[time-nuts] Lady Heather and Lucent RFTGm-II-XO / RFTGm-II-R

Mark Sims holrum at hotmail.com
Sun May 28 17:46:47 EDT 2017

I have finally managed to decode the RFTG-m voltages message and have all the values except antenna current... that is apparently hidden away in one of the other receiver messages.

As far as calculating sat positions for the receiver...   the main issue is getting the current almanac and ephemeris if the receiver does not provide them.   I don't want to make Heather dependent upon sucking in data from the web somewhere.  MANY years ago, I wrote the firmware for the (redacted) GPS receiver, so I have done the orbital math before... no fun and royal PITA to verify.

As far as calculating your position from the displayed data if the location is shown as "private",  things like az/el are only displayed to 0.1 degrees at  the most and time to a second (OK, you can show it to milliseconds).  Also the doppler, etc have a fairly low resolution.  I don't think you could get less than a few square miles of uncertainty... good enough privacy for most people.   The next version of Heather can trim the sat info display to just show az/el/snr and not show the doppler, etc.

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