100 m W can 7 Km

according http://uk.youtube.com/watch?v=xNFg8l5tjDI

I draw conclusion from the movie at 0.22 second from the above movie


1000 m W = 1 W

1 W can reach 7KM * 10

5 W = 7KM * 10 * 5

= 350 KM the signal still cannot reach the AO 51 satellite which is
850 Km away from the earth.


to reach AO 51 the power required at least 12.5 W

7KM * 10 * 12.5
=875 KM


is my calculation correct?

"nobody" wrote in message ...
100 m W can 7 Km

according http://uk.youtube.com/watch?v=xNFg8l5tjDI

I draw conclusion from the movie at 0.22 second from the above movie


1000 m W = 1 W

1 W can reach 7KM * 10

5 W = 7KM * 10 * 5

= 350 KM the signal still cannot reach the AO 51 satellite which is
850 Km away from the earth.


to reach AO 51 the power required at least 12.5 W

7KM * 10 * 12.5
=875 KM


is my calculation correct?


raw transmitter power is only one factor, you have to also consider the
antenna gain, receiver sensitivity for the different modulation used,
bandwidth, and noise. The biggest factors in this case are probably the
modulation type and noise. with ssb or even nbfm you are dealing with a
much narrower band signal than 802.11 that hops all over a wide bandwidth.
This lets the receiver pull the signal out better. Also the ssb or even
nbfm is easier for the human ear to copy through noise, and cw is even
better, but the access points have to deal with separating out the frequency
hopping digital data from all the other digital data noise on the same
frequencies... and if noise takes some of it out it is much less forgiving
than the low data rate human ear and brain.

"Dave" дÈëÏûÏ¢ÐÂÎÅ:ZIiik.560$_l.162@trnddc04...

"nobody" wrote in message ...
100 m W can 7 Km

according http://uk.youtube.com/watch?v=xNFg8l5tjDI

I draw conclusion from the movie at 0.22 second from the above movie


1000 m W = 1 W

1 W can reach 7KM * 10

5 W = 7KM * 10 * 5

= 350 KM the signal still cannot reach the AO 51 satellite which is
850 Km away from the earth.


to reach AO 51 the power required at least 12.5 W

7KM * 10 * 12.5
=875 KM


is my calculation correct?


raw transmitter power is only one factor, you have to also consider the
antenna gain, receiver sensitivity for the different modulation used,
bandwidth, and noise. The biggest factors in this case are probably the
modulation type and noise. with ssb or even nbfm you are dealing with a
much narrower band signal than 802.11 that hops all over a wide bandwidth.
This lets the receiver pull the signal out better. Also the ssb or even
nbfm is easier for the human ear to copy through noise, and cw is even
better, but the access points have to deal with separating out the
frequency hopping digital data from all the other digital data noise on
the same frequencies... and if noise takes some of it out it is much less
forgiving than the low data rate human ear and brain.



please explain what is ssb, nbfm and cw?

"nobody" wrote in message ...
100 m W can 7 Km

according http://uk.youtube.com/watch?v=xNFg8l5tjDI

I draw conclusion from the movie at 0.22 second from the above movie


1000 m W = 1 W

1 W can reach 7KM * 10

5 W = 7KM * 10 * 5

= 350 KM the signal still cannot reach the AO 51 satellite which is
850 Km away from the earth.


to reach AO 51 the power required at least 12.5 W

7KM * 10 * 12.5
=875 KM


is my calculation correct?

You have reached the wrong conclusion about the distance 100 mw can reach.
That distance is just one persons expirment and also over earth and not
direct line of sight. Also the type of equipment used is not very well
designed for maximum distance. There is no real set distance that a given
ammount of power can reach. It also depends on the antennas and receiver
and several other factors. Knowing all factors involved the distance can be
estimated very close.

"nobody" wrote in message ...

"Dave" дÈëÏûÏ¢ÐÂÎÅ:ZIiik.560$_l.162@trnddc04...

