[time-nuts] DTV tuner chip usable for GPS front end?

[David]

On Wed, 21 Mar 2012 16:40:27 -0000, "David J Taylor"
<david-taylor at blueyonder.co.uk> wrote:

>> I suppose there is limited interest in homebrew GPS receivers given how 
>> cheap the fully integrated chipsets are. However, just noticed the below 
>> tuner chip intended for DTV, actually lists GPS L1 as an applicable 
>> frequency.  A TV Tuner USB stick using this chip is available for $20, 
>> and some SDR type software is apparently working with it:
>> http://sdr.osmocom.org/trac/wiki/rtl-sdr   Has anyone here played with 
>> this device?
>>
>> from http://www.elonics.com/product.do?id=1
>> "The E4000 is a highly integrated multi band RF tuner IC implemented in 
>> CMOS, ideal for low power digital terrestrial TV and radio broadcast 
>> receiver solutions.  The E4000 contains a single input LNA with RF 
>> filter, whose centre frequency can be programmed over the complete 
>> frequency range from 64MHz to 1700MHz."
>>
>> Broadcast Standards
>>    DVB-T (174-240MHz, 470-854MHz)
>>    ISDB-T (470-862MHz)
>>    DVB-H (470-854MHz, 1672-1678MHz)
>>    CMMB (470-862MHz)
>>    D-TMB (470-862MHz)
>>    T-DMB (174-240MHz, 1452-1492MHz)
>>    DAB (174-240MHz, 1452-1492MHz)
>>    MediaFLO (470-862, 1452-1492MHz)
>>    GPS L1 band (1575MHz)
>>
>> [...]
>
>.. and available ready built here:
>
>  http://www.funcubedongle.com/
>
>but perhaps not fast enough for you.

Or not wide enough in this case.  The FunCube technical FAQ says the
bandwidth is about 80 KHz as it is designed for narrow band reception
only and accessed as a standard USB sound device.  I do not quite
understand how 96 Ksamples/sec yields 80 KHz though:

Q. What is the bandwidth?
A. 96kHz is the quadrature sampling rate. Once the ADC’s decimation
filter skirts have been taken into account, you have about 80kHz.