Reply to post: Re: RTFM

Fun fact: GPS uses 10 bits to store the week. That means it runs out... oh heck – April 6, 2019

Matthew1471!

Re: RTFM

Looks like the IS-GPS-200 documents 2 frequencies called L1 and L2. L2 fixes this but is a different frequency : http://www.catb.org/gpsd/hacking.html#y2k1 and https://www.gps.gov/technical/icwg/IS-GPS-200H.pdf (for "frequency")

"1575.42 MHz (10.23 MHz × 154) called L1;

and a second at 1227.60 MHz (10.23 MHz × 120), called L2."

CNAV is wrapped up in L2 but L2 is "pre-operational" and not to be used for critical usage.

L1 C/A (under "Legacy Signals" in Wiki has a section about 10 bits and rollover) is affected. L2C CNAV ("pre-operational") is not (blurb in wiki under "CNAV navigation message" explains increase in bits).

https://en.wikipedia.org/wiki/GPS_signals was also helpful.

Sounds like some newer receivers are on the L2 bandwagon.. but that doesn't mean there isn't a tonne of L1 only devices still around.

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