Empathy List Archives

SD

Sebastian Döring

Mon, Mar 12, 2012 12:51 PM

Hello,

I have been doing some spectrum sensing with the USRP N210
and the XCVR2450.
Today I tried the same stuff with the SBX daughterboard
and suddenly the signal level at the output seems to have
an offset of around +20dB.
With the XCVR I usually measure a noise level around
-100dB and with the SBX I get something around -80dB (both
with gain tuned to "0").

My question is, if there's some other gain parameter in
the SBX that I can´t control?
I used the same antenna and the same USRP.

Any hints highly appreciated!

Regards
Sebastian

Hello, I have been doing some spectrum sensing with the USRP N210 and the XCVR2450. Today I tried the same stuff with the SBX daughterboard and suddenly the signal level at the output seems to have an offset of around +20dB. With the XCVR I usually measure a noise level around -100dB and with the SBX I get something around -80dB (both with gain tuned to "0"). My question is, if there's some other gain parameter in the SBX that I can´t control? I used the same antenna and the same USRP. Any hints highly appreciated! Regards Sebastian

JA

Jason Abele

Mon, Mar 12, 2012 6:07 PM

Sebastian,

The units displayed in uhd_fft.py are not absolute and the XCVR and SBX
have vastly different absolute gain at a setting of "0dB". Thus, they
are not really comparable at the same gain setting.

If you want to compare them, apply a sine wave of known power (say
-50dBm) and use it to "calibrate" the units in uhd_fft.py into dBm.

Then you can compare SBX to XCVR.

Also note that the implicit scale factor in the "calibration" performed
above will vary with gain setting.

If you send your uhd_ffy.py command, it will be easier to comment on the
expected SBX behavior.

It is also helpful to provide the output of uhd_usrp_probe such that we
can see the UHD and hardware versions you are using.

Thanks
Jason

On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian Döring wrote:

Hello,

I have been doing some spectrum sensing with the USRP N210 and the
XCVR2450.
Today I tried the same stuff with the SBX daughterboard and suddenly
the signal level at the output seems to have an offset of around
+20dB.
With the XCVR I usually measure a noise level around -100dB and with
the SBX I get something around -80dB (both with gain tuned to "0").

My question is, if there's some other gain parameter in the SBX that
I can´t control?
I used the same antenna and the same USRP.

Any hints highly appreciated!

Regards
Sebastian

USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

Sebastian, The units displayed in uhd_fft.py are not absolute and the XCVR and SBX have vastly different absolute gain at a setting of "0dB". Thus, they are not really comparable at the same gain setting. If you want to compare them, apply a sine wave of known power (say -50dBm) and use it to "calibrate" the units in uhd_fft.py into dBm. Then you can compare SBX to XCVR. Also note that the implicit scale factor in the "calibration" performed above will vary with gain setting. If you send your uhd_ffy.py command, it will be easier to comment on the expected SBX behavior. It is also helpful to provide the output of uhd_usrp_probe such that we can see the UHD and hardware versions you are using. Thanks Jason On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian Döring wrote: > Hello, > > I have been doing some spectrum sensing with the USRP N210 and the > XCVR2450. > Today I tried the same stuff with the SBX daughterboard and suddenly > the signal level at the output seems to have an offset of around > +20dB. > With the XCVR I usually measure a noise level around -100dB and with > the SBX I get something around -80dB (both with gain tuned to "0"). > > My question is, if there's some other gain parameter in the SBX that > I can´t control? > I used the same antenna and the same USRP. > > Any hints highly appreciated! > > Regards > Sebastian > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

SD

Sebastian Döring

Tue, Mar 13, 2012 9:11 AM

Thanks for the answer Jason,

the output of uhd_fft.py is the same for both boards and I
no longer think that I am having problems with the gain
calibration.

I realized the offset when I was estimating the noise
power using uhd_rx_cfile.py and afterwards processing the
samples with octave.
What I do is simply reading the complex binary data,
performing fft and magnitude squaring.
I found out that the data comming from the SBX seems to be
corrupted by some sine or sine^2.
I am not talking about an unexpected peak somewhere in the
spectrum but about the whole spectrum looking like a
sine^2 instead of a rather flat white noise floor (that's
what I see using the XCVR and what it is supposed to look
like, since I checked it with some other spectrum analyzer
too).

The output of uhd_usrp_probe is the following:

I really appreciate any further information.

Regards
Sebastian

On Mon, 12 Mar 2012 11:07:39 -0700
Jason Abele jason@ettus.com wrote:

Sebastian,

The units displayed in uhd_fft.py are not absolute and
the XCVR and SBX
have vastly different absolute gain at a setting of
"0dB". Thus, they
are not really comparable at the same gain setting.

If you want to compare them, apply a sine wave of known
power (say
-50dBm) and use it to "calibrate" the units in
uhd_fft.py into dBm.

Then you can compare SBX to XCVR.

Also note that the implicit scale factor in the
"calibration" performed
above will vary with gain setting.

If you send your uhd_ffy.py command, it will be easier
to comment on the
expected SBX behavior.

It is also helpful to provide the output of
uhd_usrp_probe such that we
can see the UHD and hardware versions you are using.

Thanks
Jason

On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian
Döring wrote:

Hello,

I have been doing some spectrum sensing with the USRP
N210 and the
XCVR2450.
Today I tried the same stuff with the SBX daughterboard
and suddenly
the signal level at the output seems to have an offset
of around
+20dB.
With the XCVR I usually measure a noise level around
-100dB and with
the SBX I get something around -80dB (both with gain
tuned to "0").

My question is, if there's some other gain parameter in
the SBX that
I can´t control?
I used the same antenna and the same USRP.

Any hints highly appreciated!

