出力する。 The second comparator 17 compares the output S2 of the second subtracter 15 with the reference signal Vref and outputs a comparison result C2.
The comparison result C2 is “H” if the output S2 of the second subtractor 15 is higher than the reference signal Vref, and is higher if the output S2 of the second subtractor 15 is lower than the reference signal Vref. “L”.
That is, the second comparator 17 outputs “H” if the output S2 of the second subtracter 15 is higher than the reference signal Vref, and the output S2 of the second subtractor 15 outputs the reference signal Vref. If it is lower, “L” is output.

第１の比較器１６の出力Ｃ１と第２の比較器１７の出力Ｃ２は、ＡＮＤ回路１８へ入力され、ＡＮＤ回路１８で出力Ｃ１と出力Ｃ２の論理積が演算され、混変調歪波検出器１０の出力“ＤＥＴ‐ＯＵＴ”となる。
混変調歪波検出器１０の出力“ＤＥＴ−ＯＵＴ”が“Ｈ”ならば、第３の入力端子ＩＮ３に入力された受信信号は混変調による歪波のみであり、“Ｌ”ならば、第３の入力端子ＩＮ３に入力された受信信号は所望波を含むことを示す。 The output C1 of the first comparator 16 and the output C2 of the second comparator 17 are input to the AND circuit 18, and a logical product of the output C1 and the output C2 is calculated by the AND circuit 18 to obtain a cross modulation distortion wave detector. 10 outputs “DET-OUT”.
If the output “DET-OUT” of the intermodulation distortion wave detector 10 is “H”, the received signal input to the third input terminal IN3 is only a distortion wave due to intermodulation, and if “L”, 3 indicates that the received signal input to the input terminal IN3 includes a desired wave.

図４は、図３に示した混変調歪波検出器１０の動作を説明するためのフローチャートである。
図３および図４を用いて、混変調歪波検出器１０の動作を説明する。
第１の入力端子ＩＮ１〜第３の入力端子ＩＮ３に入力された各信号の電界強度を第１のＲＳＳＩ回路１１〜第３のＲＳＳＩ回路１３により、それぞれＲＳ１〜ＲＳ３のDC電圧に変換する。（ＳＴＥＰ１）
ＲＳ１とＲＳ３を第１の減算器１４に入力してＲＳ１とＲＳ３の電位差Ｓ１を得、ＲＳ２とＲＳ３を第２の減算器１５に入力し、ＲＳ２とＲＳ３の電位差Ｓ２を得る。
即ち、ＲＳ１とＲＳ３、ＲＳ２とＲＳ３をそれぞれ別の減算器に入力し、電位差Ｓ１とＳ２を得る。（ＳＴＥＰ２） FIG. 4 is a flowchart for explaining the operation of the intermodulation distortion wave detector 10 shown in FIG.
The operation of the cross modulation distorted wave detector 10 will be described with reference to FIGS.
The electric field strength of each signal input to the first input terminal IN1 to the third input terminal IN3 is converted into DC voltages of RS1 to RS3 by the first RSSI circuit 11 to the third RSSI circuit 13, respectively. (STEP1)
RS1 and RS3 are input to the first subtractor 14 to obtain the potential difference S1 between RS1 and RS3, and RS2 and RS3 are input to the second subtractor 15 to obtain the potential difference S2 between RS2 and RS3.
That is, RS1 and RS3, RS2 and RS3 are input to different subtracters, respectively, and potential differences S1 and S2 are obtained. (STEP2)

次に、Ｓ１とＳ２をそれぞれ第１の比較器１６、第２の１７で基準信号Ｖｒｅｆと比較して、Ｓ１の方が基準信号Ｖｒｅｆより高ければＣ１に“Ｈ”を、低ければ“Ｌ”を出力する。また、Ｓ２の方が基準信号Ｖｒｅｆより高ければＣ２に“Ｈ”を、低ければ“Ｌ”を出力する。
この時、基準信号Ｖｒｅｆは、ＲＳＳＩの特性を考慮して、入力３波の最大電力レベル差の１０ｄＢにいくらか(例えば、１０ｄＢ)を加えた電力レベル差となる電位差に設定する。（ＳＴＥＰ３）
最後に、第１の比較器１６の出力Ｃ１と第２の比較器１７の出力Ｃ２の論理積をＡＮＤ回路１８で取り、その出力“ＤＥＴ−ＯＵＴ”が、“Ｈ”ならばＩＮ３に入力された受信信号は混変調による歪波のみであり、“Ｌ”ならばＩＮ３に入力された受信信号は所望波を含むことを示す。（ＳＴＥＰ４） Next, S1 and S2 are respectively compared with the reference signal Vref by the first comparator 16 and the second 17, and if S1 is higher than the reference signal Vref, “H” is set to C1, and “L” if lower. Is output. If S2 is higher than the reference signal Vref, “H” is output to C2, and if it is lower, “L” is output.
At this time, the reference signal Vref is set to a potential difference that is a power level difference obtained by adding some (for example, 10 dB) to the maximum power level difference of 10 waves of the three input waves in consideration of the RSSI characteristics. (STEP3)
Finally, the AND circuit 18 takes the logical product of the output C1 of the first comparator 16 and the output C2 of the second comparator 17, and if the output “DET-OUT” is “H”, it is input to IN3. The received signal is only a distorted wave due to cross modulation, and “L” indicates that the received signal input to IN3 includes a desired wave. (STEP4)

図５は、混変調歪波検出器１０の出力“ＤＥＴ−ＯＵＴ”が、“Ｈ”のときと、“Ｌ”のときの“ＩＦ周波数−ＲＳＳＩ出力電圧特性”を示す。
ここで、第３の受信信号入力端子ＣＨ３の受信信号が混変調による歪波のみのときは、第３の受信信号入力端子ＣＨ３には、ＲＦ１とＲＦ２およびこの２波に起因する高調波と混変調波しか入ってこない。
このとき、“ＤＥＴ−ＯＵＴ”は“Ｈ”となる。
第３の受信信号入力端子ＣＨ３に第３の受信信号ＲＦ３が入ってくれば、“ＤＥＴ−ＯＵＴ”は“Ｌ”となる。
“ＤＥＴ−ＯＵＴ”が“Ｈ”、つまり、第３の受信信号入力端子ＣＨ３の受信信号が、混変調による３次波歪波のみのとき、この信号により後段の回路（例えば、映像信号の復調回路など）をオフさせ、最終出力装置に出力されないようにする。 FIG. 5 shows “IF frequency-RSSI output voltage characteristics” when the output “DET-OUT” of the intermodulation distortion wave detector 10 is “H” and “L”.
Here, when the reception signal at the third reception signal input terminal CH3 is only a distorted wave due to cross modulation, the third reception signal input terminal CH3 is mixed with RF1 and RF2 and harmonics resulting from these two waves. Only the modulated wave comes in.
At this time, “DET-OUT” becomes “H”.
If the third reception signal RF3 enters the third reception signal input terminal CH3, “DET-OUT” becomes “L”.
When “DET-OUT” is “H”, that is, the received signal at the third received signal input terminal CH3 is only a third-order distorted wave due to intermodulation, this signal causes a circuit (for example, demodulation of a video signal) Circuit, etc.) are turned off so that they are not output to the final output device.

