LFRX-LF Rev 2.2 troubles

I am attempting to use this receiver to analyze signals in the AM/FM
bands. However, I have had no such luck.
Since the sound card is not working on my machine I cannot attempt to
output to the sound card.

Here are some of commands I have tried:

FFT centered near a known FM station at 89.7MHz

./usrp_fft.py -R B -f 89M

results: mostly -30dB noise in the window of +/-2.0MHz with a peak of

-5dB at the center frequency.

usrp_wfm_rcv.py -R B -f 89M
#similar results

Has anyone else experienced this?
Thanks in advance!
Rana

On Thu, Feb 28, 2008 at 04:54:59PM +0100, Rana B. wrote:

-5dB at the center frequency.

usrp_wfm_rcv.py -R B -f 89M
#similar results

Has anyone else experienced this?
Thanks in advance!
Rana

The LFRX only covers 0 to 30 MHz.

Eric

Good point. However, we have the same issue in the AM band on the LFRX
and in the 2.4G range with the RFX2400.
i.e.:
python ./gr-utils/src/python/usrp_fft.py -R B -f 1.44M -d 128
#produces the same results in AM

Moreover, we are not able to detect any transmitting devices with the
USRP.

Eric B. wrote:

The LFRX only covers 0 to 30 MHz.

Eric

Have you tried using coax to isolate the problem?

  • George

ahhh sorry, wrong thread.

On Thu, Feb 28, 2008 at 06:51:45PM +0100, Rana B. wrote:

The LFRX only covers 0 to 30 MHz.

Eric

What are you using for an antenna?

For the AM band I am not using an antenna.
For the 2.4GHz band I am using a 1/4 wave whip antenna.

Is there a better way to prove that the radio is detecting a signal?

Eric B. wrote:

On Thu, Feb 28, 2008 at 06:51:45PM +0100, Rana B. wrote:

The LFRX only covers 0 to 30 MHz.

Eric

What are you using for an antenna?

Rana B. wrote:

For the AM band I am not using an antenna.

You need to use an antenna.

For the 2.4GHz band I am using a 1/4 wave whip antenna.

You need to use a daughterboard which covers 2.4 GHz.

Matt

You need to use a daughterboard which covers 2.4 GHz.

I am using the RFX2400 board for 2.4 GHz band.

Rana B. wrote:

You need to use a daughterboard which covers 2.4 GHz.

I am using the RFX2400 board for 2.4 GHz band.

What are you using to generate a signal for it?

Matt

The problem was traced to the RFX2400 board that we were using. We
didn’t realize that the RFX2400 was crossed with a black pen and it was
marked 1200. As for the LFRX, the USRP_fft.py detects when the signal is
generated by another USRP board. But I was trying to capture local AM
station signals using that and it never worked. We have couple of AM
stations very close (less than 1 mile). They also did not register in
the USRP fft.