Hi Julian,
I made two mistakes in my flow graph that’s why I was not able to receive the
messages:
1. I set the BW to 10MHz, should have been 20MHz.
2. I did not connect the output of the decoder to my detector. Really silly
mistake. I just realised it now.
Thanks a lot for your help.
Sincerely,
Saptarshi
> On 9 Dec 2020, at 23:23, Julian Arnold <jul...@elitecoding.org> wrote:
>
> 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
>>>> _______________________________________________
>>>> USRP-users mailing list
>>>> USRP-users@lists.ettus.com
>>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
> <pmt_tune.png>
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