Re: SiRF receivers

Bill Brown


I flew an Axiom Sandpiper model receiver using the SiRF chipset on a
mission in the Gulf of Mexico on our last Rockoon flew on the
launch platform gondola. Their engineer claimed it would work over 60k feet
just like the Motorola VP Oncore would...i.e. as long as you didn't exceed
the speed limit (somewhere over 600 knots or so), the altitude limit of 60k
would not be a problem. Some receivers will lock up at 60k feet regardless of
the speed travelled, it depends on the manufacturer. I know that the VP
Oncore works great, the Garmin 35 and (if specially modified, the Trimble See
Vee 6).

My experience was that although we were only travelling about 20 knots
groundspeed, the Axiom Sandpiper receiver completely locked up at 60k feet
and never came back up again during the rest of the flight. I haven't tried
any more flights with the Axiom units, although I may try an experiment using
the very tiny Swift model Axiom receiver that I have as a backup GPS to see
if it works above 60k.

73s de Bill WB8ELK

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