The real problem with this thing

Gary Lawrence Murphy garym at teledyn.com
Tue Aug 14 03:39:14 UTC 2012


so it is *designed* for FM?  That's encouraging because mostly that is all
I really need from it, only all my experiments so far have yielded only
AM-quality sound, but it's good to hear because it means there's *hope* and
so I'll just keep hanging in there until an FM recipe surfaces :)

On Mon, Aug 13, 2012 at 7:58 PM, Adam Nielsen <a.nielsen at shikadi.net> wrote:

> This clumsy Analog to Digital Converter / USB
>> interface Chip, does not have the Audio dynamic range needed for my
>> purposes.
>>
>
> That's because it's only designed for FM radio.  Anything more would have
> been overkill for the manufacturer's purposes.  This is still excellent
> value for $20 and hasn't been much of a stumbling block for what most
> people have been doing so far.
>
>  The infuriating predilection it has to crash every time you want
>> to shift frequency is another disadvantage.
>>
>
> I'm not sure where you're looking in the docs, but if you're using
> Balint's USRP ExtIO (as oppposed to the - I think - Osmocom ExtIO) then
> there are two sets of code for the tuner.  The default one offers slightly
> wider frequency range, but crashes as you have seen.  If you add
> "tuner=e4k" to the device hint then it will switch to the newer code, which
> doesn't crash, at the expense of having some gaps in the frequency coverage.
>
>  First, I attached a high gain audio amplifier's input directly to the
>> Tuner's output then to a 96K Sample per Second, 24 Bit Audio card to
>> observe
>> a high quality spectral image from the tuner.
>>
>
> Presumably this reduces your bandwidth from 3.2MHz to 96kHz, which is
> 24kHz too low to properly receive wideband/consumer FM radio.  Since many
> people are using the RTLSDR has a kind of glorified RF scanner, I am
> wondering whether you're trying to do something you really should be doing
> on a high end device like the USRP?
>
>  Next is to hack into and record the I2C sent to the Tuner, so it may be
>> controlled independent of that infuriating RTL2832. If anyone has done
>> this,
>> please share your code and understanding.
>>
>
> Don't quote me on this but AFAIK the RTL just passes the I2C commands
> through unchanged.  This is how the existing E4000 tuner code was able to
> be adapted to the RTL2832 so quickly.
>
> This list probably isn't the best place to ask about this sort of thing -
> it's mostly developers focused on improving the hardware rather than
> getting people started with it.  I strongly recommend switching to the
> ultra-cheap-sdr list[1] instead, which has many more people able to help
> beginners.  Your question about the device crashing is answered quite
> often, for example. These people can also point you to the many 'getting
> started' guides, which do explain clearly with screenshots where to put
> device hints and the like.
>
> Cheers,
> Adam.
>
> [1] https://groups.google.com/d/**forum/ultra-cheap-sdr<https://groups.google.com/d/forum/ultra-cheap-sdr>(you can subscribe via e-mail here if you don't want to use the web
> interface)
>
>


-- 
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