Hi, After reading the work of Jiao Xianjun, I was motivated to record and replay GPS signals with hackrf_transfer. With careful selection of signal strength, I can see the playback signals from HackRF One on my u-blox GPS receiver, but there are a couple of issues I need to resolve.
1. GPS signals are weak and buried under the thermal noise. The recorded I/Q samples should have Gaussian distribution, but there are eminent projections around zero. I uploaded a histogram plot to the following site: http://goo.gl/NzVulj 2. The received data transfer rate gets lower every once in a while, and some samples are lost. It occurs in a constant time interval, every 30 seconds on my Core i5 laptop, regardless sampling rates. $ hackrf_info Found HackRF board. Board ID Number: 2 (HackRF One) Firmware Version: 2014.08.1 Part ID Number: 0xa000cb3c 0x00604f39 Serial Number: 0x00000000 0x00000000 0x457863c8 0x2f52161f $ hackrf_transfer -r gps.bin -f 1575420000 -s 2600000 -n 260000000 -g 30 -l 40 -a 0 call hackrf_sample_rate_set(2600000 Hz/2.600 MHz) call hackrf_baseband_filter_bandwidth_set(2500000 Hz/2.500 MHz) call hackrf_set_freq(1575420000 Hz/1575.420 MHz) call hackrf_set_amp_enable(0) samples_to_xfer 260000000/260Mio Stop with Ctrl-C 5.0 MiB / 1.000 sec = 5.0 MiB/second 5.2 MiB / 1.000 sec = 5.2 MiB/second 5.2 MiB / 1.000 sec = 5.2 MiB/second ... 5.2 MiB / 1.000 sec = 5.2 MiB/second 5.2 MiB / 1.000 sec = 5.2 MiB/second 2.6 MiB / 1.000 sec = 2.6 MiB/second 2.4 MiB / 1.000 sec = 2.4 MiB/second 5.2 MiB / 1.000 sec = 5.2 MiB/second 5.2 MiB / 1.000 sec = 5.2 MiB/second ... 5.0 MiB / 1.000 sec = 5.0 MiB/second 4.5 MiB / 1.000 sec = 4.5 MiB/second 3.1 MiB / 1.000 sec = 3.1 MiB/second 1.0 MiB / 1.000 sec = 1.0 MiB/second 5.0 MiB / 1.000 sec = 5.0 MiB/second 5.2 MiB / 1.000 sec = 5.2 MiB/second Does anyone have any idea of what I should do to solve these problems? OSQZSS
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