On 11/24/11 3:38 AM, Attila Kinali wrote:
On Thu, 24 Nov 2011 11:19:37 +0000 Poul-Henning Kamp<p...@phk.freebsd.dk> wrote:Has any of you played with this: http://www.sparkfun.com/products/8238I 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
A typical spaceflight multiband design has a LNA and wideband filter up front (500MHz) followed by 3 parallel chains of filters and amps followed by a single bit quantizer. You might be able to find those ceramic filter based filters, which are reasonably small (Lark Engineering and others make these). If it was a full custom, the filters might cost a bit in NRE, but since others are also doing GPS, it might be a stock item.
There's an ION paper from earlier this year by Courtney Duncan that describes our receiver.
: Duncan, C.B., Robison, D.E., Koelewyn, C. Lee, "Software Defined GPS Receiver for International Space Station," Proceedings of the 2011 International Technical Meeting of The Institute of Navigation, San Diego, CA, January 2011, pp. 982-988.
http://trs-new.jpl.nasa.gov/dspace/handle/2014/41781 http://hdl.handle.net/2014/41781 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
