Yeah got it! But don't you think the tool has those capabilities to consider the entire chain and then display the output? Since I don't have actual spectrum analyzer in the lab I am forced to use the software spectrum analyzer.
The initial phase is to first confirm that the transmit and receive are proper enough to comprehend the results. I can send a table of input voltages and gains that I set and the results that I observed. I would atleast expect that given the same numbers as input , the results do not vary beyond a certain margin. That way I can declare / set that my channel of interest has passed the loop back test of transmission and reception! I am only confused that the results do not match the expected values as per path loss, power transmitted and gain equation or it could be that I am not looking the right way! regards Nirmala > > > > > On 2017-10-18 12:29, Nirmala Soundararajan via USRP-users wrote: > > Hi Marcus, > > I made a simple model using Matlab Simulink and used spectrum analyser > block to observe the transmitted and received waveform. Since 0 dbm was > the maximum input power, I just calculated (input volatge)^2 / 2. It comes > to 0.045V. I specified block parameters and gave different values. > Actually with 0 gain of transmitter and receiver I was getting -97 to > -105 dbm for the same input voltage 45mV. > > regards > > Nirmala > > On Wed, Oct 18, 2017 at 3:03 AM, Neel Pandeya via USRP-users < > usrp-users@lists.ettus.com> wrote: > >> Also note that at 0 dBm, you're at the maximum safe input power, so your >> received signal might be saturated. >> >> --Neel Pandeya >> >> >> On Oct 17, 2017 22:30, "Marcus D. Leech via USRP-users" < >> usrp-users@lists.ettus.com> wrote: >> >> On 10/18/2017 12:08 AM, Nirmala Soundararajan via USRP-users wrote: >> >>> Hi all, >>> >>> I am trying to transmit and receive a simple 10 kHz tone using a single >>> USRP B205mini-i. The input power is 0 dbm ( The amplitude of 10kHz tone >>> being 45mV). The transmitting and receiver antenna are same omnidirectional >>> type each having 3 dbi gain. I set the transmitter gain as 8 and receiver >>> gain as 70. The carrier frequency is around 800 MHz. The path loss comes to >>> around 20 db considering the fact that transmitting and receiving antenna >>> are just a foot apart. ( I took far field and did not consider near field) >>> >>> The received spectrum shows -26 dbm. How should I interpret these >>> results? >>> >>> regards >>> >>> Nirmala >>> >>> How did you get -26dBm? >> >> Unless you have painstakingly *calibrated* your USRP B205mini, and wrote >> code that converts the received data into dBm, given your carefully-derived >> calibration tables, an FFT will simply show received power relative to >> the mathematical maximum in the system. >> >> Further, given that modulating signals in the SDR world are purely >> digital number, how did you derive a figure of 45mV of modulation? >> >> >> >> _______________________________________________ >> 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 > >
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