On 3 Jul, 2013, at 21:05 , Bob Camp <li...@rtty.us> wrote: > If the WAAS sats were purpose designed to provide a high accuracy carrier, > then yes there are ways to do it. The fundamental design concept of a "bent > pipe" is that you don't do any of that. You do not care what's going through > the bird, it just maps the input frequencies to the output and amplifies them > (a lot). Again, the WAAS signal is simply piggybacking on existing hardware. > The conversion oscillator is not locked to the GPS carrier (or to any other > carrier). It's simply a free running quartz based oscillator, running into a > synthesizer to get the appropriate microwave frequency.
I'm not sure about the "Again, ..." part. All three WAAS satellites are commercial satellites but they were all launched recently enough (2 in 2005, 1 in 2008) to have had WAAS-specific payload added. The solicitation for the 2008 satellite is here <https://www.fbo.gov/index?s=opportunity&mode=form&id=f5aacd4bba2ef67b0c59b586900499b6&tab=core&_cview=1> and is dated 2002; this isn't looking for service on a satellite already in orbit. For the 2005 satellites, the Telesat one is mentioned here http://www.telesat.com/services/government-services which says Telesat’s Anik F1R includes a specialized payload for the Wide Area Augmentation System while you look at the Orbital Sciences blurb on the last three satellites it built for PanAmSat, here http://www.orbital.com/newsinfo/publications/galaxy_fact.pdf you'll see that they are all exclusively satellite TV things, with 24 active C-band transponders and 8 spares, except for Galaxy 15 which weighs 350 pounds more than the other two and about which it says: The Galaxy 15 satellite, which features a unique hybrid payload configuration, was launched on October 13, 2005. In addition to C-band commercial communications, the spacecraft also broadcasts Global Positioning System (GPS) navigation data using L-band frequencies as part of the Geostationary Communications and Control Segment (GCCS) implemented by Lockheed Martin for the U.S. Federal Aviation Administration (FAA). I don't think they can use any old satellite for WAAS, they added payload for it. Note that when Galaxy 15 went awol it took the WAAS service with it for most of a year even though it was replaced in its orbital slot for TV service by a spare within a week or so (though Wikipedia says the replacement was Galaxy 12 so I guess that's predictable from the blurb above). So I've been assuming that while the WAAS satellites are commercial the WAAS transmitters are specialized to the service and included for its exclusive use. I hence guess they could have been designed to work however they needed to. Dennis Ferguson _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.