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GNSS-GPS-SDR

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Some efferts on GPS replay, receive and test.

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최종 버전 다운로드 (.zip)

- adsb_out.grc
- - conv_1bit_bin_to_hackrf_bin.cbp
- - gps.cbp
- - gps_test.cbp
- auto.sh
- cacode.h
- channel.cpp
- conv_1bit_bin_to_hackrf_bin.cpp
- coroutines.cpp
- ephemeris.cpp
- ephemeris.h
- gps.h
- gps_offline.h
- main.cpp
- makefile
- peri.cpp
- Print.h
- search.cpp
- search_offline.cpp
- solve.cpp
- spi.cpp
- spi.h
- test_search_offline.cpp
- user.cpp
- plot_nmea-gemini-ttyACM0-ALL.py
- plot_nmea-gemini-ttyACM1-ALL.py
- plot_nmea-gemini-ttyACM2-ALL.py
- plot_nmea-gemini-ttyUSB0-9600-ALL.py
- plot_nmea-gemini-ttyUSB0-Beidou-new.py
- plot_nmea-gemini-ttyUSB0-Beidou.py
- plot_nmea1-ttyACM0-bilibili.py
- plot_nmea1-ttyACM1-bilibili.py
- plot_nmea1-ttyACM2-bilibili.py
- plot_nmea1-ttyUSB0-bilibili.py
- plot_nmea2.py
- plot_nmea3.py
- plot_nmea4-ttyUSB0-Beidou.py
- plot_nmea5.py
- plot_nmea6.py
- plot_nmea7.py
- plot_nmea8-ttyACM0-GPS.py
- plot_nmea8-ttyACM1-GPS.py
cacode.m
gps.grc
gps.samples.1bit.I.fs5456.if4092.bin
gps_8bit_proc.m
gps_bin1bit_log2bin.m
gps_Nottingham.grc
gps_sig_gen.m
gps_sig_tmp.bin
gps_wav_log2bin.m
hackrf_transfer_script.txt
Homemade GPS Receiver.html
IS-GPS-200G.pdf
LICENSE
license.txt
Makefile
proc_hackrf_bin_for_gps.m
proc_rtl_bin_for_gps.m
Raw GPS signal samples data set for testing GPS receivers.html
README.md
temp_test.m
深圳大学KeyLab-USRP重放.pdf

// repository documentation

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GNSS-GPS-SDR
============

See detailed introduction on my tech blog: [Some efforts on GPS signal replay (GPS重放)](https://sdr-x.github.io/Some-efforts-and-tools-on-GPS-signal-replay-(GPS%E9%87%8D%E6%94%BE%E6%A8%A1%E6%8B%9F)/)

-------------*NEWS:----------------------------------------------------

Use GPS replay to play pokemon go? See here: https://github.com/JiaoXianjun/poke-move

ADS-B out is verified by HACKRF --> air --> rtl-sdr dongle. [blog](https://sdr-x.github.io/ADS-B-out-by-HACKRF-and-received-over-the-air-by-rtl-sdr-dongle-and-dump1090/)

See adsb directory and video:

http://youtu.be/xpLDqBkUiKc  (out of China)

http://v.youku.com/v_show/id_XNzE4NzIzNDIw.html  (in China)

---------------*Purpose:----------------------------------------------

Some efforts were put on replaying GPS signal, but it is only partially successful, not fully successful. Some tools/scripts, as side products, are useful. Learn many things from here: [http://www.aholme.co.uk/GPS/Main.htm](http://www.aholme.co.uk/GPS/Main.htm)

**WARNING：DO NOT SEND ANY REAL GPS SIGNAL. USE CHAMBER AND CLOSE-LOOP CABLE! MAKE SURE ALL YOUR OPERATIONS ARE LEGAL!**

Get codes, program and sample GPS signals here: [https://github.com/JiaoXianjun/GNSS-GPS-SDR](https://github.com/JiaoXianjun/GNSS-GPS-SDR)

To build the C program "gps_test" in "c" directory (front part of software GPS receiver) after you get the whole repo:

cd c
    make

To let this make smooth, make sure you have fftw library installed correctly (sudo apt-get install ...). There should be /usr/lib/libfftw.a.

