228 results about "Code tracking" patented technology

A method is shown for selecting active, or hot, code traces in an executing program for storage in a code cache. A trace is a sequence of dynamic instructions characterized by a start address and a branch history which allows the trace to be dynamically disassembled. Each trace is terminated by execution of a trace terminating condition which is a backward taken branch, an indirect branch, or a branch whose execution causes the branch history for the trace to reach a predetermined limit. As each trace is generated by the executing program, it is loaded into a buffer for processing. When the buffer is full, a counter corresponding to the start address of each trace is incremented. When the count for a start address exceeds a threshold, then the start address is marked as being hot. Each hot trace is then checked to see if the next trace in the buffer shares the same start address, in which case the hot trace is cyclic. If the start address of the next trace is not the same as the hot trace, then the traces in the buffer are checked to see they form a larger cycle of execution. If the traces subsequent to the hot trace are not hot themselves and are followed by a trace having the same start address as the hot trace, then their branch histories are companded with the branch history of the hot trace to form a cyclic trace. The cyclic traces are then disassembled and the instructions executed in the trace are stored in a code cache.

An M code envelope detector receives an incoming binary offset carrier (BOC) signal, such as the M code signal, and generates inphase BOC and quadraphase BOC signals, separated by an offset, that have respective ambiguous correlation envelopes, that when combined, provide a near unimodal correlation function with respect to code phase error of the BOC signal having an inherent multimodal autocorrelation function, with the near unimodal correlation envelope being tracked by early and late code replicas at broad one chip phases for providing unambiguous but nonlinear code phase error tracking, which detector is then further improved with the use of code replicas having narrow partial chip phases, such as ⅛ chip phases, for providing near linear code phase error tracking for unambiguous and accurate code tracking of the BOC signal.

A locking mechanism that is electronically managed or Hosted at a remote central location via the Internet or wireless communication network with conditional code validations. The remote management interface software resides on Host computer servers, which are in turn accessed and managed by Users through a common browser interface via the Internet or a wireless communication network via a wireless mobile device. The remote Host software provides a variety of robust options for the user of the local access point, to program multiple access codes with varying conditions of time, date and use occurrence limitations. Additionally, the Host software provides information, distributes codes, tracks and reports usage at the respective local access points. The Host interfaces with each unique local electronic locking mechanism at the respective local access location either via a web enabled device or a common PC based Internet browser or wireless mobile device.

The invention relates to an intermediate frequency direct sequence spread spectrum receiver for satellite ranging, which consists of 37 parts of a front-end A/D, an FFT module, a local PN code generator, a correlator, an automatic threshold calculation module and the like. The connection relationship is as follows: the output of the front-end A/D and the output of a carrier tracking loop NCO are respectively connected to an in-phase branch multiplier and an orthogonal branch multiplier, the input of the front-end A/D and the input of the carrier tracking loop NCO enter into an in-phase branch FIR low-pass filter and an orthogonal branch FIR low-pass filter, consequently, on the one hand, the output is sent to an integral zero clearing device, then the output which is sent to the FFT module, a branch 1 local PN code memory ROM and a branch 2 local PN code memory ROM enters into a branch 1 complex multiplier and a branch 2 complex multiplier, the output is sent to a branch 1 root mean square module and a branch 2 root mean square module, the output is sent to the threshold calculation module and a capturing and judging module for carrying out code catching; and on the other hand, the output is sent to the correlator and the local PN code generator for carrying out code tracking. The output of the correlator is simultaneously sent into a frequency discriminator/phase discriminator of the carrier tracking loop and then enters into a loop filter of the carrier tracking loop, and the output of the loop filter of the carrier tracking loop enters into the carrier tracking loop NCO for carrying out carrier tracking.