Regards
Sebastian

USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

Thanks for the answer Jason, the output of uhd_fft.py is the same for both boards and I no longer think that I am having problems with the gain calibration. I realized the offset when I was estimating the noise power using uhd_rx_cfile.py and afterwards processing the samples with octave. What I do is simply reading the complex binary data, performing fft and magnitude squaring. I found out that the data comming from the SBX seems to be corrupted by some sine or sine^2. I am not talking about an unexpected peak somewhere in the spectrum but about the whole spectrum looking like a sine^2 instead of a rather flat white noise floor (that's what I see using the XCVR and what it is supposed to look like, since I checked it with some other spectrum analyzer too). The output of uhd_usrp_probe is the following: _____________________________________________________ / | Device: USRP2 / N-Series Device | _____________________________________________________ | / | | Mboard: USRP-N210 | | hardware: 2561 | | mac-addr: a0:36:fa:25:32:f2 | | ip-addr: 192.168.10.2 | | gpsdo: none | | serial: EFR12W2UP | | | | 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: E8R12X9XS | | | _____________________________________________________ | | | / | | | | 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: E8R12X9XS | | | _____________________________________________________ | | | / | | | | 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 I really appreciate any further information. Regards Sebastian On Mon, 12 Mar 2012 11:07:39 -0700 Jason Abele <jason@ettus.com> wrote: > Sebastian, > > The units displayed in uhd_fft.py are not absolute and >the XCVR and SBX > have vastly different absolute gain at a setting of >"0dB". Thus, they > are not really comparable at the same gain setting. > > If you want to compare them, apply a sine wave of known >power (say > -50dBm) and use it to "calibrate" the units in >uhd_fft.py into dBm. > > Then you can compare SBX to XCVR. > > Also note that the implicit scale factor in the >"calibration" performed > above will vary with gain setting. > > If you send your uhd_ffy.py command, it will be easier >to comment on the > expected SBX behavior. > > It is also helpful to provide the output of >uhd_usrp_probe such that we > can see the UHD and hardware versions you are using. > > Thanks > Jason > > On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian >Döring wrote: >> Hello, >> >> I have been doing some spectrum sensing with the USRP >>N210 and the >> XCVR2450. >> Today I tried the same stuff with the SBX daughterboard >>and suddenly >> the signal level at the output seems to have an offset >>of around >> +20dB. >> With the XCVR I usually measure a noise level around >>-100dB and with >> the SBX I get something around -80dB (both with gain >>tuned to "0"). >> >> My question is, if there's some other gain parameter in >>the SBX that >> I can´t control? >> I used the same antenna and the same USRP. >> >> Any hints highly appreciated! >> >> Regards >> Sebastian >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

NF

Nick Foster

Tue, Mar 13, 2012 3:57 PM

Please send an image of the strange output you are seeing.

--n

On Tue, Mar 13, 2012 at 2:11 AM, Sebastian Döring
sdoering@rhrk.uni-kl.dewrote:

Thanks for the answer Jason,

the output of uhd_fft.py is the same for both boards and I no longer think
that I am having problems with the gain calibration.

I realized the offset when I was estimating the noise power using
uhd_rx_cfile.py and afterwards processing the samples with octave.
What I do is simply reading the complex binary data, performing fft and
magnitude squaring.
I found out that the data comming from the SBX seems to be corrupted by
some sine or sine^2.
I am not talking about an unexpected peak somewhere in the spectrum but
about the whole spectrum looking like a sine^2 instead of a rather flat
white noise floor (that's what I see using the XCVR and what it is supposed
to look like, since I checked it with some other spectrum analyzer too).

The output of uhd_usrp_probe is the following:

I really appreciate any further information.

Regards
Sebastian

On Mon, 12 Mar 2012 11:07:39 -0700
Jason Abele jason@ettus.com wrote:

Sebastian,

The units displayed in uhd_fft.py are not absolute and the XCVR and SBX
have vastly different absolute gain at a setting of "0dB". Thus, they
are not really comparable at the same gain setting.

If you want to compare them, apply a sine wave of known power (say
-50dBm) and use it to "calibrate" the units in uhd_fft.py into dBm.

Then you can compare SBX to XCVR.

Also note that the implicit scale factor in the "calibration" performed
above will vary with gain setting.

If you send your uhd_ffy.py command, it will be easier to comment on the
expected SBX behavior.

It is also helpful to provide the output of uhd_usrp_probe such that we
can see the UHD and hardware versions you are using.

Thanks
Jason

On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian Döring wrote:

Hello,

I have been doing some spectrum sensing with the USRP N210 and the
XCVR2450.
Today I tried the same stuff with the SBX daughterboard and suddenly
the signal level at the output seems to have an offset of around
+20dB.
With the XCVR I usually measure a noise level around -100dB and with
the SBX I get something around -80dB (both with gain tuned to "0").

My question is, if there's some other gain parameter in the SBX that
I can´t control?
I used the same antenna and the same USRP.

Any hints highly appreciated!

Regards
Sebastian

____________**
USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/**mailman/listinfo/usrp-users**lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

