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Re: Long range, low bitrate, small data transceiver unit for telemetry data



.au...
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I cant for the life of me figure out why this rule would be there. I would
ignore it anyway. It's a free country.





Re: Long range, low bitrate, small data transceiver unit for telemetry data


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It is common in the aviation regulations in many countries.

Probably the reason is to prevent unauthorized map creation.

--

Tauno Voipio (commercial pilot & instructor)
tauno voipio (at) iki fi



Re: Long range, low bitrate, small data transceiver unit for telemetry data



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would


I'd be interested in researching this further. Do you have a reference? I
find the rule preposterous, and highly insulting - even impeding on my- or
anyone elses- free will.  Unauthorised maps? Who needs to authorise maps?





Re: Long range, low bitrate, small data transceiver unit for telemetry data


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Start with the AIP (Aeronautical Information Publication) of your own
country.

In my country, Finland, the current aerial photographing regulations
are pretty liberal. The most important prohibited photo targets are
military installations and penitentiary units. When I started the
aerial photographing (a couple of tens of years ago) all negatives
had to be given in for inspection before copying. Also, the list
of prohibited targets was much longer.

AFAIK, the same targets are banned in all ICAO countries.

You may be surprised to notice that most maps are else accurate,
but there are things that are not mapped for public distribution.

--

Tauno Voipio
tauno voipio (at) iki fi



Re: Long range, low bitrate, small data transceiver unit for telemetry data


iki.fi.NOSPAM.invalid> writes
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There are many regulations in many countries. Also the air regs vary
from place to place in the same country. You need to consult the air
maps.

You may be able to do "anything" where you live but try flying anything
over the residence of your local head of state and see what happens.
(survivors may like to re-tell their experiences here :-)

What may be fine for photoing an archaeological sight is a field will
get you arrested (at best) when you balloon strays a km and finds itself
over an unmarked military installation. Some places are more sensitive
than others and they don't always tell you beforehand.

This all stems from a surveying trip I was going on the ruins of the
fort were, we discovered, not to far from a "secret" military staging
area. We were foreigners in the country :-)


--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills  Staffs  England     /\/\/\/\/
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Re: Long range, low bitrate, small data transceiver unit for telemetry data


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Not actually - the ICAO standard formula for radio
horizon distance is

   d = 1.23 * sqrt(altitude)

where d is in NM (nautical miles, 1852 m) and
       altitude in feet (0.3048 m)

This gives 1927 ft (587 m) above terrain for 100 km.

Please note that the distance is larger than obtained
from direct geometric consideration. This is due to
the refraction of electromagnetic radiation in the
atmosphere.

--

Tauno Voipio
tauno voipio (at) iki fi


Re: Long range, low bitrate, small data transceiver unit for telemetry data



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Dear "Tauno Voipio"

Thank you for this formula and the information.

After your posting I've found the following link regarding equation of "d =
1.23 * sqrt(altitude)"
     http://www.megginson.com/Aviation/rules-of-thumb.html


Leo Patrick



Re: Long range, low bitrate, small data transceiver unit for telemetry data


says...
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Huh???   An altitude of about 700 meters ought to put it above the
horizon over flat ground or water.
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If the limit really is 7 grams, this looks very difficult---especially
if that has to include the power supply.
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Mark Borgerson



Re: Long range, low bitrate, small data transceiver unit for telemetry data



"Mark Borgerson"
 Phil  Allison

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**  I have already answered this point  -  twice.

Curvature of the earth is not the issue  -  but the local terrain is.

Imagine that from the ground receiver's position, there is a hill 50 metres
higher, sited 1 km away.

How high is your horizon out at 100 km now ?




...........   Phil





Re: Long range, low bitrate, small data transceiver unit for telemetry data


On Wed, 13 Jul 2005 12:55:49 +1000, "Phil Allison"

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Assuming first that the earth is flat, the horizon at 10 km would be
500 m above ground and at 100 km 5 km above ground.

Since the earth is a sphere, we have to add the horizon for a perfect
sphere at  100 km and we end up somewhere between 500-700 m depending
on some assumptions as previously calculated in this thread, thus the
required altitude would be about 5,6 km, which is not in the
stratosphere not even on the poles, even if we notice that the earth
is an ellipsoid and not a perfect sphere.

Those calculations apply for a visual contact. However, the Fresnel
zones around the direct line of sight path becomes larger at lower
frequencies. At exactly the optical horizon the lower parts of the
Fresnel zones are cut off. Assuming the hill is sharp, the knife edge
diffraction model can be applied, which yields 6 dB extra attenuation.
At angles above the optical horizon, the losses are smaller, dropping
more rapidly at higher frequencies, as the Fresnel zones are smaller.

