Theoretically we may have a free ride to the Moon for an Amateur radio repeater!
In the past, the flight to the moon for a Amateur radio project has been cost prohibitive. We just could not afford to pay for the ride to the Moon. NASA is going to the moon with unmanned landers. NASA is open to the idea of flying some public service projects to the moon on their landers.
Now there exists the possibility of getting a free ride to the moon, curtsy of NASA.
What we need are the following:
A stable club with funding to build a simple transponder project. A plan for a simple transponder (KISS no complex P3E). A link budget plan for a Moon transponder.
One theory: We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Questions: What’s the link budget? How much gain will be needed on earth for such a setup? Can we build a working mockup in 1 year or less.
The Moon is within Reach. Let’s Go for IT.
Miles WF1F MarexMG.org
--- On Wed, 7/1/09, Jack K. kd1pe.1@gmail.com wrote:
From: Jack K. kd1pe.1@gmail.com Subject: [amsat-bb] Rebuttal - Re: Unused sats To: kg4zlb@gmail.com, amsat-bb@amsat.org Date: Wednesday, July 1, 2009, 4:46 PM I have to disagree in the strongest of terms about disregarding HEOs "for now" which in essence will mean to become forever. Until, or unless, we could come up with something along the lines of a "Cell" system of leos, we are missing one of the major advantages of Satellites and that is almost guaranteed communications for long periods (several hours) at a time... I am in no way denigrating LEOs as they have their place, but in the major schema of things HEOS will and always have rule given the state of communications art...
I understand the desire to "do something" but I suggest that the major thrust should be directed at getting a transponder on the moon (or Mars) or some more KISS type HEOs up... Cubesats can take care of themselves if we do, Heck I would even join in and participate in something like I just mentioned, I just can not get excited about "Contest style" contacts with a 5-12 min window most of the time... I do that on 2 meters scatter all I want,
DE Jack - KD1PE
----- Original Message ----- From: "David - KG4ZLB" kg4zlb@googlemail.com To: amsat-bb@amsat.org Sent: Wednesday, July 01, 2009 4:09 PM Subject: [amsat-bb] Re: Unused sats
All good points but forget the HEO's for now - we just
need a good
source of regularly launched easy sats in LEO to
augment the few working
birds we have and replace what we have to as they fall
out of the sky or
just stop working.
Sent via AMSAT-BB@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
There is nothing simple about a project that can withstand the extreme temperature changes and eclipse periods that exst on the moon. It's probably the most hostile environment we're likely to build for.
MM wrote:
A plan for a simple transponder (KISS no complex P3E).
MM wrote:
Theoretically we may have a free ride to the Moon for an Amateur radio repeater!
[snip]
One theory: We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Why go with the minimal antenna gain? From the moon the whole Earth only displays less than 2 degrees in the sky. ( Moon shows 0.5 degrees from earth) Why spill all the power where people are not?
In addition, once the antennas are positioned, that's more or less it. There is a slight wobble (Libration) of 6.5 degrees So any antenna with a 3 db point that exceeds 6.5 degrees is just wasting transmitter power.
And with this link budget even an active bird that has landed and not flying it still will need some pretty hefty power to not need a major antenna setup on the earth side of the system.
Just remember what an Oscar 10 station took to have reliable communications,, At Apogee it was only 35,000 miles away, the Moon is almost a ten fold increase in distance, to keep the lander from having to run hundreds of watts to be heard on the earth, ever DB of antenna gain will be needed for sure!
Joe WB9SBD
Just remember what an Oscar 10 station took to have reliable communications, At Apogee it was only 35,000 miles away, the Moon is ...] [250,000 miles]
Which is 7 times farther, squared or 50 times more power.
exactly,
thats why every DB we could get in antenna should be taken,
Joe WB9SBD
Robert Bruninga wrote:
Just remember what an Oscar 10 station took to have reliable communications, At Apogee it was only 35,000 miles away, the Moon is ...] [250,000 miles]
Which is 7 times farther, squared or 50 times more power.
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Why go with the minimal antenna gain? ... any antenna with a 3 db point that exceeds 6.5 degrees is just wasting transmitter power.