このように、本実施の形態では、場所、時間によって受信レベルは変動するが、ある瞬間で見たときの各信号間の受信レベル差が、例えば１０ｄＢ以内であり、このときに発生する３次混変調歪波のレベルは所望波の信号に比べて低く、その差は１０ｄＢを十分に越えるという特性を利用して、３次混変調歪波か所望波かを検出し、その検出信号により後段の回路をオフし３次混変調歪波を最終出力装置に出力しないようにしている。
これにより、入力信号のＣ／Ｎ（carrier／noise）が仕様以上であれば、不要波である３次混変調波の信号レベルが仕様の受信信号レベル以上あったとしても後段回路での復調可能となり、受信信号の入力信号レベル範囲を広げることができる。 As described above, in this embodiment, the reception level varies depending on the location and time, but the reception level difference between the signals when viewed at a certain moment is, for example, within 10 dB. The level of the cross modulation distorted wave is lower than the signal of the desired wave, and the difference is sufficiently higher than 10 dB, so that it is detected whether it is the third order cross modulation distorted wave or the desired wave. This circuit is turned off so that the third-order intermodulation distortion wave is not output to the final output device.
As a result, if the C / N (carrier / noise) of the input signal is higher than the specification, even if the signal level of the third-order intermodulation wave, which is an unnecessary wave, is higher than the received signal level of the specification, it can be demodulated in the subsequent circuit. Thus, the input signal level range of the received signal can be expanded.

以上説明したように、本実施の形態による不要波検出装置は、周波数の低い方から第１のＲＦ信号（ＲＦ１）、第２のＲＦ信号（ＲＦ２）、第３のＲＦ信号（ＲＦ３）であり、第１のＲＦ信号と第２のＲＦ信号の周波数間隔と第２のＲＦ信号と第３のＲＦ信号の周波数間隔が同じである第１、第２および第３のＲＦ信号を受信し、各受信ＲＦ信号間の信号レベル差が所定値以内である受信システムに用いられる不要波検出装置であって、
受信した第１、第２および第３のＲＦ信号（ＲＦ１、ＲＦ２、ＲＦ３）を周波数が等間隔の第１、第２および第３のＩＦ信号（ＩＦ１、ＩＦ２、ＩＦ３）にそれぞれ変換する第１、第２および第３の周波数変換器（４、５、６）と、変換された第１、第２および第３のＩＦ信号をそれぞれ対応するＩＦ信号の周波数帯域に制限して出力する第１、第２および第３の周波数ろ波器（７、８、９）と、第１、第２および第３の周波数ろ波器の出力信号から得る第１、第２および第３のＲＦ信号の電界強度にそれぞれ対応する電圧値を演算処理することにより混変調波の有無を検出し、混変調波が有りと検出された場合は、受信システムの動作をオフとする検出信号を出力する混変調歪波検出器１０とを備えている。 As described above, the unnecessary wave detection device according to the present embodiment includes the first RF signal (RF1), the second RF signal (RF2), and the third RF signal (RF3) from the lowest frequency. Receiving the first, second and third RF signals having the same frequency interval between the first RF signal and the second RF signal and the same frequency interval between the second RF signal and the third RF signal; An unwanted wave detection device used in a reception system in which a signal level difference between received RF signals is within a predetermined value,
First to convert the received first, second and third RF signals (RF1, RF2, RF3) into first, second and third IF signals (IF1, IF2, IF3) of equal frequency, respectively. The first and second frequency converters (4, 5, 6) and the first, second and third IF signals thus converted are limited to the corresponding frequency band of the IF signal and output. , Second and third frequency filters (7, 8, 9) and first, second and third RF signals obtained from the output signals of the first, second and third frequency filters Intermodulation that detects the presence or absence of intermodulation waves by calculating the voltage value corresponding to each electric field strength, and outputs a detection signal that turns off the operation of the receiving system when it detects the presence of intermodulation waves And a distorted wave detector 10.

