weather station- what is being attached to the ballon--- mcu with temp probe?

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weather station- what is being attached to the balloon--- mcu with temp
probe?


can u show me url that point to making of such "probe" that attached to a
weather balloon?


TIA



Re: weather station- what is being attached to the ballon--- mcu with temp probe?

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www.vaisala.com -> Vaisala Radiosonde RS92, for example.

HTH

Tauno Voipio
tauno voipio @ iki fi




Re: weather station- what is being attached to the ballon--- mcu with temp probe?
Years ago, I happend to see one.
AFAIR, the temperature was measured with a bimetal.
What I don't remember is how the temperature was transmitted.
It was almost infinitely simple.
Eg passive, by tuning a microwave resonator that it appears
as sidebands on the tracking radar.
Eg active, by tuning a HF resonator, ...
The barometic unit worked similar, the displacement was
made into clicks.

The whole ballon measuring unit was incrediby simple,
incredibly cheap to manufacture and incredibly durable.
Definitely no processor.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net


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Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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I went to school with a lot of farming folk. They would quite
frequently find met probes on their property. I asked them to collect
them over the holidays bring them to me at the beginning of every
school term, because they were cool free techno-stuff :)

The units they used (this was in the late 1980s) were a
cylindro-conical styrofoam body with two projecting "wings", and a
barometric sensor mounted on the outer end of one of those wings. The
wings were angled so that the device would spin in any significant
airflow, somehow I think this was used to measure wind speed.

A short antenna (stiff wire) poked directly out of the center of the
"pointy end" of the device. In other words, it looked something like a
propeller with a greatly elongated boss.

There was a 28-pin IC in the device with markings filed off, which I
presume was a microcontroller. There was also a thermistor and some
kind of hygrometric sensor. The device was powered by a 9V battery.

I would imagine they were probably made or at least designed by the
CSIRO, since this was in Australia. Not terribly long ago, I saw some
of these radiosonde casings (not exactly the same, but VERY similar)
up on a web site that does US Government surplus auctions.

Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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Interesting.
I happened to see my described devices in Australia in the
mid 80ies. They were in a rectangular styrofoam box. The
costal wheather stations used to send them off to gather their
pressure and temperature profile. They were attached to those
rubber hydrogen baloons. Not the stratospheric type, just
round rubber. The baloon would burst at some height, and the
dispensable(?) measurement box would fall down.
The position was continously measured with a doppler radar,
so they got the wind directions and the wind speeds depending
on the heights.
Since they measured three times a day, the units had to be cheap,
and since most of them probably fell into the sea, was not regarded
as recoverable.
There may be different type of units depending on whatever.

Oh, I guess normal wheather stations don't have a radar. This radar
was also used to detect and track cyclones. At the northern coast
somewhere.

AFAIK, a ballon cannot measure side winds, as it always moves
with the side wind.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net


Re: weather station- what is being attached to the ballon--- mcu with temp probe?


--- 8< clip clip ---

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It has been done for decades with a thing called a radio-theodolite: a
multi-channel receiver with a specially formed antenna field which is able
to determine the azimuth and elevation angles of the incoming signal from
the radiosonde. With altitude information from the pressure sensor in the
sonde, it is possible to plot the travel of the balloon in three dimensions.

A more modern method includes a suitable GPS transponder at the sonde, which
enables the tracking with the GPS signals.

Again, for details, see www.vaisala.com.

Tauno Voipio
tauno voipio @ iki fi




Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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Sorry, Somewhat unclear. Below a baloon, a measurement unit
will not detect side winds, as the baloon always moves with the wind.
Whoever made a baloon flight is amazed as no wind can be felt.
 From the ground such a measurement is possible.

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Aha, interesting. The radio approach. The radar approach works
somewhat different.
There, measuring the barometric pressure is not for the height.
The height is calculated from the delay of the radar pulse.
The barometric pressure is measurement data and belongs to the height.
Usually, for standard applications, such as air traffic, the height
is taken from the barometric pressure as is follows some exponential
function, at least in theory. There it is calibrated from the QNH.
Meteorological measurements take the deviation of the pressure from
the theoretical values into account.
A tracking radar, recognizable from the vibrating feeder, can
output a 3D path by itself.

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Sure, GPS. But not really cheap. Also not in numbers. You have to
recover such a unit.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net


Re: weather station- what is being attached to the ballon--- mcu with temp probe?

