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GPS-SDR-SIM generates GPS baseband signal data streams, which can be converted GPS-SDR-SIM generates GPS baseband signal data streams, which can be converted
to RF using software-defined radio (SDR) platforms, such as to RF using software-defined radio (SDR) platforms, such as
[bladeRF](http://nuand.com/), HackRF, and USRP. [bladeRF](http://nuand.com/), [HackRF](https://github.com/mossmann/hackrf/wiki), and USRP.
### Windows build instructions ### Windows build instructions
1. Start Visual Studio. 1. Start Visual Studio.
2. Create an empty project for a console application. 2. Create an empty project for a console application.
3. On the Solution Explorer at right, add "gpssim.c" to the Souce Files folder. 3. On the Solution Explorer at right, add "gpssim.c" and "getopt.c" to the Souce Files folder.
4. Select "Release" in Solution Configurations drop-down list. 4. Select "Release" in Solution Configurations drop-down list.
5. Open the Property Pages dialog box and expand the Configuration Properties. 5. Open the Property Pages dialog box and expand the Configuration Properties.
6. Expand the C/C++ node and select the Language property page. 6. Expand the C/C++ node and select the Language property page.
@ -35,23 +35,37 @@ indiviual site navigation files into one. The archive for the daily file is:
These files are then used to generate the simulated pseudorange and These files are then used to generate the simulated pseudorange and
Doppler for the GPS satellites in view. This simulated range data is Doppler for the GPS satellites in view. This simulated range data is
then used to generate the digitized I/Q samples for the GPS signal. then used to generate the digitized I/Q samples for the GPS signal.
For example;
The bladeRF command line interface requires I/Q pairs stored as signed
16-bit integers, while the hackrf_transfere supports signed bytes.
``` ```
> gps-sdr-sim brdc3540.14n circle.csv gpssim.bin Usage: gps-sdr-sim [options]
Options:
-e <gps_nav> RINEX navigation file for GPS ephemerides (required)
-u <user_motion> User motion file (required)
-o <output> I/Q sampling data file (default: gpssim.bin)
-f <furequency> Sampling frequency [Hz] (default: 2.6MHz)
-b <iq_bits> I/Q data format [8/16] (default: 8)
``` ```
### Transmitting the samples with bladeRF For example:
The TX port of the bladeRF is connected to the GPS receiver under ```
test through a DC block and a fixed 50dB attenuator. > gps-sdr-sim -e brdc3540.14n -u circle.csv -b 16
```
### Transmitting the samples
The TX port of a particular SDR platform is connected to the GPS receiver
under test through a DC block and a fixed 50-60dB attenuator.
The simulated GPS signal file, named "gpssim.bin", can be loaded The simulated GPS signal file, named "gpssim.bin", can be loaded
into bladeRF for playback as shown below: into the bladeRF for playback as shown below:
``` ```
set frequency 1575.42M set frequency 1575.42M
set samplerate 4M set samplerate 2.6M
set bandwidth 2.5M set bandwidth 2.5M
set txvga1 -25 set txvga1 -25
cal lms cal lms
@ -60,6 +74,12 @@ tx config file=gpssim.bin format=bin
tx start tx start
``` ```
For the HackRF:
```
> hackrf_transfer -t gpssim.bin -f 1575420000 -s 2600000 -a 1 -x 0
```
### License ### License
Copyright &copy; 2015 Takuji Ebinuma Copyright &copy; 2015 Takuji Ebinuma