[time-nuts] L1 and L2 frequencies

Brooke Clarke brooke at pacific.net
Wed Jan 14 16:40:30 EST 2015

Hi Martyn:

On each frequency there are a couple or more different codes.
The Civilian Acess (C/A) code on the L1 frequency is all public information and so is the most commonly used.

But there are classified codes that have a much higher bit rate and allow for more accurate position, time and velocity 

Tom mentioned that there are civilian GPS receivers that make use of the L2 frequency, but they do that my using what's 
called carrier phase (that's to say they do not make use of the classified code).  This is mainly used in surveying 
applications where, by recording a lot of data and post processing, you can get a very precise location.

When two frequencies are used there's a possibility of removing an error related to the total electron count in the path 
of the signal.  The new F5 frequency allows for doing that, but as far as I know none of the commercial GPS receivers 
make use of it yet.


Mail_Attachment --
Have Fun,

Brooke Clarke
Martyn Smith wrote:
> Hello,
> I have some questions on GPS and GNSS.
> Do all the civilian GPS receivers only operate on the L1 frequency?
> Are there any GPS frequency standards out there that use L1 and L2 and that can be purchased by non-military customers?
> I am playing with the new Lea-M8T receiver.
> How do I know what satellites are GPS, GLONASS, Galileo etc.
> >From my understanding GLONASS have different SV numbers but not 100% sure.
> Any help appreciated.
> Regards
> Martyn
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