# TX characterisation of USRPN210 with SBX daughterboard **URL:** \ **Category:** GNU Radio\ **Created:** [March 24, 2014, 5:57am UTC](https://www.ruby-forum.com/t/tx-characterisation-of-usrpn210-with-sbx-daughterboard/239997 "2014-03-24T05:57:13Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\ **Post date:** [March 24, 2014, 5:57am UTC](https://www.ruby-forum.com/t/tx-characterisation-of-usrpn210-with-sbx-daughterboard/239997/1 "2014-03-24T05:57:13Z")
Hi, I am trying to characterize the TX and RX characteristics of USRPN210 with a SBX board. I have tried one test : Amplitude Variation effects, by varying the amplitude in steps and finding out the o/p power through spectrum analyser. The foll are the readings I got. Amplitude level 921.25 MHz 2.45625 GHz 0.0625 -49.18 -60.97 0.125 -43.2 -55.05 0.25 -37.25 -49.09 0.5 -31.24 -43.05 1 -25.38 -37.13 Amplitude change 921MHz 2.456GHz 1 to 0.5 5.86 5.92 0.5 to 0.25 6.01 6.04 0.25 to 0.125 5.95 5.96 0.125 to 0.0625 5.98 5.92 when i ploted the graph in excel, (O/p power Vs amplitude), i got two almost linear curves, but their was a big difference in the 2 lines @ 921.25 MHz and 2.45625 GHz (as seen above) at the start and if extrapolated could converge at a higher ampl and o/p power. I was not sure about my results and was looking to see if some one could let me know if these values look within the normal expected behaviour? if not, please let me know what is the normal expected behaviour. I am new to USRP and GRC programming and doing this for a project. [http://gnuradio.4.n7.nabble.com/file/n47157/Oppower\_vs\_ampli.png](http://gnuradio.4.n7.nabble.com/file/n47157/Oppower_vs_ampli.png) Thanks in advance – View this message in context: [http://gnuradio.4.n7.nabble.com/TX-characterisation-of-USRPN210-with-SBX-daughterboard-tp47157.html](http://gnuradio.4.n7.nabble.com/TX-characterisation-of-USRPN210-with-SBX-daughterboard-tp47157.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Gayathri\_Ramasubram](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/9fc29f/32.png) [@Gayathri\_Ramasubram](https://www.ruby-forum.com/u/Gayathri_Ramasubram)\ **Post date:** [March 24, 2014, 4:23pm UTC](https://www.ruby-forum.com/t/tx-characterisation-of-usrpn210-with-sbx-daughterboard/239997/2 "2014-03-24T16:23:03Z")
On 03/24/2014 05:56 AM, Gayathri Ramasubramanian wrote: > I am trying to characterize the TX and RX characteristics of USRPN210 > with a SBX board. I have tried one test : Amplitude Variation > effects, by varying the amplitude in steps and finding out the o/p > power through spectrum analyser. The foll are the readings I got. > Amplitude level 921.25 MHz 2.45625 GHz 0.0625 -49.18 -60.97 0.125 > -43.2 -55.05 0.25 -37.25 -49.09 0.5 -31.24 -43.05 1 -25.38 -37.13 > Amplitude change 921MHz 2.456GHz 1 to 0.5 5.86 5.92 0.5 to 0.25 6.01 > 6.04 0.25 to 0.125 5.95 5.96 0.125 to 0.0625 5.98 5.92 Gayathri, how did you measure? Did you use an antenna, or cable connection to the spectrum analyzer? Also, what were your gain settings? And your tx signal? Martin ---
**Author:** ![Gayathri\_Ramasubram](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/9fc29f/32.png) [@Gayathri\_Ramasubram](https://www.ruby-forum.com/u/Gayathri_Ramasubram)\ **Post date:** [March 24, 2014, 5:45pm UTC](https://www.ruby-forum.com/t/tx-characterisation-of-usrpn210-with-sbx-daughterboard/239997/3 "2014-03-24T17:45:32Z")
Hi Martin Thanks for looking into my post. I used a cable to connect to the spectrum analyzer ( united microflex 150 with 15 db/ft attenuation, my cable length was 1 ft). However before connecting to the spectrum analyzer, I had an attenuator set to 50 dB. These readings were taken with a gain set to zero. I used _tx\_waveforms_program provided in the examples with: BB freq: 6.25MHz Sampling rate : 13 MHz I just varied my amplitude in these steps. Thanks Gayathri On Mar 24, 2014, at 11:22 AM, “Martin B.