
Brian, WA1ZMS  wrote:
> In my case, SW masking of hold-over alarms may be a shorter fix without any HW fixes. 

If you can mask short-duration alarms while still finding out about persistent ones, then yes, that's probably the most pragmatic solution. What's your holdover tolerance?

Following from that, suppose a jammer parks nearby and doesn't leave in a timely fashion. How long does it take for the FCC to swoop in (do they swoop? in my mind they do) and find the source? Is that within your permissible holdover window?

But back to your original WAAS question, it sounds like it's time to haul out the spare hardware and do some experiments! Even with the normal antenna, you should be able to assess the validity of the configuration. Will the receiver even let you specify just those few birds? It's almost a question of whether they bothered to code an error message for such a stunt...

(This next part may deserve its own thread. Please edit the subject-line if replying to just this bit.)

You might look into a CDMA-derived time source, long term. By working one stratum away from GPS, you'll be listening to a plurality of pilots, each of which is GPS-derived, and which are geographically diverse. A single GPS jammer shouldn't knock out more than one tower at a time, and even if the tower's local holdover OCXO isn't stellar and it begins to drift, your CDMA-derived receiver is continually comparing and assessing the different signals to discard the outliers. 

Ideally, it's like having a bunch of diverse receive sites feeding back to you on a jam-resistant (very strong) channel. Pessimistically, you've got no visibility into the internal operation of those sites, and the only way to infer their status is by comparing them against each other (or a local GPS receiver, if you're not presently jammed yourself).

As far as I can tell, the CDMA receivers are less explored than GPS, so you'd be largely taking the manufacturer's word on a lot of things. 

73 de NJ8Z
