We are trying to implement OFDM point to point link using USRPN210. The frequency used is 2.49GHz. When we used RFX2400 daughter board in transmitter ,it works for rate of 5MHz for a Rx gain of 40dB-50dB. But when we use SBX daughter board(which has variable transmit gain), it doesn't work for 5 MHz rate.We can't even see a spectrum in the reciever.Can someone explain how to adjust the gain for different rates and all other specifications of SBX daughterboard.

The SBX has controllable gain on TX as well as RX. How did you set the gain? Are you able to see anything on an FFT display? Matt On Thu, Dec 13, 2012 at 11:12 PM, Usrp IITM <usrpusers.iitm@gmail.com>wrote: > We are trying to implement OFDM point to point link using USRPN210. The > frequency used is 2.49GHz. When we used RFX2400 daughter board in > transmitter ,it works for rate of 5MHz for a Rx gain of 40dB-50dB. But when > we use SBX daughter board(which has variable transmit gain), it doesn't > work for 5 MHz rate.We can't even see a spectrum in the reciever.Can > someone explain how to adjust the gain for different rates and all other > specifications of SBX daughterboard. > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >

Hi Matt, We are able to see the spectrum now. There was some small bug. However the carrier is being transmitted by the SBX board. We have a transmit filter that has a notch at DC, so technically the data has no DC component (before being sent to the USRP). The carrier is absent when we use the RFX2400 board to transmit. We are using a centre frequency of 2.49 Ghz and receiving with an RFX2400 board. Please see the attached pictures. RFX2400 TX [image: Inline image 1] *SBX* *TX* [image: Inline image 2] Any suggestion as to why this is happening? -Regards RK On Tue, Dec 18, 2012 at 1:03 PM, Matt Ettus <matt@ettus.com> wrote: > > The SBX has controllable gain on TX as well as RX. How did you set the > gain? Are you able to see anything on an FFT display? > > Matt > > > On Thu, Dec 13, 2012 at 11:12 PM, Usrp IITM <usrpusers.iitm@gmail.com>wrote: > >> We are trying to implement OFDM point to point link using USRPN210. The >> frequency used is 2.49GHz. When we used RFX2400 daughter board in >> transmitter ,it works for rate of 5MHz for a Rx gain of 40dB-50dB. But when >> we use SBX daughter board(which has variable transmit gain), it doesn't >> work for 5 MHz rate.We can't even see a spectrum in the reciever.Can >> someone explain how to adjust the gain for different rates and all other >> specifications of SBX daughterboard. >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >

Hi RK, A few questions to help narrow down the issue: 1. Did you run the calibration utilities on the TX side? (RX side would probably be beneficial too.) http://files.ettus.com/uhd_docs/manual/html/calibration.html Results are stored and selected per daughterboard, so keep that in mind when swapping between the two. 2. Have you had a look at the spectrum when you applied small shifts in the TX centre frequency? Does that spur move consistently with the rest of the OFDM signal? (The odd thing is that it's slightly offset to the left of centre between the two OFDM carriers...) Balint On Tue, Dec 18, 2012 at 3:32 AM, Usrp IITM <usrpusers.iitm@gmail.com> wrote: > Hi Matt, > > We are able to see the spectrum now. There was some small bug. > > However the carrier is being transmitted by the SBX board. We have a > transmit filter that has a notch at DC, so technically the data has no DC > component (before being sent to the USRP). The carrier is absent when we > use the RFX2400 board to transmit. We are using a centre frequency of 2.49 > Ghz and receiving with an RFX2400 board. Please see the attached pictures. > > RFX2400 TX > [image: Inline image 1] > > *SBX* *TX* > > [image: Inline image 2] > Any suggestion as to why this is happening? > > -Regards > RK > > On Tue, Dec 18, 2012 at 1:03 PM, Matt Ettus <matt@ettus.com> wrote: > >> >> The SBX has controllable gain on TX as well as RX. How did you set the >> gain? Are you able to see anything on an FFT display? >> >> Matt >> >> >> On Thu, Dec 13, 2012 at 11:12 PM, Usrp IITM <usrpusers.iitm@gmail.com>wrote: >> >>> We are trying to implement OFDM point to point link using USRPN210. The >>> frequency used is 2.49GHz. When we used RFX2400 daughter board in >>> transmitter ,it works for rate of 5MHz for a Rx gain of 40dB-50dB. But when >>> we use SBX daughter board(which has variable transmit gain), it doesn't >>> work for 5 MHz rate.We can't even see a spectrum in the reciever.Can >>> someone explain how to adjust the gain for different rates and all other >>> specifications of SBX daughterboard. >>> >>> >>> _______________________________________________ >>> 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 > >

1. Did you run the calibration utilities on the TX side? (RX side
would probably be beneficial too.)
http://files.ettus.com/uhd_docs/manual/html/calibration.html
Results are stored and selected per daughterboard, so keep that in
mind when swapping between the two.