I think that would be about a 24 dB gain antenna. Pretty big and would take some careful alignment... Kinda like a realy big EME array
Just remember what an Oscar 10 station took to have reliable communications, At Apogee it was only 35,000 miles away, the Moon is ...] [250,000 miles]
Which is 7 times farther, squared or 50 times more power (about 17 dB).
BUT one easy way to get gain is to use just a long coaxial gain cable. I think it takes about 22 feet of coaxial dipole elements at 2 meters to give about 6 dB of gain. So laying down 6 dB gain segments on the rock of the moon is as easy as unrolling a spool of cable. Unrolling 8 of these with the right spacing could yield about 17 dB.
Of course this woiuld only point straight up, so it would need to be on a moon base in the middle of the earth facing side. But since there is a lot of interest in moon bases near the poles where there might be water, then a similar array of layed down coaxial cable arrays could be phased horizontally to point at earth. Actually, just about any direction can be obtained with the right spacing.
ONLY problem of course is there has to be someone with legs to roll out the cables.
Just a thought. Bob, WB4APR
Has anyone considered the notion that the communications from a HEO or Moon or Mars need not be analog? Has anyone considered a digital mode such as WSJT for comms? I know for a fact people are running meteor scatter and EME using a single beam (albeit a long one) and 150 watts. This is not out of the reach of most hams and it is not non-viable communications mode... Heck the US Navy even ran RTTY in the 60's from Hawaii to Maryland as a normal mode of communications (yes it was big and wieldy, I just mentioned it as an aside).
DE - KD1PE - Jack
Why go with the minimal antenna gain? ... any antenna with a 3 db point that exceeds 6.5 degrees is just wasting transmitter power.
I think that would be about a 24 dB gain antenna. Pretty big and would take some careful alignment... Kinda like a realy big EME array
Just remember what an Oscar 10 station took to have reliable communications, At Apogee it was only 35,000 miles away, the Moon is ...] [250,000 miles]
Which is 7 times farther, squared or 50 times more power (about 17 dB).
Quote: Has anyone considered the notion that the communications from a HEO or Moon or Mars need not be analog? Has anyone considered a digital mode such as WSJT for comms? I know for a fact people are running meteor scatter and EME using a single beam (albeit a long one) and 150 watts. This is not out of
Personally, I have no use for ssb or cw, but I would definitely like to try EME with WSJT or similar modes. I would also prefer the higher frequencies. I can't aim a 2m beam out of my apartment window but higher bands would not be a problem. Indeed, that's probably the only way one could go in an urban environment. I can't see that my investment and effort would be any less for a "simpler" mode.
(I'd go on about how 70cm is really prevalent and that, despite what some old-timers think, most hams aren't saving their pennies for the Benton Harbor lunchbox anymore.)
73, Dave, N1KGH
It seems to me that the correct choice is the highest frequency we can get on board for at least 24dB at the longest length of antenna that we would be allowed to send up.
Gregg Wonderly W5GGW
Robert Bruninga wrote:
Why go with the minimal antenna gain? ... any antenna with a 3 db point that exceeds 6.5 degrees is just wasting transmitter power.
I think that would be about a 24 dB gain antenna. Pretty big and would take some careful alignment... Kinda like a realy big EME array
Just remember what an Oscar 10 station took to have reliable communications, At Apogee it was only 35,000 miles away, the Moon is ...] [250,000 miles]
Which is 7 times farther, squared or 50 times more power (about 17 dB).
BUT one easy way to get gain is to use just a long coaxial gain cable. I think it takes about 22 feet of coaxial dipole elements at 2 meters to give about 6 dB of gain. So laying down 6 dB gain segments on the rock of the moon is as easy as unrolling a spool of cable. Unrolling 8 of these with the right spacing could yield about 17 dB.
Of course this woiuld only point straight up, so it would need to be on a moon base in the middle of the earth facing side. But since there is a lot of interest in moon bases near the poles where there might be water, then a similar array of layed down coaxial cable arrays could be phased horizontally to point at earth. Actually, just about any direction can be obtained with the right spacing.