Please send an image of the strange output you are seeing. --n On Tue, Mar 13, 2012 at 2:11 AM, Sebastian Döring <sdoering@rhrk.uni-kl.de>wrote: > Thanks for the answer Jason, > > the output of uhd_fft.py is the same for both boards and I no longer think > that I am having problems with the gain calibration. > > I realized the offset when I was estimating the noise power using > uhd_rx_cfile.py and afterwards processing the samples with octave. > What I do is simply reading the complex binary data, performing fft and > magnitude squaring. > I found out that the data comming from the SBX seems to be corrupted by > some sine or sine^2. > I am not talking about an unexpected peak somewhere in the spectrum but > about the whole spectrum looking like a sine^2 instead of a rather flat > white noise floor (that's what I see using the XCVR and what it is supposed > to look like, since I checked it with some other spectrum analyzer too). > > The output of uhd_usrp_probe is the following: > > ______________________________**_______________________ > / > | Device: USRP2 / N-Series Device > | ______________________________**_______________________ > | / > | | Mboard: USRP-N210 > | | hardware: 2561 > | | mac-addr: a0:36:fa:25:32:f2 > | | ip-addr: 192.168.10.2 > | | gpsdo: none > | | serial: EFR12W2UP > | | > | | 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: E8R12X9XS > | | | ______________________________**_______________________ > | | | / > | | | | 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: E8R12X9XS > | | | ______________________________**_______________________ > | | | / > | | | | 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 > > > > I really appreciate any further information. > > Regards > Sebastian > > > > On Mon, 12 Mar 2012 11:07:39 -0700 > Jason Abele <jason@ettus.com> wrote: > >> Sebastian, >> >> The units displayed in uhd_fft.py are not absolute and the XCVR and SBX >> have vastly different absolute gain at a setting of "0dB". Thus, they >> are not really comparable at the same gain setting. >> >> If you want to compare them, apply a sine wave of known power (say >> -50dBm) and use it to "calibrate" the units in uhd_fft.py into dBm. >> >> Then you can compare SBX to XCVR. >> >> Also note that the implicit scale factor in the "calibration" performed >> above will vary with gain setting. >> >> If you send your uhd_ffy.py command, it will be easier to comment on the >> expected SBX behavior. >> >> It is also helpful to provide the output of uhd_usrp_probe such that we >> can see the UHD and hardware versions you are using. >> >> Thanks >> Jason >> >> On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian Döring wrote: >> >>> Hello, >>> >>> I have been doing some spectrum sensing with the USRP N210 and the >>> XCVR2450. >>> Today I tried the same stuff with the SBX daughterboard and suddenly >>> the signal level at the output seems to have an offset of around >>> +20dB. >>> With the XCVR I usually measure a noise level around -100dB and with >>> the SBX I get something around -80dB (both with gain tuned to "0"). >>> >>> My question is, if there's some other gain parameter in the SBX that >>> I can´t control? >>> I used the same antenna and the same USRP. >>> >>> Any hints highly appreciated! >>> >>> Regards >>> Sebastian >>> >>> ______________________________**_________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/**mailman/listinfo/usrp-users_**lists.ettus.com<http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> >>> >> > > ______________________________**_________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/**mailman/listinfo/usrp-users_**lists.ettus.com<http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> >

S

steam2009@t-online.de

Tue, Mar 13, 2012 5:25 PM

Out of curiousity what FPGA / UHD version are you using.

Von: "Sebastian Döring" sdoering@rhrk.uni-kl.de
Datum: Tue, 13 Mar 2012 10:11:22 +0100

The output of uhd_usrp_probe is the following:

I really appreciate any further information.

Regards
Sebastian

On Mon, 12 Mar 2012 11:07:39 -0700
Jason Abele jason@ettus.com wrote:

Sebastian,

The units displayed in uhd_fft.py are not absolute and
the XCVR and SBX
have vastly different absolute gain at a setting of
"0dB". Thus, they
are not really comparable at the same gain setting.

If you want to compare them, apply a sine wave of known
power (say
-50dBm) and use it to "calibrate" the units in
uhd_fft.py into dBm.

Then you can compare SBX to XCVR.

Also note that the implicit scale factor in the
"calibration" performed
above will vary with gain setting.

If you send your uhd_ffy.py command, it will be easier
to comment on the
expected SBX behavior.

It is also helpful to provide the output of
uhd_usrp_probe such that we
can see the UHD and hardware versions you are using.

Thanks
Jason

On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian
Döring wrote:

Hello,

I have been doing some spectrum sensing with the USRP
N210 and the
XCVR2450.
Today I tried the same stuff with the SBX daughterboard
and suddenly
the signal level at the output seems to have an offset
of around
+20dB.
With the XCVR I usually measure a noise level around
-100dB and with
the SBX I get something around -80dB (both with gain
tuned to "0").

My question is, if there's some other gain parameter in
the SBX that
I can´t control?
I used the same antenna and the same USRP.

Any hints highly appreciated!

Regards
Sebastian

USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

Out of curiousity what FPGA / UHD version are you using. Von: "Sebastian Döring" <sdoering@rhrk.uni-kl.de> Datum: Tue, 13 Mar 2012 10:11:22 +0100 > The output of uhd_usrp_probe is the following: _____________________________________________________ / | Device: USRP2 / N-Series Device | _____________________________________________________ | / | | Mboard: USRP-N210 | | hardware: 2561 | | mac-addr: a0:36:fa:25:32:f2 | | ip-addr: 192.168.10.2 | | gpsdo: none | | serial: EFR12W2UP | | | | 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: E8R12X9XS | | | _____________________________________________________ | | | / | | | | 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: E8R12X9XS | | | _____________________________________________________ | | | / | | | | 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 I really appreciate any further information. Regards Sebastian On Mon, 12 Mar 2012 11:07:39 -0700 Jason Abele <jason@ettus.com> wrote: > Sebastian, > > The units displayed in uhd_fft.py are not absolute and >the XCVR and SBX > have vastly different absolute gain at a setting of >"0dB". Thus, they > are not really comparable at the same gain setting. > > If you want to compare them, apply a sine wave of known >power (say > -50dBm) and use it to "calibrate" the units in >uhd_fft.py into dBm. > > Then you can compare SBX to XCVR. > > Also note that the implicit scale factor in the >"calibration" performed > above will vary with gain setting. > > If you send your uhd_ffy.py command, it will be easier >to comment on the > expected SBX behavior. > > It is also helpful to provide the output of >uhd_usrp_probe such that we > can see the UHD and hardware versions you are using. > > Thanks > Jason > > On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian >Döring wrote: >> Hello, >> >> I have been doing some spectrum sensing with the USRP >>N210 and the >> XCVR2450. >> Today I tried the same stuff with the SBX daughterboard >>and suddenly >> the signal level at the output seems to have an offset >>of around >> +20dB. >> With the XCVR I usually measure a noise level around >>-100dB and with >> the SBX I get something around -80dB (both with gain >>tuned to "0"). >> >> My question is, if there's some other gain parameter in >>the SBX that >> I can´t control? >> I used the same antenna and the same USRP. >> >> Any hints highly appreciated! >> >> Regards >> Sebastian >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

SD

Sebastian Döring

Wed, Mar 14, 2012 9:03 AM

@ steam: UHD version is "UHD_003.004.000-b8e41cb" and FPGA
image is the corresponding one for revision number R2.
@ Nick: I attached 2 figures. The supposed-to-look-like
case I get with XCVR and independent spectrum analyzer and
the one I get using the SBX.

