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CX2SA > SATDIG 05.07.08 21:57l 836 Lines 27428 Bytes #999 (0) @ WW
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To : SATDIG@WW
Today's Topics:
1. Re: Best type of coax to use ... in ... AMSAT-BB Digest, Vol
3, Issue 326 (Nate Duehr)
2. Re: source for LMR 400 UF connectors (Luc Leblanc)
3. Re: re best transceiver for sats (Henk, PA3GUO)
4. Re: NASA's American Student Moon Orbiter... (Joe)
5. Re: NASA's American Student Moon Orbiter... (Robert Bruninga)
6. GS-232 & SatPC32 12.8 (myoung)
7. Re: GS-232 & SatPC32 12.8 (Erich Eichmann)
8. Re: NASA's American Student Moon Orbiter... (i8cvs)
9. Logbook Software (John Henderson N4NAB)
----------------------------------------------------------------------
Message: 1
Date: Fri, 4 Jul 2008 13:22:38 -0600
From: Nate Duehr <nate(AT)natetech.com>
Subject: [amsat-bb] Re: Best type of coax to use ... in ... AMSAT-BB
Digest, Vol 3, Issue 326
To: amsat-bb <amsat-bb(AT)amsat.org>
Message-ID: <92889939-C4D7-4F96-807B-66A086C64395(AT)natetech.com>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
On Jul 2, 2008, at 9:34 PM, Jim Wright wrote:
>
> Make sure you get the correct N connector. You may have to trim some
> strands out of the center conductor if you get the wrong connector. I
> had the problem with a local Ham store that had connectors for RG8/
> RG11.
> Amphenol makes one for 9913 specifically.
> 73,
> Jim
I did a very un-scienfific test with one of these -- I put it on an
old chunk of cable and gave it the "spin test".
Swung the cable around rapidly and watched it fly off the end and
across the yard.
There's just not much there holding it all together on that type of
connector. :-)
--
Nate Duehr, WY0X
nate(AT)natetech.com
------------------------------
Message: 2
Date: Fri, 04 Jul 2008 15:10:51 -0400
From: Luc Leblanc <lucleblanc6(AT)videotron.ca>
Subject: [amsat-bb] Re: source for LMR 400 UF connectors
To: www(AT)videotron.ca, amsat-bb(AT)AMSAT.Org
Message-ID: <486E3D7B.2150.16187F7(AT)lucleblanc6.videotron.ca>
Content-Type: text/plain; charset=ISO-8859-1
On 4 Jul 2008 at 8:37, Joseph Seibert wrote:
> Hi Jim.
> ?? I've?purchased LMR cable and connectors from:
> texastowers.com
> cablexperts.com
> frigidn.com?? (Frigid North Electronics)
> ?? I use LMR cable not only for my ham shack, but at the Public Radio
station where I work. I highly recommend th "EZ" type crimp on connectors.
It's also nice to have the "EZ" stripper and crimp tool too (but they're
pretty pricey!).
> Joe- AL1F
> Bethel, Alaska
>
Our local Ham club invest in one crimping tool/dye kit few years ago and it is
available to all our members. Instead having to by it
individually a club can buy one for their membership.
"-"
Luc Leblanc VE2DWE
Skype VE2DWE
www.qsl.net/ve2dwe
WAC BASIC CW PHONE SATELLITE
------------------------------
Message: 3
Date: Fri, 4 Jul 2008 21:58:24 +0200 (CEST)
From: "Henk, PA3GUO" <hamoen(AT)iae.nl>
Subject: [amsat-bb] Re: re best transceiver for sats
To: <amsat-bb(AT)amsat.org>
Message-ID: <1781.212.61.85.173.1215201504.squirrel(AT)webmail.iae.nl>
Content-Type: text/plain; charset=iso-8859-1
Mmm what is the best transceiver for sats ... ?
I LOVE my Kenwood TS-2000X.
con:
1) has a birdie on 435.800 (AO-27)
pro:
1) has 0..30MHz, 6mtr, 2mtr, 70cm, 23cm
2) all mode (FM, AM ... USB)
3) built in TNC (1k2 and 9k6) (for packet, displays& tracks DX cluster)
4) IF-DSP: standard in, not as option, this rocks (CW filtering 50-2000HZ
filters etc.)
5) Built in TXCO (not optional, its just in !)
6) Built in antenna tuner
7) Built in RS232 port (no additional converter needed)
8) Built in cross band repeater
9) Has FM/AM sub transceiver for VHF & UHF
10)Port for remote control head RC2000
http://inform3.kenwoodusa.com/Brochures/Communications/UnitedStates/AMA/TS-
2000.pdf
... single radio: does it all !
Henk, PA3GUO
http://www.pa3guo.com
------------------------------
Message: 4
Date: Fri, 04 Jul 2008 15:38:13 -0500
From: Joe <nss(AT)mwt.net>
Subject: [amsat-bb] Re: NASA's American Student Moon Orbiter...
To: Edward Cole <kl7uw(AT)acsalaska.net>
Cc: AMSAT-BB <amsat-bb(AT)amsat.org>, G0MRF David Bowman <g0mrf(AT)aol.com>
Message-ID: <486E8A35.6040006(AT)mwt.net>
Content-Type: text/plain; charset=us-ascii; format=flowed
The whole part that is confusing me on all this power budget stuff is
the to me, the seemingly HIGH budget.
I've done moon bounce. And many of these numbers seem to be not too far
from Moonbounce numbers, and that is a horrid dead piece of rock
reflector. that has a efficiency of a wet sponge. I assume it reflects
radio waves not too far efficiently than it reflects sunlight. And it
only reflects 6% of the energy it gets.
I haven't found any numbers of the moos efficiency at reflecting radio
signals.
but i would think anything there that is active circutry is a thousand
times more efficient at sendinga signal back as compared to the moons
surface.
or what am I missing?
Joe
Edward Cole wrote:
>At 05:42 AM 7/4/2008, i8cvs wrote:
>
>
>>----snip----
>>
>>Only considering the 2 meters downlink suppose to put AO40 at 400.000
>>km with the antennas pointing at the earth with low squint angle let say
>>less than 10 degrees.
>>The gain of the AO40 2 meters antennas was 10 dBi and we put your
>>10 watt on it.
>>
>>Suppose that your 2 meter antenna has a gain of 13 dBi and the overall
>>noise figure of your receiving system is NF= 0,7 dB = 51 kelvin so that
>>the noise floor into a CW passband of 500 Hz with the antenna looking
>>at the moon (200 kelvin) is about -178 dBW
>>
>>Suppose that the station in QSO with you has a 70 cm EIRP capability to
>>get the full 2 meters 10 watt from the transponder only for you and we
>>can calculate it later on.
>>
>>2 meters downlink budged calculation:
>>
>>Satellite power ................................... + 10 dBW
>>Satellite antenna gain.......................... + 10 dBi
>> --------------
>>Satellite EIRP..................................... + 20 dBW (100 W EIRP)
>>2 m isotr. attenuation 400.000 km.. -188 dB
>> --------------
>>power density received on a ground
>>isotropic 2 meters antenna..................-168 dBW
>>
>>2 m ground station antenna gain.........+ 13 dBi
>> ---------------
>>Power density at 2 m RX input...........- 155 dBW
>>2 m receiver noise floor......................- 178 dBW
>> ---------------
>>-
>>Received CW signal S/N.................... + 23 dB
>>
>>If we increase the BW to 2500 Hz for a SSB QSO than the noise floor
>>of the receiving system increases by log (2500/500) = 7 dB i.e.
>> 10
>>it becames about -171 dB and the SSB signal will be received with a
>>S/N ratio = 23-7 = 16 dB wich is a very strong SSB signal.
>>
>>Be aware that the above figures are based on the assumption that the
>>satellite antennas are pointig toward the earth wich is not the case with
>>a moon orbiting satellite.
>>
>>In addition we assume that the station in QSO with you has a 70 cm
>>EIRP capability in order to get 10 watt from the 2m transponder only
>>for you.
>>
>>On the other side if a fixed 10 dBi 2 meters antenna is placed over the
>>moon and it is oriented toward the earth could easily cover the inclination
>>X libration window without any adjustement and only from the point of
>>view of the downlink with 10 watt it can be easily used for a transponder
>>on the moon.
>>
>>If you make again the downlink budged calculation considering that
>>the 2 meter transponder will develope only 2.5 watt for you then you
>>will realize that the transponder will accomodate 3 more stations if each
>>one is getting 2.5 watt as well.
>>In this case your S/N ratio will be still +15.5 dB on CW and +8.5 dB
>>in SSB and the same is true for the other 3 users.
>>
>>73" de
>>
>>i8CVS Domenico
>>
>>
>
>Good example of path link analysis, keeping it simple!
>
>But the trick is limiting input to four stations with a linear
>transponder and they all running an equal uplink. Reality is this
>doesn't happen so the shared portion of downlink power may and most
>likely will be less with reduced S/N. My experience with AO-40 was
>that to have a reasonably good SSB contact you needed at least S/N of
>10-dB. In fact that resulted in a fairly weak signal which was
>difficult to copy. 20-dB S/N made for arm-chair reception.
>
>Not discussed were the 70cm uplink requirements. I suppose one could
>run high power to achieve that. My AO-40 experience was running up
>to 60w at a 16.5 dBdc antenna (18.6 dBic). Most of the time I was
>good with about 5-10w if the satellite was lightly loaded. But with
>high numbers of stations trying to operate I needed the full EIRP =
>72x60 = 4320w or in dB: 18.6 + 47.8 = 66.4 dBW
>
>My AO-40 mode-US station consisted of a FT-847+60w linear at the
>antenna (M2-436CP42UG) for uplink. The 2.4 GHz downlink was a
>33-inch dish with helix feed+MKU-232A2 preamp+Drake converter+FT-847
>(on 123-MHz).
>
>I'm not going to go into those calculations.
>
>_______________________________________________
>Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
>Not an AMSAT-NA member? Join now to support the amateur satellite program!
>Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
>
>
>
>
------------------------------
Message: 5
Date: Fri, 4 Jul 2008 22:09:16 -0400
From: "Robert Bruninga" <bruninga(AT)usna.edu>
Subject: [amsat-bb] Re: NASA's American Student Moon Orbiter...
To: "'Joe'" <nss(AT)mwt.net>, "'Edward Cole'" <kl7uw(AT)acsalaska.net>
Cc: 'AMSAT-BB' <amsat-bb(AT)amsat.org>, 'G0MRF David Bowman'
<g0mrf(AT)aol.com>
Message-ID: <9F66F0DFA1814D0280B6812B1FA4444A(AT)ewlab.usna.edu>
Content-Type: text/plain; charset="US-ASCII"
> I've done moon bounce. And many of these
> numbers seem to be not too far from Moonbounce
> numbers, and that is a horrid dead piece of rock
> reflector. that has a efficiency of a wet sponge.
> ...And it only reflects 6% of the energy it gets.
My guess is ... That 6% is an awful lot of power considering the
3.6 million square miles of surface doing the reflecting.
Conversly, any amateur transmitter at the moon would have a much
smaller receiving/transmitting antenna. Though lots more
concentrated power.
So what you gain in changing from a 1/R^4 to a 1/R^2 path loss
you lose a lot of it in the loss of signal receive aperture. Or
something like that maybe.
Bob, WB4APR
> but i would think anything there that is active
> circutry is a thousand times more efficient at
> sendinga signal back as compared to the moons
> surface.
> >>2 meters downlink budged calculation:
> >>
> >>Satellite power ................................... + 10 dBW
> >>Satellite antenna gain.......................... + 10 dBi
> >>
> --------------
> >>Satellite EIRP..................................... + 20
> dBW (100 W EIRP)
> >>2 m isotr. attenuation 400.000 km.. -188 dB
> >>
> --------------
> >>power density received on a ground
> >>isotropic 2 meters antenna..................-168 dBW
> >>
> >>2 m ground station antenna gain.........+ 13 dBi
> >>
> ---------------
> >>Power density at 2 m RX input...........- 155 dBW
> >>2 m receiver noise floor......................- 178 dBW
> >>
> ---------------
> >>-
> >>Received CW signal S/N.................... + 23 dB
> >>
> >>If we increase the BW to 2500 Hz for a SSB QSO than the
noise floor
> >>of the receiving system increases by log (2500/500) = 7
dB i.e.
> >>
10
> >>it becames about -171 dB and the SSB signal will be received
with a
> >>S/N ratio = 23-7 = 16 dB wich is a very strong SSB signal.
> >>
> >>Be aware that the above figures are based on the assumption
that the
> >>satellite antennas are pointig toward the earth wich is not
> the case with
> >>a moon orbiting satellite.
> >>
> >>In addition we assume that the station in QSO with you has a
70 cm
> >>EIRP capability in order to get 10 watt from the 2m
transponder only
> >>for you.
> >>
> >>On the other side if a fixed 10 dBi 2 meters antenna is
> placed over the
> >>moon and it is oriented toward the earth could easily cover
> the inclination
> >>X libration window without any adjustement and only from
> the point of
> >>view of the downlink with 10 watt it can be easily used for
> a transponder
> >>on the moon.
> >>
> >>If you make again the downlink budged calculation
considering that
> >>the 2 meter transponder will develope only 2.5 watt for
> you then you
> >>will realize that the transponder will accomodate 3 more
> stations if each
> >>one is getting 2.5 watt as well.
> >>In this case your S/N ratio will be still +15.5 dB on CW and
+8.5 dB
> >>in SSB and the same is true for the other 3 users.
> >>
> >>73" de
> >>
> >>i8CVS Domenico
> >>
> >>
> >
> >Good example of path link analysis, keeping it simple!
> >
> >But the trick is limiting input to four stations with a
linear
> >transponder and they all running an equal uplink. Reality is
this
> >doesn't happen so the shared portion of downlink power may
and most
> >likely will be less with reduced S/N. My experience with
AO-40 was
> >that to have a reasonably good SSB contact you needed at
> least S/N of
> >10-dB. In fact that resulted in a fairly weak signal which
was
> >difficult to copy. 20-dB S/N made for arm-chair reception.
> >
> >Not discussed were the 70cm uplink requirements. I suppose
> one could
> >run high power to achieve that. My AO-40 experience was
running up
> >to 60w at a 16.5 dBdc antenna (18.6 dBic). Most of the time
I was
> >good with about 5-10w if the satellite was lightly loaded.
But with
> >high numbers of stations trying to operate I needed the full
EIRP =
> >72x60 = 4320w or in dB: 18.6 + 47.8 = 66.4 dBW
> >
> >My AO-40 mode-US station consisted of a FT-847+60w linear at
the
> >antenna (M2-436CP42UG) for uplink. The 2.4 GHz downlink was
a
> >33-inch dish with helix feed+MKU-232A2 preamp+Drake
converter+FT-847
> >(on 123-MHz).
> >
> >I'm not going to go into those calculations.
> >
> >_______________________________________________
> >Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of
> the author.
> >Not an AMSAT-NA member? Join now to support the amateur
> satellite program!
> >Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
> >
> >
> >
> >
> >
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of
> the author.
> Not an AMSAT-NA member? Join now to support the amateur
> satellite program!
> Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 6
Date: Sat, 05 Jul 2008 10:15:35 -0400
From: myoung <myoung(AT)neo.rr.com>
Subject: [amsat-bb] GS-232 & SatPC32 12.8
To: AMSAT-BB(AT)amsat.org
Message-ID: <486F8207.9070100(AT)neo.rr.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Anyone else having trouble getting the GS-232 interface to work on ver 12.8?
The rotor setup "Search" takes me to the KEPS folder, then I select the
SDX folder.
When the program is re-run a pop-up window indicates "SDXParem.exe is
missing.
I can't find it either using XP Search. I've tried this on a laptop
that has never seen any other
version of SatPC32 to avoid any conflicts.
Went back to 12.7 which works fine.
73's
Mike, WB8CXO
------------------------------
Message: 7
Date: Sat, 5 Jul 2008 18:53:54 +0200
From: "Erich Eichmann" <erich.eichmann(AT)t-online.de>
Subject: [amsat-bb] Re: GS-232 & SatPC32 12.8
To: "myoung" <myoung(AT)neo.rr.com>
Cc: AMSAT-BB(AT)amsat.org
Message-ID: <000a01c8debf$b61999b0$0201a8c0(AT)DK1TB>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Hello Mike,
open the menu Rotor-Setup and open the list of supported
interfaces/controllers. To open the list click on the little control (arrow
down) left of the "Search" button. In the list that opens select the item
"Yaesu_GS-232". Then click on the "Store" button in the upper section of the
menu and restart SatPC32. The program should then start ServerSDX. Click on
it in the taskbar to show it normally. In the ServerSDX setup window select
COM port and baudrate, save the settings and re-start SatPC32 again.
You clicked the "Search" button and navigated to the SatPC32 DATA folder,
sub folder SDX. ServerSDX.Exe, however, is located in the sub folder SDX in
the SatPC32 PROGRAM folder (usually C:\Program Files\SatPC32\SDX).
Please, let me know whether it works.
73s, Erich, DK1TB
----- Original Message -----
From: "myoung" <myoung(AT)neo.rr.com>
To: <AMSAT-BB(AT)AMSAT.Org>
Sent: Saturday, July 05, 2008 4:15 PM
Subject: [amsat-bb] GS-232 & SatPC32 12.8
> Anyone else having trouble getting the GS-232 interface to work on ver
> 12.8?
> The rotor setup "Search" takes me to the KEPS folder, then I select the
> SDX folder.
> When the program is re-run a pop-up window indicates "SDXParem.exe is
> missing.
> I can't find it either using XP Search. I've tried this on a laptop
> that has never seen any other
> version of SatPC32 to avoid any conflicts.
>
> Went back to 12.7 which works fine.
>
> 73's
>
> Mike, WB8CXO
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 8
Date: Sat, 5 Jul 2008 19:20:39 +0200
From: "i8cvs" <domenico.i8cvs(AT)tin.it>
Subject: [amsat-bb] Re: NASA's American Student Moon Orbiter...
To: "Bob Bruninga" <bruninga(AT)usna.edu>, "'Joe'" <nss(AT)mwt.net>,
"'Edward Cole'" <kl7uw(AT)acsalaska.net>
Cc: 'AMSAT-BB' <amsat-bb(AT)amsat.org>, 'G0MRF David Bowman'
<g0mrf(AT)aol.com>
Message-ID: <009601c8dec3$72f1d720$0201a8c0(AT)tin.it>
Content-Type: text/plain; charset="iso-8859-1"
----- Original Message -----
From: "Robert Bruninga" <bruninga(AT)usna.edu>
To: "'Joe'" <nss(AT)mwt.net>; "'Edward Cole'" <kl7uw(AT)acsalaska.net>
Cc: "'AMSAT-BB'" <amsat-bb(AT)amsat.org>; "'G0MRF David Bowman'"
<g0mrf(AT)aol.com>
Sent: Saturday, July 05, 2008 4:09 AM
Subject: [amsat-bb] Re: NASA's American Student Moon Orbiter...
> > The whole part that is confusing me on all this power
> > budget stuff is the to me, the seemingly HIGH budget.
> > I've done moon bounce. And many of these
> > numbers seem to be not too far from Moonbounce
> > numbers, and that is a horrid dead piece of rock
> > reflector. that has a efficiency of a wet sponge.
> > ...And it only reflects 6% of the energy it gets.
>
> My guess is ... That 6% is an awful lot of power considering the
> 3.6 million square miles of surface doing the reflecting.
> Conversly, any amateur transmitter at the moon would have a much
> smaller receiving/transmitting antenna. Though lots more
> concentrated power.
>
> So what you gain in changing from a 1/R^4 to a 1/R^2 path loss
> you lose a lot of it in the loss of signal receive aperture. Or
> something like that maybe.
>
> Bob, WB4APR
>
> > but i would think anything there that is active
> > circutry is a thousand times more efficient at
> > sendinga signal back as compared to the moons
> > surface.
> > or what am I missing?
> >Joe
Hi Bob, WB4APR
Your guess is.......absolutely correct.
I also did 432 MHz EME from 1977 to 1980 and I will try to demonstrate
in more datails to Joe that your analysis hit the centre of his question.
Hi Joe
Suppose to be in the center of a sphere with radius of 380.000 km that is
the average distance from the earth to the moon.
The internal surface S of the above sphere computed in square meters is:
6 2 18
S= 4 x 3,14 x ( 380 x 10 ) = 1,81 x 10 square meters
Suppose now to have in your hand an isotropic antenna radiating all around
and uniformly the power P = 1 watt at 432 MHz
As soon the wave has reached the internal surface of the above sphere the
full power of 1 watt will be collected on it so that the power density D
collected in each square meter is:
1 -19
D = ------------------------ = 5,52 x 10 watt / square meter
18
1,81 x 10
But in one point of the above sphere there is the disc of the moon which
radius is 1735 km =1735000 meters and so the surface S1 of the lunar
disc is:
2 12
S1 = 1735000 x 3,14= 9,45 x 10 square meters
The full power density P1 collected over the disc of the lunar surface will
be D x S1 and so
-19 12
P1= 5,52 x 10 x 9,45 x 10 = 0,0000052164 watt
Only the 7% of P1 at 432 MHz is reflected back by the lunar surface
and very important the reflected power P2 is reirradiated and scattered
back "isotropically" by the lunar disc and so the reflected power is
P2=(0,0000052164 / 100) x 7= 0,0000003651 watt
Now P2 make another trip of 380.000 km from the moon to the earth
but actually the power P3 collected by each square meter over the earth
surface will be only:
0,0000003651 -25
P3= ----------------------- = 2,017 x 10 watt / square meter
18
1,81 x 10
Since we have in our hand an isotropic antenna at 432 MHz originally
radiating 1 watt we want to know what actually is the power Pr received
back from the moon into the same isotropic antenna.
The aperture area A of an isotropic antenna at 432 MHz i.e. at a wavelenght
of 0,6944 meters is:
/ 2 2
/\ 0,6944
A = -------- = ----------- = 0,0383 square meters
4 x 3,14 4 x 3,14
It follow that the power Pr received by the isotropic antenna on the earth
is Pr = P3 x A and so
-25 -27
Pr= 2,017 x 10 x 0,0383 = 7,725 x 10 watt
Consequently the round trip isotropic attenuation (Att) earth-moon-earth for
380.000 km at 432 MHz off the moon is P / Pr and so in dB
1
(Att) = 10 log ------------------- = 261 dB
10 -27
7,725 x 10
The average of 432 MHz EME active stations are using the following:
Antenna gain = 30 dBi
Power at the antenna feed = 1000 watt
Overall RX noise figure NF= 0.6 dB = 43 kelvin
BW for CW = 500 Hz
Equivalent antenna temperature Ta when pointed at the cold-sky = 50 kelvin
With the above data NF, BW and Ta the noise floor of the receiving system
KTB = -182 dBW or -152 dBm
Link budged calculation 432 MHz:
TX power at the feed.............................+30 dBW
TX Antenna gain....................................+30 dBi
--------------
Transmitted EIRP toward the moon.....+60 dBW = 1 Megawatt
Round trip attenuation 380.000 km.. - 261 dB
--------------
Received power Pr on isotropic
antenna at the earth .............................-201 dBW
RX antenna gain................................. +30 dB
--------------
-
Available power at RX input............. - 171 dBW
RX noise floor.....................................- 182 dBW
--------------
CW signal received with a S/N ratio + 11 dB
To get a S/N ratio of 11 dB off the moon on CW it was necessary to
6
transmit + 60 dBW = 10 watt = 1 Megawatt toward the moon but
calculating the round trip attenuation we remember that transmitting
isotropically 1 watt from the earth the power collected by the lunar
disc was
P1= 0,0000052164 watt
6
If now we multiply P1 by 10 we get the full power Pc collected by the
lunar disc while transmitting on CW toward the moon and so:
6
Pc = 0,0000052164 x 10 = 5.21 watt ( an awful lot of power as Bob said)
Only the 7% of Pc at 432 MHz is reflected back by the lunar surface
and very important the reflected power P is reirradiated and scattered
back "isotropically" by the lunar disc and so the reflected power is
P = ( 5.21 / 100) x 7= 0, 3651 watt
If I want to receive a CW signal of 0,3651 watt transmitted isotropically
from the moon and if I want to receive it with a S/N ratio of 11 dB it is
evident that I need a 30 dBi antenna gain and a receiving system with
a noise floor of - 182 dBW.........no way !
