Re: [Discuss-gnuradio] sending single tone Am modulated using usrp1+wbx

[Marcus D. Leech]

On 01/04/2013 08:24 PM, José María Valencia wrote:

Hi, I want to transmit and receive a 1kHz cosine tone using dsb am modulation and usrp1 with 2 wbx dbs, I have connected from  tx/rx output  wbx-a to rx2 input wbx-b with a 50ohm sma cable, I’m expecting in scope sink the cosine tone with 1KHz but I have another signal, can you tell me what could be the error?

I’m based on the complex envelope theory:   I=Ac(1+m(t))    Q=0

You can see the diagram and the signals on the attached image.

Thanks.

<<...>>

_______________________________________________
Discuss-gnuradio mailing list
address@hidden
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

So, did you use an attenuator, or did you connect directly?

I suggest that you put in a 30dB attenuator in-line, and carefully adjust both the TX and RX gain until you see the spectral component you need.

Connecting a transmitter directly to a receiver (whether it's a USRP or any other piece of radio equipment) is generally a bad idea -- there's a *strong*
  risk of damaging the front-end of the receiver.  More so when the receiver (such as with WBX) has a low-noise front-end.  So, when you're doing
  laboratory "loopback" tests, you use an attenuator.  The WBX receiver is easily capable of "seeing" extremely weak narrowband signals, so there's
  no reason not to put in a fair amount of attenuation and experiment with gain levels on both the RX and TX side.

-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org