Hi,
(Ubuntu 13.04, GNURADIO 3.7)
The snr was determined only by looking at uhd_fft display and making the
difference between the plateau of the signal and the noise floor. The
maximum level I could obtain moving the antenna in the lab close to the
window was between 45dB-50dB and of course it is just a calitative
information only as the USRP was not calibrated for precise
measurements.
On longer term it is necessary that the program itself will measure the
SNR as the OFDM synchronizer uses maximum likelihood algorithm for now
which is dependent on SNR. I’m working on an SNR estimator based on the
pilots that are sent on the OFDM together with the payload and that will
also display the SNR for the end user.
One other SNR measure that is usually employed for characterization of
constellation type of signals is MER (Modulation Error Ratio) which
should be easily added as a gnuradio block.
Bogdan
On Friday, May 9, 2014 12:09 AM, Nasi [email protected] wrote:
you said ‘SNR was above a certain level’.
How much was it?
How did you measure the SNR?
Thu, 8 May 2014 12:46:17 -0700 (PDT) от Bogdan D.
[email protected]:
Hi, I did experiment with real life signals from a local DVB-T
transmitter and it worked when the SNR was above a certain level. That
was with wbx card.
I also experimented with the same signals using a Philips TV room
antenna containing integrated RF amplifier and it actually worsen the
SNR than just VERT900 antenna. When using the highest gain on the
antenna the signal was totally buried in noise. In the end the best
antenna was the small stock antenna that came with rtl2832 stick.
Bogdan
On Thursday, May 8, 2014 10:25 PM, Nasi [email protected] wrote:
Hi Bogdan,
Did you try real TV transmission? Off air reception?
Thu, 8 May 2014 12:22:37 -0700 (PDT) от Bogdan D.
[email protected]:
Hi,
I did not try N200 but I do not think that you’ll be able to use
sampling rate of 9.14msps (which is more precisely 64/7) with N2xx. The
sample rate does not depend on the dautherboard you are using but on the
motherboard.
Bogdan
On Thursday, May 8, 2014 10:08 PM, Nasi via USRP-users
[email protected] wrote:
Hi,
Is it possible to receive directly with a sampling rate of 9.14 Mps for DVB-T?
Or should I resample it from 10 Mps? I was resampling with daughterboard XRCV 2450
since it cannot produce 9.14 Mps.Is it possible at all to get off air TV boadcasting using above equipment?
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