Re: [Discuss-gnuradio] Noise levels from a RTL dongle

[Mark McCarron]

Replace the low pass filter with a band pass filter.  The low pass filter is not extracting the signal at the center frequency, but the first 70KHz of the 1MHz bandwidth.  Also, the decimation and interpolation chosen in the resampler will destroy all information in the channel.  At the chosen values, the interpolation would be essentially inventing the signal, rather than upsampling it.

Regards,

Mark McCarron

---

Date: Fri, 24 May 2013 15:40:39 -0700
From: address@hidden
To: address@hidden
Subject: [Discuss-gnuradio] Noise levels from a RTL dongle

Hi, I am new to Gnu radio but have it working on Mac OS X 10.8 and am using a E4000 tuner in a usb dongle. I have been experimenting with a Gqrx as well as GRC and am getting mixed results, with Gqrx I can get reasonable quality FM reception on 89.31 Mhz (radio 2 in the UK) with the wide band FM (mono) receiver and a 70Khz filter band. I have tried to replicate this in GRC as I want access to the demodulated signal as a live file (to be fed into a std unix pipe) for onward processing, however, the quality is significantly worse than Gqrx. Can anyone help with my GRC graph. Details are on my site, Woodstercorp.com Any help gratefully received. Alan

---

View this message in context: Noise levels from a RTL dongle
Sent from the GnuRadio mailing list archive at Nabble.com.

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