JP5376762B2 - Satellite signal noise estimation device, signal-to-noise ratio calculation device, and satellite signal reception device - Google Patents

Satellite signal noise estimation device, signal-to-noise ratio calculation device, and satellite signal reception device Download PDF

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JP5376762B2
JP5376762B2 JP2007027657A JP2007027657A JP5376762B2 JP 5376762 B2 JP5376762 B2 JP 5376762B2 JP 2007027657 A JP2007027657 A JP 2007027657A JP 2007027657 A JP2007027657 A JP 2007027657A JP 5376762 B2 JP5376762 B2 JP 5376762B2
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勝男 由井
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Abstract

<P>PROBLEM TO BE SOLVED: To find a noise distribution value (noise average and noise dispersion) and a noise-to-signal ratio, when tracking a satellite signal from a navigation satellite such as a GPS under a very weak environment thereof in an indoor space, under a high-level structure or the like, and to allow stable frequency tracking. <P>SOLUTION: A non-correlative signal not correlated with a reception signal from a satellite is carrier-correlated by a 1 ms correlation channel circuit 1n for a noise, to be output in every 1 ms, and a noise power dispersion &sigma;<SP>2</SP>during the 1 ms in every 1 ms by a noise dispersion measuring instrument 4. A prescribed time (N) coherent addition is executed using the noise power dispersion &sigma;<SP>2</SP>during the 1ms, so as to find the noise distribution value including the noise average and the noise dispersion, corresponding to the case when added by a prescribed frequency (M). <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

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本発明は、携帯電話機や車などの移動体に設置され、ＧＰＳなどの航法衛星からの衛星信号が屋内や高架下など非常に弱い環境の場合でも安定して周波数追尾を行うための雑音推定装置、信号対雑音比演算装置、及び衛星信号受信装置に関する。   The present invention relates to a noise estimation device that is installed in a mobile body such as a mobile phone or a car, and performs frequency tracking stably even in a very weak environment such as a satellite signal from a navigation satellite such as GPS indoors or under an overhead. The present invention relates to a signal-to-noise ratio calculation device and a satellite signal reception device.

地球を周回する航法衛星（人工衛星）までの距離及び当該航法衛星の軌道に関する情報を利用し、地球上の物体(以下「利用者」と呼ぶ)の位置、速度等を求めるシステムである米国のGlobal Positioning System(ＧＰＳ)等のGlobal Navigation Satellite System(ＧＮＳＳ)の衛星信号受信装置において、衛星信号を捕捉する際に、受信する衛星信号が非常に弱い環境であっても衛星信号を順次サーチすることによって、低加速状態であることや数秒以上の観測時間を要する等の制約はあるものの、衛星信号を捕捉し測位位置を求められる捕捉手段が利用できるようになってきている。しかし、衛星信号の追尾中において加速度が高い状態（受信キャリア周波数が変化する状態）でもリアルタイムで測位可能になる簡易構成で高感度な追尾手段の実現が望まれている。   A system for determining the position, velocity, etc. of objects on the earth (hereinafter referred to as “users”) using information on the distance to navigation satellites (artificial satellites) that orbit the earth and the orbits of the navigation satellites. When a satellite signal is received by a Global Navigation Satellite System (GNSS) satellite signal receiver such as the Global Positioning System (GPS), the satellite signal is searched sequentially even in an environment where the received satellite signal is very weak. Therefore, although there are restrictions such as a low acceleration state and an observation time of several seconds or more, it is possible to use a capturing means that captures a satellite signal and obtains a positioning position. However, it is desired to realize a high-sensitivity tracking means with a simple configuration that allows positioning in real time even when the acceleration of the satellite signal is high (when the received carrier frequency changes).

まず、衛星信号が非常に弱い環境下でその衛星信号をサーチ（高感度サーチ）する場合は、衛星信号を受信した受信信号に対してＰＮコード相関及びキャリア周波数相関が取られた相関信号を加算する加算時間を長くすることによって、信号対雑音比（Ｓ／Ｎ比）を改善した加算相関信号を得、その加算相関信号に基づいてキャリア周波数相関に用いる局部発振器（キャリアＮＣＯ）の発振周波数信号の周波数（及び位相）を制御することが必要である。そのために、特許文献１にはコヒーレント加算とノンコヒーレント加算の２種類の加算処理を併用することが示されている。   First, when searching for a satellite signal in an environment where the satellite signal is very weak (high-sensitivity search), a correlation signal obtained by taking a PN code correlation and a carrier frequency correlation is added to the received signal. The added correlation signal with improved signal-to-noise ratio (S / N ratio) is obtained by lengthening the addition time, and the oscillation frequency signal of the local oscillator (carrier NCO) used for carrier frequency correlation based on the added correlation signal It is necessary to control the frequency (and phase). For this purpose, Patent Document 1 shows that two types of addition processing, coherent addition and non-coherent addition, are used in combination.

コヒーレント加算は、Ｉ（搬送波正位相）相関信号とＱ（搬送波９０°移相）相関信号を各々そのまま加算する加算方法であり、大きなＳ／Ｎ比の改善が行える方法である。ＧＰＳでは２０ｍｓ毎しかＩ，Ｑ相関信号の反転は起こらないので、２０ｍｓまではコヒーレント加算が行える。   Coherent addition is an addition method in which an I (carrier positive phase) correlation signal and a Q (carrier 90 ° phase shift) correlation signal are added as they are, and a method capable of greatly improving the S / N ratio. In GPS, inversion of the I and Q correlation signals occurs only every 20 ms, so that coherent addition can be performed up to 20 ms.

ノンコヒーレント加算は、Ｉ，Ｑ相関信号またはこれらをコヒーレント加算した信号の信号パワーＰ（＝Ｉ2＋Ｑ2、又は、＝（Ｉ2＋Ｑ2）1/2）を加算していく方法である。この方法のＳ／Ｎ比の改善度はコヒーレント加算に劣るが、Ｉ，Ｑ相関信号の反転の影響を受けないため、衛星からの航法メッセージの反転パターンが未知の場合でもＳ／Ｎ比の改善が行える利点がある。 Non-coherent addition is a method of adding the signal power P (= I 2 + Q 2 or = (I 2 + Q 2 ) 1/2 ) of an I, Q correlation signal or a signal obtained by coherent addition of these signals. Although the degree of improvement in the S / N ratio of this method is inferior to coherent addition, it is not affected by the inversion of the I and Q correlation signals, so the S / N ratio is improved even when the inversion pattern of the navigation message from the satellite is unknown. There is an advantage that can be done.

感度向上のためにはそれらの加算時間を長くすることが望ましいが、加速度への追従の面では加算時間が短い方が望ましい。しかしながら、移動等による受信環境変化に伴う信号パワー変動及び移動加速度は、一般的には測定前には未知である。そこで、加算時間が長くＳ／Ｎ比の改善度が高い第１方式と、加算時間が短くＳ／Ｎ比の改善度は低いが加速度追従性が良い第２方式とを同時に実施しておき、第１方式と第２方式から例えば測定期間中のＳ／Ｎ比に適した方式の加算結果を用いることが考えられる。このためには、測定期間中のＳ／Ｎ比を求める必要がある。   In order to improve sensitivity, it is desirable to increase the addition time, but in terms of following the acceleration, it is desirable that the addition time is short. However, the signal power fluctuation and the movement acceleration accompanying the reception environment change due to movement or the like are generally unknown before measurement. Therefore, the first method having a long addition time and a high improvement in the S / N ratio and the second method having a short addition time and a low improvement in the S / N ratio but good acceleration follow-up are performed simultaneously. From the first method and the second method, for example, it is conceivable to use an addition result of a method suitable for the S / N ratio during the measurement period. For this purpose, it is necessary to obtain the S / N ratio during the measurement period.

高感度サーチ時においては、特定衛星信号に関する受信信号に対して、内部の拡散コード（ＰＮコード）の開始タイミングを順次ずらすことで、図２の（ａ）に示すような相関パワー分布が得られる。この図２（ａ）では、横軸はコードオフセット値（ｃｈｉｐ）を示しており、受信信号の拡散コードの位相と内部の拡散コードの位相とが一致したときに一番強い自己相関パワー（即ち、信号パワー）Ｓｍｅｓが得られ、信号パワーＳｍｅｓ以外の自己相関パワーは雑音である。信号パワーＳｍｅｓ以外の自己相関パワーを用いれば、同図（ａ）、（ｂ）に示されるように雑音平均Ｎｍｅａｎ及びその雑音分散Ｎｒｍｓは同時に算出可能である。それらの測定結果及び算出結果を用いて、高感度サーチ時のＳ／Ｎ比を、「Ｓ／Ｎ＝（Ｓｍｅｓ−Ｎｍｅａｎ）／Ｎｒｍｓ」により求めることができる。   At the time of high sensitivity search, the correlation power distribution as shown in FIG. 2A can be obtained by sequentially shifting the start timing of the internal spreading code (PN code) with respect to the received signal related to the specific satellite signal. . In FIG. 2A, the horizontal axis indicates the code offset value (chip), and the strongest autocorrelation power (ie, when the phase of the spreading code of the received signal matches the phase of the internal spreading code) , Signal power) Smes, and the autocorrelation power other than the signal power Smes is noise. If autocorrelation power other than the signal power Smes is used, the noise average Nmean and its noise variance Nrms can be calculated simultaneously as shown in FIGS. Using these measurement results and calculation results, the S / N ratio at the time of high sensitivity search can be obtained by “S / N = (Smes−Nmean) / Nrms”.

また、追尾時におけるＳ／Ｎ比は、追尾周波数制御に用いるＩ，Ｑ相関信号に関して、コヒーレント加算をする区間（時間）とノンコヒーレント加算をする区間（時間）が同一の区間内における、［コヒーレント加算値／ノンコヒーレント加算値］からＳ／Ｎ比を求めることが、非特許文献１に記載されている。
米国特許第６，７２４，３４３号明細書 GLOBAL POSITIONING SYSTEM:Theory and Applications Vol.1、Bradford W. Parkinson，James J.Spilker Jr. 、pp391-393 Also, the S / N ratio at the time of tracking is [coherent for the I and Q correlation signals used for tracking frequency control within the same interval (time) where coherent addition is performed (time) and noncoherent addition (interval). Non-Patent Document 1 describes that the S / N ratio is obtained from “added value / non-coherent added value”].
US Pat. No. 6,724,343 GLOBAL POSITIONING SYSTEM: Theory and Applications Vol.1, Bradford W. Parkinson, James J. Spilker Jr., pp391-393

この高感度サーチ用に実施されている図２の方法を追尾でも行うことを考えた場合、追尾中であるから信号パワーＳｍｅｓは当然に得られるが、追尾チャンネルのみでは雑音情報は得られない。雑音情報を得るために、再公表特許ＷＯ０１／０９４９７２号公報に示されるように、雑音推定用のチャンネルを設けて雑音レベルを求め、その雑音レベルによって追尾チャンネルでの信号パワーＳｍｅｓを判定することが知られている。しかし、この再公表特許では、雑音レベルが求まるだけであり、雑音分散Ｎｒｍｓを求めることはできない。また、雑音分散Ｎｒｍｓを求めるために複数回観測することはリアルタイムでの計算ができないし、観測区間以外の変動の影響を受けるから実用上この方法でのＳ／Ｎ比は計算できない欠点があった。   When considering that the method of FIG. 2 implemented for the high-sensitivity search is also performed in tracking, the signal power Smes can be naturally obtained because tracking is in progress, but noise information cannot be obtained only by the tracking channel. In order to obtain noise information, a noise estimation channel is provided to obtain a noise level, and the signal power Smes in the tracking channel is determined based on the noise level, as shown in the republished patent application WO01 / 094972. Are known. However, in this re-published patent, only the noise level is obtained, and the noise variance Nrms cannot be obtained. In addition, in order to obtain the noise variance Nrms, it is impossible to calculate in real time, and it is not possible to calculate the S / N ratio in this method practically because it is affected by fluctuations other than the observation interval. .