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It depends how much processing you do on the probe and how much on the
ground. It would be sufficient to rebroadcast the actual received data
and the "phase" difference between the PRN chip clocks from various
satellites and do the actual position determination on the ground.
Depending on the availability of suitable integrated circuits, this
does not have to be very expensive.

An other option is to install a 100 kHz Loran-C receiver and
rebroadcast the signal received from multiple Loran-C stations. Again,
the _difference_ between the signals from various transmitters are
summed at the balloon and the time difference between the pulses can
be determined on the ground and the location of the balloon
determined. Since the spectrum of these pulses are quite wide and the
SNR from some stations can be quite bad, the down link requires a wide
bandwidth and good SNR in order to not degrade the signal very much
more. Of course this method requires that some Loran-C chains are in
the region.

Other radio navigation systems can be used on the balloon and
rebroadcast the raw signal to the ground station for processing,
simplifying the electronics on the probe. Multifrequency systems, such
as the discontinued Decca, are much more problematic, if the carrier
frequency and phase must be maintained through various heterodyning
processes.

Paul
    

Re: weather station- what is being attached to the ballon--- mcu with temp probe?

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which

No need - a cleverly designed GPS transponder is inexpensive enough to be
disposable.

(I'm not going to repeat the URL)

Tauno Voipio
tauno voipio @ iki fi




Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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There was no price to be found.
A GPS receiver outputting NMEA code and subsequent retransmission
is hardly to be done below say 200$. Then on the other hand it
depends on the project what is considered cheap. Letting them up
three times a day, daily, is different to a one time experiment
where you can write half a dozend papers afterwards.

Rene


Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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Nahhh, GPS chipsets cost around $10 in large volume. You can buy complete
modules outputting NMEA for $50-$70.
A uBlox GPS module costs around EUR 70-80 in single qty.

Meindert



Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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Oh, thanks for the note.
I wasn't aware. My distributor sells this stuff obviously a bit
overpriced.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net


Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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Assuming the data transmission is already built into the project, a
GPS receiver module can be bought for around $50.

Re: weather station- what is being attached to the ballon--- mcu with temp probe?

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be

AFAIK, the transponder is not priced separately - it's an integral part of
the sonde and it uses the data link used for weather data also.

The transponder does not decode the GPS signal - the calculation-intensive
part is done at the ground receiver (which is not just the next-door
Garmin). What is important to the position determination is where the
signals from separate satellites meet. The combined signal can be sent with
a data link elsewhere for final processing.

HTH

Tauno Voipio
tauno voipio @ iki fi



Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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You mean, you don't decode the spread spectrum signal ?
You take the whole band where the spread spectrum is in and
retransmit it at some other frequency. With the GPS signals
burried in the noise ?

A bold approach.

I see some problems in just mixing it with a carrier also in the
microwave bands because the mirror bands also appear unless you use
single side band modulation with quadrature mixing.
For wide bands there is the problem of phase errors.

Well, it is doable with SSB, I guess. But having a stabilized
GUNN oscillator up there isn't cheap either, is it ?


Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net


Re: weather station- what is being attached to the ballon--- mcu with temp probe?

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The signal is not decoded, but it is partly detected using a clever new
algorithm, which I'm not in a position to elaborate. The bandwidth of the
down-link signal is much less than the original satellite signals.

Tauno Voipio
tauno voipio @ iki fi



Re: weather station- what is being attached to the ballon--- mcu with temp probe?

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You can use GPS without decoding the code, just by using the carriers.
One possible embodiment of such a system is described in
the patent EP 0 732 596 A2. The patent documents can be found at,
e.g., http://www.espacenet.com/ .

This makes the ground station rather complicated, but that is not
an issue at it is not thrown away after use.

- Ville

--
Ville Voipio, Dr.Tech., M.Sc. (EE)

Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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Hmmm, I can't see how you can get any airflow, let alone any
significant airflow, over any part of a free balloon.  You might
be able to read the difference between the airflow at the instrument
and the average airflow over the entire balloon, but I'm not sure
how this would be useful.

--
Trevor Barton

Re: weather station- what is being attached to the ballon--- mcu with temp probe?

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The climb of the balloon creates a hefty vertical wind over the sonde,
suspenede well below the balloon. It was used in earlier (1930's to 1960's)
Vaisala sondes to turn the mechanical multiplexor switch inside the sonde.

Tauno Voipio
tauno voipio @ iki fi



Re: weather station- what is being attached to the ballon--- mcu with temp probe?
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Ah, yes of course.  I forgot the vertical component.  Still, that's not
"wind speed" as I'd refer to it.

Trev

--
Trevor Barton

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