また、混変調歪波検出器１０は、上記第１、第２および第３の周波数ろ波器（７、８、９）の出力信号がそれぞれ入力され、第１、第２および第３のＲＦ信号（ＲＦ１、ＲＦ２、ＲＦ３）の電界強度に対応する電圧値を出力する第１、第２および第３のＲＳＳＩ(Receiving Signal Strength Indicator)回路（１１、１２、１３）と、第１と第３のＲＳＳＩ回路の出力電圧値の電位差を出力する第１の減算器（１４）と、第１と第３のＲＳＳＩ回路の出力電圧値の電位差を出力する第２の減算器（１５）と、第１の減算器の出力と基準信号（Ｖｒｅｆ）とを比較する第１の比較器（１６）と、第２の減算器の出力と基準信号とを比較する第２の比較器（１７）とで構成され、第１の比較器（１６）と第２の比較器（１７）の比較結果に基づいて混変調波の有無を検出し、混変調波が有りと検出された場合は受信システムの動作をオフとする検出信号を出力するように構成されている。 The intermodulation distortion detector 10 receives the output signals of the first, second, and third frequency filters (7, 8, 9), respectively, and receives the first, second, and third RF signals. First, second, and third RSSI (Receiving Signal Strength Indicator) circuits (11, 12, 13) that output voltage values corresponding to the electric field strength of the signals (RF1, RF2, RF3), and first and third A first subtractor (14) for outputting a potential difference between output voltage values of the RSSI circuit, a second subtractor (15) for outputting a potential difference between output voltage values of the first and third RSSI circuits, A first comparator (16) that compares the output of the first subtractor with the reference signal (Vref), and a second comparator (17) that compares the output of the second subtractor with the reference signal. Based on the comparison result of the first comparator (16) and the second comparator (17). When the absence is detected and the presence of intermodulation waves is detected, a detection signal for turning off the operation of the reception system is output.

また、上記基準信号（Ｖｒｅｆ）は、各受信ＲＦ信号間の信号レベル差よりも所定レベル大きい電界強度差を表すDC電圧に設定されており、第１の比較器（１６）は、該DC電圧よりも第１の減算器（１４）の出力値が高ければ“Ｈ”を、低ければ“Ｌ”を比較出力として出力し、第２の比較器（１７）は、上記DC電圧よりも第２の減算器（１５）の出力値が高ければ“Ｈ”を、低ければ“Ｌ”を比較出力として出力し、第１の比較器と第２の比較器の比較出力はＡＮＤ回路（１８）に接続されて論理積が取られ、ＡＮＤ回路の出力が“Ｈ”ならば第３の受信信号入力端子に入力された信号は混変調による３次の歪波のみであり、ＡＮＤ回路の出力が“Ｌ”ならば第３の受信信号入力端子に入力された信号は所望波であるとして混変調波の有無を検出するように構成されている。 The reference signal (Vref) is set to a DC voltage that represents a difference in electric field strength that is a predetermined level greater than the signal level difference between the received RF signals. The first comparator (16) If the output value of the first subtractor (14) is higher than “H”, and if it is lower, “L” is output as the comparison output, and the second comparator (17) outputs the second voltage higher than the DC voltage. When the output value of the subtracter (15) is high, "H" is output as a comparison output, and when the output value is low, the comparison output of the first comparator and the second comparator is output to the AND circuit (18). If the AND circuit is ANDed and the output of the AND circuit is “H”, the signal input to the third received signal input terminal is only the third-order distorted wave due to cross modulation, and the output of the AND circuit is “ If “L”, it is determined that the signal input to the third received signal input terminal is a desired wave, and the presence / absence of the intermodulation wave is determined. It is configured to output.

なお、上記実施の形態では、第１の比較器と第２の比較器の比較出力は、ＡＮＤ回路に接続されて論理積が取られ構成の場合について説明しているが、ＡＮＤ回路に代えてＮＡＮＤ回路（図示なし）を用いてもよい。
即ち、基準信号（Ｖｒｅｆ）は、各受信ＲＦ信号間の信号レベル差よりも所定レベル大きい電界強度差を表すＤＣ電圧に設定されており、第１の比較器（１６）は、該ＤＣ電圧よりも第１の減算器（１４）の出力値が高ければ“Ｌ”を、低ければ“Ｈ”を比較出力として出力し、第２の比較器（１７）は、上記ＤＣ電圧よりも（１５）第２の減算器の出力値が高ければ“Ｌ”を、低ければ“Ｈ”を比較出力として出力し、第１の比較器と上記第２の比較器の比較出力はＮＡＮＤ回路に接続されて論理積が取られ、ＮＡＮＤ回路の出力が“Ｌ”ならば第３の受信信号入力端子に入力された信号は混変調による３次の歪波のみであり、ＮＡＮＤ回路の出力が“Ｈ”ならば第３の受信信号入力端子に入力された信号は所望波であるとして混変調波の有無を検出するように構成してもよい。 In the above-described embodiment, the comparison output of the first comparator and the second comparator is described as being configured by being connected to the AND circuit and taking the logical product. A NAND circuit (not shown) may be used.
That is, the reference signal (Vref) is set to a DC voltage that represents a difference in electric field strength that is a predetermined level greater than the signal level difference between the received RF signals, and the first comparator (16) If the output value of the first subtractor (14) is high, "L" is output as a comparison output, and if the output value is low, the second comparator (17) outputs (15) When the output value of the second subtracter is high, “L” is output as a comparison output, and when the output value is low, the comparison output of the first comparator and the second comparator is connected to a NAND circuit. If the logical product is taken and the output of the NAND circuit is “L”, the signal input to the third received signal input terminal is only the third-order distorted wave due to cross modulation, and if the output of the NAND circuit is “H”. If the signal input to the third received signal input terminal is a desired wave, It may be configured to detect a no.