Both data sets have been recorded using "uhd_rx_cfile.py
-f 2.4G -N 1024".
I processed the samples with octave performing fft, square
magnitude and translated them to dB level scaled with
20*log10(x).

-Sebastian

On Tue, 13 Mar 2012 18:25:34 +0100
"steam2009@t-online.de" steam2009@t-online.de wrote:

Out of curiousity what FPGA / UHD version are you using.

Von: "Sebastian Döring" sdoering@rhrk.uni-kl.de
Datum: Tue, 13 Mar 2012 10:11:22 +0100

The output of uhd_usrp_probe is the following:

I really appreciate any further information.

Regards
Sebastian

On Mon, 12 Mar 2012 11:07:39 -0700
Jason Abele jason@ettus.com wrote:

Sebastian,

The units displayed in uhd_fft.py are not absolute and
the XCVR and SBX
have vastly different absolute gain at a setting of
"0dB". Thus, they
are not really comparable at the same gain setting.

If you want to compare them, apply a sine wave of known
power (say
-50dBm) and use it to "calibrate" the units in
uhd_fft.py into dBm.

Then you can compare SBX to XCVR.

Also note that the implicit scale factor in the
"calibration" performed
above will vary with gain setting.

If you send your uhd_ffy.py command, it will be easier
to comment on the
expected SBX behavior.

It is also helpful to provide the output of
uhd_usrp_probe such that we
can see the UHD and hardware versions you are using.

Thanks
Jason

On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian
Döring wrote:

Hello,

I have been doing some spectrum sensing with the USRP
N210 and the
XCVR2450.
Today I tried the same stuff with the SBX daughterboard
and suddenly
the signal level at the output seems to have an offset
of around
+20dB.
With the XCVR I usually measure a noise level around
-100dB and with
the SBX I get something around -80dB (both with gain
tuned to "0").

My question is, if there's some other gain parameter in
the SBX that
I can´t control?
I used the same antenna and the same USRP.

Any hints highly appreciated!

Regards
Sebastian

USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

@ steam: UHD version is "UHD_003.004.000-b8e41cb" and FPGA image is the corresponding one for revision number R2. @ Nick: I attached 2 figures. The supposed-to-look-like case I get with XCVR and independent spectrum analyzer and the one I get using the SBX. Both data sets have been recorded using "uhd_rx_cfile.py -f 2.4G -N 1024". I processed the samples with octave performing fft, square magnitude and translated them to dB level scaled with 20*log10(x). -Sebastian On Tue, 13 Mar 2012 18:25:34 +0100 "steam2009@t-online.de" <steam2009@t-online.de> wrote: > Out of curiousity what FPGA / UHD version are you using. > > > Von: "Sebastian Döring" <sdoering@rhrk.uni-kl.de> > Datum: Tue, 13 Mar 2012 10:11:22 +0100 > >> The output of uhd_usrp_probe is the following: > > _____________________________________________________ > / > | Device: USRP2 / N-Series Device > | > _____________________________________________________ > | / > | | Mboard: USRP-N210 > | | hardware: 2561 > | | mac-addr: a0:36:fa:25:32:f2 > | | ip-addr: 192.168.10.2 > | | gpsdo: none > | | serial: EFR12W2UP > | | > | | 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: E8R12X9XS > | | | > _____________________________________________________ > | | | / > | | | | 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: E8R12X9XS > | | | > _____________________________________________________ > | | | / > | | | | 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 > > > > I really appreciate any further information. > > Regards > Sebastian > > > On Mon, 12 Mar 2012 11:07:39 -0700 > Jason Abele <jason@ettus.com> wrote: >> Sebastian, >> >> The units displayed in uhd_fft.py are not absolute and >>the XCVR and SBX >> have vastly different absolute gain at a setting of >>"0dB". Thus, they >> are not really comparable at the same gain setting. >> >> If you want to compare them, apply a sine wave of known >>power (say >> -50dBm) and use it to "calibrate" the units in >>uhd_fft.py into dBm. >> >> Then you can compare SBX to XCVR. >> >> Also note that the implicit scale factor in the >>"calibration" performed >> above will vary with gain setting. >> >> If you send your uhd_ffy.py command, it will be easier >>to comment on the >> expected SBX behavior. >> >> It is also helpful to provide the output of >>uhd_usrp_probe such that we >> can see the UHD and hardware versions you are using. >> >> Thanks >> Jason >> >> On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian >>Döring wrote: >>> Hello, >>> >>> I have been doing some spectrum sensing with the USRP >>>N210 and the >>> XCVR2450. >>> Today I tried the same stuff with the SBX daughterboard >>>and suddenly >>> the signal level at the output seems to have an offset >>>of around >>> +20dB. >>> With the XCVR I usually measure a noise level around >>>-100dB and with >>> the SBX I get something around -80dB (both with gain >>>tuned to "0"). >>> >>> My question is, if there's some other gain parameter in >>>the SBX that >>> I can´t control? >>> I used the same antenna and the same USRP. >>> >>> Any hints highly appreciated! >>> >>> Regards >>> Sebastian >>> >>> _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

AP

Andre Puschmann

Wed, Mar 14, 2012 10:21 AM

On 03/14/2012 10:03 AM, Sebastian Döring wrote:

@ steam: UHD version is "UHD_003.004.000-b8e41cb" and FPGA image is the
corresponding one for revision number R2.
@ Nick: I attached 2 figures. The supposed-to-look-like case I get with
XCVR and independent spectrum analyzer and the one I get using the SBX.

Both data sets have been recorded using "uhd_rx_cfile.py -f 2.4G -N 1024".
I processed the samples with octave performing fft, square magnitude and
translated them to dB level scaled with 20*log10(x).

What rx rate are you using? Have you tried modifying it? I've seen
similar things happening at certain rx rates.

-Andre

-Sebastian

On Tue, 13 Mar 2012 18:25:34 +0100
"steam2009@t-online.de" steam2009@t-online.de wrote:

Out of curiousity what FPGA / UHD version are you using.

Von: "Sebastian Döring" sdoering@rhrk.uni-kl.de
Datum: Tue, 13 Mar 2012 10:11:22 +0100

The output of uhd_usrp_probe is the following:

I really appreciate any further information.

Regards
Sebastian

On Mon, 12 Mar 2012 11:07:39 -0700
Jason Abele jason@ettus.com wrote:

Sebastian,

The units displayed in uhd_fft.py are not absolute and the XCVR and SBX
have vastly different absolute gain at a setting of "0dB". Thus, they
are not really comparable at the same gain setting.

If you want to compare them, apply a sine wave of known power (say
-50dBm) and use it to "calibrate" the units in uhd_fft.py into dBm.

Then you can compare SBX to XCVR.

Also note that the implicit scale factor in the "calibration" performed
above will vary with gain setting.

If you send your uhd_ffy.py command, it will be easier to comment on the
expected SBX behavior.

It is also helpful to provide the output of uhd_usrp_probe such that we
can see the UHD and hardware versions you are using.

Thanks
Jason

On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian Döring wrote:

Hello,

I have been doing some spectrum sensing with the USRP N210 and the
XCVR2450.
Today I tried the same stuff with the SBX daughterboard and suddenly
the signal level at the output seems to have an offset of around
+20dB.
With the XCVR I usually measure a noise level around -100dB and with
the SBX I get something around -80dB (both with gain tuned to "0").

My question is, if there's some other gain parameter in the SBX that
I can´t control?
I used the same antenna and the same USRP.

Any hints highly appreciated!

Regards
Sebastian

USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

--
Andre Puschmann
Ilmenau University of Technology, Integrated Communication Systems Group
Phone: +49 3677 69-4132, Fax: +49 3677 69-1614
Email: andre.puschmann@tu-ilmenau.de, Web: http://www.tu-ilmenau.de/ics
Office: Zuse Building, room 1071

On 03/14/2012 10:03 AM, Sebastian Döring wrote: > @ steam: UHD version is "UHD_003.004.000-b8e41cb" and FPGA image is the > corresponding one for revision number R2. > @ Nick: I attached 2 figures. The supposed-to-look-like case I get with > XCVR and independent spectrum analyzer and the one I get using the SBX. > > Both data sets have been recorded using "uhd_rx_cfile.py -f 2.4G -N 1024". > I processed the samples with octave performing fft, square magnitude and > translated them to dB level scaled with 20*log10(x). What rx rate are you using? Have you tried modifying it? I've seen similar things happening at certain rx rates. -Andre > > -Sebastian > > > On Tue, 13 Mar 2012 18:25:34 +0100 > "steam2009@t-online.de" <steam2009@t-online.de> wrote: >> Out of curiousity what FPGA / UHD version are you using. >> >> >> Von: "Sebastian Döring" <sdoering@rhrk.uni-kl.de> >> Datum: Tue, 13 Mar 2012 10:11:22 +0100 >> >>> The output of uhd_usrp_probe is the following: >> >> _____________________________________________________ >> / >> | Device: USRP2 / N-Series Device >> | _____________________________________________________ >> | / >> | | Mboard: USRP-N210 >> | | hardware: 2561 >> | | mac-addr: a0:36:fa:25:32:f2 >> | | ip-addr: 192.168.10.2 >> | | gpsdo: none >> | | serial: EFR12W2UP >> | | >> | | 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: E8R12X9XS >> | | | _____________________________________________________ >> | | | / >> | | | | 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: E8R12X9XS >> | | | _____________________________________________________ >> | | | / >> | | | | 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 >> >> >> >> I really appreciate any further information. >> >> Regards >> Sebastian >> >> >> On Mon, 12 Mar 2012 11:07:39 -0700 >> Jason Abele <jason@ettus.com> wrote: >>> Sebastian, >>> >>> The units displayed in uhd_fft.py are not absolute and the XCVR and SBX >>> have vastly different absolute gain at a setting of "0dB". Thus, they >>> are not really comparable at the same gain setting. >>> >>> If you want to compare them, apply a sine wave of known power (say >>> -50dBm) and use it to "calibrate" the units in uhd_fft.py into dBm. >>> >>> Then you can compare SBX to XCVR. >>> >>> Also note that the implicit scale factor in the "calibration" performed >>> above will vary with gain setting. >>> >>> If you send your uhd_ffy.py command, it will be easier to comment on the >>> expected SBX behavior. >>> >>> It is also helpful to provide the output of uhd_usrp_probe such that we >>> can see the UHD and hardware versions you are using. >>> >>> Thanks >>> Jason >>> >>> On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian Döring wrote: >>>> Hello, >>>> >>>> I have been doing some spectrum sensing with the USRP N210 and the >>>> XCVR2450. >>>> Today I tried the same stuff with the SBX daughterboard and suddenly >>>> the signal level at the output seems to have an offset of around >>>> +20dB. >>>> With the XCVR I usually measure a noise level around -100dB and with >>>> the SBX I get something around -80dB (both with gain tuned to "0"). >>>> >>>> My question is, if there's some other gain parameter in the SBX that >>>> I can´t control? >>>> I used the same antenna and the same USRP. >>>> >>>> Any hints highly appreciated! >>>> >>>> Regards >>>> Sebastian >>>> >>>> _______________________________________________ >>>> USRP-users mailing list >>>> USRP-users@lists.ettus.com >>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com -- Andre Puschmann Ilmenau University of Technology, Integrated Communication Systems Group Phone: +49 3677 69-4132, Fax: +49 3677 69-1614 Email: andre.puschmann@tu-ilmenau.de, Web: http://www.tu-ilmenau.de/ics Office: Zuse Building, room 1071

SD

Sebastian Döring

Wed, Mar 14, 2012 1:05 PM

On Wed, 14 Mar 2012 11:21:29 +0100
Andre Puschmann andre.puschmann@tu-ilmenau.de wrote:

On 03/14/2012 10:03 AM, Sebastian Döring wrote:

@ steam: UHD version is "UHD_003.004.000-b8e41cb" and
FPGA image is the
corresponding one for revision number R2.
@ Nick: I attached 2 figures. The supposed-to-look-like
case I get with
XCVR and independent spectrum analyzer and the one I get
using the SBX.

