Experience on BladeRF

Receiver:
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: