Method and apparatus for testing code division multiple access receivers

Patent metadata

Field	Value
Publication number	US-11086022-B2
Application number	US-201916966519-A
Country	US
Kind code	B2
Filing date	Feb 20, 2019
Priority date	Feb 27, 2018
Publication date	Aug 10, 2021
Grant date	Aug 10, 2021

Abstract

A method for testing a receiver in a code division multiple access (CDMA) communications system. Frequency spectrums for each of a plurality of provided CDMA code patterns (31) are generated (35) and phase shifted (36), before being combined (37) to generate a constellation spectrum. The constellation spectrum is converted 38 to a time domain constellation signal which can be injected (33) into a CDMA receiver under test. The method allows for fast and cost-effective synthetic generation of constellation signals that are particularly suited to testing global navigation satellite system (GNSS) receivers. Also relates to apparatus for providing the same.

First claim

The invention claimed is:

1. A method of testing a code division multiple access (CDMA) communications system receiver, the method comprising the following steps:
providing at least one receiver and a plurality of CDMA code patterns;
generating a constellation signal from the plurality of code patterns;
injecting the constellation signal into the receiver at a predetermined carrier frequency; and
determining a response of the receiver, thereby testing the receiver;
wherein the step of generating a constellation signal comprises the following steps:
computing a precomputed frequency spectrum from each of the code patterns in the plurality of CDMA code patterns, each precomputed frequency spectrum comprising a plurality of frequency bins;
applying a predetermined phase shift to each of the frequency bins in each of the plurality of precomputed frequency spectrums, thereby generating a plurality of modified frequency spectrums wherein the predetermined phase shift represents a propagation delay in a given signal reaching the CDMA receiver after its emission from the respective CDMA transmitter;
performing a vector sum of the modified frequency spectrums to generate a constellation frequency spectrum; and
applying an inverse Fourier transform to the constellation frequency spectrum to generate a constellation signal.

2. The method according to claim 1 wherein the steps of generating the constellation signal, injecting the constellation signal, and determining the response of the receiver, are repeated across a plurality of time steps.

3. The method according to claim 1 wherein the step of computing the plurality of precomputed frequency spectrums comprises computing a Fast Fourier Transform of each code pattern.

4. The method according to claim 1 wherein the CDMA communications system is a Global Navigation Satellite System (GNSS).

5. The method according to claim 4 wherein the GNSS is a Global Positioning System (GPS).

6. The method according to claim 5 wherein the CDMA code patterns are the GPS coarse acquisition codes.

7. Apparatus for testing a code division multiple access (CDMA) communications system receiver, the apparatus comprising a signal injection means configured to inject a constellation signal into the receiver at a predetermined carrier frequency, and a computer system, wherein the computer system is configured to:
store a plurality of CDMA code patterns;
compute a precomputed frequency spectrum from each of the code patterns in the plurality of CDMA code patterns, each precomputed frequency spectrum comprising a plurality of frequency bins;
apply a predetermined phase shift to each frequency bin in each of the plurality of precomputed frequency spectrums, thereby generating a plurality of modified frequency spectrums wherein the predetermined phase shift represents a propagation delay in a given signal reaching the CDMA receiver after its emission from the respective CDMA transmitter;
perform a vector sum of the modified frequency spectrums to generate a constellation frequency spectrum; and
apply an inverse Fourier transform to the constellation frequency spectrum to generate the constellation signal.

8. A GPS receiver test kit comprising the apparatus of claim 7 , wherein the CDMA code patterns are the GPS coarse acquisition codes.

9. A computer implemented method of generating a constellation signal for testing a CDMA receiver, the method comprising the following steps:
receiving a plurality of CDMA code patterns; and
generating a constellation signal from the plurality of CDMA code patterns, wherein generating the constellation signal comprises:
computing a precomputed frequency spectrum from each of the code patterns in the plurality of CDMA code patterns, each precomputed frequency spectrum comprising a plurality of frequency bins;
applying a predetermined phase shift to each of the frequency bins in each of the plurality of precomputed frequency spectrums, thereby generating a plurality of modified frequency spectrums, wherein the predetermined phase shift represents a propagation delay in a given signal reaching the CDMA receiver after its emission from the respective CDMA transmitter;
performing a vector sum of the modified frequency spectrums to generate a constellation frequency spectrum; and
applying an inverse Fourier transform to the constellation frequency spectrum to generate a constellation signal.

10. A system comprising:
a processing device; and
a non-transitory computer-readable medium communicatively coupled to the processing device, wherein the processing device is configured to execute program code stored in the non-transitory computer-readable medium and thereby perform the steps of the computer implemented method of claim 9 .

11. A non-transitory computer readable storage medium having instructions stored therein, wherein the instructions are executable by a processor for performing the computer implemented method of claim 9 .

Assignees

• Secr Defence

Inventors

• Williams Stephen

Classifications

• G01S19/23 Primary

  Testing, monitoring, correcting or calibrating of receiver elements · CPC title

• G01S19/03

  Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers · CPC title