Both data sets have been recorded using "uhd_rx_cfile.py
-f 2.4G -N 1024".
I processed the samples with octave performing fft,
square magnitude and
translated them to dB level scaled with 20*log10(x).

What rx rate are you using? Have you tried modifying it?
I've seen
similar things happening at certain rx rates.

-Andre

Yes, tried it and always had the same effect.
Also tried it with the WBX by now --> same distortion.

-Sebastian

On Tue, 13 Mar 2012 18:25:34 +0100
"steam2009@t-online.de" steam2009@t-online.de wrote:

Out of curiousity what FPGA / UHD version are you using.

Von: "Sebastian Döring" sdoering@rhrk.uni-kl.de
Datum: Tue, 13 Mar 2012 10:11:22 +0100

The output of uhd_usrp_probe is the following:

/
| Device: USRP2 / N-Series Device
|

I really appreciate any further information.

Regards
Sebastian

On Mon, 12 Mar 2012 11:07:39 -0700
Jason Abele jason@ettus.com wrote:

Sebastian,

The units displayed in uhd_fft.py are not absolute and
the XCVR and SBX
have vastly different absolute gain at a setting of
"0dB". Thus, they
are not really comparable at the same gain setting.

If you want to compare them, apply a sine wave of known
power (say
-50dBm) and use it to "calibrate" the units in
uhd_fft.py into dBm.

Then you can compare SBX to XCVR.

Also note that the implicit scale factor in the
"calibration" performed
above will vary with gain setting.

If you send your uhd_ffy.py command, it will be easier
to comment on the
expected SBX behavior.

It is also helpful to provide the output of
uhd_usrp_probe such that we
can see the UHD and hardware versions you are using.

Thanks
Jason

On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian
Döring wrote:

Hello,

I have been doing some spectrum sensing with the USRP
N210 and the
XCVR2450.
Today I tried the same stuff with the SBX daughterboard
and suddenly
the signal level at the output seems to have an offset
of around
+20dB.
With the XCVR I usually measure a noise level around
-100dB and with
the SBX I get something around -80dB (both with gain
tuned to "0").

My question is, if there's some other gain parameter in
the SBX that
I can´t control?
I used the same antenna and the same USRP.

Any hints highly appreciated!

Regards
Sebastian

USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

--
Andre Puschmann
Ilmenau University of Technology, Integrated
Communication Systems Group
Phone: +49 3677 69-4132, Fax: +49 3677 69-1614
Email: andre.puschmann@tu-ilmenau.de, Web:
http://www.tu-ilmenau.de/ics
Office: Zuse Building, room 1071

On Wed, 14 Mar 2012 11:21:29 +0100 Andre Puschmann <andre.puschmann@tu-ilmenau.de> wrote: > On 03/14/2012 10:03 AM, Sebastian Döring wrote: >> @ steam: UHD version is "UHD_003.004.000-b8e41cb" and >>FPGA image is the >> corresponding one for revision number R2. >> @ Nick: I attached 2 figures. The supposed-to-look-like >>case I get with >> XCVR and independent spectrum analyzer and the one I get >>using the SBX. >> >> Both data sets have been recorded using "uhd_rx_cfile.py >>-f 2.4G -N 1024". >> I processed the samples with octave performing fft, >>square magnitude and >> translated them to dB level scaled with 20*log10(x). > > What rx rate are you using? Have you tried modifying it? >I've seen > similar things happening at certain rx rates. > > -Andre Yes, tried it and always had the same effect. Also tried it with the WBX by now --> same distortion. -Sebastian > > >> >> -Sebastian >> >> >> On Tue, 13 Mar 2012 18:25:34 +0100 >> "steam2009@t-online.de" <steam2009@t-online.de> wrote: >>> Out of curiousity what FPGA / UHD version are you using. >>> >>> >>> Von: "Sebastian Döring" <sdoering@rhrk.uni-kl.de> >>> Datum: Tue, 13 Mar 2012 10:11:22 +0100 >>> >>>> The output of uhd_usrp_probe is the following: >>> >>> _____________________________________________________ >>> / >>> | Device: USRP2 / N-Series Device >>> | >>> _____________________________________________________ >>> | / >>> | | Mboard: USRP-N210 >>> | | hardware: 2561 >>> | | mac-addr: a0:36:fa:25:32:f2 >>> | | ip-addr: 192.168.10.2 >>> | | gpsdo: none >>> | | serial: EFR12W2UP >>> | | >>> | | 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: E8R12X9XS >>> | | | >>> _____________________________________________________ >>> | | | / >>> | | | | 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: E8R12X9XS >>> | | | >>> _____________________________________________________ >>> | | | / >>> | | | | 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 >>> >>> >>> >>> I really appreciate any further information. >>> >>> Regards >>> Sebastian >>> >>> >>> On Mon, 12 Mar 2012 11:07:39 -0700 >>> Jason Abele <jason@ettus.com> wrote: >>>> Sebastian, >>>> >>>> The units displayed in uhd_fft.py are not absolute and >>>>the XCVR and SBX >>>> have vastly different absolute gain at a setting of >>>>"0dB". Thus, they >>>> are not really comparable at the same gain setting. >>>> >>>> If you want to compare them, apply a sine wave of known >>>>power (say >>>> -50dBm) and use it to "calibrate" the units in >>>>uhd_fft.py into dBm. >>>> >>>> Then you can compare SBX to XCVR. >>>> >>>> Also note that the implicit scale factor in the >>>>"calibration" performed >>>> above will vary with gain setting. >>>> >>>> If you send your uhd_ffy.py command, it will be easier >>>>to comment on the >>>> expected SBX behavior. >>>> >>>> It is also helpful to provide the output of >>>>uhd_usrp_probe such that we >>>> can see the UHD and hardware versions you are using. >>>> >>>> Thanks >>>> Jason >>>> >>>> On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian >>>>Döring wrote: >>>>> Hello, >>>>> >>>>> I have been doing some spectrum sensing with the USRP >>>>>N210 and the >>>>> XCVR2450. >>>>> Today I tried the same stuff with the SBX daughterboard >>>>>and suddenly >>>>> the signal level at the output seems to have an offset >>>>>of around >>>>> +20dB. >>>>> With the XCVR I usually measure a noise level around >>>>>-100dB and with >>>>> the SBX I get something around -80dB (both with gain >>>>>tuned to "0"). >>>>> >>>>> My question is, if there's some other gain parameter in >>>>>the SBX that >>>>> I can´t control? >>>>> I used the same antenna and the same USRP. >>>>> >>>>> Any hints highly appreciated! >>>>> >>>>> Regards >>>>> Sebastian >>>>> >>>>> _______________________________________________ >>>>> USRP-users mailing list >>>>> USRP-users@lists.ettus.com >>>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >>> >>> _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >>> >>> >>> >>> _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > -- > Andre Puschmann > Ilmenau University of Technology, Integrated >Communication Systems Group > Phone: +49 3677 69-4132, Fax: +49 3677 69-1614 > Email: andre.puschmann@tu-ilmenau.de, Web: >http://www.tu-ilmenau.de/ics > Office: Zuse Building, room 1071

