Thanks Marcus, I have now implemented the tune request with a python module. Integer N mode really helps with eliminating the spurs.
I have also added timed commands within the python file, but when I read the N210 timer, all the fractional values are fixed at .99999998. I have therefore re-compiled the UHD Source Block C Code to output to the console the time which is correct and all the fractional values are counting. Does this mean implementing time commands in python does not work ? Thanks, From: discuss-gnuradio-bounces+nigel.steed=xenint....@gnu.org [mailto:discuss-gnuradio-bounces+nigel.steed=xenint....@gnu.org] On Behalf Of Marcus D. Leech Sent: 01 March 2016 15:44 To: discuss-gnuradio@gnu.org Subject: Re: [Discuss-gnuradio] UHD Source Block and N210/SBX Synchronisation On 03/01/2016 04:57 AM, Nigel Steed wrote: Hi All, Has anyone managed to use/modify the UHD Source Block to phase synchronise multiple N210/SBX ? >From what I have read I must perform the following (1) Configure to use external references (10MHz and 1PPS) using the options in the UHD Source Block (2) Use integer N mode for the PLL (3) Re-tune the frequency of the PLL's on multiple N210/SBX at the same using a time command (4) Align the CORDIC's at initialisation and after a re-tune from (2) above by stopping and starting a stream disciplined to a time command which issues a reset to the CORDIC's at the same time Thanks, Nigel The only thing really missing in gr-uhd is the ability to do timed commands. You can force integer-N mode by constructing your own tune_request that includes the integer-N option. You'd use a feature from the latest Gnu Radio to help you with this, because it involves getting into the internal structure of a tune_request blob. So, use the "Python module" block, and in that Python do something like: def integer_N_tune_me(freq): r = uhd.tune_request(freq) r.args = {"mode_n" : "integer"} return r Then, in your UHD source/sink block, instead of using your target frequency directly, use: your_module_name.integer_N_tune_me(desired_freq) Martin could probably comment on the feasibility of adding timed commands to gr-uhd.
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