# 1. offline GPS simulation method

## 1.1 use C program "gps_test" to receive GPS signal generated by Matlab script gps_sig_gen.m

**a**. generate GPS signal file by running gps_sig_gen.m in Matlab

gps_sig_gen.m

to get file gps_sig_tmp.bin

**b**. use "gps_test" program to do some initial demodulation and check C/A codes:

gps_test gps_sig_tmp.bin 2.046e6 8.184e6 5000

Above program gps_test performs initial GPS signal capture by multi-bins correlation in frequency domain.

gps_sig_tmp.bin: input GPS signal generated by gps_sig_gen.m (MATLAB).

2.046e6: carrier frequency

8.184e6: sampling rate

5000: maximum frequency offset for frequency searching

You will find that C/A codes results are aligned with GPS signal we generate by Matlab script.

## 1.2 use C program "gps_test" to receive GPS signal captured by others instead of my our Matlab script gps_sig_gen.m

gps_test gps.samples.1bit.I.fs5456.if4092.bin 4.092e6 5.456e6 5000

gps.samples.1bit.I.fs5456.if4092.bin: captured by others and can be downloaded here: [http://www.jks.com/gps/gps.html](http://www.jks.com/gps/gps.html)

You will find C/A codes results are equal to those shown here: [http://www.jks.com/gps/gps.html](http://www.jks.com/gps/gps.html)

# 2. over the air GPS test method

# 2.1 playback gps.samples.1bit.I.fs5456.if4092.bin( [http://www.jks.com/gps/gps.html](http://www.jks.com/gps/gps.html) )

**a**. run gps_bin1bit_log2bin.m in Matlab to generate playback file for HACKRF (they capture GPS signal with 1bit quantization. we convert it to 8bit format which is needed by HACKRF): gps.samples.8bit.IQ.fs5456.baseband.bin

**b**. run gps_Nottingham.grc to playback gps.samples.8bit.IQ.fs5456.baseband.bin over the air. And meanwhile/immediately,

**c**. use rtl-sdr to capture signal:

rtl_sdr -g 60 -f 1575.42e6 -s 2.8e6 -n 19.2e6 rtl_2.8Msps_1575.42MHz.bin

**d**. run proc_rtl_bin_for_gps('rtl_2.8Msps_1575.42MHz.bin') in Matlab to convert 8bit file to 1bit file which is needed by gps_test program：rtl_2.8Msps_1575.42MHz_1bit.bin

**e**. see C/A codes initial capture result by running gps_test program:

gps_test rtl_2.8Msps_1575.42MHz_1bit.bin 0.62e6 2.8e6 100000

You will find C/A codes results are equal to those shown here: [http://www.jks.com/gps/gps.html](http://www.jks.com/gps/gps.html)

## 2.2 playback gps_sig_tmp_for_hackrf_tx.bin (generated by gps_sig_gen.m) to air by gps.grc.

**a**. run gps.grc to playback gps_sig_tmp_for_hackrf_tx.bin over the air. And meanwhile/immediately,

**b**. capture air GPS signal by:

rtl_sdr -g 60 -f 1574.8e6 -s 2.8e6 -n 19.2e6 rtl_2.8Msps_1574.8MHz.bin

**c**. convert captured 8bit file to 1bit bin file which is needed by gps_test: rtl_2.8Msps_1574.8MHz_1bit.bin

proc_rtl_bin_for_gps('rtl_2.8Msps_1574.8MHz.bin'); (MATLAB)

**d**. RUN:

gps_test rtl_2.8Msps_1574.8MHz_1bit.bin 0.62e6 2.8e6 100000

to see GPS signal capture result: C/A codes are supposed to align with our expectation (Matlab script).

**e**. you can also capture air GPS signal with different intermediate frequency by:

rtl_sdr -g 60 -f 1575.42e6 -s 2.8e6 -n 19.2e6 rtl_2.8Msps_1575.42MHz.bin

**f**. convert captured 8bit file to 1bit bin file which is needed by gps_test: rtl_2.8Msps_1575.42MHz_1bit.bin

proc_rtl_bin_for_gps('rtl_2.8Msps_1575.42MHz.bin'); (MATLAB)

**g**. RUN:

gps_test rtl_2.8Msps_1575.42MHz_1bit.bin 0.62e6 2.8e6 100000
    
to see GPS signal capture result: C/A codes are supposed to align with our expectation (Matlab script).