Hello,
There was a competitor, long ago, AIR (Atmospheric Instrumentation
Research Inc.) that produced something similar. As usual, Vaisala bought
that company in order to make it dissapear, like a lot others, but this
is another history.
I never had the details of how it worked (it was kept quite as a secret
then), but the radiosonde GPS section was very very simple, without any
digital signal processing. I remember something like an LNA and one or
two mixers. I think that real sonde position was never calculated, only
speed (probably 2D, since the sonde also had a pressure sensor for
providing the height), by comparison of satellite doppler as received by
the sonde and as received on ground, but as I said, it was never
disclosed to me then, but I've found that Dave B. Call (then owner of
AIR) did patented it, US patent nr 5347285, so perhaps it worths to read
it (I will do as soon as I get a time slot available for it :) ).
Of course, operating principle for Vaisala sondes can be different.
Perhaps I've somewhere one of those sondes... but most surely I've lost
it quite long ago.
Best regards,
Javier
El 07/06/2012 22:08, EB4APL escribió:
Maybe you can avoid COCOM limits: Vaisala radiosondes (the most used
type here in Europe, see www.vaisala.com) include "half" GPS receiver
on it and the other "half" is in the ground tracking program. The
balloons go up to about 30 Km and while the speed is very low this
height is above the limit. Maybe you can get a recovered sonde and
use it either directly or modulating its telemetry on your radio. The
receiving program SondeMonitor is licensed to amateurs by a small fee
and can be downloaded free for evaluation.
Ignacio, EB4APL
On 07/06/2012 5:35, Robert Watzlavick.com wrote:
Onboard gps units tend to drop out at high altitude and/or high
velocities due to COCOM limits. Some will re-acquire at apogee but it
doesn't always work. I'm planning for onboard telemetry but a
multilateration system is the backup.
I correspond with others on aRocket and unrestricted gps units still
aren't available to the average person without a lot of paperwork and
$$$.
-Bob
On Jun 6, 2012, at 22:13, Chris Albertson<albertson.ch...@gmail.com>
wrote:
Why not fly a tiny GPS inside the rocket? Either modulated the
beacon with
the GPS serial data or record it to a micro SD card.
On Wed, Jun 6, 2012 at 7:33 PM, Robert
Watzlavick<roc...@watzlavick.com>wrote:
Sorry to resurrect an old thread but I also have a question about
using
the Thunderbolt in the future. I'm considering using 4 of them in a
multilateration setup to track an amateur rocket with an onboard
beacon.
Chris Albertson
Redondo Beach, California
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------------------------------------------------------------------------
Javier Herrero
Chief Technology Officer EMAIL: jherr...@hvsistemas.com
HV Sistemas S.L. PHONE: +34 949 336 806
Los Charcones, 17 FAX: +34 949 336 792
19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com
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