[time-nuts] WAAS.....

[Brian, WA1ZMS]

Hal-

Maybe *I* don't understand the WAAS data stream then.  In the case of a common-view single satellite timing "transfer" or calibration like is done every day by NIST, et al., could not a WAAS SVN be used for such an application? I short, my idea was to use just such a fixed common-view single WAAS SVN as the common source of 1PPS. Now if the WAAS data format does not fully replicate a classic GPS satellite, then yes my idea is all hog-wash.

As I said before, usual hold over during jamming events is working fine. But an idealy placed GPS antenna with full 360 degs of azimuth view only helps to hear more RF jamming sources in heavy urban environments. The result is our customers see log files that show sometimes  frequent (say once every 10 days) events where BOTH the active and hot standy by GPS timing receivers go into hold-over from jamming. 

My desire is to try and mitigate the appearence that our critical RF comm systems are of poor quality since there are these hold-over events taking place more often today than say 5 years ago.

We do not build the timing receivers, but we buy brand X. Switching to brand Y as a new vendor and getting them
qualified is painfull. Thus my original thought of trying a narrow beam width fixed antenna aimed at a WAAS satellite to reduce the effective antenna apperature and not "hear" the cars and trucks on the highways with their personal GPS jammers as they drive by  a classic GPS antenna.

Does that help explain it?
Or does WAAS not offer a classic 1PPS signal in it's data stream? I thought it had to in order to offer compatability.


-Brian, WA1ZMS/4
iPhone

On Jan 8, 2014, at 3:50 AM, Hal Murray <hmurray at megapathdsl.net> wrote:

> 
> wa1zms at att.net said:
>> In this case the timing rcvrs are located all with in a 20km radius with
>> fixed known surveyed locations. The problem is GPS jamming that happens at
>> random times. So one "what if" idea is to use a WAAS enabled rcvr and a yet
>> to be selected parabolic antenna to point at a given WAAS sat. The concept
>> is to give all rcvrs a single common view for critcal timing use in a comm
>> system. 
> 
> Either you are trying to do something crazy or I don't understand what you 
> are trying to do.
> 
> The WAAS satellites don't provide timing info.  They provide corrections to 
> the timing a receiver gets from normal GPS satellites.  So if all you can 
> hear is the WAAS satellites, you won't have any timing info to correct.
> 
> How long does the jamming last and how close do your receivers have to track? 
> Can you use normal GPSDO hold-over mechanisms?
> 
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.