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[aprssig] K6RPT-12 Balloon Seems To Be Having GPS Problems

Greg Clark k7rkt at bigredbee.com
Mon Dec 3 18:53:11 UTC 2012


It's identical hardware and firmware (obviously not the same unit!)

Greg


On Mon, Dec 3, 2012 at 10:51 AM, Steve Noskowicz <noskosteve at yahoo.com>wrote:

>
>
> Thanks, Greg,
>   Is the payload similar to CNSP-11 that made it to the Med?
>
> 73, Steve, K9DCI
>
>
> --- On Mon, 12/3/12, Greg Clark wrote:
>
>
> There is some evidence of the entire system resetting.
>
> take a look back at UTC TIME 13:37:10, and you'll see an altitude reading
> of 109373, and note that for the previous 37 minutes or so the lat/lon are
> repeated.
>
> When the firmware powers up, it initializes the altitude to 33,333 meters
> (or roughly 109373 feet).  If  the firmware doesn't get a valid set of
> coordinates from the GPS, it transmits this altitude along with the last
> known good coordinates
>
>
> Then at time 13:39:02 it gets new coordinates and an altitude of 102174.
>
>
> This doesn't explain the other behavior that we're seeing now, where a
> large percentage of the packets have an altitude way too low.
>
>
> Greg K7RKT
>
>
>
> On Mon, Dec 3, 2012 at 8:13 AM, Stephen H. Smith <wa8lmf2 at aol.com> wrote:
>
>
>
>
> On 12/3/2012 10:38 AM, Greg Clark wrote:
>
> I don't think it's resetting, I think it's losing lock, or dropping
> intermittently into 2D mode as it gets fewer than 4 satellites.
>
>
> Greg K7RKT
>
>
> How could it EVER get fewer than 4 satellites at 100,000 feet?
>
> It is clearly losing lock, whether from resets, low battery voltage,  RFI
> from the two-meter transmitter when it keys up (crap quarter-wave whip
> without a proper ground plane??), or possibly extreme cold at 100,000 feet.
>    I haven't seen any details on the packaging of the payload.
>
>
>
>
> .
>
>
>
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