Long range, low bitrate, small data transceiver unit for tel

Paul Keinanen wrote:
To realistically reach the 10 km distance, the other station would
have to be high up in a cellular or water tower or alternatively, at
both ends of the link, the antenna would have to be above the tree
tops or on top of the buildings in urban areas.
Click to expand...

I suppose he could have his receiver up a tethered balloon
too to increase line of sight.
 
"Mark Harriss"


** How vague is this functionally illiterate Brisbane cunt ??

And what a useless fucking smartarse.

Probably thinks RF stands for Rabid Fuckwit.




.......... Phil
 
"Tauno Voipio" = wog fuckhead

Phil Allison wrote:

** At 100 km range, that damn balloon better be up in the stratosphere
for a free line of sight !

Not actually - the ICAO standard formula for radio
horizon distance is....
Click to expand...

** Shame about the effect of terrestrial obstructions - like hills and
mountains.

They are more than bloody 600 m high - you fucking ass.





............. Phil
 
"Mark Harriss"

I suppose he could have his receiver up a tethered balloon
too to increase line of sight.
Click to expand...


** How vague is this functionally illiterate Brisbane cunt ??

And what a useless fucking smartarse.

Probably thinks RF stands for Rabid Fuckwit.





.......... Phil
 
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
Click to expand...
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
 
"Mark Harriss"


** Harriss is one stinking, net stalking Neo Nazi, lying criminal.

From Brisbane - where else ?




........... Phil
 
"Leo Patrick"

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

** NOTE:

The words ".. above terrain.. " are crucial.

Even a mere 100m high hill in the first 10 km makes this silly calc
useless.

Make a simple drawing if you are to fucking dumb to realise this.




........... Phil
 
"Mark Harriss"
Phil Allison wrote:

** How vague is this functionally illiterate Brisbane cunt ??


They seek him here, they seek him there....
Click to expand...

** The " Scarlet Pimple " refers to this criminal's fat, pustulous head.




............ Phil
 
They seek him high, they seek him low....
They mistakenly think he's somewhere in Brisbane.
Hmm time for a better packet tracer Phil?
 
"Mark Harriss"

They seek him high, they seek him low....
They mistakenly think he's somewhere in Brisbane.
Hmm time for a better packet tracer Phil?
Click to expand...

** So you even lied about that.

Beware - the cops can get your home address from you ISP in about ten
minutes.






........... Phil
 
Hmmm he's taking his time to reply to that last post
.......must be scrabbling for some personal details
to Google and post to impress us all, or maybe paying
money for a company search or credit check....must be
really upset this time.
 
"Mark Harriss"

They seek him high, they seek him low....
They mistakenly think he's somewhere in Brisbane.
Hmm time for a better packet tracer Phil?
Click to expand...

** So you even lied about that.

Beware Fuckwit - the cops can get your home address from you ISP in
about ten
minutes.




........... Phil
 
In article <3jh6l3Fpu5vhU1@individual.net>, philallison@tpg.com.au
says...
"Paul Keinanen"
"Leo Patrick"


My intented implementation in the original posting/question is a
semi-controlled baloon. Because of the very limited weight carrying
capability of the baloon, we can not carry big, high power transceivers.

Why didn't you say that in the first place ?


** Don't get too excited just yet - there are still heaps of important
details the OP has not revealed about his app.


It makes *ALL* the difference if the stations are down in the ground
clutter of if you have a free line-of-sight path.


** At 100 km range, that damn balloon better be up in the stratosphere for
a free line of sight !
Click to expand...
Huh??? An altitude of about 700 meters ought to put it above the
horizon over flat ground or water.
Could you use directional tracking antennas on the ground ?


** With a Tx weighing in at circa 7 gm all up @ 100 km range plus hovering
barely on the horizon, the OP will need access to the Parkes radio telescope
dish !


If the limit really is 7 grams, this looks very difficult---especially
Click to expand...
if that has to include the power supply.
With such applications, I would suggest that you stay away from the
license free bands and get a dedicated frequency (pair) with a
sufficient power limit (say 1-100 W) for the ground transmitter from
your telecom authorities.


** Needs plenty of watts on the up link plus massive gain with a tracking
dish for the down link.



For the control functions, you might even consider systems intended
for model aircraft control and use a completely separate system for
telemetry downlink on a different frequency band and thus be able to
continuously communicate in both directions. You might even set up
multiple telemetry receiving stations on the ground at different
locations.


** Or just get NASA to help out.

They could help the OP with his spelling too.



Mark Borgerson
Click to expand...
 
On Tue, 12 Jul 2005 17:24:48 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

"Paul Keinanen"
"Phil Allison"

With such applications, I would suggest that you stay away from the
license free bands and get a dedicated frequency (pair) with a
sufficient power limit (say 1-100 W) for the ground transmitter from
your telecom authorities.