この発明は、不要波の信号レベルを受信システムの受信感度レベル以下に抑圧しきれない状態の場合でも、不要波の有無を検出することが可能となり、受信可能な入力信号レベルの範囲を広げることができる不要波検出装置の実現に有用である。 This invention makes it possible to detect the presence / absence of an unwanted wave even when the signal level of the unwanted wave cannot be suppressed below the reception sensitivity level of the receiving system, and to expand the range of input signal levels that can be received. This is useful for realizing an unnecessary wave detection device capable of

本発明の実施の形態１に係わる不要波検出装置の全体構成を示すブロック図である。It is a block diagram which shows the whole structure of the unnecessary wave detection apparatus concerning Embodiment 1 of this invention. ２つの受信信号波のみが入力される場合の受信信号と歪成分のレベル差を示す周波数特性図である。It is a frequency characteristic figure which shows the level difference of a received signal and distortion component in case only two received signal waves are input. 実施の形態１による混変調歪波検出器の構成を示すブロック図である。2 is a block diagram showing a configuration of a cross modulation distortion wave detector according to Embodiment 1. FIG. 混変調歪波検出器の動作を説明するためのフローチャートである。It is a flowchart for demonstrating operation | movement of a cross modulation distortion wave detector. 混変調歪波検出器の出力が“Ｈ”のときと、“Ｌ”のときの“ＩＦ周波数−ＲＳＳＩ出力電圧特性”を示す図である。It is a figure which shows "IF frequency-RSSI output voltage characteristic" when the output of a cross modulation distortion wave detector is "H" and when it is "L".

符号の説明Explanation of symbols

１〜３第１〜第３の増幅器
４〜６第１〜第３のダウンミキサー（周波数変換器）
７〜９第１〜第３の周波数ろ波器
１０混変調歪波検出器
１１〜１３第１〜第３のＲＳＳＩ回路
１４第１の減算器
１５第２の減算器
１６第１の比較器
１７第２の比較器
１８ＡＮＤ回路
ＣＨ１〜ＣＨ３第１〜第３の受信信号入力端子
ＲＦ１〜ＲＦ３第１〜第３の受信信号
ＬＯ１〜ＬＯ３第１〜第３のローカル発振信号
ＩＦ１〜ＩＦ３第１〜第３の中間周数信号
ＩＮ１〜ＩＮ３第１〜第３の入力端子
ＲＳ１〜ＲＳ３第１〜第３のＲＳＳＩ出力
Ｖｒｅｆ基準信号
Ｓ１第１の減算器出力
Ｓ２第２の減算器出力
Ｃ１第１の比較器出力
Ｃ２第２の比較器出力
ＤＥＴ−ＯＵＴ混変調歪波検出器出力 1-3 1st-3rd amplifier 4-6 1st-3rd down mixer (frequency converter)
7 to 9 First to third frequency filters 10 Intermodulation distortion detector 11 to 13 First to third RSSI circuits 14 First subtractor 15 Second subtractor 16 First comparator 17 Second comparator 18 AND circuit CH1 to CH3 First to third reception signal input terminals RF1 to RF3 First to third reception signals LO1 to LO3 First to third local oscillation signals IF1 to IF3 First to third Third intermediate frequency signal IN1 to IN3 First to third input terminals RS1 to RS3 First to third RSSI outputs Vref Reference signal S1 First subtractor output S2 Second subtractor output C1 First Comparator output C2 Second comparator output DET-OUT Intermodulation distortion detector output