S

steam2009@t-online.de

Wed, Mar 14, 2012 2:53 PM

Did you have the same issues with 3.2?

Von: "Sebastian Döring" sdoering@rhrk.uni-kl.de
Betreff: Re: [USRP-users] SBX and XCVR Gain
Datum: Wed, 14 Mar 2012 14:05:17 +0100

On 03/14/2012 10:03 AM, Sebastian Döring wrote:

@ steam: UHD version is "UHD_003.004.000-b8e41cb" and
FPGA image is the
corresponding one for revision number R2.

Did you have the same issues with 3.2? Von: "Sebastian Döring" <sdoering@rhrk.uni-kl.de> Betreff: Re: [USRP-users] SBX and XCVR Gain Datum: Wed, 14 Mar 2012 14:05:17 +0100 > On 03/14/2012 10:03 AM, Sebastian Döring wrote: >> @ steam: UHD version is "UHD_003.004.000-b8e41cb" and >>FPGA image is the >> corresponding one for revision number R2.

NF

Nick Foster

Wed, Mar 14, 2012 5:15 PM

Sebastian,

You are seeing the effect of finite tuning time. The N210 will start
returning samples immediately after the tune command, and so you will be
able to observe the SBX/WBX PLL locking on and settling at its final
frequency. You need to discard the first few hundred microseconds of data
after a tune command before you will see reliable data.

--n

On Wed, Mar 14, 2012 at 6:05 AM, Sebastian Döring
sdoering@rhrk.uni-kl.dewrote:

On Wed, 14 Mar 2012 11:21:29 +0100
Andre Puschmann <andre.puschmann@tu-ilmenau.de**> wrote:

On 03/14/2012 10:03 AM, Sebastian Döring wrote:

@ steam: UHD version is "UHD_003.004.000-b8e41cb" and FPGA image is the
corresponding one for revision number R2.
@ Nick: I attached 2 figures. The supposed-to-look-like case I get with
XCVR and independent spectrum analyzer and the one I get using the SBX.

Both data sets have been recorded using "uhd_rx_cfile.py -f 2.4G -N
1024".
I processed the samples with octave performing fft, square magnitude and
translated them to dB level scaled with 20*log10(x).

What rx rate are you using? Have you tried modifying it? I've seen
similar things happening at certain rx rates.

-Andre

Yes, tried it and always had the same effect.
Also tried it with the WBX by now --> same distortion.

-Sebastian

On Tue, 13 Mar 2012 18:25:34 +0100
"steam2009@t-online.de" steam2009@t-online.de wrote:

Out of curiousity what FPGA / UHD version are you using.

Von: "Sebastian Döring" sdoering@rhrk.uni-kl.de
Datum: Tue, 13 Mar 2012 10:11:22 +0100

The output of uhd_usrp_probe is the following:

I really appreciate any further information.

Regards
Sebastian

On Mon, 12 Mar 2012 11:07:39 -0700
Jason Abele jason@ettus.com wrote:

Sebastian,

The units displayed in uhd_fft.py are not absolute and the XCVR and SBX
have vastly different absolute gain at a setting of "0dB". Thus, they
are not really comparable at the same gain setting.

If you want to compare them, apply a sine wave of known power (say
-50dBm) and use it to "calibrate" the units in uhd_fft.py into dBm.

Then you can compare SBX to XCVR.

Also note that the implicit scale factor in the "calibration" performed
above will vary with gain setting.

If you send your uhd_ffy.py command, it will be easier to comment on
the
expected SBX behavior.

It is also helpful to provide the output of uhd_usrp_probe such that we
can see the UHD and hardware versions you are using.

Thanks
Jason

On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian Döring wrote:

Hello,

I have been doing some spectrum sensing with the USRP N210 and the
XCVR2450.
Today I tried the same stuff with the SBX daughterboard and suddenly
the signal level at the output seems to have an offset of around
+20dB.
With the XCVR I usually measure a noise level around -100dB and with
the SBX I get something around -80dB (both with gain tuned to "0").

My question is, if there's some other gain parameter in the SBX that
I can´t control?
I used the same antenna and the same USRP.

Any hints highly appreciated!