** Needs plenty of watts on the up link plus massive gain with a tracking
dish for the down link.

A 100 km troposcatter path not very hard with directional antennas and
moderate transmitter power.


** How lovely and vague.

And useless and smartarse.
Click to expand...
Just in case someone might be more interested in technical details
than in the mud slinging contest, here are some details.

Troposcatter links have been used for decades in areas with no
infrastructure to carry telephone circuits prior to Inmarsat satellite
phones.

For instance between the North Sea oil rigs and main land
England/Scotland. On the land side huge fixed reflectors were erected,
but still quite high transmitter (kilowatts) power was required. There
was even a fear that the high field strength at the oil rig might
create some sparks and ignite the oil/gas vapour floating around.

The idea with a troposcatter link is that both stations should see the
same air mass in the lower troposphere (1-2 km) and when the
transmitted signal hits that air volume, it will scatter somewhat and
part of it will scatter towards the receiving station.

This is a similar situation as the afterglow after sunset, when the
western sky (on both hemispheres) is still bright, while the sun is
below the horizon. The sky is brightest around the area where the sun
just set, i.e. the scattering is strongest in directions close to the
ray direction.

The situation in troposcatter is similar, the larger the scatter
angle, the weaker the signal will be. The longer the troposcatter
link, the higher the commonly visible air volume must be (and thus the
air is less thick) and also the scattering angle becomes large, thus
hugely increasing the attenuation.

For a 100 km line of sight path (e.g. between two balloons), the path
loss will be about 120 dB. A 100 mW (+20 dBm) transmitter and a
receiver with -120 dBm sensitivity should be easily be able to
communicate with a 20 dB margin. However, on a license free band, all
devices that are within the radio horizon of the receiver would appear
as interference, most likely interrupting the communication.

However, if we want to build a ground to ground troposcatter link at
100 km, in addition to the 120 dB free space loss, you would have to
add about 50 dB (100000 times more power) for the troposcatter losses
at this distance for maybe 50 % of the time. Thus, a few wats with a
small yagi at both ends should do the trick.

However, the troposcatter link is notorious for fading, so if you need
a higher reliability, the transmitter power needs to be increased. To
get from 50 to 90% reliability of the time, the transmitter power
would have to be increased 10 times (10 dB). Also stepping up to 99%
would add an other 10 dB as would going to 99.9 %. Even the Perks dish
with a huge transmitter would not be able to provide 100 %
reliability, since maybe during an hour each year the signal would
simply escape into space due to the air refractive index.

All the previous calculations have assumed that there is a free view
to the horizon. However, if there are some local mountains, you would
have to beam your signal higher to get above the mountains and hit a
common air volume above them. The higher in the air the scattering
volume is, the larger deflection is required and the losses will
increase.

As a rule of thumb, for every degree you have to increase the antenna
elevation to get past the mountain, the troposcatter attenuation will
increase by 10 dB, i.e. the transmitter power should be increased 10
times.

VHF/UHF/microwave communication is certainly possible behind the
horizon, but to get a reliable link, you might end up at power levels
that are hazardous to your health.
-------------
One other interesting observation of wireless products advertised by
various vendors is that in order to get the distances claimed, the
station would have to be in orbiting satellites, preferably on the far
side of the Moon :), to avoid the noise and interference from other
stations in the same frequency band.

Paul
 
On Tue, 12 Jul 2005 23:35:31 +1000, Mark Harriss wrote:

Hmmm he's taking his time to reply to that last post
......must be scrabbling for some personal details
to Google and post to impress us all, or maybe paying
money for a company search or credit check....must be
really upset this time.
Click to expand...


** I'm not a dickhead!!??!!

I'm a fucking autistic toaster-boy from Summwer Hill!!!!!!!!!!


** And don't you fucking forget it************????!!!!!!!!!!!




...............Phil
 
On Wed, 13 Jul 2005 10:40:03 +1000, Psycho-boy wrote:

On Tue, 12 Jul 2005 23:35:31 +1000, Mark Harriss wrote:

Hmmm he's taking his time to reply to that last post
......must be scrabbling for some personal details
to Google and post to impress us all, or maybe paying
money for a company search or credit check....must be
really upset this time.



** I'm not a dickhead!!??!!

I'm a fucking autistic toaster-boy from Summwer Hill!!!!!!!!!!


** And don't you fucking forget it************????!!!!!!!!!!!




..............Phil
Click to expand...

*** You can't even spell correctly - I'm a fucking autistic toaster-boy
from Summer Hill!!!!!!!!!! See, you dumb cunt%^&%#^*^




..................Phil (the real)
 
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