[time-nuts] Compensating phase differnces in dual frequency GPS receviers?

Peter Monta pmonta at gmail.com
Wed Nov 30 22:56:25 EST 2011


Hi Attila,

> [ L1 / L2 timing differences ]
> How do dual frequency receivers deal with that?

I've also been toying with the idea of an inexpensive dual- or
tri-band GPS SDR, especially since there are now quite a few
satellites emitting L2C, the civil L2 signal.  (Though I'd still like
to try my hand at the fancy L2 semicodeless schemes.)

I think that manufacturers calibrate out the timing differences
between channels (as well as group-delay variations within a channel).
 There must be some remaining error, though, e.g. over temperature,
depending on the filter technology.

ObTimeNuts:  There's an interesting recent thesis on GPS for time and
frequency metrology:

http://www.ptb.de/cms/fileadmin/internet/fachabteilungen/abteilung_4/4.4_zeit_und_frequenz/pdf/Feldmann_2011_Dissertation.pdf

Section 5.1.3 has a few words on exactly this channel-filter-delay
issue.  The author measures a coefficient of 20 ps per degree for a
pair of receivers.

Cheers,
Peter




More information about the time-nuts mailing list