ONLY problem of course is there has to be someone with legs to roll out the cables.
Just a thought. Bob, WB4APR
Sent via AMSAT-BB@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
On Thu, 2009-07-02 at 18:21 -0500, Gregg Wonderly wrote:
It seems to me that the correct choice is the highest frequency we can get on board for at least 24dB at the longest length of antenna that we would be allowed to send up.
Lunar gravity is weaker and there is no wind. So, a collapsible antenna that wouldn't last five minutes in typical Earth weather will be a lot more usable on the Moon.
Maybe something like a telescopic boom with a gas canister or pyro charge to pop the sections out?
Gordon
The thermal cycling would make a gas "Bag" antenna interesting as the gas expands and contracts with temperature changes.
I like Bob's idea of an array of collinears lying on the moon's surface, since "ground" on the moon must be quite deep due to the lack of moisture.
This makes 2 meters very attractive as a down-link. We could take advantage of the reduced path loss and higher efficiencies in the circuits that 2 meters (or ten meters) has to offer.
I suspect it would be possible to build such antenna that uses a "wound up" spring to unwind the antennas for deployment, like a reverse tape measure that uncoils instead of coils up.
73, Joe kk0sd -----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Gordon JC Pearce Sent: Friday, July 03, 2009 11:41 AM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: The Moon is our Future
On Thu, 2009-07-02 at 18:21 -0500, Gregg Wonderly wrote:
It seems to me that the correct choice is the highest frequency we can get
on
board for at least 24dB at the longest length of antenna that we would be allowed to send up.
Lunar gravity is weaker and there is no wind. So, a collapsible antenna that wouldn't last five minutes in typical Earth weather will be a lot more usable on the Moon.
Maybe something like a telescopic boom with a gas canister or pyro charge to pop the sections out?
Gordon
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Path loss for a lunar downlink at 435 MHz is 197 dB and the sky temperature is about 75 K. If you assume a 2.5 kHz wide SSB voice downlink and 10dB average SNR (16 dB peak) a perfect receiver needs to see -130 dBm PEP input. Given 5 dBic of gain on the moon and 17 dBic (one long yagi) of gain on the earth, the lunar transmitter needs to provide +45 dBm PEP (32 Watts) per user.
73,
John KD6OZH
----- Original Message ----- From: "MM" ka1rrw@yahoo.com To: kg4zlb@gmail.com; amsat-bb@amsat.org; "Jack K." kd1pe.1@gmail.com Sent: Thursday, July 02, 2009 11:31 UTC Subject: [amsat-bb] The Moon is our Future
Theoretically we may have a free ride to the Moon for an Amateur radio repeater!
In the past, the flight to the moon for a Amateur radio project has been cost prohibitive. We just could not afford to pay for the ride to the Moon. NASA is going to the moon with unmanned landers. NASA is open to the idea of flying some public service projects to the moon on their landers.
Now there exists the possibility of getting a free ride to the moon, curtsy of NASA.
What we need are the following:
A stable club with funding to build a simple transponder project. A plan for a simple transponder (KISS no complex P3E). A link budget plan for a Moon transponder.
One theory: We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Questions: What’s the link budget? How much gain will be needed on earth for such a setup? Can we build a working mockup in 1 year or less.
The Moon is within Reach. Let’s Go for IT.
Miles WF1F MarexMG.org
--- On Wed, 7/1/09, Jack K. kd1pe.1@gmail.com wrote:
From: Jack K. kd1pe.1@gmail.com Subject: [amsat-bb] Rebuttal - Re: Unused sats To: kg4zlb@gmail.com, amsat-bb@amsat.org Date: Wednesday, July 1, 2009, 4:46 PM I have to disagree in the strongest of terms about disregarding HEOs "for now" which in essence will mean to become forever. Until, or unless, we could come up with something along the lines of a "Cell" system of leos, we are missing one of the major advantages of Satellites and that is almost guaranteed communications for long periods (several hours) at a time... I am in no way denigrating LEOs as they have their place, but in the major schema of things HEOS will and always have rule given the state of communications art...