また、一般の追尾に用いられている非特許文献１に示されている方法の場合には、非特許文献１の図３９に示されているように、信号パワーが弱くなるにつれてＳ／Ｎ比の信頼度が急激に低下し、高感度（信号対雑音比で約２０ｄＢ以下）の場合には、実質上利用できない欠点があった。   Further, in the case of the method shown in Non-Patent Document 1 used for general tracking, as shown in FIG. 39 of Non-Patent Document 1, as the signal power becomes weaker, the S / N ratio. In the case of high sensitivity (signal-to-noise ratio of about 20 dB or less), there is a drawback that it cannot be used practically.

本発明は、以上の点に鑑みてなされたものであり、ＧＰＳなどの航法衛星からの衛星信号が屋内や高架下など非常に弱い環境での追尾時に、ノイズ分布値（ノイズ平均及びノイズ分散）及び信号対雑音比を求めるとともに、安定して周波数追尾を行うための、雑音推定装置、信号対雑音比演算装置、及び衛星信号受信装置を提供することを目的とする。   The present invention has been made in view of the above points, and at the time of tracking in a very weak environment such as a satellite signal from a navigation satellite such as GPS indoors or under an overpass, a noise distribution value (noise average and noise variance). An object of the present invention is to provide a noise estimation device, a signal-to-noise ratio calculation device, and a satellite signal reception device for obtaining a signal-to-noise ratio and performing frequency tracking stably.

請求項１に記載の雑音推定装置は、衛星信号を変換し入力される特定衛星信号に関する受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路１ｎと、
前記雑音用１ｍｓ相関チャンネル回路１ｎからのＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとから１ｍｓ間の雑音パワーの分散σ２を１ｍｓ毎に測定するノイズ分散測定器４と、
前記１ｍｓ間の雑音パワーの分散σ２、所定時間のコヒーレント加算時間（Ｎ）、及び所定回数のコヒーレント加算回数（Ｍ）を統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応したノイズ平均Ｎｍｅａｎ及びノイズ分散Ｎｒｍｓを含むノイズ分布値を求めるノイズ分布演算器５と、を有することを特徴とする。
The noise estimation apparatus according to claim 1, wherein a carrier correlation between a received signal related to a specific satellite signal input by converting a satellite signal and a non-correlated signal that cannot be correlated with the received signal is taken. A 1 ms correlation channel circuit 1n for noise that outputs the I correlation signal I0n and the Q correlation signal Q0n simultaneously every 1 ms;
A noise variance measuring device 4 for measuring a noise power variance σ 2 between 1 ms from the I correlation signal I0n and the Q correlation signal Q0n from the noise 1 ms correlation channel circuit 1n;
By substituting the noise power variance σ 2 for 1 ms, the coherent addition time (N) for a predetermined time, and the number of coherent additions (M) for a predetermined number of times into a statistically determined noise distribution function expression, And a noise distribution calculator 5 for obtaining a noise distribution value including a noise average Nmean and a noise variance Nrms corresponding to the received signal .

請求項２に記載の雑音推定装置は、衛星信号を変換し入力される特定衛星信号に関する受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路１ｎと、
前記雑音用１ｍｓ相関チャンネル回路１ｎからのＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとから１ｍｓ間の雑音パワーの分散σ２を１ｍｓ毎に測定するノイズ分散測定器４と、
前記１ｍｓ間の雑音パワーの分散σ２を第１ノイズ平均Ｎ１ｍｅａｎ及び第１ノイズ分散Ｎ１ｒｍｓを含む第１ノイズ分布値を求める第１ノイズ分布演算器５１と、
前記１ｍｓ間の雑音パワーの分散σ２、第１所定時間のコヒーレント加算時間（Ｎ１）、及び第１所定回数のコヒーレント加算回数（Ｍ１）を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第１ノイズ平均Ｎ１ｍｅａｎ及び第１ノイズ分散Ｎ１ｒｍｓを含む第１ノイズ分布値を求める第１ノイズ分布演算器５１と、
前記１ｍｓ間の雑音パワーの分散σ２を、前記第１所定時間（Ｎ１）より短い第２所定時間のコヒーレント加算時間（Ｎ２＜Ｎ１）、及び第２所定回数のコヒーレント加算回数（Ｍ２）を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第２ノイズ平均Ｎ２ｍｅａｎ及び第２ノイズ分散Ｎ２ｒｍｓを含む第２ノイズ分布値を求める第２ノイズ分布演算器５２と、を有することを特徴とする。
The noise estimation apparatus according to claim 2 converts a satellite signal and receives a carrier correlation between a received signal related to a specific satellite signal input and a non-correlated signal that cannot be correlated with the received signal. A 1 ms correlation channel circuit 1n for noise that outputs the I correlation signal I0n and the Q correlation signal Q0n simultaneously every 1 ms;
A noise variance measuring device 4 for measuring a noise power variance σ 2 between 1 ms from the I correlation signal I0n and the Q correlation signal Q0n from the noise 1 ms correlation channel circuit 1n;
A first noise distribution calculator 51 for obtaining the first noise distribution value containing a dispersion sigma 2 of the noise power of the first noise average N1mean and first noise variance N1rms between the 1 ms,
The noise power variance σ 2 for 1 ms, the first predetermined time coherent addition time (N1), and the first predetermined number of coherent addition times (M1) are substituted into a statistically determined noise distribution function expression. A first noise distribution calculator 51 for obtaining a first noise distribution value including a first noise average N1mean and a first noise variance N1rms corresponding to the received signal ;
The noise power variance σ 2 between 1 ms, a coherent addition time (N2 <N1) of a second predetermined time shorter than the first predetermined time (N1), and a second predetermined number of times of coherent addition (M2), A second noise distribution calculator 52 for obtaining a second noise distribution value including a second noise average N2mean and a second noise variance N2rms corresponding to the received signal by substituting into a statistically determined noise distribution function expression. It is characterized by having.

請求項３に記載の信号対雑音比演算装置は、周波数制御信号Ｆｏｕｔを受けてキャリア周波数信号を発生するキャリア局部発振器（キャリアＮＣＯ）１ａを含み、衛星信号を変換し入力される特定衛星信号に関する受信信号とＰＮコードとのコード相関及び前記キャリア周波数信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｉとＱ相関信号Ｑ０ｉとを同時に１ｍｓ毎に出力する信号用１ｍｓ相関チャンネル回路１ｓと、
前記信号用１ｍｓ相関チャンネル回路１ｓからのＩ相関信号Ｉ０ｉとＱ相関信号Ｑ０ｉを前記特定衛星信号の航法データの切り替わりタイミングに同期して所定時間（Ｎ）分コヒーレント加算を行い、そのＩコヒーレント加算値ＩｃｉとＱコヒーレント加算値Ｑｃｉとを出力するコヒーレント加算器２と、
前記Ｉコヒーレント加算値Ｉｃｉ及びＱコヒーレント加算値Ｑｃｉから、コヒーレント加算区間内の信号パワーを求め、その信号パワーの所定回数（Ｍ）の累積加算を行って累積信号パワーＰを求めて出力するノンコヒーレント加算器３と、
前記受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路１ｎと、
前記雑音用１ｍｓ相関チャンネル回路１ｎからのＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとから１ｍｓ間の雑音パワーの分散σ２を１ｍｓ毎に測定するノイズ分散測定器４と、
前記１ｍｓ間の雑音パワーの分散σ２、前記所定時間のコヒーレント加算時間（Ｎ）、及び前記所定回数のコヒーレント加算回数（Ｍ）を統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応したノイズ平均Ｎｍｅａｎ及びノイズ分散Ｎｒｍｓを含むノイズ分布値を求めるノイズ分布演算器５と、
前記累積信号パワーＰと、前記ノイズ平均Ｎｍｅａｎ及びノイズ分散Ｎｒｍｓを用いて、信号対雑音比Ｓ／Ｎを、［信号対雑音比Ｓ／Ｎ＝（累積信号パワーＰ−ノイズ平均Ｎｍｅａｎ）／ノイズ分散Ｎｒｍｓ］により算出する演算手段６と、を有することを特徴とする。
The signal-to-noise ratio calculation apparatus according to claim 3 includes a carrier local oscillator (carrier NCO) 1a that receives a frequency control signal Fout and generates a carrier frequency signal, and relates to a specific satellite signal that is input after converting the satellite signal. A 1 ms correlation channel circuit 1s for a signal that takes a code correlation between a received signal and a PN code and a carrier correlation with the carrier frequency signal and outputs an I correlation signal I0i and a Q correlation signal Q0i for 1 ms at the same time every 1 ms; ,
The I correlation signal I0i and the Q correlation signal Q0i from the signal 1 ms correlation channel circuit 1s are subjected to coherent addition for a predetermined time (N) in synchronization with the navigation data switching timing of the specific satellite signal, and the I coherent addition value is obtained. A coherent adder 2 that outputs Ici and a Q coherent addition value Qci;
Non-coherent that obtains signal power P in a coherent addition section from the I coherent addition value Ici and Q coherent addition value Qci, obtains the accumulated signal power P by performing cumulative addition of the signal power a predetermined number of times (M), and outputs it Adder 3;
A carrier correlation between the received signal and a non-correlated signal that cannot be correlated with the received signal, and a 1 ms correlation channel for noise that simultaneously outputs an I correlation signal I0n and a Q correlation signal Q0n for 1 ms every 1 ms. Circuit 1n;
A noise variance measuring device 4 for measuring a noise power variance σ 2 between 1 ms from the I correlation signal I0n and the Q correlation signal Q0n from the noise 1 ms correlation channel circuit 1n;
By substituting the noise power variance σ 2 for 1 ms, the coherent addition time (N) for the predetermined time, and the coherent addition number (M) for the predetermined number of times into a statistically determined noise distribution function expression. A noise distribution calculator 5 for obtaining a noise distribution value including a noise average Nmean and a noise variance Nrms corresponding to the received signal ;
Using the cumulative signal power P, the noise average Nmean, and the noise variance Nrms, the signal-to-noise ratio S / N is calculated as [signal-to-noise ratio S / N = (cumulative signal power P−noise average Nmean) / noise variance. Nrms] is calculated.

