Hi Henry, Given that your main issue is that you get different results simply by rotating your antenna 180 degree (and changing nothing else) and that if you use a different transceiver, you get consistent results, I'm not sure that the following will help. But, the following are some things I noticed based on the code you sent. Rob
- I noticed that your analog signal is a 20kHz sine wave. I don't know GR well, but I'm wondering if this is a complex or real signal. If real, then I assume that there is a spectral tone at both +/- 20kHz. Note that you could really just sent a constant (e.g., 1.0) rather than a sine wave if you simply want a CW tone at your center frequency. Otherwise, you might need a complex tone (exp(jwt)) if you want just a tone at +20kHz. - You might want to change your master_clock_rate to be double your sample rate so that the DDC/DUC can appropriately produce a desired LO offset. I believe that the master_clock_rate must be at least 2*(lo_offset+sample_rate/2) in order to digitally shift the baseband signal. (if the master_clock_rate is equal to the sample rate, then UHD is likely ignoring your request for an LO offset) - You might want to use a bigger LO offset. 50 kHz is only about 5 FFT bins (fft bin size is ~ 10kHz). If you change the master_clock_rate to 20 MHz, you could set the LO_offset to 1 MHz (if you want to see it in your spectrum) or perhaps 5 MHz (if you want to move it all the way to the edge of your spectrum). - You might want to set 'bw' as large as possible. I don't really know what the bandwidth setting does on the ad9361, but if it is a filter that is symmetric about the LO, you don't want it to clip your desired signal. On Thu, Mar 2, 2023 at 5:17 AM <[email protected]> wrote: > Addition: > > I think the problem is about LO leakage. > > I made 4 different experiment. > > First, I used just my B200 both receiver and transmitter and a specific > location which is the difference between 0 and 180 degree of Horn antenna > is 2,5dB. > > Second, I used just my B210 both receiver and transmitter at same location > with previous experiment, the difference is 0,7dB. > > Third, I used my B200 as receiver and B210 as transmitter at same location > with previous experiment, the difference is almost 0. > > Fourth, I used my B200 as transmitter and B210 as receiver at same > location with previous experiment, the difference is 0,1dB ~ 0,2dB. > > > And I take screenshot in GNU Radio, you can check this band. > _______________________________________________ > USRP-users mailing list -- [email protected] > To unsubscribe send an email to [email protected] >
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