I understand the desire to "do something" but I suggest that the major thrust should be directed at getting a transponder on the moon (or Mars) or some more KISS type HEOs up... Cubesats can take care of themselves if we do, Heck I would even join in and participate in something like I just mentioned, I just can not get excited about "Contest style" contacts with a 5-12 min window most of the time... I do that on 2 meters scatter all I want,
DE Jack - KD1PE
----- Original Message ----- From: "David - KG4ZLB" kg4zlb@googlemail.com To: amsat-bb@amsat.org Sent: Wednesday, July 01, 2009 4:09 PM Subject: [amsat-bb] Re: Unused sats
All good points but forget the HEO's for now - we just
need a good
source of regularly launched easy sats in LEO to
augment the few working
birds we have and replace what we have to as they fall
out of the sky or
just stop working.
Sent via AMSAT-BB@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@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
Now thats pretty good!
But why is it soo good, when the HEO birds were soo hard?
something missing?
John B. Stephensen wrote:
Path loss for a lunar downlink at 435 MHz is 197 dB and the sky temperature is about 75 K. If you assume a 2.5 kHz wide SSB voice downlink and 10dB average SNR (16 dB peak) a perfect receiver needs to see -130 dBm PEP input. Given 5 dBic of gain on the moon and 17 dBic (one long yagi) of gain on the earth, the lunar transmitter needs to provide +45 dBm PEP (32 Watts) per user.
73,
John KD6OZH
----- Original Message ----- From: "MM" ka1rrw@yahoo.com To: kg4zlb@gmail.com; amsat-bb@amsat.org; "Jack K." kd1pe.1@gmail.com Sent: Thursday, July 02, 2009 11:31 UTC Subject: [amsat-bb] The Moon is our Future
Theoretically we may have a free ride to the Moon for an Amateur radio repeater!
In the past, the flight to the moon for a Amateur radio project has been cost prohibitive. We just could not afford to pay for the ride to the Moon. NASA is going to the moon with unmanned landers. NASA is open to the idea of flying some public service projects to the moon on their landers.
Now there exists the possibility of getting a free ride to the moon, curtsy of NASA.
What we need are the following:
A stable club with funding to build a simple transponder project. A plan for a simple transponder (KISS no complex P3E). A link budget plan for a Moon transponder.
One theory: We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Questions: What’s the link budget? How much gain will be needed on earth for such a setup? Can we build a working mockup in 1 year or less.
The Moon is within Reach. Let’s Go for IT.
Miles WF1F MarexMG.org
--- On Wed, 7/1/09, Jack K. kd1pe.1@gmail.com wrote:
From: Jack K. kd1pe.1@gmail.com Subject: [amsat-bb] Rebuttal - Re: Unused sats To: kg4zlb@gmail.com, amsat-bb@amsat.org Date: Wednesday, July 1, 2009, 4:46 PM I have to disagree in the strongest of terms about disregarding HEOs "for now" which in essence will mean to become forever. Until, or unless, we could come up with something along the lines of a "Cell" system of leos, we are missing one of the major advantages of Satellites and that is almost guaranteed communications for long periods (several hours) at a time... I am in no way denigrating LEOs as they have their place, but in the major schema of things HEOS will and always have rule given the state of communications art...
I understand the desire to "do something" but I suggest that the major thrust should be directed at getting a transponder on the moon (or Mars) or some more KISS type HEOs up... Cubesats can take care of themselves if we do, Heck I would even join in and participate in something like I just mentioned, I just can not get excited about "Contest style" contacts with a 5-12 min window most of the time... I do that on 2 meters scatter all I want,
DE Jack - KD1PE
----- Original Message ----- From: "David - KG4ZLB" kg4zlb@googlemail.com To: amsat-bb@amsat.org Sent: Wednesday, July 01, 2009 4:09 PM Subject: [amsat-bb] Re: Unused sats
All good points but forget the HEO's for now - we just
need a good
source of regularly launched easy sats in LEO to
augment the few working
birds we have and replace what we have to as they fall
out of the sky or
just stop working.
Sent via AMSAT-BB@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@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
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I received my QSL from Richard today along with a nice letter explaining, among other things, why it's taken this long to get the 500+ QSLs out in the mail.