Regards
Sebastian

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--
Andre Puschmann
Ilmenau University of Technology, Integrated Communication Systems Group
Phone: +49 3677 69-4132, Fax: +49 3677 69-1614
Email: andre.puschmann@tu-ilmenau.de, Web: http://www.tu-ilmenau.de/ics
Office: Zuse Building, room 1071

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Sebastian, You are seeing the effect of finite tuning time. The N210 will start returning samples immediately after the tune command, and so you will be able to observe the SBX/WBX PLL locking on and settling at its final frequency. You need to discard the first few hundred microseconds of data after a tune command before you will see reliable data. --n On Wed, Mar 14, 2012 at 6:05 AM, Sebastian Döring <sdoering@rhrk.uni-kl.de>wrote: > > > On Wed, 14 Mar 2012 11:21:29 +0100 > Andre Puschmann <andre.puschmann@tu-ilmenau.de**> wrote: > >> On 03/14/2012 10:03 AM, Sebastian Döring wrote: >> >>> @ steam: UHD version is "UHD_003.004.000-b8e41cb" and FPGA image is the >>> corresponding one for revision number R2. >>> @ Nick: I attached 2 figures. The supposed-to-look-like case I get with >>> XCVR and independent spectrum analyzer and the one I get using the SBX. >>> >>> Both data sets have been recorded using "uhd_rx_cfile.py -f 2.4G -N >>> 1024". >>> I processed the samples with octave performing fft, square magnitude and >>> translated them to dB level scaled with 20*log10(x). >>> >> >> What rx rate are you using? Have you tried modifying it? I've seen >> similar things happening at certain rx rates. >> >> -Andre >> > > Yes, tried it and always had the same effect. > Also tried it with the WBX by now --> same distortion. > > -Sebastian > > >> >> >>> -Sebastian >>> >>> >>> On Tue, 13 Mar 2012 18:25:34 +0100 >>> "steam2009@t-online.de" <steam2009@t-online.de> wrote: >>> >>>> Out of curiousity what FPGA / UHD version are you using. >>>> >>>> >>>> Von: "Sebastian Döring" <sdoering@rhrk.uni-kl.de> >>>> Datum: Tue, 13 Mar 2012 10:11:22 +0100 >>>> >>>> The output of uhd_usrp_probe is the following: >>>>> >>>> >>>> ______________________________**_______________________ >>>> / >>>> | Device: USRP2 / N-Series Device >>>> | ______________________________**_______________________ >>>> | / >>>> | | Mboard: USRP-N210 >>>> | | hardware: 2561 >>>> | | mac-addr: a0:36:fa:25:32:f2 >>>> | | ip-addr: 192.168.10.2 >>>> | | gpsdo: none >>>> | | serial: EFR12W2UP >>>> | | >>>> | | 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: E8R12X9XS >>>> | | | ______________________________**_______________________ >>>> | | | / >>>> | | | | 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: E8R12X9XS >>>> | | | ______________________________**_______________________ >>>> | | | / >>>> | | | | 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 >>>> >>>> >>>> >>>> I really appreciate any further information. >>>> >>>> Regards >>>> Sebastian >>>> >>>> >>>> On Mon, 12 Mar 2012 11:07:39 -0700 >>>> Jason Abele <jason@ettus.com> wrote: >>>> >>>>> Sebastian, >>>>> >>>>> The units displayed in uhd_fft.py are not absolute and the XCVR and SBX >>>>> have vastly different absolute gain at a setting of "0dB". Thus, they >>>>> are not really comparable at the same gain setting. >>>>> >>>>> If you want to compare them, apply a sine wave of known power (say >>>>> -50dBm) and use it to "calibrate" the units in uhd_fft.py into dBm. >>>>> >>>>> Then you can compare SBX to XCVR. >>>>> >>>>> Also note that the implicit scale factor in the "calibration" performed >>>>> above will vary with gain setting. >>>>> >>>>> If you send your uhd_ffy.py command, it will be easier to comment on >>>>> the >>>>> expected SBX behavior. >>>>> >>>>> It is also helpful to provide the output of uhd_usrp_probe such that we >>>>> can see the UHD and hardware versions you are using. >>>>> >>>>> Thanks >>>>> Jason >>>>> >>>>> On Mon, Mar 12, 2012 at 01:51:51PM +0100, Sebastian Döring wrote: >>>>> >>>>>> Hello, >>>>>> >>>>>> I have been doing some spectrum sensing with the USRP N210 and the >>>>>> XCVR2450. >>>>>> Today I tried the same stuff with the SBX daughterboard and suddenly >>>>>> the signal level at the output seems to have an offset of around >>>>>> +20dB. >>>>>> With the XCVR I usually measure a noise level around -100dB and with >>>>>> the SBX I get something around -80dB (both with gain tuned to "0"). >>>>>> >>>>>> My question is, if there's some other gain parameter in the SBX that >>>>>> I can´t control? >>>>>> I used the same antenna and the same USRP. >>>>>> >>>>>> Any hints highly appreciated! >>>>>> >>>>>> Regards >>>>>> Sebastian >>>>>> >>>>>> ______________________________**_________________ >>>>>> USRP-users mailing list >>>>>> USRP-users@lists.ettus.com >>>>>> http://lists.ettus.com/**mailman/listinfo/usrp-users_** >>>>>> lists.ettus.com<http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> >>>>>> >>>>> >>>> >>>> ______________________________**_________________ >>>> USRP-users mailing list >>>> USRP-users@lists.ettus.com >>>> http://lists.ettus.com/**mailman/listinfo/usrp-users_**lists.ettus.com<http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> >>>> >>>> >>>> >>>> >>>> ______________________________**_________________ >>>> USRP-users mailing list >>>> USRP-users@lists.ettus.com >>>> http://lists.ettus.com/**mailman/listinfo/usrp-users_**lists.ettus.com<http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> >>>> >>> >>> >>> ______________________________**_________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/**mailman/listinfo/usrp-users_**lists.ettus.com<http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> >>> >> >> >> -- >> Andre Puschmann >> Ilmenau University of Technology, Integrated Communication Systems Group >> Phone: +49 3677 69-4132, Fax: +49 3677 69-1614 >> Email: andre.puschmann@tu-ilmenau.de, Web: http://www.tu-ilmenau.de/ics >> Office: Zuse Building, room 1071 >> > > > ______________________________**_________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/**mailman/listinfo/usrp-users_**lists.ettus.com<http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> >

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SBX and XCVR Gain