[time-nuts] L1 and L2 frequencies

Jim Lux jimlux at earthlink.net
Thu Jan 15 05:05:33 UTC 2015


On 1/14/15 1:40 PM, Brooke Clarke wrote:
> 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 measurements.
>
> 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.

Actually, there's L2c available for civil use now, on many satellites.

And L5 is available for civilian use (on fewer satellites than L2c)

L2 has an issue with "safety of life" applications: it's not an 
exclusive allocation, so there's an effort to move L1/L2 to L1/L5




>
> 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.

There's only half a dozen or so L5 satellites so far..

>
> http://www.prc68.com/I/DAGR.shtml#GPSs
>
> Mail_Attachment --
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> http://www.prc68.com/I/DietNutrition.html
> 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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