Glenn AA5PK
Actually, its very bad as it barely supports 1 user at 3 times the proposed maximum power level. You could support 100 users on a HEO with the same SNR and power output. Most users will consider 10 dB SNR to be marginal and want another 10 dB of signal strength on the downlink. The same amount of power has been consumed by 10 stations on HEOs.
73,
John KD6OZH ----- Original Message ----- From: Joe To: John B. Stephensen ; amsat-bb@amsat.org Sent: Thursday, July 02, 2009 22:01 UTC Subject: Re: [amsat-bb] Re: The Moon is our Future
Now thats pretty good!
But why is it soo good, when the HEO birds were soo hard?
something missing?
John B. Stephensen wrote:
Path loss for a lunar downlink at 435 MHz is 197 dB and the sky temperature is about 75 K. If you assume a 2.5 kHz wide SSB voice downlink and 10dB average SNR (16 dB peak) a perfect receiver needs to see -130 dBm PEP input. Given 5 dBic of gain on the moon and 17 dBic (one long yagi) of gain on the earth, the lunar transmitter needs to provide +45 dBm PEP (32 Watts) per user.
73,
John KD6OZH
----- Original Message ----- From: "MM" ka1rrw@yahoo.com To: kg4zlb@gmail.com; amsat-bb@amsat.org; "Jack K." kd1pe.1@gmail.com Sent: Thursday, July 02, 2009 11:31 UTC Subject: [amsat-bb] The Moon is our Future
Theoretically we may have a free ride to the Moon for an Amateur radio repeater!
In the past, the flight to the moon for a Amateur radio project has been cost prohibitive. We just could not afford to pay for the ride to the Moon. NASA is going to the moon with unmanned landers. NASA is open to the idea of flying some public service projects to the moon on their landers.
Now there exists the possibility of getting a free ride to the moon, curtsy of NASA.
What we need are the following:
A stable club with funding to build a simple transponder project. A plan for a simple transponder (KISS no complex P3E). A link budget plan for a Moon transponder.
One theory: We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Questions: What’s the link budget? How much gain will be needed on earth for such a setup? Can we build a working mockup in 1 year or less.
The Moon is within Reach. Let’s Go for IT.
Miles WF1F MarexMG.org
--- On Wed, 7/1/09, Jack K. kd1pe.1@gmail.com wrote:
From: Jack K. kd1pe.1@gmail.com Subject: [amsat-bb] Rebuttal - Re: Unused sats To: kg4zlb@gmail.com, amsat-bb@amsat.org Date: Wednesday, July 1, 2009, 4:46 PM I have to disagree in the strongest of terms about disregarding HEOs "for now" which in essence will mean to become forever. Until, or unless, we could come up with something along the lines of a "Cell" system of leos, we are missing one of the major advantages of Satellites and that is almost guaranteed communications for long periods (several hours) at a time... I am in no way denigrating LEOs as they have their place, but in the major schema of things HEOS will and always have rule given the state of communications art...
I understand the desire to "do something" but I suggest that the major thrust should be directed at getting a transponder on the moon (or Mars) or some more KISS type HEOs up... Cubesats can take care of themselves if we do, Heck I would even join in and participate in something like I just mentioned, I just can not get excited about "Contest style" contacts with a 5-12 min window most of the time... I do that on 2 meters scatter all I want,
DE Jack - KD1PE
----- Original Message ----- From: "David - KG4ZLB" kg4zlb@googlemail.com To: amsat-bb@amsat.org Sent: Wednesday, July 01, 2009 4:09 PM Subject: [amsat-bb] Re: Unused sats
All good points but forget the HEO's for now - we just need a good source of regularly launched easy sats in LEO to augment the few working birds we have and replace what we have to as they fall out of the sky or just stop working. _______________________________________________ Sent via AMSAT-BB@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@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@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 ----------------------------------------------------------------------------
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----- Original Message ----- From: "MM" ka1rrw@yahoo.com To: kg4zlb@gmail.com; amsat-bb@amsat.org; "Jack K." kd1pe.1@gmail.com Sent: Thursday, July 02, 2009 1:31 PM Subject: [amsat-bb] The Moon is our Future
We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Questions: What’s the link budget? How much gain will be needed on earth for such a setup? Can we build a working mockup in 1 year or less.