Claims

周波数が低い方から第１、第２、第３のＲＦ信号であり、上記第１と第２のＲＦ信号の周波数間隔と上記２と第３のＲＦ信号の周波数間隔が同じである第１、第２および第３のＲＦ信号を受信し、各受信ＲＦ信号間の信号レベル差が所定値以内である受信システムに用いられる不要波検出装置であって、
上記受信した第１、第２および第３のＲＦ信号を、周波数が等間隔の第１、第２および第３のＩＦ信号にそれぞれ変換する第１、第２および第３の周波数変換器と、
変換された上記第１、第２および第３のＩＦ信号をそれぞれ対応するＩＦ信号の周波数帯域に制限して出力する第１、第２および第３の周波数ろ波器と、
上記第１、第２および第３の周波数ろ波器の出力信号から得る上記第１、第２および第３のＲＦ信号の電界強度にそれぞれ対応する電圧値を演算処理することにより混変調波の有無を検出し、混変調波が有りと検出された場合は、上記受信システムの動作をオフとする検出信号を出力する混変調歪波検出器とを備えたことを特徴とする不要波検出装置。 First, second, and third RF signals from the lowest frequency, and the frequency interval between the first and second RF signals is the same as the frequency interval between the second and third RF signals. An unnecessary wave detection device used in a reception system that receives the second and third RF signals and that has a signal level difference between the received RF signals within a predetermined value,
First, second, and third frequency converters for converting the received first, second, and third RF signals into first, second, and third IF signals having equally spaced frequencies, respectively;
First, second, and third frequency filters that output the converted first, second, and third IF signals, respectively, by limiting the frequency band of the corresponding IF signals;
By calculating the voltage values corresponding to the electric field strengths of the first, second, and third RF signals obtained from the output signals of the first, second, and third frequency filters, An unnecessary wave detection device comprising: a cross modulation distortion wave detector that detects a presence / absence and outputs a detection signal for turning off the operation of the reception system when the presence of a cross modulation wave is detected. .

上記混変調歪波検出器は、上記第１、第２および第３の周波数ろ波器の出力信号がそれぞれ入力され、上記第１、第２および第３のＲＦ信号の電界強度に対応する電圧値を出力する第１、第２および第３のＲＳＳＩ(Receiving Signal Strength Indicator)回路と、上記第１と第３のＲＳＳＩ回路の出力電圧値の電位差を出力する第１の減算器と、上記第１と第３のＲＳＳＩ回路の出力電圧値の電位差を出力する第２の減算器と、上記第１の減算器の出力と基準信号とを比較する第１の比較器と、上記第２の減算器の出力と上記基準信号とを比較する第２の比較器とで構成され、上記第１の比較器と上記第２の比較器の比較結果に基づいて混変調波の有無を検出し、混変調波が有りと検出された場合は受信システムの動作をオフとする検出信号を出力することを特徴とする請求項１に記載の不要波検出装置。 The intermodulation distorted wave detector receives the output signals of the first, second and third frequency filters, respectively, and the voltages corresponding to the electric field strengths of the first, second and third RF signals. First, second, and third RSSI (Receiving Signal Strength Indicator) circuits that output values, a first subtractor that outputs a potential difference between output voltage values of the first and third RSSI circuits, and the first A second subtractor that outputs a potential difference between the output voltage values of the first and third RSSI circuits, a first comparator that compares the output of the first subtractor with a reference signal, and the second subtraction. A second comparator for comparing the output of the comparator and the reference signal, and detecting the presence or absence of intermodulation waves based on the comparison result of the first comparator and the second comparator. When a modulated wave is detected, a detection signal that turns off the operation of the receiving system is output. The unnecessary wave detection device according to claim 1, wherein:

上記基準信号は、各受信ＲＦ信号間の信号レベル差よりも所定レベル大きい電界強度差を表すDC電圧に設定されており、
上記第１の比較器は、上記DC電圧よりも上記第１の減算器の出力値が高ければ“Ｈ”を、低ければ“Ｌ”を比較出力として出力し、
上記第２の比較器は、上記DC電圧よりも上記第２の減算器の出力値が高ければ“Ｈ”を、低ければ“Ｌ”を比較出力として出力し、
上記第１の比較器と上記第２の比較器の比較出力はＡＮＤ回路に接続されて論理積が取られ、上記ＡＮＤ回路の出力が“Ｈ”ならば第３の受信信号入力端子に入力された信号は混変調による３次の歪波のみであり、上記ＡＮＤ回路の出力が“Ｌ”ならば第３の受信信号入力端子に入力された信号は所望波であるとして混変調波の有無を検出することを特徴とする請求項２に記載の不要波検出装置。 The reference signal is set to a DC voltage representing a difference in electric field strength that is a predetermined level greater than the signal level difference between the received RF signals.
The first comparator outputs “H” as a comparison output if the output value of the first subtractor is higher than the DC voltage, and “L” if the output value is lower than the DC voltage,
The second comparator outputs “H” as a comparison output if the output value of the second subtractor is higher than the DC voltage, and “L” if the output value is lower than the DC voltage,
The comparison outputs of the first comparator and the second comparator are connected to an AND circuit to obtain a logical product. If the output of the AND circuit is “H”, the comparison output is input to the third reception signal input terminal. The signal is only a third-order distorted wave due to cross modulation. If the output of the AND circuit is “L”, the signal input to the third reception signal input terminal is assumed to be a desired wave and the presence / absence of the cross modulation wave is determined. The unnecessary wave detecting device according to claim 2, wherein the unnecessary wave detecting device is detected.

上記基準信号は、各受信ＲＦ信号間の信号レベル差よりも所定レベル大きい電界強度差を表すDC電圧に設定されており、
上記第１の比較器は、上記DC電圧よりも上記第１の減算器の出力値が高ければ“Ｌ”を、低ければ“Ｈ”を比較出力として出力し、
上記第２の比較器は、上記DC電圧よりも上記第２の減算器の出力値が高ければ“Ｌ”を、低ければ“Ｈ”を比較出力として出力し、
上記第１の比較器と上記第２の比較器の比較出力はＮＡＮＤ回路に接続されて論理積が取られ、上記ＮＡＮＤ回路の出力が“Ｌ”ならば第３の受信信号入力端子に入力された信号は混変調による３次の歪波のみであり、上記ＮＡＮＤ回路の出力が“Ｈ”ならば第３の受信信号入力端子に入力された信号は所望波であるとして混変調波の有無を検出することを特徴とする請求項２に記載の不要波検出装置。 The reference signal is set to a DC voltage representing a difference in electric field strength that is a predetermined level greater than the signal level difference between the received RF signals.
The first comparator outputs “L” as a comparison output if the output value of the first subtractor is higher than the DC voltage, and “H” if the output value is lower than the DC voltage,
The second comparator outputs “L” as a comparison output if the output value of the second subtractor is higher than the DC voltage, and “H” if the output value is lower than the DC voltage,
The comparison outputs of the first comparator and the second comparator are connected to a NAND circuit to obtain a logical product. If the output of the NAND circuit is “L”, the comparison output is input to the third reception signal input terminal. The signal is only a third-order distorted wave due to cross modulation, and if the output of the NAND circuit is “H”, the signal input to the third reception signal input terminal is assumed to be a desired wave and the presence / absence of the cross modulation wave is determined. The unnecessary wave detecting device according to claim 2, wherein the unnecessary wave detecting device is detected.