1. Have you had a look at the spectrum when you applied small shifts
in the TX centre frequency? Does that spur move consistently with the rest
of the OFDM signal? (The odd thing is that it's slightly offset to the left
of centre between the two OFDM carriers...)

On Tue, Dec 18, 2012 at 11:17 PM, Balint Seeber <balint.seeber@ettus.com>wrote: > Hi RK, > > A few questions to help narrow down the issue: > > 1. Did you run the calibration utilities on the TX side? (RX side > would probably be beneficial too.) > http://files.ettus.com/uhd_docs/manual/html/calibration.html > Results are stored and selected per daughterboard, so keep that in > mind when swapping between the two. > > We ran the calibration tests for both the transmitter and the receiver. > > 1. Have you had a look at the spectrum when you applied small shifts > in the TX centre frequency? Does that spur move consistently with the rest > of the OFDM signal? (The odd thing is that it's slightly offset to the left > of centre between the two OFDM carriers...) > > I observed it too, I have to check this. Will post the results in the morning. BTW, > Balint > > > On Tue, Dec 18, 2012 at 3:32 AM, Usrp IITM <usrpusers.iitm@gmail.com>wrote: > >> Hi Matt, >> >> We are able to see the spectrum now. There was some small bug. >> >> However the carrier is being transmitted by the SBX board. We have a >> transmit filter that has a notch at DC, so technically the data has no DC >> component (before being sent to the USRP). The carrier is absent when we >> use the RFX2400 board to transmit. We are using a centre frequency of 2.49 >> Ghz and receiving with an RFX2400 board. Please see the attached pictures. >> >> RFX2400 TX >> [image: Inline image 1] >> >> *SBX* *TX* >> >> [image: Inline image 2] >> Any suggestion as to why this is happening? >> >> -Regards >> RK >> >> On Tue, Dec 18, 2012 at 1:03 PM, Matt Ettus <matt@ettus.com> wrote: >> >>> >>> The SBX has controllable gain on TX as well as RX. How did you set the >>> gain? Are you able to see anything on an FFT display? >>> >>> Matt >>> >>> >>> On Thu, Dec 13, 2012 at 11:12 PM, Usrp IITM <usrpusers.iitm@gmail.com>wrote: >>> >>>> We are trying to implement OFDM point to point link using USRPN210. >>>> The frequency used is 2.49GHz. When we used RFX2400 daughter board in >>>> transmitter ,it works for rate of 5MHz for a Rx gain of 40dB-50dB. But when >>>> we use SBX daughter board(which has variable transmit gain), it doesn't >>>> work for 5 MHz rate.We can't even see a spectrum in the reciever.Can >>>> someone explain how to adjust the gain for different rates and all other >>>> specifications of SBX daughterboard. >>>> >>>> >>>> _______________________________________________ >>>> 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 >> >> >

1. Did you run the calibration utilities on the TX side? (RX side
would probably be beneficial too.)
http://files.ettus.com/uhd_docs/manual/html/calibration.html
Results are stored and selected per daughterboard, so keep that in
mind when swapping between the two.

1. Have you had a look at the spectrum when you applied small shifts
in the TX centre frequency? Does that spur move consistently with the rest
of the OFDM signal? (The odd thing is that it's slightly offset to the left
of centre between the two OFDM carriers...)