The Moon is within Reach. Let’s Go for IT.
Miles WF1F MarexMG.org
Hi Miles, WF1F
The gain of the 2 meters antenna on the Lander is 3 dBd = 5.14 dBi Assume that the Noise Figure of the 2 meter receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 2 meter Lander antenna looking at the earth is conservatively 290 kelvin but (probably more ). The isotropic path loss earth-moon in 2 meters at an average distance of 380.000 km is 187 dB You don't specify the IF bandwidth of your transponder so that for simplicity I will assume that only one QSO will be possible in SSB and 3 on CW in a total BW = 2.5 KHz With the above data the calculated Noise Floor (KTB) of the above 2 meter Lander receiver is -139 dBm We assume to use an earth 2 meters antenna with a gain of 13 dBi and a power of 100 watt pep in 2 meters.
UPLINK BUDGED:
Earth TX power 100 watt.............................+ 50 dBm Earth antenna gain............................. .............+ 13 dB ------ Earth EIRP.....................................................+ 63 dBm 2 m isotropic attenuation earth-moon..............-187 dB ------ Isoptropic power received on the moon .........- 124 dBm 2 meters Lander antenna gain.........................+ 5 dBi ------ Power applied to the 2 m Lander receiver......- 119 dBm Lander receiver 2 m Noise Floor...................- 139 dBm ------ S/N ratio available from the Lander receiver.. + 20 dB
COMMENT: With a 2 meter signal +20 dB above the noise floor the 70 cm TX on the Lander transponder is in condition to supply a noise-less power between 5 to 10 watt pep to the 70 cm TX antenna.
DOWNLINK BUDGED:
The gain of the 70 cm antenna on the Lander is 3 dBd = 5.14 dBi and the 70 cm power is 10 watt pep Assume that the Noise Figure of the 70 cm earth receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 70 cm antenna looking at the moon is 75 kelvin Assume that the antenna gain of the 70 cm earth receiver is 18 dBi The isotropic path loss earth-moon in 70 cm at an average distance of 380.000 km is 197 dB With the above data the calculated Noise Floor (KTB) of the 70 cm ground receiver is -144 dBm
Lander 70 cm TX power 10 watt...................+ 40 dBm Lander antenna gain.......................................+ 5 dBi ------ 70 cm EIRP from the moon...........................+ 45 dBm 70 cm moon-earth isotropic attenuation .........-197 dB ------ 70 cm power available in to isotropic antenna -152 dBm 70 cm earth receiving antenna gain..................+ 18 dBi ------ 70 cm power on input of the earth receiver.....-134 dBm 70 cm Noise Floor of the earth receiver..........-144 dBm ------ S/N ratio at the output of 70 cm receiver.......+ 10 dB
COMMENT: Using a Lander transponder on the moon with 2 meters and 70 cm antenna's gain in the order of 5 dBi will not produce serious problems of pointing at the earth due of libration. If the Lander transponder is capable to develope 10 watt pep and the IF bandwidth is very narrow in the order of 2.5 KHz it is possible to accomodate one SSB QSO or 3 CW QSO just using the actually available TX and RX equipments for satellite communications i.e. For the uplink in 2 meters 100 watt pep and a 13 dBi antenna gain For the downlink in 70 cm a receiving system with an overall Noise Figure of 0.5 dB and antenna gain of 18 dBi The rate of change of the frequency due of doppler shift in 2 meters and 70 cm is very slow and easily manually compensated even into only a 2.5 KHz bandwidth The antenna polarization is very important because a linear signal transmitted from the earth or from the moon by stations located in different continents can be reversed from Vertical to Horizontal polarization so that at least on the earth circular RHCP and LHCP switchable polarization is recommended.
Best 73" de
i8CVS Domenico
This is all good except for one thing,
The IF window is 10 times too small.
