GPS future plans

[DougPaul]

The DoD has announced plans for future modernization of the GPS signals.

Background:
There are 3 GPS frequencies: L1 (1575 MHz), L2 (1227 MHz), and L5 (1176 MHz) and several codes (types) of signal in use: C/A (civilian), P(Y) (encrypted military). The original transmissions were:
* L1 C/A, P(Y)
* L2 P(Y)
Current consumer GPSes use the L1 C/A signals and the higher accuracy P(Y) was intended for government and military use. However, engineers figured out how to use the L1 P(Y) and the L2 P(Y) together (without knowing the encryption) to increase accuracy for commercial surveying-class operation. (These are called codeless/semi-codeless techniques.)

(Multi-frequency operation allows the receiver to measure the ionospheric delay and remove the largest source of error from GPS surveying.)

Synopsis of plans:
The plans are to add another frequency, L5 and modernized signals L1C and L2C (better civilian signals) by 2020 and remove the guarantee of the availability of the P(Y) signals.

Effect on users:
* The L1 C/A signal will not be changed, so your current consumer GPSRs should be unaffected. (In fact, the transmission power of this signal will be increased which may help in weak signal areas.)
* The L1C, L2C, and L5 signals will certainly be useful to surveyors, but they may have to replace expensive equipment. (The old equipment may not be upgradeable and may become expensive junk if the P(Y) signals become unavailable.)
* I don't know if the new L1C, L2C, and L5 signals will be usable in low-cost consumer GPSRs.

Refs:
http://edocket.access.gpo.gov/2008/E8-11148.htm
http://sc.gpsworld.com/gpssc/S&C+Ne...Article/detail/521868?contextCategoryId=25249
http://groups.google.fr/group/sci.geo.satellite-nav/browse_thread/thread/6d03df70035e20e1

Doug

 

[Papa Bear]

What about the European and other non-US systems. I've heard they are coming on-line and may improve reception and accuracy of a new generation of consumer GPSrs

 

[DougPaul]

What about the European and other non-US systems. I've heard they are coming on-line and may improve reception and accuracy of a new generation of consumer GPSrs

None (except possibly Russian Glonass*) are currently operational.

* IIRC, Glonass does not have a full constellation in orbit, but the Russians are actively launching more satellites.

The European Galileo community has been blowing smoke in their advertisements. They have been comparing projected future performance with the current US GPS performance, carefully neglecting the planned improvements in GPS. In actually, their projected future performance is about the same as the projected future GPS performance. Their signal design has been coordinated with the design of the GPS signals so the two satellite constellations will augment each other.

Galileo has also had funding problems**--they are now on plan 2 and do not yet have any operational satellites in orbit. (They might have one experimental satellite in orbit, but I haven't been following it in detail.) I'm not holding my breath.

** And problems justifying duplicating the US GPS system. Thus the smoke.


PB: You may have to keep carrying your metal detector for a while yet...

Doug