"nobody" wrote in message
...
100 m W can 7 Km

according http://uk.youtube.com/watch?v=xNFg8l5tjDI

I draw conclusion from the movie at 0.22 second from the above movie


1000 m W = 1 W

1 W can reach 7KM * 10

5 W = 7KM * 10 * 5

= 350 KM the signal still cannot reach the AO 51 satellite which is
850 Km away from the earth.


to reach AO 51 the power required at least 12.5 W

7KM * 10 * 12.5
=875 KM


is my calculation correct?


raw transmitter power is only one factor, you have to also consider the
antenna gain, receiver sensitivity for the different modulation used,
bandwidth, and noise. The biggest factors in this case are probably the
modulation type and noise. with ssb or even nbfm you are dealing with a
much narrower band signal than 802.11 that hops all over a wide
bandwidth. This lets the receiver pull the signal out better. Also the
ssb or even nbfm is easier for the human ear to copy through noise, and
cw is even better, but the access points have to deal with separating out
the frequency hopping digital data from all the other digital data noise
on the same frequencies... and if noise takes some of it out it is much
less forgiving than the low data rate human ear and brain.



please explain what is ssb, nbfm and cw?





ssb = single side band
nbfm = narrow band fm
cw = 'continuous wave' or Morse code

nobody wrote:
100 m W can 7 Km

according http://uk.youtube.com/watch?v=xNFg8l5tjDI

I draw conclusion from the movie at 0.22 second from the above movie


1000 m W = 1 W

1 W can reach 7KM * 10

5 W = 7KM * 10 * 5

= 350 KM the signal still cannot reach the AO 51 satellite which is
850 Km away from the earth.


to reach AO 51 the power required at least 12.5 W

7KM * 10 * 12.5
=875 KM


is my calculation correct?

No.Bear in mind that signal strength goes as inverse square of
distance.. Doubling the distance requires 4 times the power. Or
conversely, 10 times the power only gives you about 3x the range (square
root of 10)).

However, the initial assumptions for required power (100mW = 700m) is
invalid.


For example Pioneer 10 radiated about 8 Watts at 2.2 GHz from well past
the orbit of Saturn, and we detected it here on Earth (but we used a big
70m dish with a cryogenic receiver to do it). And it's not like it
carried voice.. more like telemetry at 8 bits/second.

So, let's get back in the realm of possibility.

Since you're looking at AO51, that's an FM receiver on the bird. It's
spec'd to require -125dBm on 2meters. The range to the satellite varies
from 800km (satellite overhead) to 3000km (satellite on horizon).

On 2M uplink, the path loss due to distance is about -145 to -134 dB
plus another 3 or 4 dB for ionosphere and polarization losses. Working
backwards: -125dBm +140dB = about +25dBm (300mW) into a omnidirectional
antenna should do it. In reality, you might want to use a 4-5 Watt
transmitter and a 6 dB gain antenna to really get a good signal in there.



http://www.qsl.net/kb7ino/2_sat_calc.html has more info, as does
http://www.amsat.org/amsat-new/echo/Echo_Linkbudget.php

In article ,
Ralph Mowery wrote:

You have reached the wrong conclusion about the distance 100 mw can reach.
That distance is just one persons expirment and also over earth and not
direct line of sight. Also the type of equipment used is not very well
designed for maximum distance. There is no real set distance that a given
ammount of power can reach. It also depends on the antennas and receiver
and several other factors. Knowing all factors involved the distance can be
estimated very close.

As a point of comparison: the Voyager space probes have transmitters
running at around 23 watts, and are capable of sending a useful
telemetry signal over a distance of 7 billion (!) miles.

Lots of antenna gain on the sending end (14-foot dish), lots of
antenna gain on the receiving end (100-foot dish), and a low data rate
(and hence a narrow signal bandwidth, minimizing the impact of noise).

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Jim Lux wrote in
:

....
http://www.amsat.org/amsat-new/echo/Echo_Linkbudget.php

Interestingly, the working on the above document ignores rx antenna gain in
the uplink calcs, which may mislead the beginner.

The spreadsheet has the uplink 2m rx ant gain at 2dBi, and includes a
somewhat unrealistic 3dB of tx line loss on the uplink. These compensating
factors deliver somewhat similar outcomes.

The 2m uplink margin with a 5W tx is huge, something less than 1W might
still be adequate for the proposed 6dBi antenna and say 1dB of line loss.

Owen

so one does not need arrow antenna to receive signal from AO 51, just build
2.4 G omni antenna

will be ok?