A method and apparatus for estimating channel tap delays of multipath components in a CDMA received signal. The search for the tap delays are split into two phases namely, a phase 1 and a phase 2 search. The phase 1 search is a coarse resolution quick search adapted to generate a rough estimate of the location of the tap delays. During this phase, the candidate codes are summed and the input signal correlated with the code sum creating an ambiguity in the code associated with the multipath. A finer resolution slower phase 2 search resolves the code ambiguity present in the initial rough estimates of the phase 1 search. Additional phase 2 correlations may be performed to implement a code-tracking loop.

This invention discloses a baseband signal processing method for GNSS receivers, particularly for common ranging-code signal for GNSS receiver, completing: the baseband signal catching, the tracking processing within frequency domain, easily for realization in large scale integrated circuit. During the signal catching step, FFT and IFFT calculation method is used for grouped calculation to simplify the time-domain related calculation. During the code-tracking, thus obtained related peak positions are found, then precision est1 mate of code phase is fulfilled by utilizing curve-fitting method. During the carrier tracking, DFT values of these points is calculated by using sliding DFT method, after the DFT point values ranges are determined based on rough carrier frequency estimate, and then proceeding estimate of carrier frequency, data demodulation by using IFFT output result.

A multipath mitigation method consists of locating a multipath-invariant (MPI) point of an ideal autocorrelation function and measuring the distance between the MPI point and DLL. The same MPI point is located in a received correlation function, and the distance between the point and the DLL, now affected by multipath, is measured. The difference between the ideal distance and the actual distance is the code tracking error resulting from multipath. The error is subtracted from the computed pseudorange or used to control the DLL. The method can be used to reduce the effects of all types of tracking error sources, such as signal transmission failure or code noise.

A code tracking system and method especially for use in direct sequence code division multiple access (DS-CDMA) communication systems employs multiple timing references within a chip by tracking the multiple timing references relative to the exact midpoint of the chip, then adjusting the timing references to the exact midpoint of the chip, and outputting an error tracking signal in accordance with the minimum error associated with the multiple timing references. The system performs effective code tracking with low lock-loss rate even when the noise of a receiving path interferes with detection of some of the timing references. The system uses multiple delay-locked loops for the different timing references.

A system and method for generating a multidimensional navigation solution utilizes Global Positioning System (GPS) data to obtain highly reliable and accurate navigational solutions in high interference and dynamic environments, at a performance level which has been heretofore unattainable. Additional sensors such as inertial (gyros and accelerometers), altimeters, radars, etc. may be employed in a deeply integrated configuration. The approach taken in the present invention differs from that of previous techniques through its exploitation of nonlinear filtering methods; as a result, the navigation system architecture and processes employed yield significant improvements in navigation system performance, both in code tracking and reacquisition, and in carrier tracking and reacquisition. The improvements are particularly significant at low signal/noise ratios, where conventional approaches are especially susceptible to loss of code lock or carrier lock.

The invention relates to a code-tracking method and a rake receiver for CDMA communication systems of low complexity yielding stable tracking. Received signal are distributed to a plurality of receiver fingers of a rake receiver. Each receiver finger i is assigned to a signal path of the transmitted signal which is subject to phase shift and power dissipation due to reflection, diffraction and scattering. According to the invention in each receiver finger i an estimation of the timing delay {circumflex over (τ)}⁽ⁱ⁾ is provided and interference from other signal components j are subtracted from signal components of the current signal path i (i≠j) yielding a reliable estimated timing delay {circumflex over (τ)}.

A method for detecting observed quantity validity in a navigation receiver mainly includes: S1. calculating a carrier-to-noise ratio of a signal; S2. judging stability of carrier tracking; S3. Extracting carrier Doppler frequency observed quantity of a carrier tracking loop and pseudo-range observed quantity of a code tracking loop in each epoch; S4. utilizing the two kinds of observed quantity to calculate a pseudo-range difference of corresponding two successive epoch respectively; S5. calculating a difference value of the pseudo-range differences and comparing with a threshold, thereby judging whether pseudo-range observed quantity of the current epoch is correct; S6. summing a difference of delta pseudo ranges of the current epoch and differences of delta pseudo ranges of n previous epochs, comparing with a threshold, and judging whether pseudo range observed quantity is correct; and S7. performing the abovementioned steps on each satellite which keeps tracking, collecting all signals of satellites whose observed quantity is judged to be correct, and inputting the signals to a positioning resolving module. The method provided by the invention does not need redundant information, and solves the problem of positioning stability of a receiver in complex environment with a relatively small calculated amount.

