I'm using Ubuntu 14.04 LTS, GNU Radio 3.7.9rc1, UHD 3.9.1 with two USRP N210s with WBX daughtercards.
I'm trying to determine what the fastest hopping rate is with the given setup above. Using the provided gr-uhd/examples/python frequency hopping script, it seems that 100 ms (10 Hz) is the fastest. What I haven't been able to figure out yet, is if this is due to a limitation imposed by that script, or if this is the fastest way (or right around the fastest way) that any script could hope to approach.
What I did to arive at this 100 ms limit is the following:
1) The first N210 is used as a transmitter and I use the following command to initiate hopping
./freq_hopping.py -a "addr=10.0.8.5" --antenna TX/RX --verbose --freq 915e6 --gain 20 --rate 5e6 --num-bursts 10000 --freq-delta 0.1e6 --samp-per-burst 10 --hop-time 50
2) The second N210 is a spectrum analyzer using the following command and the waterfall tab
uhd_fft -f 915M -s 0.5M -A TX/RX
3) I stop the waterfall plot, so it stops scrolling, and measure the smallest length of time at one frequency I can achieve given any batch of settings in step 1. The settings I linked in step one should have set a hop time of 50 ms, but this measurements shows 100 ms.
I'm going to try writing my own custom script, but would like to know if others have pushed this before and found ~100 ms (10 Hz) as the limit for frequency hopping intervals using the N210+WBX combo.