[time-nuts] SDR GPS

[Attila Kinali]

On Thu, 24 Nov 2011 11:19:37 +0000
Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> Has any of you played with this:
> 
> 	http://www.sparkfun.com/products/8238

I had a look at this (and a few other GPS SDR solutions) back a year
or two ago and decided that they are either way too expensive or
do not lend themselves well for time-nutty experimentation and are
still too expensive.

I guesstimate that a L1 GPS SDR receiver (SAW filter + LNA + down mixer +
filter + second downmixer + filter + 8bit 40MHz ADC + FPGA) could be
build with a budget of 500CHF at single pieces, rivaling the price of
the sparkfun device you mentioned, while being 1) fully documented
and 2) could lend itself to tinkering.
Hence i dont think it's worth buying such a device (unless you are a
software only guy who sees hardware as a necessary evil).

An L1 + L2 receiver should be not that much more expenive, but the
availability of filters for the L2 range is bad (you'd have to build
one in microstrips) and depending on the exact design of the IF stage
you'd have to doublicate the L1 path earlier or later for the L2 path.
Hence i gues, a L1 + L2 reciever should have an additional cost of
100-200CHF (to the L1 only receiver)

			Attila Kinali


-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
		-- Tirin, The Dispossessed, U. Le Guin