In one embodiment, a rake receiver for a spread-spectrum (SS) signal has a plurality of rake fingers corresponding to different multipath components of the SS signal and sampling circuitry generating a stream of samples corresponding to the SS signal. A first rake finger has a detection path detecting symbols based on the samples, a synchronization (synch) path, and a weighting controller. Front-end circuitry in the synch path applies three or more time delays, weighting, and SS correlation to the stream of samples to generate front-end output signals. Back-end circuitry in the synch path generates one or more control signals for controlling the timing of the sampling circuitry based on the front-end output signals. The weighting controller adaptively controls the weighting applied by the front-end synch circuitry to minimize effects of one or more other multipath components associated with one or more other rake fingers of the rake receiver.

Disclosed is a GPS (global positioning system) software receiver tracking method based on an FPGA (field programmable gate array). Inputted digital intermediate-frequency signals are transmitted into a code correlator after multiplying two channels I and Q of a carrier generator to obtain six channels of relevant results; in a carrier tracking loop, IP and QP in six channels of relevant outputs are transmitted into a phase decision device, frequency discrimination computation is carried out by a carrier frequency discriminator when phase deviation meets the condition that delta theta is larger than theta H, phase discrimination computation is carried out by a carrier phase discriminator if the phase deviation meets the condition that delta theta is smaller than theta H, a result is transmitted into the carrier generator after being filtered by a carrier loop filter so that carrier frequency is adjusted; and in a code tracking loop, IE, IL, QE and QL are taken to be transmitted into a code loop discriminator to be in phase discrimination computation, and results are transmitted into a CA (coarse acquisition) code generator after being filtered by a code loop filter so that phase ofCA codes is adjusted. The two loops are cross-coupled, the carrier frequency and the phase of the codes are synchronously tracked, accordingly, locally reproduced carriers and codes are aligned with signals, and navigation data bits are obtained after integral judgment for the IP is carried out by a posterior integral accumulation decision device.

The invention discloses an automatic confirmation testing method and system for embedded software. The testing method comprises the following steps that: customizing a testing process, managing testing data, parsing the testing process, analyzing tested software, analyzing a testing result, carrying out network communication, controlling a testing interface, controlling a testing time sequence and reading tested platform software environment. The testing system comprises a testing process customization module, a testing data management module, a testing process parsing module, a tested software analyzer, a testing result analysis module, a network communication module, a testing interface control module, a testing time sequence control module and a tested platform software environment reader. By use of the method, the problems of the accurate input of a test case and the real-time collection of the output of tested software in an embedded software testing process are solved, the operation situation of the tested software is tracked under a situation that the code bloat rate of the tested software is almost not changed, and a full-automatic and visual corresponding relational graph of the test case and the operation situation of the tested software can be provided for testing personnel.

The invention discloses a GPS positioning method and GPS software receiver which is based on dual-core processor, wherein, GPS positioning method includes the following steps: lower frequency process, signal capture, parallel arithmetic carrier wave, C/A code tracking process, pseudorange and ephemeris data resolving, satellite preferable choice, single point positioning resolving involved in GPS receiver and output; GPS software receiver which is based on dual-core processor, including GPS PF hardware part and PC, the PC machine at least includes two parallel equipped processors the first arithmetic processor and second arithmetic processor. The invention GPS positioning method uses multi-operation core processor as the operation platform, which designs and achieves parallel processing and algorithms for capturing and tracking GPS signal, which reduces resolving time significantly and enhances working efficiency of work.

