The challenges needs to realize:
- The power of GPS signal at the receiver is about -160dBW, but the BladeRF sensitivity is about -130dBW. Consequently, we need an active antenna with 30dB or more in gain.
- The USB 2.0 is more stable than 3.0, but the speed is much lower than 3.0. Particularly, laptops have very unstable USB ports, this problem is taken into account in the experience.
- There is no detector to recognize the loss of samples.
Scenario:
Step 1, Connect the bladeRF with the active antenna in NavSAS Lab
Step 2, Collect the signal and observe the received signal in the Oscilloscope. The following commands is given by http://bladerf.blogspot.it/2014/01/finally-i-can-see-gps-satellites-with.html for collecting signal:
[WARNING] extract_field: Field checksum mismatch
[WARNING] Could not extract VCTCXO trim value
[WARNING] extract_field: Field checksum mismatch
[WARNING] Could not extract FPGA size
bladeRF> load fpga hostedx115.rbf
Loading fpga from hostedx115.rbf...
Done.
bladeRF> print frequency
RX Frequency: 1000000000Hz
TX Frequency: 1000000000Hz
bladeRF> set frequency 1575420000
Set RX frequency: 1575420000Hz
Set TX frequency: 1575420000Hz
bladeRF> set samplerate 4000000
Setting RX sample rate - req: 4000000Hz, actual: 4000000Hz
Setting TX sample rate - req: 4000000Hz, actual: 4000000Hz
bladeRF> set bandwidth 2.5E6
Set RX bandwidth - req: 2500000Hz actual: 2500000Hz
Set TX bandwidth - req: 2500000Hz actual: 2500000Hz
bladeRF> set rxvga1 30
bladeRF> set rxvga2 30
bladeRF> rx config format=csv n=40000 file=/temp/AKIEL.csv
bladeRF> rx start
bladeRF> rx config format=csv n=40000 file=/temp/BKIEL.csv
bladeRF> rx start
bladeRF> rx config format=csv n=40000 file=/temp/CKIEL.csv
bladeRF> rx start
bladeRF> rx start
bladeRF> rx start
bladeRF> rx config format=csv n=40000 file=/temp/DKIEL.csv
bladeRF> rx start
bladeRF> rx start
bladeRF> rx start
bladeRF> rx config format=csv n=80000 file=/temp/CKIEL.csv
bladeRF> rx config format=csv n=80000 file=/temp/DKIEL.csv
bladeRF> rx start
bladeRF> rx start
bladeRF>
Step 3, Using Matlab-based-GNSS-RX to acquire and track the signal
Step 4, Increasing the sampling frequency and repeat steps from 1 to 3,
Transmitter:
