I have been looking more at the performance of the udh_cal_* routines to try and understand the operation of my N210 and the SBX card. I found the cal files that I had previously generated and moved them into a separate directory to prevent the UHD driver from finding them. From the documentation, I think this should apply no corrections. Then I removed the antennas and terminated both inputs with 50 ohm terminators, running uhd_fft.grc with a frequency of 2.0087MHz (which is away from other spurious signals and near a calibration point), a sampling rate at 5M, a 2.048k FFT size, and an average of 0.004 produces a graph where I can observe both the average leakage power of the LO and the average noise floor. This produced data for the LO [A - -99.21 dB, FFT: -106.14 dB] and noise [A: -117.138, FFT: -117.1 dB].
I then ran uhd_rx_iq_balance which produced the file /home/gnube/.uhd/cal/rx_iq_cal_v0.1_E2R12X1XS.csv. With correction line of 2.0087e+09, 0.961492, -0.307198, 76.7275, 38.7414 Running uhd_fft.grc again produced no change to the measurements. I then ran uhd_tx_iq_balance which produced the file /home/gnube/.uhd/cal/tx_iq_cal_v0.1_E2R12X1XS.csv. With correction line of 2.0087e+09, 0.962229, 0.0709783, 77.7254, 39.0847 Running uhd_fft.grc again produced no change to the measurements. I then ran uhd_tx_dc_offset which produced the file /home/gnube/.uhd/cal/tx_dc_cal_v0.1_E2R12X1XS.csv. With correction line of 2.0087e+09, -0.0108594, -0.00078125, -95.2992, 51.6633 Running uhd_fft.grc again produced no change to the measurements. Can anyone tell me what mistake I am making? Evan Merewether
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