CN102590787B

CN102590787B - Double early-late loop tracking method of spread spectrum receiver

Info

Publication number: CN102590787B
Application number: CN 201210050603
Authority: CN
Inventors: 张波; 王艺燃; 李署坚; 于龙洋; 冯剑锋
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2012-02-29
Filing date: 2012-02-29
Publication date: 2013-05-08
Anticipated expiration: 2032-02-29
Also published as: CN102590787A

Abstract

The invention relates to a double early-late loop tracking method of a spread spectrum receiver, which consists of two early-late tracking loop circuits, an energy comparison module, a control signal gating module and a tracking loop output module. The invention has the advantages of providing a tracking method of the spread spectrum receiver that effectively improves the tracking precision of the receiver while guaranteeing the dynamic performance of the loop so as to improve the positioning precision of the real time position system (included but not limited).

Description

The two trackings that early encircle late of band spread receiver

Technical field

The present invention relates to a kind of new band spread receiver tracking.More particularly, be a kind of shake that utilizes parallel two-way tracking loop to reduce local spreading code, thereby reduce the Spectrum Spread Tracking method of the positioning error that the spread-spectrum location system produces because of the shake of receiver local code.

Background technology

General spread-spectrum location system is comprised of emission label and band spread receiver, and basic positioning principle is to position by the mistiming that the signal arrival that label launch is positioned over the diverse location receiver to resolve.The band spread receiver early shake of tracking loop local code late is to adopt one of positioning system positioning error important sources of spread spectrum.In order to improve bearing accuracy, method commonly used is to improve clock frequency, reduce loop bandwidth, but such mode can cause the dynamic property variation in loop, is unfavorable for the despread-and-demodulation of burst, and the receiver hardware performance is had stricter requirement.

Two early slow ring trackings of this band spread receiver are the effective ways that improve bearing accuracy.It utilizes that clock phase is opposite, two identical tracking loops of broader bandwidth carry out spread-spectrum signal and follow the tracks of, to totally four tunnel leading, the phase place that delay signal compares the final local code of rear adjustment of two tracking loops outputs.Effectively improved tracking accuracy when guaranteeing to follow the tracks of dynamic property.Under equal tracking accuracy condition, required system clock frequency can reduce half, therefore can effectively reduce the requirement to hardware resource.

Summary of the invention

The object of the invention is to: propose a kind of new band spread receiver tracking, can effectively improve tracking accuracy when guaranteeing the track loop dynamic property, reduced under equal tracking accuracy condition the requirement to hardware performance.

Technical scheme of the present invention is: a kind of two trackings that early encircle late of band spread receiver, it by two morning slow track loop circuit, energy comparison module, control signal gating module, track loop output module consist of, control clock signal frequency and include but not limited to 160MHz.System's global clock and inversion clock thereof are respectively controlled a track loop signal after catching are followed the tracks of; The energy comparison module is carried out choose large decision to leading, the delay signal that two track loop NCO produce, and according to court verdict output control signal; Control signal gating module is carried out gating according to control signal to control clock and the NCO clock of two tracking loops, and the track loop output module uses clock signal and the more high-precision tracking results of code clock control signal output after gating.The bandwidth in this receiver tracking loop and tracking loop 1,2 identical are therefore kept same tracking dynamic property when having improved tracking accuracy

Advantage of the present invention is: a kind of two trackings that early encircle late of band spread receiver that can be applicable to include but not limited to real-time positioning system are provided.The method can when guaranteeing the track loop dynamic property, effectively improve the tracking accuracy of band spread receiver under limited hardware condition, thereby improves the bearing accuracy of system.

Description of drawings

Fig. 1 is the theory diagram of band spread receiver.

Fig. 2 is the local pseudo-code tracing result in oscillograph.

Embodiment

The below is described in further detail the present invention.Referring to Fig. 1, the present invention by two morning slow track loop circuit, energy comparison module, control signal gating module, track loop output module consist of.

Two functions that morning, slow track loop circuit was completed of A are: respectively the intermediate-freuqncy signal after catching is followed the tracks of and mistake is arrested and sentenced certainly, if judgement is caught for losing, the control signal of recapturing is set to 0, and capture circuit is recaptured.

The function that B energy comparison module is completed is: if two tracking loops have all been realized the tracking of signal, the energy comparison module is carried out after square operation big or small to leading, the energy value of totally four road signals that lags behind that are produced by two track loop NCO of input, if Energy maximum value results from track loop 1, clock selection signal is set to 0, otherwise is set to 1.

The function that C control signal gating module is completed is: because the control clock of two track loop is anti-phase, namely sequential is different, therefore this module uses the mode that includes, but are not limited to logical assignment to carry out gating to control clock and the NCO clock of two tracking loops.Clock selection signal is 0 o'clock, the control clock of output tracking loop 2 and NCO clock, if the clock selection signal saltus step is 1, and the control clock of output tracking loop 1 and NCO clock.

The function that D track loop output module is completed is: the control clock after the use gating and NCO clock control NCO produce one group of new local pseudo-code and are used for despreading and demodulation, the jitter range of local pseudo-code signal are reduced to half of track loop 1, the 2 local pseudo-code signal jitter range of exporting.

The method is used for spread spectrum real-time positioning system receiver (being not limited to) equipment, when controlling clock and inversion clock frequency thereof and be 160MHz, the oscillograph tracking results as shown in Figure 2, upper square signal is the pseudo-code of label emission, lower signal is the local pseudo-code (having fixing processing time-delay and path delay) that the receiver tracking loop circuit output module produces, local pseudo-code is leading, jitter range that lag behind is 3.125ns, has reached the limit tracking accuracy level that general band spread receiver can reach under the 320MHz clock control.

Claims

1. two early ring trackings late of a new band spread receiver, it by two morning slow track loop circuit, energy comparison module, control signal gating module, track loop output module consist of; Two tracking loops are exported respectively leading, delay signal under the control of system's global clock and inversion clock thereof, provide clock selection signal after energy comparison module choose large decision, control signal gating module is carried out gating according to clock selection signal to clock signal and the NCO clock signal of two tracking loops, the final tracking results of signal controlling track loop output module output after gating.

2. tracking according to claim 1 is characterized in that system controls clock and inversion clock thereof and respectively controls a track loop signal after catching is followed the tracks of.

3. tracking according to claim 1, is characterized in that leading, delay signal that two track loop NCO produce are sent into the energy comparison module, and after choose large decision, output clock is selected signal.

4. tracking according to claim 1 is characterized in that control signal gating module uses the mode that includes, but are not limited to logical assignment to carry out gating to control clock and the NCO clock of two tracking loops.

5. tracking according to claim 1, is characterized in that clock signal and the more high-precision tracking results of NCO clock control signal output after the track loop output module uses gating.