Re: [Discuss-gnuradio] about uhd_fft.py

[Orkhan Badirkhanli]

I am sending two screenshots of ffy, one with center freq 2.40002G and the other 2.40005

Please note the difference between them

I ran the calibrations too

Does anybody have an idea about how I can correct this? - Or what is the source of it?

Here is my uhd_usrp_probe output:

  _____________________________________________________
 /
|       Device: USRP2 / N-Series Device
|     _____________________________________________________
|    /
|   |       Mboard: USRP-N210-REV4
|   |   hardware: 2577
|   |   mac-addr: a0:36:fa:25:37:df
|   |   ip-addr: 192.168.10.2
|   |   gpsdo: none
|   |   serial: EDR17SFUP
|   |   
|   |   Time sources: none, external, _external_, mimo
|   |   Clock sources: internal, external, mimo
|   |   Sensors: mimo_locked, ref_locked
|   |     _____________________________________________________
|   |    /
|   |   |       RX DSP: 0
|   |   |   Freq range: -50.000 to 50.000 Mhz
|   |     _____________________________________________________
|   |    /
|   |   |       RX DSP: 1
|   |   |   Freq range: -50.000 to 50.000 Mhz
|   |     _____________________________________________________
|   |    /
|   |   |       RX Dboard: A
|   |   |   ID: SBX (0x0054)
|   |   |   Serial: E3R13X6XS
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       RX Subdev: 0
|   |   |   |   Name: SBX RX
|   |   |   |   Antennas: TX/RX, RX2, CAL
|   |   |   |   Sensors: lo_locked
|   |   |   |   Freq range: 400.000 to 4400.000 Mhz
|   |   |   |   Gain range PGA0: 0.0 to 31.5 step 0.5 dB
|   |   |   |   Connection Type: IQ
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       RX Codec: A
|   |   |   |   Name: ads62p44
|   |   |   |   Gain range digital: 0.0 to 6.0 step 0.5 dB
|   |   |   |   Gain range fine: 0.0 to 0.5 step 0.1 dB
|   |     _____________________________________________________
|   |    /
|   |   |       TX DSP: 0
|   |   |   Freq range: -250.000 to 250.000 Mhz
|   |     _____________________________________________________
|   |    /
|   |   |       TX Dboard: A
|   |   |   ID: SBX (0x0055)
|   |   |   Serial: E3R13X6XS
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       TX Subdev: 0
|   |   |   |   Name: SBX TX
|   |   |   |   Antennas: TX/RX, CAL
|   |   |   |   Sensors: lo_locked
|   |   |   |   Freq range: 400.000 to 4400.000 Mhz
|   |   |   |   Gain range PGA0: 0.0 to 31.5 step 0.5 dB
|   |   |   |   Connection Type: QI
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       TX Codec: A
|   |   |   |   Name: ad9777
|   |   |   |   Gain Elements: None

On Sat, Mar 10, 2012 at 4:26 PM, Andrew Davis <address@hidden> wrote:

They might be internal noise from the USRP, turn up the gain input to
drown them out. That's what I do.

~Andrew

On Sat, Mar 10, 2012 at 6:28 AM, Orkhan Badirkhanli <address@hidden> wrote:
> Andrew
>
> Sorry for the late reply. I am using SBX daughterboard.
>
> The attachments I included earlier are inaccurate and seems like I was see
> that output because I was terminating uhd_fft file using ctrl+c
>
> Right now I have my noise level at -110dB and I can see different carriers.
> The only ambiguity I am facing is that as I change by center frequency by
> 0.0001GHz I see some carriers gone and different ones emerged at various
> frequencies.
>
> This is happening in every band.
>
>
> On Thu, Mar 8, 2012 at 7:24 PM, Andrew Davis <address@hidden>
> wrote:
>>
>> The thing in the center is caused by a lot of things, like IQ
>> imbalances and the distribution of noise towards zero etc. We all get
>> it when the gain is high. Do you have something you are trying to
>> detect? Do you have an antenna connected to the right port? What
>> front-end board are you using? Try 100MHz and look at some local radio
>> stations.
>>
>> On Thu, Mar 8, 2012 at 8:47 AM, Orkhan Badirkhanli <address@hidden>
>> wrote:
>> > Hello
>> >
>> > I've just successully installed gnuradio and connected my new USRP n210.
>> > I
>> > run uhd_fft.py to test my hardware and it all works well, I activity in
>> > the
>> > spectrum.
>> >
>> > The thing is, whatever I set the center frequency, all I see is a
>> > carrier at
>> > that center frequence at -50dB and "noise" at other frequencies at
>> > -70dB. I
>> > have included 2 screenshots with center frequencies of 2.4G and 2.4001G,
>> > the
>> > situation is the same in both of them.
>> >
>> > I thing there is something really wrong with this. Besides, I remember a
>> > few
>> > time when I ran uhd_fft.py file, I saw noise at -110dB and several
>> > carriers
>> > at different frequencies. But that carrier at center frequency was there
>> > too.
>> >
>> > I appreciate any help
>> >
>> > Thanks
>> >
>> > --
>> > Orkhan
>> >
>> > _______________________________________________
>> > Discuss-gnuradio mailing list
>> > address@hidden
>> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>> >
>
>
>
>
> --
> Orkhan

-- 
Orkhan

2.40002.png
Description: PNG image

2.40005.png
Description: PNG image