Official bladeRF forum

I tested rx,tx GPS signal.
I connected active antenna, bias-tee, external LNA, and feeded DC using USB port.

and tested with following configures.
- set frequency 1575.42M
- set samplerate 8M
- set bandwidth 2.5M
- set rxvga1 27
- set rxvga2 12
- rx config file=r.csv format=csv n=8M
- tx config file=r.csv format=csv

But, I can't detected GPS signal.

So, I downloaded GNSS-SDR, and tested it with bladeRF.
I passed all tests with "run_tests" program, but didn't work well with "gnss-sdr", "front-end-cal" programs.
It shows some errors.
- "no GPS satellites detected in front-end capture, please check the antenna setup..."
- "SUPL client for Almanac returned -8" and "Unable to connect flowgraph"
- "Loss of lock in channel"
- "PLL Frequency tune error 0.000000 [Hz]"
And program ended.

How can I solve these problems? I want to know your tips about it.
https://goo.gl/photos/NMcDfwzSdcK2NGoy9
Here's pictures about it.

In the configuration with the bladeRF CLI -- what do your samples look like? Have you plotted them and verified that there's a reasonable SNR, no clipping (i.e., too much gain), or other issues?

I'm not familiar with what GNSS-SDR, unfortunately. You might want to reach out to their community and team to understand what type of debug information you can collect. Please share that here and we can try to understand what's going on when those messages are printed.