If instead I want to receive a SSB or CW signal transmitted in 2 meters
by a satellite or from the moon with a power of 10 watt feed into a 10 dBi
antenna gain and using a 2 meters ground station antenna with gain of only
13 dBi and a receiving system with a noise floor of - 178 dBW then
everyting in SSB and CW becomes very easy as calculation shows.
2 meters downlink budged calculation:
Satellite power ................................... + 10 dBW
Satellite antenna gain.......................... + 10 dBi
--------------
Satellite EIRP..................................... + 20 dBW (100 W EIRP)
2 m isotr. attenuation 400.000 km.. -188 dB
--------------
power density received on a ground
isotropic 2 meters antenna..................-168 dBW
2 m ground station antenna gain.........+ 13 dBi
---------------
Power density at 2 m RX input...........- 155 dBW
2 m receiver noise floor......................- 178 dBW
---------------
-
Received CW signal S/N.................... + 23 dB
If we increase the BW to 2500 Hz for a SSB QSO than the noise floor
of the receiving system increases by 10 log (2500/500) = 7 dB i.e.
10
it becames about -171 dB and the SSB signal will be received with a
S/N ratio = 23-7 = 16 dB wich is a very strong SSB signal.
Be aware that the above figures are based on the assumption that the
satellite antennas are pointig toward the earth wich is not the case with
a moon orbiting satellite.
In addition we assume that the station in QSO with you has a 70 cm
EIRP capability in order to get 10 watt from the 2m transponder only
for you.
On the other side if a fixed 10 dBi 2 meters antenna is placed over the
moon and it is oriented toward the earth could easily cover the inclination
X libration window without any adjustement and only from the point of
view of the downlink with 10 watt it can be easily used for a transponder
on the moon.
If you make again the downlink budged calculation considering that
the 2 meter transponder will develope only 2.5 watt for you then you
will realize that the transponder will accomodate 3 more stations if each
one is getting 2.5 watt as well.
In this case your S/N ratio will be still +15.5 dB on CW and +8.5 dB
in SSB and the same is true for the other 3 users.
I hope this helps
73" de
i8CVS Domenico
------------------------------
Message: 9
Date: Sat, 5 Jul 2008 14:57:18 -0400
From: "John Henderson N4NAB" <jah(AT)ec.rr.com>
Subject: [amsat-bb] Logbook Software
To: <amsat-bb(AT)amsat.org>
Message-ID: <001501c8ded0$f300aa10$d901fe30$(AT)rr.com>
Content-Type: text/plain; charset="us-ascii"
Thanks to all who shared their info on logbook sw. I have settled on N3FJP's
product which is quite easy to use and customize. Only need a way to get
paper logs transferred, hihi/
John
John Henderson N4NAB
212 Bayside Drive
Cape Carteret, NC 28584
------------------------------
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End of AMSAT-BB Digest, Vol 3, Issue 335
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