請求項４に記載の信号対雑音比演算装置は、周波数制御信号Ｆｏｕｔを受けてキャリア周波数信号を発生するキャリア局部発振器（キャリアＮＣＯ）１ａを含み、衛星信号を変換し入力される特定衛星信号に関する受信信号とＰＮコードとのコード相関及び前記キャリア周波数信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｉとＱ相関信号Ｑ０ｉとを同時に１ｍｓ毎に出力する信号用１ｍｓ相関チャンネル回路１ｓと、
前記信号用１ｍｓ相関チャンネル回路１ｓからのＩ相関信号Ｉ０ｉとＱ相関信号Ｑ０ｉを前記特定衛星信号の航法データの切り替わりタイミングに同期して第１所定時間（Ｎ１）分コヒーレント加算を行い、その第１Ｉコヒーレント加算値Ｉｃｉ１と第１Ｑコヒーレント加算値Ｑｃｉ１とを出力する第１コヒーレント加算器２１と、
前記第１Ｉコヒーレント加算値Ｉｃｉ１び第１Ｑコヒーレント加算値Ｑｃｉ１から、第１コヒーレント加算区間内の信号パワーを求め、その信号パワーの第１所定回数（Ｍ１）の累積加算を行って第１累積信号パワーＰ１を求めて出力する第１ノンコヒーレント加算器３１と、
前記信号用１ｍｓ相関チャンネル回路１ｓからのＩ相関信号Ｉ０ｉとＱ相関信号Ｑ０ｉを前記第１所定時間（Ｎ１）よりも短い第２所定時間（Ｎ２＜Ｎ１）分コヒーレント加算を行い、その第２Ｉコヒーレント加算値Ｉｃｉ２と第２Ｑコヒーレント加算値Ｑｃｉ２とを出力する第２コヒーレント加算器２２と、
前記第２Ｉコヒーレント加算値Ｉｃｉ２及び第２Ｑコヒーレント加算値Ｑｃｉ２から、第２コヒーレント加算区間内の信号パワーを求め、その信号パワーの第２所定回数（Ｍ２）の累積加算を行って第２累積信号パワーＰ２を求めて出力する第２ノンコヒーレント加算器３２と、
前記受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路１ｎと、
前記雑音用１ｍｓ相関チャンネル回路１ｎからのＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとから１ｍｓ間の雑音パワーの分散σ２を１ｍｓ毎に測定するノイズ分散測定器４と、
前記１ｍｓ間の雑音パワーの分散σ２、前記第１所定時間のコヒーレント加算時間（Ｎ１）、及び前記第１所定回数のコヒーレント加算回数（Ｍ１）を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第１ノイズ平均Ｎ１ｍｅａｎ及び第１ノイズ分散Ｎ１ｒｍｓを含む第１ノイズ分布値を求める第１ノイズ分布演算器５１と、
前記１ｍｓ間の雑音パワーの分散σ２、前記第２所定時間のコヒーレント加算時間（Ｎ２）、及び前記第２所定回数のコヒーレント加算回数（Ｍ２）を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第２ノイズ平均Ｎ２ｍｅａｎ及び第２ノイズ分散Ｎ２ｒｍｓを含む第２ノイズ分布値を求める第２ノイズ分布演算器５２と、
前記第１，第２累積信号パワーＰ１，Ｐ２と、前記第１，第２ノイズ平均Ｎ１ｍｅａｎ，Ｎ２ｍｅａｎ及び第１，第２ノイズ分散Ｎ１ｒｍｓ，Ｎ２ｒｍｓを用いて、第１，第２信号対雑音比Ｓ１／Ｎ１、Ｓ２／Ｎ２を、［第１信号対雑音比Ｓ１／Ｎ１＝（第１累積信号パワーＰ１−第１ノイズ平均Ｎ１ｍｅａｎ）／第１ノイズ分散Ｎ１ｒｍｓ］、及び［第２信号対雑音比Ｓ２／Ｎ２＝（第２累積信号パワーＰ２−第２ノイズ平均Ｎ２ｍｅａｎ）／第２ノイズ分散Ｎ２ｒｍｓ］、により算出する演算手段６と、を有することを特徴とする。
The signal-to-noise ratio calculation apparatus according to claim 4 includes a carrier local oscillator (carrier NCO) 1a that receives a frequency control signal Fout and generates a carrier frequency signal, and relates to a specific satellite signal that is input after converting a satellite signal. A 1 ms correlation channel circuit 1s for a signal that takes a code correlation between a received signal and a PN code and a carrier correlation with the carrier frequency signal and outputs an I correlation signal I0i and a Q correlation signal Q0i for 1 ms at the same time every 1 ms; ,
The I correlation signal I0i and the Q correlation signal Q0i from the signal 1 ms correlation channel circuit 1s are coherently added for a first predetermined time (N1) in synchronization with the navigation data switching timing of the specific satellite signal, and the first I A first coherent adder 21 that outputs a coherent addition value Ici1 and a first Q coherent addition value Qci1;
The signal power in the first coherent addition interval is obtained from the first I coherent addition value Ici1 and the first Q coherent addition value Qci1, and the first accumulated signal power is accumulated for the first predetermined number of times (M1). A first non-coherent adder 31 for obtaining and outputting P1,
The I correlation signal I0i and the Q correlation signal Q0i from the signal 1 ms correlation channel circuit 1s are subjected to a second predetermined time (N2 <N1) shorter than the first predetermined time (N1), and the second I coherent is obtained. A second coherent adder 22 that outputs the addition value Ici2 and the second Q coherent addition value Qci2,
The signal power in the second coherent addition interval is obtained from the second I coherent addition value Ici2 and the second Q coherent addition value Qci2, and the signal power is accumulated for a second predetermined number of times (M2) to obtain the second accumulated signal power. A second non-coherent adder 32 for determining and outputting P2,
A carrier correlation between the received signal and a non-correlated signal that cannot be correlated with the received signal, and a 1 ms correlation channel for noise that simultaneously outputs an I correlation signal I0n and a Q correlation signal Q0n for 1 ms every 1 ms. Circuit 1n;
A noise variance measuring device 4 for measuring a noise power variance σ 2 between 1 ms from the I correlation signal I0n and the Q correlation signal Q0n from the noise 1 ms correlation channel circuit 1n;
The noise distribution variance σ 2 for the 1 ms, the first predetermined time coherent addition time (N1), and the first predetermined number of coherent addition times (M1) are statistically determined function expressions of noise distribution. A first noise distribution calculator 51 for obtaining a first noise distribution value including a first noise average N1mean and a first noise variance N1rms corresponding to the received signal ,
The noise distribution variance σ 2 for 1 ms, the second predetermined time coherent addition time (N2), and the second predetermined number of coherent addition times (M2) are statistically determined function expressions of noise distribution. And a second noise distribution calculator 52 for obtaining a second noise distribution value including a second noise average N2mean and a second noise variance N2rms corresponding to the received signal ,
Using the first and second accumulated signal powers P1 and P2, the first and second noise averages N1mean and N2mean and the first and second noise variances N1rms and N2rms, the first and second signal-to-noise ratio S1. / N1, S2 / N2, [first signal-to-noise ratio S1 / N1 = (first cumulative signal power P1−first noise average N1mean) / first noise variance N1rms], and [second signal-to-noise ratio S2] / N2 = (second cumulative signal power P2−second noise average N2mean) / second noise variance N2rms].

請求項５に記載の衛星信号受信装置は、周波数制御信号Ｆｏｕｔを受けてキャリア周波数信号を発生するキャリア局部発振器（キャリアＮＣＯ）１ａを含み、衛星信号を変換し入力される特定衛星信号に関する受信信号とＰＮコードとのコード相関及び前記キャリア周波数信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｉとＱ相関信号Ｑ０ｉとを同時に１ｍｓ毎に出力する信号用１ｍｓ相関チャンネル回路１ｓと、
前記信号用１ｍｓ相関チャンネル回路１ｓからのＩ相関信号Ｉ０ｉとＱ相関信号Ｑ０ｉを前記特定衛星信号の航法データの切り替わりタイミングに同期して第１所定時間（Ｎ１）分コヒーレント加算を行い、その第１Ｉコヒーレント加算値Ｉｃｉ１と第１Ｑコヒーレント加算値Ｑｃｉ１とを出力する第１コヒーレント加算器２１と、
前記第１Ｉコヒーレント加算値Ｉｃｉ１及び第１Ｑコヒーレント加算値Ｑｃｉ１から、第１コヒーレント加算区間内の信号パワーを求め、その信号パワーの第１所定回数（Ｍ１）の累積加算を行って第１累積信号パワーＰ１を求めて出力する第１ノンコヒーレント加算器３１と、
前記第１Ｉ，Ｑコヒーレント加算値Ｉｃｉ１，Ｑｃｉ１に基づいて前記周波数制御信号Ｆｏｕｔを決定するコスタスループ演算器４と、
前記信号用１ｍｓ相関チャンネル回路１ｓからのＩ相関信号Ｉ０ｉとＱ相関信号Ｑ０ｉを前記第１所定時間（Ｎ１）よりも短い第２所定時間（Ｎ２＜Ｎ１）分コヒーレント加算を行い、その第２Ｉコヒーレント加算値Ｉｃｉ２と第２Ｑコヒーレント加算値Ｑｃｉ２とを出力する第２コヒーレント加算器２２と、
前記第２Ｉコヒーレント加算値Ｉｃｉ２及び第２Ｑコヒーレント加算値Ｑｃｉ２から、第２コヒーレント加算区間内の信号パワーを求め、その信号パワーの第２所定回数（Ｍ２）の累積加算を行って第２累積信号パワーＰ２を求めて出力する第２ノンコヒーレント加算器３２と、
前記受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路１ｎと、
前記雑音用１ｍｓ相関チャンネル回路１ｎからのＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとから１ｍｓ間の雑音パワーの分散σ２を１ｍｓ毎に測定するノイズ分散測定器４と、
前記１ｍｓ間の雑音パワーの分散σ２、前記第１所定時間のコヒーレント加算時間（Ｎ１）、及び前記第１所定回数のコヒーレント加算回数（Ｍ１）を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第１ノイズ平均Ｎ１ｍｅａｎ及び第１ノイズ分散Ｎ１ｒｍｓを含む第１ノイズ分布値を求める第１ノイズ分布演算器５１と、
前記１ｍｓ間の雑音パワーの分散σ２、前記第２所定時間のコヒーレント加算時間（Ｎ２）、及び前記第２所定回数のコヒーレント加算回数（Ｍ２）を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第２ノイズ平均Ｎ２ｍｅａｎ及び第２ノイズ分散Ｎ２ｒｍｓを含む第２ノイズ分布値を求める第２ノイズ分布演算器５２と、
前記第１，第２累積信号パワーＰ１，Ｐ２と、前記第１，第２ノイズ平均Ｎ１ｍｅａｎ，Ｎ２ｍｅａｎ及び第１，第２ノイズ分散Ｎ１ｒｍｓ，Ｎ２ｒｍｓを用いて、第１，第２信号対雑音比Ｓ１／Ｎ１、Ｓ２／Ｎ２を、［第１信号対雑音比Ｓ１／Ｎ１＝（第１累積信号パワーＰ１−第１ノイズ平均Ｎ１ｍｅａｎ）／第１ノイズ分散Ｎ１ｒｍｓ］、及び［第２信号対雑音比Ｓ２／Ｎ２＝（第２累積信号パワーＰ２−第２ノイズ平均Ｎ２ｍｅａｎ）／第２ノイズ分散Ｎ２ｒｍｓ］、により算出するとともに、前記第１、第２信号対雑音比Ｓ１／Ｎ１，Ｓ２／Ｎ２に基づいて前記コスタスループ演算器４の特性もしくは入力を変更して前記周波数制御信号Ｆｏｕｔを制御する演算・制御手段６と、を有することを特徴とする。
The satellite signal receiving apparatus according to claim 5 includes a carrier local oscillator (carrier NCO) 1a that receives a frequency control signal Fout and generates a carrier frequency signal, and converts the satellite signal into a received signal related to a specific satellite signal that is input. A 1 ms correlation channel circuit 1s for a signal that outputs the I correlation signal I0i and the Q correlation signal Q0i for 1 ms at the same time every 1 ms.
The I correlation signal I0i and the Q correlation signal Q0i from the signal 1 ms correlation channel circuit 1s are coherently added for a first predetermined time (N1) in synchronization with the navigation data switching timing of the specific satellite signal, and the first I A first coherent adder 21 that outputs a coherent addition value Ici1 and a first Q coherent addition value Qci1;
From the first I coherent addition value Ici1 and the first Q coherent addition value Qci1, the signal power in the first coherent addition interval is obtained, and the first predetermined signal power is accumulated for the first predetermined number of times (M1). A first non-coherent adder 31 for obtaining and outputting P1,
A Costas loop computing unit 4 for determining the frequency control signal Fout based on the first I and Q coherent addition values Ici1 and Qci1;
The I correlation signal I0i and the Q correlation signal Q0i from the signal 1 ms correlation channel circuit 1s are subjected to a second predetermined time (N2 <N1) shorter than the first predetermined time (N1), and the second I coherent is obtained. A second coherent adder 22 that outputs the addition value Ici2 and the second Q coherent addition value Qci2,
The signal power in the second coherent addition interval is obtained from the second I coherent addition value Ici2 and the second Q coherent addition value Qci2, and the signal power is accumulated for a second predetermined number of times (M2) to obtain the second accumulated signal power. A second non-coherent adder 32 for determining and outputting P2,
A carrier correlation between the received signal and a non-correlated signal that cannot be correlated with the received signal, and a 1 ms correlation channel for noise that simultaneously outputs an I correlation signal I0n and a Q correlation signal Q0n for 1 ms every 1 ms. Circuit 1n;
A noise variance measuring device 4 for measuring a noise power variance σ 2 between 1 ms from the I correlation signal I0n and the Q correlation signal Q0n from the noise 1 ms correlation channel circuit 1n;
The noise distribution variance σ 2 for the 1 ms, the first predetermined time coherent addition time (N1), and the first predetermined number of coherent addition times (M1) are statistically determined function expressions of noise distribution. A first noise distribution calculator 51 for obtaining a first noise distribution value including a first noise average N1mean and a first noise variance N1rms corresponding to the received signal ,
The noise distribution variance σ 2 for 1 ms, the second predetermined time coherent addition time (N2), and the second predetermined number of coherent addition times (M2) are statistically determined function expressions of noise distribution. And a second noise distribution calculator 52 for obtaining a second noise distribution value including a second noise average N2mean and a second noise variance N2rms corresponding to the received signal ,
Using the first and second accumulated signal powers P1 and P2, the first and second noise averages N1mean and N2mean and the first and second noise variances N1rms and N2rms, the first and second signal-to-noise ratio S1. / N1, S2 / N2, [first signal-to-noise ratio S1 / N1 = (first cumulative signal power P1−first noise average N1mean) / first noise variance N1rms], and [second signal-to-noise ratio S2] / N2 = (second cumulative signal power P2−second noise average N2mean) / second noise variance N2rms], and based on the first and second signal-to-noise ratios S1 / N1 and S2 / N2. And calculating / controlling means 6 for controlling the frequency control signal Fout by changing the characteristic or input of the Costas loop calculator 4.

本発明の雑音推定装置、信号対雑音比演算装置、及び衛星信号受信装置によれば、ＧＰＳなどの航法衛星からの衛星信号が屋内や高架下など非常に弱い環境での追尾時に、ノイズ分布値（ノイズ平均及びノイズ分散）及び信号対雑音比をリアルタイムに求めることができるとともに、安定して周波数追尾を行うことができる。   According to the noise estimation device, the signal-to-noise ratio calculation device, and the satellite signal reception device of the present invention, the noise distribution value is obtained when the satellite signal from the navigation satellite such as GPS is tracked in a very weak environment such as indoors or under an overhead. (Noise average and noise variance) and signal-to-noise ratio can be obtained in real time, and frequency tracking can be performed stably.

以下、図１，図２を参照して、ＧＰＳを例として本発明の雑音推定装置、信号対雑音比演算装置、及び衛星信号受信装置の実施例について説明する。   Hereinafter, with reference to FIGS. 1 and 2, embodiments of the noise estimation device, the signal-to-noise ratio calculation device, and the satellite signal reception device of the present invention will be described using GPS as an example.

図１において、衛星からアンテナ１０１に到来した衛星信号は、ダウンコンバータ１０２で中間周波数に変換され、Ａ／Ｄ変換回路１０３にてディジタル処理のためにディジタル信号に変換され、受信信号としてキャリアＮＣＯ１ａを含む信号用１ｍｓ相関チャンネル回路１ｓに入力される。また、その受信信号は、雑音用１ｍｓ相関チャンネル１ｎにも入力される。   In FIG. 1, a satellite signal arriving at an antenna 101 from a satellite is converted to an intermediate frequency by a down converter 102, converted to a digital signal for digital processing by an A / D conversion circuit 103, and a carrier NCO 1a is received as a received signal. The input signal is input to the 1 ms correlation channel circuit 1s. The received signal is also input to the 1 ms correlation channel 1n for noise.

１ｍｓ相関チャンネル回路１ｓは、周波数制御信号Ｆｏｕｔを受けてキャリア周波数信号を発生するキャリア局部発振器１ａを含み、衛星信号を変換し入力される特定衛星信号に関する受信信号とＰＮコードとのコード相関及び前記キャリア周波数信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｉとＱ相関信号Ｑ０ｉとを同時に１ｍｓ毎に出力する。この１ｍｓ相関チャンネル回路１ｓは、従来のＧＰＳ受信装置で使用されているものと同様のものでよい。念のためにその主要構成について例示する。   The 1 ms correlation channel circuit 1s includes a carrier local oscillator 1a that receives a frequency control signal Fout and generates a carrier frequency signal. The 1ms correlation channel circuit 1s converts the satellite signal and receives the code correlation between the received signal and the PN code related to the input specific satellite signal. The carrier correlation with the carrier frequency signal is taken, and the I correlation signal I0i and the Q correlation signal Q0i for 1 ms are simultaneously output every 1 ms. The 1 ms correlation channel circuit 1s may be the same as that used in a conventional GPS receiver. As a precaution, the main configuration is illustrated.

即ち、受信しようとする衛星のＰＮコードと同一のＰＮコードをコード発生器で発生し、受信信号と発生したＰＮコードとをコード相関器で相関を採る。このコード相関器の相関値が最大となるようにコードＮＣＯにてコード発生器のＰＮコード位相を制御するように遅延ロックループ（ＤＬＬ）を構成する。このコード相関器の出力は、Ｉキャリア相関器にてキャリアＮＣＯ１ａで発生したＩキャリア周波数信号と、またＱキャリア相関器にてキャリアＮＣＯ１ａで発生したＱキャリア周波数信号とそれぞれ相関が採られて相関値を出力する。Ｉキャリア相関器の出力はレジスタなどで構成されるＩ１ｍｓ積分器で積分され、１ｍｓ間のＩ加算相関値Ｉ０ｉとして１ｍｓ毎に出力される。同様に、Ｑキャリア相関器の出力はＱ１ｍｓ積分器で積分され、１ｍｓ間のＱ加算相関値Ｑ０ｉとして１ｍｓ毎に出力される。   That is, a PN code identical to the PN code of the satellite to be received is generated by the code generator, and the received signal and the generated PN code are correlated by the code correlator. A delay lock loop (DLL) is configured so that the code NCO controls the PN code phase of the code generator so that the correlation value of the code correlator is maximized. The output of the code correlator is correlated with the I carrier frequency signal generated by the carrier NCO 1a by the I carrier correlator and the Q carrier frequency signal generated by the carrier NCO 1a by the Q carrier correlator. Is output. The output of the I carrier correlator is integrated by an I1 ms integrator composed of a register or the like, and output as an I addition correlation value I0i for 1 ms every 1 ms. Similarly, the output of the Q carrier correlator is integrated by a Q1 ms integrator and is output every 1 ms as a Q addition correlation value Q0i for 1 ms.

１ｍｓ相関チャンネル回路１ｓから出力されるＩ，Ｑ加算相関値Ｉ０ｉ，Ｑ０ｉは真に追尾されるべき真追尾周波数と、その時点でキャリアＮＣＯ１ａから出力されている現追尾周波数との周波数差、位相差に応じた周波数成分を持つことになる。現追尾周波数が真追尾周波数に等しい場合には、Ｉ，Ｑ加算相関値Ｉ０ｉ，Ｑ０ｉの周波数成分は理想的には零になる。   The I and Q addition correlation values I0i and Q0i output from the 1 ms correlation channel circuit 1s are the frequency difference and phase difference between the true tracking frequency to be truly tracked and the current tracking frequency output from the carrier NCO 1a at that time. It has a frequency component corresponding to. When the current tracking frequency is equal to the true tracking frequency, the frequency components of the I and Q addition correlation values I0i and Q0i are ideally zero.

第１コヒーレント加算器であるＮ１ｍｓコヒーレント加算器２１では、１ｍｓ相関チャンネル回路１ｓから１ｍｓ間のＩ，Ｑ加算相関値Ｉ０ｉ，Ｑ０ｉが出力される毎にＩ加算相関値Ｉ０ｉ及びＱ加算相関値Ｑ０ｉのコヒーレント加算を、Ｎ１ｍｓ間だけ行う。具体的には、衛星からの航法データの切替タイミング（エッジ情報）の間だけ、コヒーレント加算を行う。そして、エッジタイミングになった時に、Ｎ１ｍｓ（例えば、２０ｍｓ）毎に、そのコヒーレント加算結果であるＩ，Ｑコヒーレント加算値Ｉｃｉ１，Ｑｃｉ１を出力し、その後の次回コヒーレント区間での積算のために内部加算結果をリセットする。   In the N1ms coherent adder 21 that is the first coherent adder, the I addition correlation value I0i and the Q addition correlation value Q0i are output every time I, Q addition correlation values I0i, Q0i are output from the 1 ms correlation channel circuit 1s for 1 ms. Coherent addition is performed for N1 ms. Specifically, coherent addition is performed only during the switching timing (edge information) of the navigation data from the satellite. When the edge timing is reached, the I and Q coherent addition values Ici1 and Qci1 as the coherent addition results are output every N1 ms (for example, 20 ms), and then added internally for integration in the next coherent interval. Reset the result.

エッジ情報発生器８からエッジ情報が、供給される。このエッジ情報は、概略のユーザ位置（即ち、衛星信号受信装置の存在位置）、衛星軌道情報が既知で、１つ以上の衛星信号の強い衛星に追尾している条件下であれば全衛星のエッジ位置は正確に求められる。その求め方は例えば、（１）通常感度の衛星を１衛星以上追尾してＧＰＳ時刻を得る、（２）アシスト情報から得られるエフェメリス情報（衛星軌道情報）を用いて、現在時刻におけるＧＰＳ衛星位置を求める、（３）概略のユーザ位置を用い、ＧＰＳ衛星と現在位置間の距離差を求め、それを光速で割ってＧＰＳ衛星からの信号が到達するまでの時間を求める、（４）その時間をエッジ間隔で割ったあまりの時間Ｔ２を求め、その値を切替タイミングとして記憶する、（５）ＧＰＳ時刻をエッジ間隔で割った余りが値Ｔ２になったときに切り替える、ことにより得られる。
Edge information is supplied from the edge information generator 8. This edge information is the approximate user position (that is, the position where the satellite signal receiver is present), the satellite orbit information is known, and if all satellites are tracked under the condition of tracking one or more strong satellite signals, The edge position is accurately determined. For example, (1) the GPS time is obtained by tracking one or more satellites of normal sensitivity, and (2) the GPS satellite position at the current time using the ephemeris information (satellite orbit information) obtained from the assist information. (3) Using the approximate user position, the distance difference between the GPS satellite and the current position is obtained, and divided by the speed of light to obtain the time until the signal from the GPS satellite arrives. (4) The time Is obtained by determining the time T2 that is excessively divided by the edge interval and storing the value as the switching timing, and (5) switching when the remainder obtained by dividing the GPS time by the edge interval becomes the value T2.

コスタスループ演算器７は、通常、コヒーレント加算時間分Ｓ／Ｎ比が改善されたＩ，Ｑコヒーレント加算値Ｉｃｉ１，Ｑｃｉ１に基づいて、キャリアＮＣＯ１ａへ与えるキャリア周波数制御信号Ｆｏｕｔを決定する。なお、キャリア周波数制御信号Ｆｏｕｔは、Ｓ／Ｎ演算・制御装置からの制御信号（重み付け値ｗや、切替信号ｃｏｓ）によって、コスタスループ演算器４の特性もしくは入力を変更して、制御される。   The Costas loop calculator 7 normally determines the carrier frequency control signal Fout to be given to the carrier NCO 1a based on the I and Q coherent addition values Ici1 and Qci1 whose S / N ratio is improved by the coherent addition time. The carrier frequency control signal Fout is controlled by changing the characteristic or input of the Costas loop calculator 4 by a control signal (weight value w or switching signal cos) from the S / N calculation / control device.

このコスタスループ演算器７、キャリアＮＣＯ１ａを含む１ｍｓ相関チャンネル回路１ｓ，Ｎ１ｍｓコヒーレント加算器２１によってコスタスループが形成される。このコスタスループは、閉ループ制御であり、コヒーレント加算時間はＮ１ｍｓ（＝２０ｍｓ）であるためにＳ／Ｎ比が改善されるから、衛星信号が弱い場合にも精度良いキャリア周波数制御信号Ｆｏｕｔ、即ち高精度のキャリア周波数を得ることができる。   A Costas loop is formed by the Costas loop calculator 7, the 1 ms correlation channel circuit 1 s including the carrier NCO 1 a, and the N 1 ms coherent adder 21. This Costas loop is closed loop control, and since the S / N ratio is improved because the coherent addition time is N1 ms (= 20 ms), the carrier frequency control signal Fout with high accuracy even when the satellite signal is weak, An accurate carrier frequency can be obtained.

第１ノンコヒーレント加算器であるＭ１回ノンコヒーレント加算器３１は、第１Ｉコヒーレント加算値Ｉｃｉ１及び第１Ｑコヒーレント加算値Ｑｃｉ１から、第１コヒーレント加算区間内の信号パワーを求め、その信号パワーの第１所定回数（例えば、Ｍ１＝２５回）の累積加算を行って第１累積信号パワーＰ１を求めて出力する。累積信号パワーＰ１は、出力する毎にリセットされる。   The M1-th non-coherent adder 31 as the first non-coherent adder obtains the signal power in the first coherent addition section from the first I coherent addition value Ici1 and the first Q coherent addition value Qci1, and the first of the signal power Accumulative addition is performed a predetermined number of times (for example, M1 = 25 times) to obtain and output the first cumulative signal power P1. The accumulated signal power P1 is reset every time it is output.

第２コヒーレント加算器であるＮ２ｍｓコヒーレント加算器２２では、１ｍｓ相関チャンネル回路１ｓから１ｍｓ間のＩ，Ｑ加算相関値Ｉ０ｉ，Ｑ０ｉが出力される毎にＩ加算相関値Ｉ０ｉ及びＱ加算相関値Ｑ０ｉのコヒーレント加算を、Ｎ２ｍｓ（例えば、５ｍｓ）間だけ行う。この場合にも、衛星からの航法データの切替タイミング（エッジ情報）に合わせて、コヒーレント加算を行うことが望ましい。但し、Ｎ２ｍｓは、Ｎ１ｍｓより格段に短いから、必ずしもエッジ情報に同期させる必要はない。そして、そのコヒーレント加算結果であるＩ，Ｑコヒーレント加算値Ｉｃｉ２，Ｑｃｉ２を出力し、その後の次回コヒーレント区間での積算のために内部加算結果をリセットする。   In the N2ms coherent adder 22 as the second coherent adder, the I addition correlation value I0i and the Q addition correlation value Q0i are output each time the I, Q addition correlation values I0i and Q0i are output from the 1 ms correlation channel circuit 1s for 1 ms. Coherent addition is performed for N2 ms (for example, 5 ms). Also in this case, it is desirable to perform coherent addition in accordance with the switching timing (edge information) of the navigation data from the satellite. However, since N2ms is much shorter than N1ms, it is not always necessary to synchronize with the edge information. Then, I and Q coherent addition values Ici2 and Qci2 as the coherent addition results are output, and the internal addition results are reset for integration in the next coherent interval.

第２ノンコヒーレント加算器であるＭ２回ノンコヒーレント加算器３２は、第２Ｉコヒーレント加算値Ｉｃｉ２及び第２Ｑコヒーレント加算値Ｑｃｉ２から、第２コヒーレント加算区間内の信号パワーを求め、その信号パワーの第２所定回数（例えば、Ｍ２＝４０回）の累積加算を行って第２累積信号パワーＰ２を求めて出力する。累積信号パワーＰ２は、出力する毎にリセットされる。   The M2 non-coherent adder 32, which is the second non-coherent adder, obtains the signal power in the second coherent addition interval from the second I coherent addition value Ici2 and the second Q coherent addition value Qci2, and obtains the second of the signal power. Accumulative addition is performed a predetermined number of times (for example, M2 = 40 times) to obtain and output the second cumulative signal power P2. The accumulated signal power P2 is reset every time it is output.

Ｎ１ｍｓコヒーレント加算器２１は加算時間が長くＳ／Ｎ比の改善度が高い追尾を行うために長いコヒーレント加算時間Ｎ１＝２０ｍｓが用いられ、Ｎ２ｍｓコヒーレント加算器２２は加算時間が短くＳ／Ｎ比改善度は低いが加速度追従性がよい追尾を行うために短い加算時間Ｎ２＝５ｍｓが用いられる。即ち、Ｎ１≧Ｎ２（Ｎ１とＮ２とが等しい場合も含まれて良い）であり、また、ノンコヒーレント回数を加味すると、Ｎ１＊Ｍ１＞Ｎ２＊Ｍ２であることがよい。   The N1ms coherent adder 21 uses a long coherent addition time N1 = 20 ms for tracking with a long addition time and a high improvement in the S / N ratio, and the N2ms coherent adder 22 has a short addition time and an improved S / N ratio. A short addition time N2 = 5 ms is used to perform tracking with a low degree of acceleration but good acceleration tracking. That is, N1 ≧ N2 (the case where N1 and N2 are equal may be included), and it is preferable that N1 * M1> N2 * M2 considering the number of non-coherent times.

雑音用１ｍｓ相関チャンネル回路１ｎは、受信信号とこの受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎとを同時に１ｍｓ毎に出力する。   The 1 ms correlation channel circuit 1n for noise takes a carrier correlation between a received signal and a non-correlated signal that cannot be correlated with the received signal, and simultaneously outputs an I correlated signal I0n and a Q correlated signal Q0n for 1 ms every 1 ms. Output to.

この雑音用１ｍｓ相関チャンネル回路１ｎは、キャリアＮＣＯは有しておらず、固定周波数でのキャリア相関を行う。ダウンコンバータ１０２のコンバート周波数（例えば、数１０ＭＨｚ）と数ＭＨｚ程度異なる周波数をその固定周波数とすることでよい。   The 1 ms correlation channel circuit 1n for noise does not have a carrier NCO and performs carrier correlation at a fixed frequency. A frequency different from the conversion frequency (for example, several tens of MHz) of the down converter 102 by about several MHz may be set as the fixed frequency.

また、雑音用１ｍｓ相関チャンネル回路１ｎでのコード相関は、雑音との相関を得ることが目的であるから、上空にいない測位衛星のＰＮコードとの相関を採れば雑音との相関が採れる。ただ、上空にいない測位衛星を選択するものでは、測位衛星を選択するために用いるアルマナック情報が正しくない場合（例えば、起動直後とか、アルマナック情報が更新されていないとき）には、上空にいる測位衛星のコードを選んでしまう可能性がある。このような事態を避けるために当該衛星受信装置の航法システムのコードと異なるコードを用いることがよい。異なるコードとしては、当該衛星受信装置の航法システムがＧＰＳシステムである場合には、例えばＧＬＯＮＡＳＳシステムのコードを用いればよいし、また、単純な繰り返し信号であっても良い。また、そのような異なるコードを使用せずに、受信信号を１ｍｓ間だけ加算した信号を用いても良い。
The purpose of the code correlation in the 1 ms correlation channel circuit 1n for noise is to obtain a correlation with noise. Therefore, if the correlation with the PN code of a positioning satellite not in the sky is taken, the correlation with noise can be obtained. However, if you select a positioning satellite that is not in the sky, if the almanac information used to select the positioning satellite is incorrect (for example, immediately after startup or when the almanac information has not been updated), positioning in the sky There is a possibility of selecting a satellite code. In order to avoid such a situation , it is preferable to use a code different from the code of the navigation system of the satellite receiver. As a different code, when the navigation system of the satellite receiver is a GPS system, for example, a code of a GLONASS system may be used, or a simple repetitive signal may be used. Moreover, you may use the signal which added the received signal only for 1 ms, without using such a different code | cord | chord.

ノイズ分散測定器４は、雑音用１ｍｓ相関チャンネル回路１ｎからの１ｍｓ毎に出力されるＩ相関信号Ｉ０ｎとＱ相関信号Ｑ０ｎを一定期間（例えば、５００ｍｓ）観測し、１ｍｓ間の雑音パワーの分散σ2を１ｍｓ毎に測定する。 The noise variance measuring device 4 observes the I correlation signal I0n and the Q correlation signal Q0n output every 1 ms from the 1 ms correlation channel circuit 1n for noise for a certain period (for example, 500 ms), and disperses the noise power σ between 1 ms. 2 is measured every 1 ms.

第１ノイズ分布演算器である方式１のノイズ分布演算器５１は、１ｍｓ間の雑音パワーの分散σ2を用いて、第１所定時間（Ｎ１＝２０ｍｓ）分コヒーレント加算し、そのコヒーレント加算結果を第１所定回数（Ｍ１＝２５回）加算した場合に相当する、第１ノイズ平均Ｎ１ｍｅａｎ及び第１ノイズ分散Ｎ１ｒｍｓを含む第１ノイズ分布値を求める。 The noise distribution calculator 51 of method 1 which is a first noise distribution calculator performs coherent addition for a first predetermined time (N1 = 20 ms) using the noise power variance σ 2 for 1 ms, and the coherent addition result is obtained. A first noise distribution value including a first noise average N1mean and a first noise variance N1rms, corresponding to a case where the first predetermined number of times (M1 = 25) is added, is obtained.

