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+address@hidden [mailto:discuss-gnuradio-bounces+address@hidden
On Behalf Of Marcus D. Leech
Sent: 01 March 2016 15:44
To: address@hidden
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.