The spur is not consistent. For example see the spectrum when fc = 2.49G and 2.46 G. In the 2.46G case, the spur is at the centre of the null sub-carriers, while for the 2.49 case, the spur is slightly towards the left. I have tested this with a couple of SBX boards? Is this a feature;) of the board? Is there any special API (different from rfx2400) for this board? I -RK On Tue, Dec 18, 2012 at 11:54 PM, Usrp IITM <usrpusers.iitm@gmail.com>wrote: > > > On Tue, Dec 18, 2012 at 11:17 PM, Balint Seeber <balint.seeber@ettus.com>wrote: > >> Hi RK, >> >> A few questions to help narrow down the issue: >> >> 1. Did you run the calibration utilities on the TX side? (RX side >> would probably be beneficial too.) >> http://files.ettus.com/uhd_docs/manual/html/calibration.html >> Results are stored and selected per daughterboard, so keep that in >> mind when swapping between the two. >> >> We ran the calibration tests for both the transmitter and the receiver. > > >> >> 1. Have you had a look at the spectrum when you applied small shifts >> in the TX centre frequency? Does that spur move consistently with the rest >> of the OFDM signal? (The odd thing is that it's slightly offset to the left >> of centre between the two OFDM carriers...) >> >> I observed it too, I have to check this. Will post the results in the > morning. BTW, > > >> Balint >> >> >> On Tue, Dec 18, 2012 at 3:32 AM, Usrp IITM <usrpusers.iitm@gmail.com>wrote: >> >>> Hi Matt, >>> >>> We are able to see the spectrum now. There was some small bug. >>> >>> However the carrier is being transmitted by the SBX board. We have a >>> transmit filter that has a notch at DC, so technically the data has no DC >>> component (before being sent to the USRP). The carrier is absent when we >>> use the RFX2400 board to transmit. We are using a centre frequency of 2.49 >>> Ghz and receiving with an RFX2400 board. Please see the attached pictures. >>> >>> RFX2400 TX >>> [image: Inline image 1] >>> >>> *SBX* *TX* >>> >>> [image: Inline image 2] >>> Any suggestion as to why this is happening? >>> >>> -Regards >>> RK >>> >>> On Tue, Dec 18, 2012 at 1:03 PM, Matt Ettus <matt@ettus.com> wrote: >>> >>>> >>>> The SBX has controllable gain on TX as well as RX. How did you set the >>>> gain? Are you able to see anything on an FFT display? >>>> >>>> Matt >>>> >>>> >>>> On Thu, Dec 13, 2012 at 11:12 PM, Usrp IITM <usrpusers.iitm@gmail.com>wrote: >>>> >>>>> We are trying to implement OFDM point to point link using USRPN210. >>>>> The frequency used is 2.49GHz. When we used RFX2400 daughter board in >>>>> transmitter ,it works for rate of 5MHz for a Rx gain of 40dB-50dB. But when >>>>> we use SBX daughter board(which has variable transmit gain), it doesn't >>>>> work for 5 MHz rate.We can't even see a spectrum in the reciever.Can >>>>> someone explain how to adjust the gain for different rates and all other >>>>> specifications of SBX daughterboard. >>>>> >>>>> >>>>> _______________________________________________ >>>>> 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 >>> >>> >> >

Hi, On 12/19/2012 06:51 AM, Usrp IITM wrote: > The spur is not consistent. For example see the spectrum when fc = 2.49G > and 2.46 G. In the 2.46G case, the spur is at the centre of the null > sub-carriers, while for the 2.49 case, the spur is slightly towards the > left. did you place the USRPs close to each other and thus, see the oscillator of the second one as a slightly shifted DC component. Bastian

We are placing them about 2.5 meters apart and we are using a TX gain of 35 for SBX and RX gain of 40 for the RFX2400. -RK On Wed, Dec 19, 2012 at 11:32 AM, Bastian Bloessl <bastianbloessl@gmail.com>wrote: > Hi, > > > On 12/19/2012 06:51 AM, Usrp IITM wrote: > >> The spur is not consistent. For example see the spectrum when fc = 2.49G >> and 2.46 G. In the 2.46G case, the spur is at the centre of the null >> sub-carriers, while for the 2.49 case, the spur is slightly towards the >> left. >> > > did you place the USRPs close to each other and thus, see the oscillator > of the second one as a slightly shifted DC component. > > Bastian > > > ______________________________**_________________ > 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> >

Any help please! On Wed, Dec 19, 2012 at 11:53 AM, Usrp IITM <usrpusers.iitm@gmail.com>wrote: > We are placing them about 2.5 meters apart and we are using a TX gain of > 35 for SBX and RX gain of 40 for the RFX2400. > > -RK > > > On Wed, Dec 19, 2012 at 11:32 AM, Bastian Bloessl < > bastianbloessl@gmail.com> wrote: > >> Hi, >> >> >> On 12/19/2012 06:51 AM, Usrp IITM wrote: >> >>> The spur is not consistent. For example see the spectrum when fc = 2.49G >>> and 2.46 G. In the 2.46G case, the spur is at the centre of the null >>> sub-carriers, while for the 2.49 case, the spur is slightly towards the >>> left. >>> >> >> did you place the USRPs close to each other and thus, see the oscillator >> of the second one as a slightly shifted DC component. >> >> Bastian >> >> >> ______________________________**_________________ >> 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> >> > >