On Sun, Apr 15, 2012 at 10:50 AM, Farhad Abdolian <address@hidden> wrote: > Hi folks, > Yesterday after a long wait I received my DVB-T unit in the mail (it arrived
> on my birthday). After some initial work, I got it to work with GNU Radio > and GRC and today I made my first working FM receiver using the same blocks > as the video from Ettus Research (building GR FM Radio in 10 minutes).
> > The design is using the Linux driver and the GR blocks made by Balint Seeber > (thanks a million mate). > > I have attached the GRC with this e-mail, hope you find it useful. I am now > going to work on the RTL2832 block to fine tune it (I have the complete
> datasheet) and add more feature to it. > The problem I have is that the signals are not very strong, no matter how > much I change the gain, the signal level is pretty low and the received > audio is pretty noisy. I have managed to sample at 2Msps without any
> problems but when I sample more than that on my laptop, I get a lot of > overflow.
As you may have seen in my on air tests I just posted, I have no problem with low signal levels, however, there is an active hardware AGC which may be causing you troubles. If you have a strong signal in the analog passband of the tuner it will drive the gain down and the weaker signal you are trying to receive will become noisy. You can see that in all 3 videos which show an EzCAP666 with E4000 tuner in action.
I don't know if this AGC is in the RTL chip or the E4000 tuner. I suspect it is in the tuner.