[time-nuts] L1/L2 GPS Receiver

[Magnus Danielson]

On 17/01/14 19:17, Dennis Ferguson wrote:
>
> On 17 Jan, 2014, at 11:43 , Michael Perrett <mkperrett at gmail.com> wrote:
>> Magnus, I believe that he is referencing the the new L2 C/A code, which is
>> not protected. Reference
>> http://www.gps.gov/systems/gps/modernization/civilsignals/
>
> It would be nice to have a receiver for that when they turn it on, but I
> don't think that's what he wants.  The observables used for PPP processing
> are L1 and L2 carrier phase.  You don't need a receiver capable of decoding
> the P(Y) code but you do need a receiver capable of receiving the full
> bandwidth of its carrier on both L1 and L2 and tracking the phase.
>
> The commercial receivers which do this seem to cost dearly.

The receivers out there use the fact that the known P-code is encrypted 
with a W-code into the Y-code using XOR. Over the years have various 
degrees of advanced methods provided means to measure L1 C/A-code phase, 
L1 P(Y) code phase, L1 carrier phase, L2 P(Y) code phase and L2 carrier 
phase. Some of the earlier receivers only provided a sub-set.

Commercial receivers maintain a high price because they see a less 
price-sensitive market.

Cheers,
Magnus