Re: [Discuss-gnuradio] This is nice

[Andrew Davis]

>entirely agnostic about hardware

I thought that was the point of UHD?

Devices like Funcube and even a sound card with high sampling rates
should be considered when designing this framework as they all should
be selectable from a simple source/sink API. They could have
definitions and return sampling rates and such. I'll have to
brainstorm a bit for ideas...

~Andrew

On Thu, Mar 22, 2012 at 6:45 PM, Marcus D. Leech <address@hidden> wrote:
> On 03/22/2012 11:17 AM, Andrew Davis wrote:
>>
>> Right, but I think the idea here is for $20 why not?
>
> Right, for $20.00, why not indeed!  I just didn't want people making
> long-term plans based on something that amounts to
>  a serendipitous accident.
>
> I really don't think doing a UHD driver is the right approach, for reasons
> of maintenance headaches, and support headaches.
>
> But this *does* raise a bigger issue of perhaps needing an abstraction layer
> for "SDR-like" hardware sinks/sources for flow-graphs
>  that could reasonably be entirely agnostic about hardware.  Myself, I have
> a couple of "radio science" applications that try to
>  be agnostic by supported both UHD devices and gr-fcd--but that required two
> separate flow-graphs because there's no reasonable
>  way to abstract that stuff away, which I think is a shortcoming.
>
>
>
>> As far as a driver goes what they have now is a program that starts
>> the thing and tunes it, then reads samples, all of this is already
>> build into the UHD framework. I'm not sure but I would like to make
>> this a UHD compatible USB device. ( Much like the USRP1 )
>>
>> ~Andrew
>>
>> On Thu, Mar 22, 2012 at 11:06 AM,<address@hidden>  wrote:
>>>
>>> I also have a trio on order.  The issues I can see surrounding this
>>> approach
>>> are:
>>>
>>>    o Consumer electronics parts lineups are capricious and
>>> unreliable--the
>>> target device may use the "SDR-capable chip" this month, and next month,
>>> they've found that they can shave $0.35 of off the B.O.M. by going with a
>>> totally different parts line-up they will, even though it will cost them
>>> $50K in engineering costs up front--they sell thousands and thousands a
>>> month.  There are already *TWO* versions of this dongle, one using the
>>> "good" RTL2832U chip, and the other using an Afatech chip (AF9015 or
>>> AF9035). The "magic sauce" that Antti discovered in the RTL2832U chip to
>>> do
>>> "raw samples" is peculiar to the RTL2832U chip, and doesn't necessarily
>>> map
>>> on to other DVB-T digital demod chips on the market.
>>>
>>>
>>>
>>>   o The 28.8MHz master oscillator is a very cheap 100PPM part, which will
>>> produce unpleasant frequency offsets, and phase-noise to match
>>>
>>>
>>>
>>>   o Not sure how good the noise figure is, since there's no LNA in front
>>> of
>>> the E4000 tuner chip.
>>>
>>>
>>>
>>>   o Don't know how they implement re-sampling.  If it's not done right,
>>> then
>>> there'll be nasty aliases in the passband handed to the host
>>>
>>>
>>>
>>> None of these are fatal, but be aware that the approach of "re-purposing"
>>> consumer electronics is fraught with dangers as described above.
>>>
>>>
>>>
>>> -Marcus
>>>
>>>
>>>
>>> On Thu, 22 Mar 2012 10:53:13 -0400, Tom Rondeau wrote:
>>>
>>> Andrew and Sean,
>>>
>>> Glad to hear you both thinking about doing this! Coordinate as you can
>>> and keep us up to date on the progress.
>>>
>>> Tom
>>>
>>>
>>> On Thu, Mar 22, 2012 at 10:45 AM, Nowlan, Sean
>>> <address@hidden>  wrote:
>>>
>>> Funny enough, a coworker mentioned it to me yesterday morning and then it
>>> popped up on discuss-gnuradio. He must have seen it on Reddit as well.
>>>
>>> I have one on order too, and I was also contemplating a GNUradio
>>> driver...
>>> let me know if you want to coordinate.
>>>
>>> Sean
>>>
>>> -----Original Message-----
>>> From: address@hidden
>>> [mailto:address@hidden On
>>> Behalf Of Andrew Davis
>>> Sent: Wednesday, March 21, 2012 9:34 PM
>>> To: David Kierzkowski; address@hidden
>>> Subject: Re: [Discuss-gnuradio] This is nice
>>>
>>> Saw it on Reddit a couple days ago, already have one on order. Then I
>>> might
>>> work on making a GnuRadio driver or something for real-time use.
>>>
>>> On Wed, Mar 21, 2012 at 3:17 AM, David Kierzkowski<address@hidden>
>>> wrote:
>>>
>>> The osmocom guys are using a 20$ USB catv tuner as a RF source in
>>> gnuradio.
>>> 3.2MS/s !
>>>
>>> http://sdr.osmocom.org/trac/wiki/rtl-sdr
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>>
>
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>