Receiver sensitivity of wbx, TVRX

GNU Radio
1

Hi All,
Guess it has now become a cliche question. but we have been trying to
make a link budget for the usrp and the AO-51 satellite and are looking
for some help finding the receiver sensitivity of either the WBX or the
TVRX. I have seen the discuss GNU radio archives and found like 50
questions about receiver sensitivity but did not find any answer. so if
any of you who have been trying to know the same or do know how it works
can help us get some information about it would be greatly appreciated.
Thanks & Regards,NaveenÂ

2

Hi Naveen,

Ive been using the TVRX for AO-51 and NOAA APT (Automatic Picture
Transmission). I have found that the TVRX is VERY sensitive
I have been able to demodulate signals @ ~-115 dB. I always use a preamp
at the antenna.
My test results can be found here
http://www.poes-weather.com/~patrik/AO-51/
and http://noaaport.poes-weather.com:8081/AO-51/

My TVRX is using Microtune 4937 and the tuner spec can be found at
http://www.comsec.com/usrp/microtune/4937-DI5-3x8899-2.pdf

I have no experience using the WBX.

Patrik
----- Original Message -----
From: naveen nischal
To: [email protected]
Sent: Sunday, July 18, 2010 0:54
Subject: [Discuss-gnuradio] Receiver sensitivity of wbx, TVRX.

    Hi All,


    Guess it has now become a cliche question. but we have been

trying to make a link budget for the usrp and the AO-51 satellite and
are looking for some help finding the receiver sensitivity of either the
WBX or the TVRX. I have seen the discuss GNU radio archives and found
like 50 questions about receiver sensitivity but did not find any
answer. so if any of you who have been trying to know the same or do
know how it works can help us get some information about it would be
greatly appreciated.

    Thanks & Regards,
    Naveen

Discuss-gnuradio mailing list
[email protected]
Discuss-gnuradio Info Page

3

On 07/17/2010 02:54 PM, naveen nischal wrote:

Hi All,

Guess it has now become a cliche question. but we have been trying to
make a link budget for the usrp and the AO-51 satellite and are looking
for some help finding the receiver sensitivity of either the WBX or the
TVRX. I have seen the discuss GNU radio archives and found like 50
questions about receiver sensitivity but did not find any answer. so if
any of you who have been trying to know the same or do know how it works
can help us get some information about it would be greatly appreciated.

The reason you didn’t find an answer is that there is no answer. It’s
kind of like asking what the temperature is without specifying when and
where the measurement is to be taken.

Sensitivity is only a meaningful measurement when you state the type of
modulation, error correction coding, data rate, and acceptable error
rate. 100 kbits/sec will have better sensitivity than 1 Mbit/sec. BPSK
will have better sensitivity than QAM64. Rate 7 convolutional coding
will perform better than hamming code. A required BER of 10e-3 will
have better sensitivity than a required BER of 10e-6.

The ONLY true universal measure of receiver quality is noise figure, and
that is what we measure. If you have all the above info plus the noise
figure, you can calculate the sensitivity.

The TVRX will have a noise figure of 7-10 dB. The WBX noise figure is
shown in great detail vs. frequency and vs. gain in the plots at:

http://code.ettus.com/redmine/ettus/documents/16

At low frequencies the noise figure is 3 dB. At higher frequencies it
rises to about 6 dB.

Matt