Saptarshi,
Ok, I see, you did not set set analog filter bandwidth of your USRP to 5
MHz but your signal has 5 MHz bandwidth. This, in combination with the
20 MHz MCR should then be absolutely fine.
I'm still not sure how you are trying to detect your signal. Maybe you
could share the relevant parts of you flow-graph here?
I just tested what I thing you are doing (see attached image of
flow-graph) and as far as I can tell, it is working as expected.
I'm feeding in a tone at 2.48 GHz on channel A and a tone at 2.475 GHz
on channel B. After the message strobe triggered
(pmt.to_pmt({"chan":0, "lo_freq":2.475e9, "dsp_freq": -5e6}))
I receive both tones just fine.
I'm using GNU Radio 3.8.2 and UHD 3.15.
Cheers,
Julian
On 12/9/20 7:03 PM, saptarshiv2ha...@gmail.com wrote:
Hi Julian,
Thanks for your reply.
I am basically trying to receive signals of BW 5MHz at two different centre
frequencies (2.475GHz and 2.48GHz) using the two subdevs of the B210.
The master clock rate gets set to 20MHz which makes me assume that the analog
bandwidth for the USRP source is 20 MHz.
With a centre frequency of 2.475GHz, it should cover from 2.465GHz to 2.485GHz.
The main problem I have difficulty understanding is why it works in Case 1 and
why it behaves randomly in Case 2.
Thanks,
Saptarshi
On 9 Dec 2020, at 15:49, Julian Arnold <jul...@elitecoding.org> wrote:
Saptarshi,
I'm not entirely sure I fully understand what you are doing. You probably need
to provide some more details.
However, in general, depending on what you master-clock-rate is,
doing a 5MHz shift in the DSP does not make much sense if your
sample-rate and your analog bandwidth are only 5 MHz. There is just no signal
at your 5MHz offset you could possibly shift down to base-band.
Cheers,
Julian
On 12/9/20 10:41 AM, Saptarshi Hazra via USRP-users wrote:
Hi,
I am trying to receive on two different centre frequencies (2.475e9 and 2.48e9)
using the two receiver chains on B210. Since they are close by, I thought can
receive them by setting the “dsp_freq” parameter.
Case 1:
Subdev: A:A or A:B
Nchannel : 1
Centre Frequency: 2.475e9
Sampling Rate: 5e6
BW: 5e6
If I use the command port the USRP source block to pass a pmt dictionary:
pmt.to_pmt({“lo_freq”:2.475e9, “dsp_freq”: -5e6})
I am able to receive radio packets sent by nodes on 2.48e9 Hz
Case 2:
Subdev: A:A A:B
Nchannel : 2
Sampling Rate: 5e6
Centre Frequency 1: 2.475e9
Centre Frequency 2: 2.475e9
BW: 5e6
I use the pmt dictionary:
pmt.to_pmt({“chan”:0, “lo_freq”:2.475e9, “dsp_freq”: -5e6})
When I do this sometimes I receive data from nodes transmitting on 2.48e9Hz.
and sometimes on 2.475Hz. The behaviour becomes entirely random.
I would really appreciate any help in figuring out how to receive
simultaneously on these two centre frequencies.
Thanks,
Saptarshi
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