Look at the mess the FM single channel birds are with their tiny surface foot print. Imagine now a whole hemisphere worth of people trying to use it at once. The thing would be useless
i8cvs wrote:
----- Original Message ----- From: "MM" ka1rrw@yahoo.com To: kg4zlb@gmail.com; amsat-bb@amsat.org; "Jack K." kd1pe.1@gmail.com Sent: Thursday, July 02, 2009 1:31 PM Subject: [amsat-bb] The Moon is our Future
We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Questions: What’s the link budget? How much gain will be needed on earth for such a setup? Can we build a working mockup in 1 year or less.
The Moon is within Reach. Let’s Go for IT.
Miles WF1F MarexMG.org
Hi Miles, WF1F
The gain of the 2 meters antenna on the Lander is 3 dBd = 5.14 dBi Assume that the Noise Figure of the 2 meter receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 2 meter Lander antenna looking at the earth is conservatively 290 kelvin but (probably more ). The isotropic path loss earth-moon in 2 meters at an average distance of 380.000 km is 187 dB You don't specify the IF bandwidth of your transponder so that for simplicity I will assume that only one QSO will be possible in SSB and 3 on CW in a total BW = 2.5 KHz With the above data the calculated Noise Floor (KTB) of the above 2 meter Lander receiver is -139 dBm We assume to use an earth 2 meters antenna with a gain of 13 dBi and a power of 100 watt pep in 2 meters.
UPLINK BUDGED:
Earth TX power 100 watt.............................+ 50 dBm Earth antenna gain............................. .............+ 13 dB ------ Earth EIRP.....................................................+ 63 dBm 2 m isotropic attenuation earth-moon..............-187 dB ------ Isoptropic power received on the moon .........- 124 dBm 2 meters Lander antenna gain.........................+ 5 dBi ------ Power applied to the 2 m Lander receiver......- 119 dBm Lander receiver 2 m Noise Floor...................- 139 dBm ------ S/N ratio available from the Lander receiver.. + 20 dB
COMMENT: With a 2 meter signal +20 dB above the noise floor the 70 cm TX on the Lander transponder is in condition to supply a noise-less power between 5 to 10 watt pep to the 70 cm TX antenna.
DOWNLINK BUDGED:
The gain of the 70 cm antenna on the Lander is 3 dBd = 5.14 dBi and the 70 cm power is 10 watt pep Assume that the Noise Figure of the 70 cm earth receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 70 cm antenna looking at the moon is 75 kelvin Assume that the antenna gain of the 70 cm earth receiver is 18 dBi The isotropic path loss earth-moon in 70 cm at an average distance of 380.000 km is 197 dB With the above data the calculated Noise Floor (KTB) of the 70 cm ground receiver is -144 dBm
Lander 70 cm TX power 10 watt...................+ 40 dBm Lander antenna gain.......................................+ 5 dBi ------ 70 cm EIRP from the moon...........................+ 45 dBm 70 cm moon-earth isotropic attenuation .........-197 dB ------ 70 cm power available in to isotropic antenna -152 dBm 70 cm earth receiving antenna gain..................+ 18 dBi ------ 70 cm power on input of the earth receiver.....-134 dBm 70 cm Noise Floor of the earth receiver..........-144 dBm ------ S/N ratio at the output of 70 cm receiver.......+ 10 dB
COMMENT: Using a Lander transponder on the moon with 2 meters and 70 cm antenna's gain in the order of 5 dBi will not produce serious problems of pointing at the earth due of libration. If the Lander transponder is capable to develope 10 watt pep and the IF bandwidth is very narrow in the order of 2.5 KHz it is possible to accomodate one SSB QSO or 3 CW QSO just using the actually available TX and RX equipments for satellite communications i.e. For the uplink in 2 meters 100 watt pep and a 13 dBi antenna gain For the downlink in 70 cm a receiving system with an overall Noise Figure of 0.5 dB and antenna gain of 18 dBi The rate of change of the frequency due of doppler shift in 2 meters and 70 cm is very slow and easily manually compensated even into only a 2.5 KHz bandwidth The antenna polarization is very important because a linear signal transmitted from the earth or from the moon by stations located in different continents can be reversed from Vertical to Horizontal polarization so that at least on the earth circular RHCP and LHCP switchable polarization is recommended.
