I came across this article indicating a problem with SVN 62/PRN 25, similar to the SVN 49 problem with L1/L2/L5.
Download the article here:
http://trs-new.jpl.nasa.gov/dspace/handle/2014/41917
What seems to be a big future problem is that different clocks will be used for L1/L2 vs. L1/L5.
Does not sound well for the future.
I was checking because I received the following NANU:
NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2012035 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
The U.S. Government is accomplishing an integration assessment of the current software baseline in conjunction with the restoration of M-code signal on SVN 62 (PRN 25) turn-on. There are no planned GPS satellite outages for this activity and the broadcast navigation signal will remain IS-GPS-200 compliant. Any military or civil users who encounter user equipment problems during this period should contact the GPSOC (military) or NAVCEN (civil, non-aviation) as soon as possible or aviation users should file reports consistent with FAA-approved procedures.
*** GENERAL MESSAGE TO ALL GPS USERS ***
POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTP://WWW.NAVCEN.USCG.GOV
MILITARY - GPS OPERATIONS CENTER at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, [email protected], HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3514,
COMM 805-606-3514, [email protected]
Paul in PA
From the PDF :
Who Cares? (and not) about SVN 62
type phase variations?
• L5 carrier phase is not coherent with L1 and L2 phases but same for all
directions for SVN62, varies with angle for SVN49
• This is a problem for
1. Stand Alone Trilaning (navigation within lanes on highway)
2. Data editor programs that rely on coherent carriers
3. Ionospheric science
4. Estimate different clock for L1, L5 than for L1, L2, ISC not frequent
enough to capture ~20 cm cycle over 12 hours
5. …
• This is not a problem for
1. Stand alone users who only use phase to smooth pseudorange over
few hundred seconds
2. High accuracy network users who form differenced observables
(SVN 62 problem cancels, but note SVN 49 carrier variation does NOT
cancel)