また、第２ノイズ分布演算器である方式２のノイズ分布演算器５２は、１ｍｓ間の雑音パワーの分散σ2を用いて、第１所定時間（Ｎ１）より短い第２所定時間（Ｎ２＝５ｍｓ＜Ｎ１）分コヒーレント加算し、そのコヒーレント加算結果を第２所定回数（Ｍ２＝４０回）加算した場合に相当する、第２ノイズ平均Ｎ２ｍｅａｎ及び第２ノイズ分散Ｎ２ｒｍｓを含む第２ノイズ分布値を求める。 In addition, the noise distribution calculator 52 of the method 2, which is the second noise distribution calculator, uses the noise power variance σ 2 for 1 ms, and the second predetermined time (N2 = 5 ms) shorter than the first predetermined time (N1). <N1) Coherent addition is performed, and a second noise distribution value including the second noise average N2mean and the second noise variance N2rms corresponding to a case where the coherent addition result is added a second predetermined number of times (M2 = 40 times) is obtained. .

第１，第２ノイズ分布値を求めるに際して、コヒーレント加算時間Ｎｍｓとノンコヒーレント回数Ｍが与えられた場合、雑音が正規分布（０、σ2）のガウス雑音であれば、コヒーレント加算時間Ｎｍｓとノンコヒーレント回数Ｍの加算を行った場合のノイズ分布が統計的に得られる。つまり、ノイズ分布のノイズ平均Ｎｍｅａｎ及びそのノイズ分散Ｎｒｍｓは、Ｎｍｅａｎ＝Ｆ１（Ｎ、Ｍ、σ2）、Ｎｒｍｓ＝Ｆ２（Ｎ、Ｍ、σ2）、の関数となる。 When obtaining the first and second noise distribution values, if the coherent addition time Nms and the non-coherent number M are given, and if the noise is Gaussian noise of the normal distribution (0, σ 2 ), the coherent addition time Nms and the non-coherent addition time Nms. A noise distribution when the number of coherent times M is added is statistically obtained. That is, the noise average Nmean of the noise distribution and its noise variance Nrms are functions of Nmean = F1 (N, M, σ 2 ) and Nrms = F2 (N, M, σ 2 ).

このノイズ平均Ｎｍｅａｎ及びそのノイズ分散Ｎｒｍｓの関数におけるＮ，Ｍに関する部分は複雑であるが、実際にはＮ、Ｍは予め決めた値しか採らないので、結局、ノイズ平均Ｎｍｅａｎ及びそのノイズ分散Ｎｒｍｓは、
Ｎｍｅａｎ＝Ｆｎｍ（σ2）≒Ａｎｍσ2＋Ｂｎｍ、
Ｎｒｍｓ ＝Ｆｎｍ（σ2）≒Ｃｎｍσ2＋Ｄｎｍ、
で近似できる。この近似式により求めたノイズ平均Ｎｍｅａｎ及びそのノイズ分散Ｎｒｍｓは、元の関数によって求めた値に、それぞれ相当する。 Although the parts related to N and M in the function of this noise average Nmean and its noise variance Nrms are complicated, in reality, N and M take only predetermined values, so that the noise average Nmean and its noise variance Nrms are eventually ,
Nmean = Fnm (σ 2 ) ≈Anmσ 2 + Bnm,
Nrms = Fnm (σ 2 ) ≈Cnmσ 2 + Dnm,
Can be approximated by The noise average Nmean and the noise variance Nrms obtained by this approximate expression correspond to the values obtained by the original function, respectively.

このことを利用して、方式１のノイズ分布演算器５１に特定の係数Ａ１ｎｍ、Ｂ１ｎｍ、Ｃ１ｎｍ、Ｄ１ｎｍを、方式２のノイズ分布演算器５２に特定の係数Ａ２ｎｍ、Ｂ２ｎｍ、Ｃ２ｎｍ、Ｄ２ｎｍを、それぞれ予め設定する。そして、方式１のノイズ分布演算器５１では、Ｎ１ｍｅａｎ≒Ａ１ｎｍσ2＋Ｂ１ｎｍ、Ｎ１ｒｍｓ≒Ｃ１ｎｍσ2＋Ｄ１ｎｍ、で求め、方式２のノイズ分布演算器５２では、Ｎ２ｍｅａｎ≒Ａ２ｎｍσ2＋Ｂ２ｎｍ、Ｎ２ｒｍｓ≒Ｃ２ｎｍσ2＋Ｄ２ｎｍ、で求める。 Using this, specific coefficients A1 nm, B1 nm, C1 nm, and D1 nm are assigned to the noise distribution calculator 51 of method 1, and specific coefficients A2 nm, B2 nm, C2 nm, and D2 nm are assigned to the noise distribution calculator 52 of method 2, respectively. Set in advance. Then, in the noise distribution calculator 51 of method 1, N1mean≈A1 nmσ 2 + B1 nm, N1rms≈C1 nmσ 2 + D1 nm, and in the noise distribution calculator 52 of method 2, N2mean≈A2 nmσ 2 + B2 nm, N2rms≈C2 nmσ 2 + D2 nm Ask.

演算・制御手段であるＳ／Ｎ演算・制御装置６は、第１，第２累積信号パワーＰ１，Ｐ２と、第１，第２ノイズ平均Ｎ１ｍｅａｎ，Ｎ２ｍｅａｎ及び第１，第２ノイズ分散Ｎ１ｒｍｓ，Ｎ２ｒｍｓが入力され、それらを用いて第１，第２信号対雑音比Ｓ１／Ｎ１、Ｓ２／Ｎ２を、［第１信号対雑音比Ｓ１／Ｎ１＝（第１累積信号パワーＰ１−第１ノイズ平均Ｎ１ｍｅａｎ）／第１ノイズ分散Ｎ１ｒｍｓ］、及び［第２信号対雑音比Ｓ２／Ｎ２＝（第２累積信号パワーＰ２−第２ノイズ平均Ｎ２ｍｅａｎ）／第２ノイズ分散Ｎ２ｒｍｓ］、により算出する。このＳ／Ｎ演算・制御装置６から、第１，第２信号対雑音比Ｓ１／Ｎ１，Ｓ２／Ｎ２、及び第１，第２累積信号パワーＰ１，Ｐ２、第１，第２ノイズ平均Ｎ１ｍｅａｎ，Ｎ２ｍｅａｎ、第１，第２ノイズ分散Ｎ１ｒｍｓ，Ｎ２ｒｍｓを外部に出力して、図示しない他の装置で利用できる。   The S / N calculation / control device 6 serving as calculation / control means includes first and second cumulative signal powers P1, P2, first and second noise averages N1mean and N2mean, and first and second noise variances N1rms and N2rms. Are used, and the first and second signal-to-noise ratios S1 / N1 and S2 / N2 are used as [first signal-to-noise ratio S1 / N1 = (first accumulated signal power P1−first noise average N1mean ) / First noise variance N1rms] and [second signal-to-noise ratio S2 / N2 = (second accumulated signal power P2−second noise average N2mean) / second noise variance N2rms]. From the S / N calculation / control device 6, the first and second signal-to-noise ratios S1 / N1, S2 / N2, the first and second accumulated signal powers P1, P2, the first and second noise averages N1mean, N2mean, the first and second noise variances N1rms and N2rms are output to the outside and can be used in another device (not shown).

本発明では、第１，第２信号対雑音比Ｓ１／Ｎ１，Ｓ２／Ｎ２、ノイズ平均Ｎ１ｍｅａｎ，Ｎ２ｍｅａｎ及びそのノイズ分散Ｎ１ｒｍｓ，Ｎ２ｒｍｓは、それらの算出の元になっている、１ｍｓ間の雑音パワーの分散σ2がノイズ分散測定器４により常時更新されているので、リアルタイムに正確に求められる。また、複数の加算方式に関しても、単にノイズ分布計算用の係数を設定するだけで、同時に求められる。 In the present invention, the first and second signal-to-noise ratios S1 / N1, S2 / N2, the noise averages N1mean and N2mean and their noise variances N1rms and N2rms are the sources of their calculation. since variance sigma 2 of are constantly updated by the noise variance measuring device 4 is accurately determined in real time. Also, a plurality of addition methods can be obtained simultaneously by simply setting a coefficient for noise distribution calculation.

Ｓ／Ｎ演算・制御装置６は、信号対雑音比Ｓ１／Ｎ１，Ｓ２／Ｎ２に基づいてコスタスループ演算器４の特性もしくは入力を変更して周波数制御信号Ｆｏｕｔを制御する。   The S / N calculation / control device 6 controls the frequency control signal Fout by changing the characteristic or input of the Costas loop calculation unit 4 based on the signal-to-noise ratios S1 / N1 and S2 / N2.

Ｓ／Ｎ演算・制御装置６で求められた、加算時間が長くＳ／Ｎ改善度が高い第１信号対雑音比Ｓ１／Ｎ１と、加算時間は短くＳ／Ｎ改善度は低いが加速度追従性がよい第２信号対雑音比Ｓ２／Ｎ２の両方を勘案して、重み値ｗをコスタスループ演算器７に供給する。コスタスループ演算器７ではＩ，Ｑコヒーレント加算値Ｉｃｉ１，Ｑｃｉ１による周波数制御信号Ｆｏｕｔの制御に重み値ｗによる重み付けを行う。例えば、重み値ｗによる重み付けは、第１，第２信号対雑音比Ｓ１／Ｎ１，第２信号対雑音比Ｓ２／Ｎ２の両方を勘案して得られた雑音成分が、大きいときにはコスタスループ演算器７の応答性を高くし、小さいときにはコスタスループ演算器７の応答性を低くすることでよい。   The first signal-to-noise ratio S1 / N1 obtained by the S / N arithmetic / control device 6 and having a long addition time and a high S / N improvement degree, and an acceleration follow-up property although the addition time is short and the S / N improvement degree is low. The weight value w is supplied to the Costas loop computing unit 7 in consideration of both the second signal-to-noise ratio S2 / N2 that is good. The Costas loop calculator 7 weights the frequency control signal Fout by the I and Q coherent addition values Ici1 and Qci1 using the weight value w. For example, weighting by the weight value w is performed when the noise component obtained by considering both the first and second signal-to-noise ratios S1 / N1 and the second signal-to-noise ratio S2 / N2 is large. 7 may be increased, and when small, the response of the Costas loop calculator 7 may be decreased.

また、Ｓ／Ｎ演算・制御装置６による制御として、図１に破線で示すように、コスタスループ演算器７に、第１Ｉコヒーレント加算値Ｉｃｉ１と第１Ｑコヒーレント加算値Ｑｃｉ１とともに、第２コヒーレント加算器２２からの第２Ｉコヒーレント加算値Ｉｃｉ２と第２Ｑコヒーレント加算値Ｑｃｉ２をも入力する。そして、Ｓ／Ｎ演算・制御装置６で求められた重み値ｗと同様にして得られた切替信号ｃｏｓによって、第１コヒーレント加算値Ｉｃｉ１，Ｑｃｉ１と第２コヒーレント加算値Ｉｃｉ２，Ｑｃｉ２とを切り替えて使用する。即ち、コスタスループ演算器４への入力を、常時使用している第１コヒーレント加算値Ｉｃｉ１，Ｑｃｉ１から、第２コヒーレント加算値Ｉｃｉ２，Ｑｃｉ２へ、あるいはその逆に切り替え変更して周波数制御信号Ｆｏｕｔを制御する。例えば、その切替は、第１，第２信号対雑音比Ｓ１／Ｎ１，Ｓ２／Ｎ２の両方を勘案して得られた雑音成分が、小さいときには加算時間が長くＳ／Ｎ改善度が高い第１コヒーレント加算値Ｉｃｉ１，Ｑｃｉ１を使用し、大きいときには加算時間は短くＳ／Ｎ改善度は低いが加速度追従性がよい第２コヒーレント加算値Ｉｃｉ１，Ｑｃｉ２を使用するようにすることでよい。   Further, as control by the S / N calculation / control device 6, as shown by a broken line in FIG. 1, the Costas loop calculation unit 7 is supplied with the first I coherent addition value Ici1 and the first Q coherent addition value Qci1 together with the second coherent adder. The second I coherent addition value Ici2 and the second Q coherent addition value Qci2 from 22 are also input. Then, the first coherent addition values Ici1, Qci1 and the second coherent addition values Ici2, Qci2 are switched by the switching signal cos obtained in the same manner as the weight value w obtained by the S / N calculation / control device 6. use. That is, the frequency control signal Fout is changed by switching the input to the Costas loop calculator 4 from the first coherent addition value Ici1, Qci1 that is always used to the second coherent addition value Ici2, Qci2, or vice versa. Control. For example, in the switching, the first and second signal-to-noise ratios S1 / N1 and S2 / N2 are taken into account when the noise component obtained is small, the addition time is long and the S / N improvement degree is high. The coherent addition values Ici1 and Qci1 may be used. When the coherent addition values Ici1 and Qci1 are large, the second coherent addition values Ici1 and Qci2 having a short addition time and low S / N improvement but good acceleration follow-up may be used.