The invention relates to an inertial navigation platform and Beidou satellite-based high-precision and ultra-tightly coupled navigation method. According to the method, a stochastic linear time-invariant discrete system mechanical model is established according to a moving object state equation and a measurement equation; statistic analysis is performed on the first-order difference sequence and second-order difference sequence of redundancy measurement values of a system, so that a redundancy measurement-based adaptive Kalman filtering algorithm can be realized, and therefore, the measurement noises of the system can be estimated accurately, and noise variance R can be adjusted adaptively; according to a traditional ultra-tightly coupled structure, a neural network prediction module is introduced so as to be used for assisting a Beidou satellite carrier tracking loop and a code tracking loop under a lock loss state; a time delay filter is adopted for a Beidou satellite receiver, and therefore, the correlation between loop tracking errors and update time in the ultra-tightly coupled system can be significantly improved. The method of the invention belongs to the navigation control technical field and can be applied to high-precision navigation of carriers carrying strapdown inertial navigation platforms.

The invention provides a GPS (Global Positioning System) pseudo-random code tracking loop for preventing multi-path interference and a method for preventing the multi-path interference thereof. The loop comprises a mixer, a correlator, an integration accumulator, a small wave phase detector, a loop filter and a local pseudo-random code generator. In the invention, the GPS pseudo-random code tracking loop adopts the small wave phase detector to detect a discontinuity point wherein the self-correlation function curve slope changes into a positive value from a zero value, is more accurate in the phase detection result, is free from the influence of the number of multi-path signals, and does not need to estimate the multi-path signals. In the invention, the pseudo code tracking accurate of the GPS pseudo-random code tracking loop is higher than the tracking accuracy of the typical sooner-later pseudo code delay locking loop so that the measurement accuracy of the pseudo range is improved; therefore, the invention is beneficial to positioning accurately.

A variable code-tracking loop filter in a receiver having the ability to change its parameters multiple times in response to received signals.

The invention discloses a network supporting GUID migration. The network supporting GUID migration comprises at least one HSvr (Home server) serving as an MDSvr (Migration Destination HSvr) of a GUID to be migrated and used for creating a migration account according to the GUID to be migrated, and for messages containing the GUID to be migrated in a destination address, the MDSvr determines a target account according to the GUID. Therefore, addressing can be performed on the migration account of the GUID when one GUID is migrated to another HSvr. The invention also discloses several kinds of message processing methods to assist the HSver in leading messages where destination accounts are the migration accounts to be subjected to addressing. The invention further discloses two migration recognition methods to obtain the migration dynamics of a GUID. The invention further discloses a code tracking message processing method, during the code tracking migration achievement, not only message bypasses can be avoided, but also the migration dynamics can be tracked effectively.

The invention discloses an anti-multipath interference device of a GNSS receiving system and a method thereof. The device comprises a first multiplier, a second multiplier, a feedforward filter, an adder, a down sampler, a decision device, a feedback filter, an equalizer coefficient updating device, a code tracking loop and a carrier tracking loop. The method comprises the steps of firstly using the anti-multipath interference device for receiving digital intermediate frequency GNSS signals and carrying out down frequency conversion, then carrying out decision feedback equalization on complexsignals formed by in-phase branch signals and orthogonal branch signals, finally carrying out code tracking and carrier tracking on the signals after equalization and demodulating a navigation message. The device and the method thereof can effectively resist the impacts of multipath interference, when the multipath interference exists in a channel, the pseudo code tracking precision after introducing the method into the tracking loop is higher than the tracking precision of the typical early-late DLL loop, thereby improving the measurement precision of pseudo range and being conductive to precise positioning.

An improved GNSS or GPS receiver with a code-tracking loop comprising a plurality of correlators, arranged to extract a plurality of samples of the autocorrelation function of the C/A code, and a discriminator performing linear regression on both sides of the autocorrelation peak, to determine the autocorrelation peak position at the crossing point of two straight lines. The lines are independently adapted to the sides of the correlation peak and, therefore, the receiver can handle well multipath situations, in which the correlation peaks are distorted.