-2 [via GnuRadio]” \< [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)\> wrote: On 03/24/2014 05:56 AM, Gayathri Ramasubramanian wrote: > I am trying to characterize the TX and RX characteristics of USRPN210 > with a SBX board. I have tried one test : Amplitude Variation > effects, by varying the amplitude in steps and finding out the o/p > power through spectrum analyser. The foll are the readings I got. > Amplitude level 921.25 MHz 2.45625 GHz 0.0625 -49.18 -60.97 0.125 > -43.2 -55.05 0.25 -37.25 -49.09 0.5 -31.24 -43.05 1 -25.38 -37.13 > Amplitude change 921MHz 2.456GHz 1 to 0.5 5.86 5.92 0.5 to 0.25 6.01 > 6.04 0.25 to 0.125 5.95 5.96 0.125 to 0.0625 5.98 5.92 Gayathri, how did you measure? Did you use an antenna, or cable connection to the spectrum analyzer? Also, what were your gain settings? And your tx signal? Martin > when i ploted the graph in excel, (O/p power Vs amplitude), i got two > almost linear curves, but their was a big difference in the 2 lines @ > 921.25 MHz and 2.45625 GHz (as seen above) at the start and if > extrapolated could converge at a higher ampl and o/p power. I was not > sure about my results and was looking to see if some one could let me > know if these values look within the normal expected behaviour? if > not, please let me know what is the normal expected behaviour. I am > new to USRP and GRC programming and doing this for a project. * * * Discuss-gnuradio mailing list [hidden email] [http://user/SendEmail.jtp?type=node&node=47161&i=0](http://user/SendEmail.jtp?type=node&node=47161&i=0) > **[Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio)** * * * If you reply to this email, your message will be added to the discussion below: [http://gnuradio.4.n7.nabble.com/TX-characterisation-of-USRPN210-with-SBX-daughterboard-tp47157p47161.html](http://gnuradio.4.n7.nabble.com/TX-characterisation-of-USRPN210-with-SBX-daughterboard-tp47157p47161.html) To unsubscribe from TX characterisation of USRPN210 with SBX daughterboard, click here[http://gnuradio.4.n7.nabble.com/template/NamlServlet.jtp?macro=unsubscribe\_by\_code&node=47157&code=Z3JhbWFzdWJAdnQuZWR1fDQ3MTU3fDEzNjkyOTkyNzY=](http://gnuradio.4.n7.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=47157&code=Z3JhbWFzdWJAdnQuZWR1fDQ3MTU3fDEzNjkyOTkyNzY=) . NAML[http://gnuradio.4.n7.nabble.com/template/NamlServlet.jtp?macro=macro\_viewer&id=instant\_html!nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify\_subscribers!nabble%3Aemail.naml-instant\_emails!nabble%3Aemail.naml-send\_instant\_email!nabble%3Aemail.naml](http://gnuradio.4.n7.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml) ---
**Author:** ![Gayathri\_Ramasubram](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/9fc29f/32.png) [@Gayathri\_Ramasubram](https://www.ruby-forum.com/u/Gayathri_Ramasubram)\ **Post date:** [March 24, 2014, 8:48pm UTC](https://www.ruby-forum.com/t/tx-characterisation-of-usrpn210-with-sbx-daughterboard/239997/4 "2014-03-24T20:48:39Z")
The graph doesn’t match your numbers. Ron ---
**Author:** ![Gayathri\_Ramasubram](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/9fc29f/32.png) [@Gayathri\_Ramasubram](https://www.ruby-forum.com/u/Gayathri_Ramasubram)\ **Post date:** [March 25, 2014, 12:32pm UTC](https://www.ruby-forum.com/t/tx-characterisation-of-usrpn210-with-sbx-daughterboard/239997/5 "2014-03-25T12:32:11Z")
On 03/24/2014 05:44 PM, Gayathri Ramasubramanian wrote: > Thanks for looking into my post. > I used a cable to connect to the spectrum analyzer ( united microflex > 150 with 15 db/ft attenuation, my cable length was 1 ft). However before > connecting to the spectrum analyzer, I had an attenuator set to 50 dB. > These readings were taken with a gain set to zero. I used _tx\_waveforms_ > program provided in the examples with: > BB freq: 6.25MHz > Sampling rate : 13 MHz BTW, that’s an unusual sampling rate… are you running off of your own clock? Still, the differences are pretty big. I’m not surprised to see less for the higher frequency, but the magnitude does surprise me. > I just varied my amplitude in these steps. Can you play around with the gain (say, set it to mid-point in dB) and see if the differences are still that big? M