図１の実施例では、Ｎ１ｍｓコヒーレント加算器２１、Ｍ１回ノンコヒーレント加算器３１、方式１のノイズ分布演算器５１により第１信号対雑音比Ｓ１／Ｎ１を求める第１系列と、Ｎ２ｍｓコヒーレント加算器２２、Ｍ２回ノンコヒーレント加算器３２、方式２のノイズ分布演算器５２により第２信号対雑音比Ｓ２／Ｎ２を求める第２系列とを設けているが、このうち第２系列を省略して、第１系列のみで構成しても良い。しかし、図１の実施例のように、第１系列と第２系列の両方を設けることにより、加算結果（時間及び回数）が異なる２種の信号対雑音比Ｓ１／Ｎ１、Ｓ２／Ｎ２が得られるから、受信信号中の信号レベルや雑音レベル、さらにはそれらの時間的変動などの状況をより詳しく把握することができる。なお、第１，第２系列に、さらに第３系列などを加えて、３系列以上として、３種以上の信号対雑音比を得るようにしてもよい。   In the embodiment of FIG. 1, a first sequence for determining a first signal-to-noise ratio S1 / N1 by an N1 ms coherent adder 21, an M1 non-coherent adder 31, and a noise distribution calculator 51 of method 1; and an N2 ms coherent adder 22, M2 times non-coherent adder 32, and the second series for obtaining the second signal-to-noise ratio S2 / N2 by the noise distribution computing unit 52 of method 2 are provided. Of these, the second series is omitted, You may comprise only the 1st series. However, as in the embodiment of FIG. 1, by providing both the first sequence and the second sequence, two types of signal-to-noise ratios S1 / N1 and S2 / N2 with different addition results (time and frequency) are obtained. Therefore, it is possible to grasp in more detail the situation such as the signal level and noise level in the received signal, and their temporal variation. Note that a third series or the like may be added to the first and second series to obtain three or more types of signal-to-noise ratios.

本発明の雑音推定装置、信号対雑音比演算装置及び衛星信号受信装置をハードウエアで実現する構成に代えて、それらの処理の一部又は全部をソフトウエア処理で行っても良い。   Instead of the configuration in which the noise estimation device, signal-to-noise ratio calculation device, and satellite signal reception device of the present invention are implemented by hardware, some or all of the processing may be performed by software processing.

本発明の実施例に係る衛星信号受信装置の全体構成図1 is an overall configuration diagram of a satellite signal receiving device according to an embodiment of the present invention. 高感度サーチ時に得られる相関パワー分布を説明するための図Diagram for explaining correlation power distribution obtained during high-sensitivity search

符号の説明Explanation of symbols

１０１ アンテナ、１０２ ダウンコンバータ、１０３ Ａ／Ｄ変換器
１ｓ 信号用１ｍｓ相関チャンネル回路、１ｎ 雑音用１ｍｓ相関チャンネル回路
１ａ キャリアＮＣＯ、２１ Ｎ１ｍｓコヒーレント加算器、２２ Ｎ２ｍｓコヒーレント加算器、３１ Ｍ１回ノンコヒーレント加算器、３２ Ｍ２回ノンコヒーレント加算器
４ ノイズ分散測定器、５１ 方式１のノイズ分布演算器、５２ 方式２のノイズ分布演算器、６ Ｓ／Ｎ演算・制御装置、７ コスタスループ演算器、８ エッジ情報発生器 101 antenna, 102 down converter, 103 A / D converter 1 s 1 ms correlation channel circuit for signal, 1 n 1 ms correlation channel circuit for noise 1 a carrier NCO, 21 N1 ms coherent adder, 22 N2 ms coherent adder, 31 M1 times non-coherent addition , 32 M2 times non-coherent adder 4 Noise variance measuring device, 51 Method 1 noise distribution calculator, 52 Method 2 noise distribution calculator, 6 S / N calculation / control device, 7 Costas loop calculator, 8 Edge Information generator

Claims (5)