Paul
 

Re: Long range, low bitrate, small data transceiver unit for telemetry data



"Paul Keinanen"
"Phil Allison"
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 **  Which is a HELL of a lot more than 700m -  fuckhead.


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**  The phrase used was  " ... free line of sight ".


  (snip rest of this tedious wanker's shite )



..............   Phil




Re: Long range, low bitrate, small data transceiver unit for telemetry data



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***   Humphhh!!!????!!!!

That showed him, eh, toaster-boy.  He won't want to try fooling with us
again!!!!!!!!!!????????????!!!!!!!!!!!!!


**  Don't know why he bothered in the first place...




..............Phil


Re: Long range, low bitrate, small data transceiver unit for telemetry data


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Do you normally correspond with any customers that you may have in this
manner? Other people are responding reasonably to the OP's requests for
information and you did indeed respond in the same vein originally. Just
because you disagree with other peoples replies there is no need to descend
into personal abuse: a cogent and coherent response would be much better.
Several of the people that you have insulted have made, and continue to
make, many useful contributions to this group on a number of subjects. Your
response merely demeans you not them.

    Andrew



Re: Long range, low bitrate, small data transceiver unit for telemetry data



"Andrew Jackson"  >>
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** Oh lordy lordy  -  now we have a self appointed member of the manners
police butting his pointy nose in.


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**  Who made YOU  into a one man judge,  jury and executioner  ??

 Or maybe you just puff yourself up like a toad whenever the mood takes
you -  right  ???



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**  Complaints should always be quite specific and contain no unjustified
assumptions.

     Or else they are no more than mindless abuse posturing as comment.

     Which is what your post is.



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 **   Add yourself to the list,  please.

   You get my pompous, ignorant ass award.




............   Phil





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  **   Well, you would, but it's mine, all mine, and I'll never, ever,
give it up!   So there!!!!!!!!!!!   [Autistics are like that.]





................   Phil

Re: Long range, low bitrate, small data transceiver unit for telemetry data




Andrew Jackson wrote:
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<bad joke>
Methylphenidate or clonidine could help here but
in definitive nothing can be achieved if the
person is not willing to cooperate.

It is said also that behavioural therapy can alleviate
these problems.
</bad joke>

This is really tragic for parents and for the persons
who suffer from that syndrome so this is a bad joke hopefuly.


Re: Long range, low bitrate, small data transceiver unit for telemetry data



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These people would seem to have trod the same path already

http://balloons.space.edu/habp /

Re: Long range, low bitrate, small data transceiver unit for telemetry data



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A few suggestions:

- Contact your aviation authorities early in the project. You might
get some useful hints.

- Contact your telecom authorities early in the project. You might get
good suggestions of what kind of systems to use and what _not_ to use.
If this is a one off launch, you might even get dedicated frequencies
for the launch with generous power limits etc.

- I would suggest keeping the command and telemetry circuits separate,
i.e. keeping both unidirectional at the protocol level, i.e. no ACKs
transmitted back at the protocol level.

If the telemetry is constantly transmitted, try to grab as much as
possible, but do not expect 100 % capture.

The telemetry could be sent on a license free band (check your local
telecommunication authority if this is acceptable for airborne
systems) and use a steerable high gain receiving antenna to recover
the telemetry. There is no limitation on the receive only antenna gain
that can be used and thus it is easy to attenuate any local noise
source from similar equipment in the same band.

Use some telemetry inputs to monitor the command receiver outputs.

When you want to command the balloon, blindly and repeatedly send
commands to the balloon and monitor the telemetry for the command
receiver outputs. When the command receiver output has changed, you
can stop sending that command.

If the balloon is going to ascend to say 10 km, the radio horizon will
be about 400 km away and practically any station within that 500000
square kilometers  (larger than most European countries) will be in
LOS path. If you are using some shared frequency bands, be prepared to
compete with all other transmitters within that frequency range. Thus,
I would _strongly_ suggest that you get a dedicated command frequency
for your balloon.

Regarding the problem of a hill 50 m high at 1 km distance as someone
pointed out, I actually live 1 km from a sandy ridge created by the
Ice Age, which is 50 m higher than my balcony and 70 m above a nearby
lake. It is one of the steepest hills within a few hundred kilometers.
While I agree that it is hard to get any signals from that direction,
I am also very happy, since by climbing that hill, I can make VHF/UHF
contacts from 100-300 km with 2-5 W transmitter power and a 10 dB yagi
antenna.

If one would be fortunate enough to have such a hill close by, I would
strongly suggest moving the balloon telemetry station on such hill.

Paul


Re: Long range, low bitrate, small data transceiver unit for telemetry data



"Leo Patrick"
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**  Sure  -  long as they are installed onboard a space craft.

    Try asking NASA.



.........    Phil








Re: Long range, low bitrate, small data transceiver unit for telemetry data



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wireless ap and decent directional dishs

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