On 16/03/2011 1:37 AM, Yan Nie wrote:
On 03/15/11, Alexandru Csete<oz9...@gmail.com> wrote:
On Wed, Mar 16, 2011 at 1:07 AM, Marcus D. Leech<mle...@ripnet.com> wrote:
Dear all,
What is the lowest power of the signal that LFRX can receive?
Really appreciate any of your help
Yan
The LFRX has almost no gain, so you're limited by the noise floor of the
ADC. In the USRP2, you can probably reliably detect
signals down to about -60dBm or so. In the USRP1, you need somewhat more
signal, about -50dBm or so. But those are
ballpark numbers. But it depends on the details, and what kind of signals
you're trying to detect, and whether you want to
demodulate them, or merely detect their presence, etc.
Using a signal generator I could measure the "CW sensitivity" down to
about -90 dBm. Using a 2 kHz filter this produced a tone clear enough
for me to decode morse code. With a tuned vertical antenna ~10 meters
long, I get very good reception of AM broadcasting and ham radio
traffic around 7 MHz. I was using USRP1.
Alex
Really appreciate your reply. The signal that is trying to be detected is
-117dBm, which turns out a larger amplifier is need in my case.
I have another question really need your help: how to corresponds the amplitude
set by program to the Vp-p of the front end output of LFTX? Also the same
question with receiver side, how to corresponds the amplitude to the received
signal Vp-p. The amplitude at transmitter side is set by the program and at
receiver side the amplitude is the one of the signal after DDC.
Really appreciate your help
Yan
The only way to do this is to measure and calibrate. The
USRP+Daughtercard family aren't precision measurement instruments.
There's significant variability in the analog components. So, the only
way to do is to use already-calibrated measurement tools, and construct
your own calibration tables.
_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