衛星信号を変換し入力される特定衛星信号に関する受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号とＱ相関信号とを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路と、
前記雑音用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号とから１ｍｓ間の雑音パワーの分散を１ｍｓ毎に測定するノイズ分散測定器と、
前記１ｍｓ間の雑音パワーの分散、所定時間のコヒーレント加算時間、及び所定回数のコヒーレント加算回数を統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応したノイズ平均及びノイズ分散を含むノイズ分布値を求めるノイズ分布演算器と、を有することを特徴とする、雑音推定装置。 The carrier correlation between the received signal related to the specific satellite signal that is converted from the satellite signal and the uncorrelated signal that cannot be correlated with the received signal is taken, and the I correlation signal and the Q correlation signal for 1 ms are simultaneously converted to 1 ms. 1 ms correlation channel circuit for noise to be output every time,
A noise variance measuring device for measuring the variance of noise power between 1 ms from the I correlation signal and the Q correlation signal from the 1 ms correlation channel circuit for noise every 1 ms;
By substituting the noise power distribution for 1 ms, the coherent addition time for a predetermined time, and the predetermined number of coherent additions into a function expression of a statistically determined noise distribution, the noise average corresponding to the received signal and And a noise distribution computing unit for obtaining a noise distribution value including noise variance. 衛星信号を変換し入力される特定衛星信号に関する受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号とＱ相関信号とを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路と、
前記雑音用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号とから１ｍｓ間の雑音パワーの分散を１ｍｓ毎に測定するノイズ分散測定器と、
前記１ｍｓ間の雑音パワーの分散σ２、第１所定時間のコヒーレント加算時間、及び第１所定回数のコヒーレント加算回数を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第１ノイズ平均及び第１ノイズ分散を含む第１ノイズ分布値を求める第１ノイズ分布演算器と、
前記１ｍｓ間の雑音パワーの分散σ２を、前記第１所定時間より短い第２所定時間のコヒーレント加算時間、及び第２所定回数のコヒーレント加算回数を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第２ノイズ平均及び第２ノイズ分散を含む第２ノイズ分布値を求める第２ノイズ分布演算器と、を有することを特徴とする、雑音推定装置。 The carrier correlation between the received signal related to the specific satellite signal that is converted from the satellite signal and the uncorrelated signal that cannot be correlated with the received signal is taken, and the I correlation signal and the Q correlation signal for 1 ms are simultaneously converted to 1 ms. 1 ms correlation channel circuit for noise to be output every time,
A noise variance measuring device for measuring the variance of noise power between 1 ms from the I correlation signal and the Q correlation signal from the 1 ms correlation channel circuit for noise every 1 ms;
By substituting the noise power variance σ 2 for 1 ms, the first predetermined time coherent addition time, and the first predetermined number of coherent addition times into a statistically determined noise distribution function formula, A first noise distribution calculator for obtaining a first noise distribution value including a first noise average and a first noise variance corresponding to the signal ;
The noise power variance σ 2 for 1 ms, the coherent addition time for a second predetermined time shorter than the first predetermined time, and the second predetermined number of coherent additions are statistically determined as a functional expression of noise distribution And a second noise distribution computing unit that obtains a second noise distribution value including a second noise average and a second noise variance corresponding to the received signal by substituting into the received signal . 周波数制御信号を受けてキャリア周波数信号を発生するキャリア局部発振器を含み、衛星信号を変換し入力される特定衛星信号に関する受信信号とＰＮコードとのコード相関及び前記キャリア周波数信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号とＱ相関信号とを同時に１ｍｓ毎に出力する信号用１ｍｓ相関チャンネル回路と、
前記信号用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号を前記特定衛星信号の航法データの切り替わりタイミングに同期して所定時間分コヒーレント加算を行い、そのＩコヒーレント加算値とＱコヒーレント加算値とを出力するコヒーレント加算器と、
前記Ｉコヒーレント加算値及びＱコヒーレント加算値から、コヒーレント加算区間内の信号パワーを求め、その信号パワーの所定回数の累積加算を行って累積信号パワーを求めて出力するノンコヒーレント加算器と、
前記受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号とＱ相関信号とを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路と、
前記雑音用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号とから１ｍｓ間の雑音パワーの分散を１ｍｓ毎に測定するノイズ分散測定器と、
前記１ｍｓ間の雑音パワーの分散σ２、前記所定時間のコヒーレント加算時間、及び前記所定回数のコヒーレント加算回数を統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応したノイズ平均及びノイズ分散を含むノイズ分布値を求めるノイズ分布演算器と、
前記累積信号パワーと、前記ノイズ平均及びノイズ分散を用いて、信号対雑音比を、［信号対雑音比＝（累積信号パワー−ノイズ平均）／ノイズ分散］により算出する演算手段と、を有することを特徴とする、信号対雑音比演算装置。 It includes a carrier local oscillator that receives a frequency control signal and generates a carrier frequency signal, and takes the code correlation between the received signal and the PN code related to the input specific satellite signal after converting the satellite signal and the carrier correlation with the carrier frequency signal. A 1 ms correlation channel circuit for a signal that simultaneously outputs an I correlation signal and a Q correlation signal for 1 ms every 1 ms;
The I correlation signal and the Q correlation signal from the 1 ms correlation channel circuit for signals are subjected to coherent addition for a predetermined time in synchronization with the navigation data switching timing of the specific satellite signal, and the I coherent addition value and the Q coherent addition value are A coherent adder that outputs
A non-coherent adder for obtaining a signal power in a coherent addition section from the I coherent addition value and the Q coherent addition value, performing a cumulative addition of the signal power a predetermined number of times, and obtaining and outputting the accumulated signal power;
A 1 ms correlation channel circuit for noise that takes a carrier correlation between the received signal and a non-correlated signal that cannot be correlated with the received signal, and simultaneously outputs an I correlation signal and a Q correlation signal for 1 ms every 1 ms; ,
A noise variance measuring device for measuring the variance of noise power between 1 ms from the I correlation signal and the Q correlation signal from the 1 ms correlation channel circuit for noise every 1 ms;
Corresponding to the received signal by substituting the noise power variance σ 2 for 1 ms, the coherent addition time of the predetermined time, and the coherent addition number of the predetermined number of times into a statistically determined noise distribution function expression a noise distribution calculator for obtaining the noise distribution value containing the noise mean and noise variance,
And a calculation means for calculating a signal-to-noise ratio by [signal-to-noise ratio = (cumulative signal power−noise average) / noise variance] using the accumulated signal power and the noise average and noise variance. A signal-to-noise ratio calculation device. 周波数制御信号を受けてキャリア周波数信号を発生するキャリア局部発振器を含み、衛星信号を変換し入力される特定衛星信号に関する受信信号とＰＮコードとのコード相関及び前記キャリア周波数信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号とＱ相関信号とを同時に１ｍｓ毎に出力する信号用１ｍｓ相関チャンネル回路と、
前記信号用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号を前記特定衛星信号の航法データの切り替わりタイミングに同期して第１所定時間分コヒーレント加算を行い、その第１Ｉコヒーレント加算値と第１Ｑコヒーレント加算値とを出力する第１コヒーレント加算器と、
前記第１Ｉコヒーレント加算値び第１Ｑコヒーレント加算値から、第１コヒーレント加算区間内の信号パワーを求め、その信号パワーの第１所定回数の累積加算を行って第１累積信号パワーを求めて出力する第１ノンコヒーレント加算器と、
前記信号用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号を前記第１所定時間よりも短い第２所定時間分コヒーレント加算を行い、その第２Ｉコヒーレント加算値と第２Ｑコヒーレント加算値とを出力する第２コヒーレント加算器と、
前記第２Ｉコヒーレント加算値及び第２Ｑコヒーレント加算値から、第２コヒーレント加算区間内の信号パワーを求め、その信号パワーの第２所定回数の累積加算を行って第２累積信号パワーを求めて出力する第２ノンコヒーレント加算器と、
前記受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号とＱ相関信号とを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路と、
前記雑音用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号とから１ｍｓ間の雑音パワーの分散を１ｍｓ毎に測定するノイズ分散測定器と、
前記１ｍｓ間の雑音パワーの分散σ２、前記第１所定時間のコヒーレント加算時間、及び前記第１所定回数のコヒーレント加算回数を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第１ノイズ平均及び第１ノイズ分散を含む第１ノイズ分布値を求める第１ノイズ分布演算器と、
前記１ｍｓ間の雑音パワーの分散σ２、前記第２所定時間のコヒーレント加算時間、及び前記第２所定回数のコヒーレント加算回数を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第２ノイズ平均及び第２ノイズ分散を含む第２ノイズ分布値を求める第２ノイズ分布演算器と、
前記第１，第２累積信号パワーと、前記第１，第２ノイズ平均及び第１，第２ノイズ分散を用いて、第１，第２信号対雑音比を、［第１信号対雑音比＝（第１累積信号パワー−第１ノイズ平均）／第１ノイズ分散］、及び［第２信号対雑音比＝（第２累積信号パワー−第２ノイズ平均）／第２ノイズ分散］、により算出する演算手段と、を有することを特徴とする、信号対雑音比演算装置。 It includes a carrier local oscillator that receives a frequency control signal and generates a carrier frequency signal, and takes the code correlation between the received signal and the PN code related to the input specific satellite signal after converting the satellite signal and the carrier correlation with the carrier frequency signal. A 1 ms correlation channel circuit for a signal that simultaneously outputs an I correlation signal and a Q correlation signal for 1 ms every 1 ms;
The I correlation signal and the Q correlation signal from the signal 1 ms correlation channel circuit are subjected to coherent addition for a first predetermined time in synchronization with the navigation data switching timing of the specific satellite signal, and the first I coherent addition value and the first Q A first coherent adder that outputs a coherent addition value;
From the first I coherent addition value and the first Q coherent addition value, the signal power in the first coherent addition interval is obtained, the first predetermined number of times of cumulative addition of the signal power is performed, and the first cumulative signal power is obtained and output. A first non-coherent adder;
The I correlation signal and the Q correlation signal from the 1 ms correlation channel circuit for signal are subjected to coherent addition for a second predetermined time shorter than the first predetermined time, and the second I coherent addition value and the second Q coherent addition value are output. A second coherent adder,
The signal power in the second coherent addition interval is obtained from the second I coherent addition value and the second Q coherent addition value, and the second predetermined signal power is accumulated for a second predetermined number of times to obtain and output the second accumulated signal power. A second non-coherent adder;
A 1 ms correlation channel circuit for noise that takes a carrier correlation between the received signal and a non-correlated signal that cannot be correlated with the received signal, and simultaneously outputs an I correlation signal and a Q correlation signal for 1 ms every 1 ms; ,
A noise variance measuring device for measuring the variance of noise power between 1 ms from the I correlation signal and the Q correlation signal from the 1 ms correlation channel circuit for noise every 1 ms;
By substituting the noise power variance σ 2 for 1 ms, the coherent addition time of the first predetermined time, and the coherent addition number of the first predetermined number of times into a statistical expression of a noise distribution function expression, A first noise distribution calculator for obtaining a first noise distribution value including a first noise average and a first noise variance corresponding to the received signal ;
By substituting the noise power variance σ 2 for 1 ms, the coherent addition time of the second predetermined time, and the coherent addition number of the second predetermined number of times into a statistically determined function expression of the noise distribution, A second noise distribution calculator for obtaining a second noise distribution value including a second noise average and a second noise variance corresponding to the received signal ;
Using the first and second accumulated signal powers, the first and second noise averages, and the first and second noise variances, the first and second signal-to-noise ratios are expressed as [first signal-to-noise ratio = (First cumulative signal power-first noise average) / first noise variance] and [second signal-to-noise ratio = (second cumulative signal power-second noise average) / second noise variance]. And a signal-to-noise ratio calculation device. 周波数制御信号を受けてキャリア周波数信号を発生するキャリア局部発振器を含み、衛星信号を変換し入力される特定衛星信号に関する受信信号とＰＮコードとのコード相関及び前記キャリア周波数信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号とＱ相関信号とを同時に１ｍｓ毎に出力する信号用１ｍｓ相関チャンネル回路と、
前記信号用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号を前記特定衛星信号の航法データの切り替わりタイミングに同期して第１所定時間分コヒーレント加算を行い、その第１Ｉコヒーレント加算値と第１Ｑコヒーレント加算値とを出力する第１コヒーレント加算器と、
前記第１Ｉコヒーレント加算値及び第１Ｑコヒーレント加算値から、第１コヒーレント加算区間内の信号パワーを求め、その信号パワーの第１所定回数の累積加算を行って第１累積信号パワーを求めて出力する第１ノンコヒーレント加算器と、
前記第１Ｉ，Ｑコヒーレント加算値に基づいて前記周波数制御信号を決定するコスタスループ演算器と、
前記信号用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号を前記第１所定時間よりも短い第２所定時間分コヒーレント加算を行い、その第２Ｉコヒーレント加算値と第２Ｑコヒーレント加算値とを出力する第２コヒーレント加算器と、
前記第２Ｉコヒーレント加算値及び第２Ｑコヒーレント加算値から、第２コヒーレント加算区間内の信号パワーを求め、その信号パワーの第２所定回数の累積加算を行って第２累積信号パワーを求めて出力する第２ノンコヒーレント加算器と、
前記受信信号と該受信信号と相関を採ることができない非相関信号とのキャリア相関が採られ、１ｍｓ間のＩ相関信号とＱ相関信号とを同時に１ｍｓ毎に出力する雑音用１ｍｓ相関チャンネル回路と、
前記雑音用１ｍｓ相関チャンネル回路からのＩ相関信号とＱ相関信号とから１ｍｓ間の雑音パワーの分散を１ｍｓ毎に測定するノイズ分散測定器と、
前記１ｍｓ間の雑音パワーの分散σ２、前記第１所定時間のコヒーレント加算時間、及び前記第１所定回数のコヒーレント加算回数を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第１ノイズ平均及び第１ノイズ分散を含む第１ノイズ分布値を求める第１ノイズ分布演算器と、
前記１ｍｓ間の雑音パワーの分散σ２、前記第２所定時間のコヒーレント加算時間、及び前記第２所定回数のコヒーレント加算回数を、統計的に決定されるノイズ分布の関数式に代入することにより、前記受信信号に対応した第２ノイズ平均及び第２ノイズ分散を含む第２ノイズ分布値を求める第２ノイズ分布演算器と、
前記第１，第２累積信号パワーと、前記第１，第２ノイズ平均及び第１，第２ノイズ分散を用いて、第１，第２信号対雑音比を、［第１信号対雑音比＝（第１累積信号パワー−第１ノイズ平均）／第１ノイズ分散］、及び［第２信号対雑音比＝（第２累積信号パワー−第２ノイズ平均）／第２ノイズ分散］、により算出するとともに、前記第１、第２信号対雑音比に基づいて前記コスタスループ演算器の特性もしくは入力を変更して前記周波数制御信号を制御する演算・制御手段６と、を有することを特徴とする、衛星信号受信装置。
It includes a carrier local oscillator that receives a frequency control signal and generates a carrier frequency signal, and takes the code correlation between the received signal and the PN code related to the input specific satellite signal after converting the satellite signal and the carrier correlation with the carrier frequency signal. A 1 ms correlation channel circuit for a signal that simultaneously outputs an I correlation signal and a Q correlation signal for 1 ms every 1 ms;
The I correlation signal and the Q correlation signal from the signal 1 ms correlation channel circuit are subjected to coherent addition for a first predetermined time in synchronization with the navigation data switching timing of the specific satellite signal, and the first I coherent addition value and the first Q A first coherent adder that outputs a coherent addition value;
From the first I coherent addition value and the first Q coherent addition value, the signal power in the first coherent addition interval is obtained, and the signal power is accumulated for a first predetermined number of times to obtain and output the first accumulated signal power. A first non-coherent adder;
A Costas loop computing unit that determines the frequency control signal based on the first I and Q coherent addition values;
The I correlation signal and the Q correlation signal from the 1 ms correlation channel circuit for signal are subjected to coherent addition for a second predetermined time shorter than the first predetermined time, and the second I coherent addition value and the second Q coherent addition value are output. A second coherent adder,
The signal power in the second coherent addition interval is obtained from the second I coherent addition value and the second Q coherent addition value, and the second predetermined signal power is accumulated for a second predetermined number of times to obtain and output the second accumulated signal power. A second non-coherent adder;
A 1 ms correlation channel circuit for noise that takes a carrier correlation between the received signal and a non-correlated signal that cannot be correlated with the received signal, and simultaneously outputs an I correlation signal and a Q correlation signal for 1 ms every 1 ms; ,
A noise variance measuring device for measuring the variance of noise power between 1 ms from the I correlation signal and the Q correlation signal from the 1 ms correlation channel circuit for noise every 1 ms;
By substituting the noise power variance σ 2 for 1 ms, the coherent addition time of the first predetermined time, and the coherent addition number of the first predetermined number of times into a statistical expression of a noise distribution function expression, A first noise distribution calculator for obtaining a first noise distribution value including a first noise average and a first noise variance corresponding to the received signal ;
By substituting the noise power variance σ 2 for 1 ms, the coherent addition time of the second predetermined time, and the coherent addition number of the second predetermined number of times into a statistically determined function expression of the noise distribution, A second noise distribution calculator for obtaining a second noise distribution value including a second noise average and a second noise variance corresponding to the received signal ;
Using the first and second accumulated signal powers, the first and second noise averages, and the first and second noise variances, the first and second signal-to-noise ratios are expressed as [first signal-to-noise ratio = (First cumulative signal power-first noise average) / first noise variance] and [second signal-to-noise ratio = (second cumulative signal power-second noise average) / second noise variance]. And an arithmetic / control means 6 for controlling the frequency control signal by changing characteristics or inputs of the Costas loop arithmetic unit based on the first and second signal-to-noise ratios. Satellite signal receiver.
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