[Milsurplus] Viz radiosonde ?

[David I. Emery]

On Sat, Mar 18, 2017 at 11:29:25PM +0000, arc5 at ix.netcom.com wrote:

>     What is the "record motor" and stylie all about?
>     Sent from my Ain't Smart Phone.

	I once had access (way back in the mid 60s) to a then old (new
stock) dropsonde (intended to be ejected from an aircraft and fall on a
parachute through a storm while transmitting weather data).

	It had just what you described - a disk shaped  aluminum record
platter coated with some kind of vinyl record material with a pie shaped
radial wedge of maybe 30-40 degrees where the aluminum and record was
bent down maybe 1/8 inch with little ramps back up to the plane of the
rest of the record surface.

	And three swing "tone arms"  - one attached to an aneroid cell
from a barometer, another to a bimetallic strip mechanism that responded
to ambient temperature and a third driven by a hair hygrometer (human or
animal hair under tension) to report relative humidity...  all of these
tipped with a stylus and some kind of simple piezo-electric "cartridge"
and arranged so that the tip of the stylus swung approximately on a
radius of the disk at different angles of the clock so it did not
interfere with the other swing arms... and was free to swing when the
depressed "speed dip" went by the tip, but otherwise engaged in a grove
on the raised part of the platter.

	The disk was driven by a motor with some sort of Governor and
gear down arrangement... 

	Each grove of the "record" contained recordings of Morse code
sequences which encoded  a numeric distance for that grove from the
center of the platter... 

	IIRC there was a switch contact  mechanism to switch between the
three "tone arms" and chose the output of one to feed a circuit that
detected the recorded audio bursts and drove a relay which keyed a one
tube crystal controlled HF transmitter (seems to me 3 MHz area)...

	I believe the switch had a fourth position that just turned the
carrier on (or off) or maybe keyed a fixed CW ID... so the CW had either
a long pause, or a period of carrier (or fixed CW ID) followed by
temperature, pressure and humidity, then the pause again...

	The dropsonde operator would transcribe the strings of numbers
and note the time and look the values up in a set of charts/nomographs
to get actual humidity (or dew point), pressure, and temperature...

	I believe the parachutes were calibrated for a particular fall
rate, but I also vaguely remember a radar corner reflector attached so
the thing could be tracked by radar... which would allow the collection
of wind information and perhaps correlation of pressure with actual
altitude.

	The same thing is done today with cute little GPS based devices
with MEMS sensors for pressure and humidity and temp and a one chip
micro to run the whole thing... mostly transmitting around 400 MHz
and of course not in CW...


-- 
  Dave Emery N1PRE/AE, die at dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in 
celebration of what could have been, but wasn't and is not to be now either."