On 04/07/2018 10:39 AM, Rob Kossler wrote:
Hi Marcus,
No, I haven't fooled with LO level adjustments. I set the LO at about
3 dBm and did not change it. The LO freq is indeed 2x (LO at 4884MHz
with center freq at 2442MHz). I suspect that my custom software,
which was developed for first B210 and then X310 with several
daughterboard variants, may be sending tune commands in a way that is
not ideal for an external LO configuration. There was a similar issue
when I first started using TwinRx with "companion" or "external" LO
and UHD would issue warnings about tuning one channel first and then
the other when both channels had to be at the same freq because they
shared an LO. So, my request for examples was to help me see if I am
issuing the tuning requests correctly for this external LO config.
Rob
Understood.
Hopefully, one of the R&D folks will chime in here. I don't currently
have one in my inventory, so running a bit blind.
On Fri, Apr 6, 2018 at 7:32 PM, Marcus D. Leech via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>> wrote:
On 04/06/2018 05:14 PM, Rob Kossler via USRP-users wrote:
Hi,
Are there any examples for using the N310 with external LO? I
have gotten some strange results (strange spectral mirror-ing)
when using as just a 4 channel receiver. I am using the
"args" argument to set rx_lo_source, but my code is setting
the individual channel frequencies as I do for other USRPs and
I noticed various warnings in the terminal window for each
channel that I tune.
On a separate note, I get some strange results if I set the
clock_source to external in the args (using with OctoClock).
If I leave it internal, no problem. For now, I am leaving it
internal until I can solve the problem above with LO source.
Rob
Rob, just shooting from the hip here, since I haven't "lived" with
an N310 yet...
Have you tried adjusting the LO levels let's say 2dB in either
direction to see if that changes the imaging behavior? Also,
remember that the external LO input
on the N310 must be a 2XLO -- at twice the desired Fc, and only
up to 8GHz (giving a 4GHz antenna frequency).
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