Best 73" de
i8CVS Domenico
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Hi Joe,
The specification given by Miles WF1F is for a Lander transmit power of 5 to 10 watt in 70 cm from the moon.My calculation shoves that a single SSB station to be received in 70 cm with a S/N ratio of 10 dB on the earth a power of 10 watt in 70 cm is necessary on the moon.
If you like an IF window 10 time greater i.e. 250 KHz to accomodate more stations at the same time than the Lander transponder must have the capability to get around 100 watt wich is out the WF1F specifications.
73" de
i8CVS Domenico ----- Original Message ----- From: Joe To: i8cvs Cc: MM ; kg4zlb@gmail.com ; AMSAT-BB ; Jack K. Sent: Friday, July 03, 2009 12:59 PM Subject: Re: [amsat-bb] Re: The Moon is our Future
This is all good except for one thing,
The IF window is 10 times too small.
Look at the mess the FM single channel birds are with their tiny surface foot print. Imagine now a whole hemisphere worth of people trying to use it at once. The thing would be useless
i8cvs wrote: ----- Original Message ----- From: "MM" ka1rrw@yahoo.com To: kg4zlb@gmail.com; amsat-bb@amsat.org; "Jack K." kd1pe.1@gmail.com Sent: Thursday, July 02, 2009 1:31 PM Subject: [amsat-bb] The Moon is our Future
We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Questions: What’s the link budget? How much gain will be needed on earth for such a setup? Can we build a working mockup in 1 year or less.
The Moon is within Reach. Let’s Go for IT.
Miles WF1F MarexMG.org
Hi Miles, WF1F
The gain of the 2 meters antenna on the Lander is 3 dBd = 5.14 dBi Assume that the Noise Figure of the 2 meter receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 2 meter Lander antenna looking at the earth is conservatively 290 kelvin but (probably more ). The isotropic path loss earth-moon in 2 meters at an average distance of 380.000 km is 187 dB You don't specify the IF bandwidth of your transponder so that for simplicity I will assume that only one QSO will be possible in SSB and 3 on CW in a total BW = 2.5 KHz With the above data the calculated Noise Floor (KTB) of the above 2 meter Lander receiver is -139 dBm We assume to use an earth 2 meters antenna with a gain of 13 dBi and a power of 100 watt pep in 2 meters.
UPLINK BUDGED:
Earth TX power 100 watt.............................+ 50 dBm Earth antenna gain............................. .............+ 13 dB ------ Earth EIRP.....................................................+ 63 dBm 2 m isotropic attenuation earth-moon..............-187 dB ------ Isoptropic power received on the moon .........- 124 dBm 2 meters Lander antenna gain.........................+ 5 dBi ------ Power applied to the 2 m Lander receiver......- 119 dBm Lander receiver 2 m Noise Floor...................- 139 dBm ------ S/N ratio available from the Lander receiver.. + 20 dB
COMMENT: With a 2 meter signal +20 dB above the noise floor the 70 cm TX on the Lander transponder is in condition to supply a noise-less power between 5 to 10 watt pep to the 70 cm TX antenna.
DOWNLINK BUDGED:
The gain of the 70 cm antenna on the Lander is 3 dBd = 5.14 dBi and the 70 cm power is 10 watt pep Assume that the Noise Figure of the 70 cm earth receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 70 cm antenna looking at the moon is 75 kelvin Assume that the antenna gain of the 70 cm earth receiver is 18 dBi The isotropic path loss earth-moon in 70 cm at an average distance of 380.000 km is 197 dB With the above data the calculated Noise Floor (KTB) of the 70 cm ground receiver is -144 dBm
Lander 70 cm TX power 10 watt...................+ 40 dBm Lander antenna gain.......................................+ 5 dBi ------ 70 cm EIRP from the moon...........................+ 45 dBm 70 cm moon-earth isotropic attenuation .........-197 dB ------ 70 cm power available in to isotropic antenna -152 dBm 70 cm earth receiving antenna gain..................+ 18 dBi ------ 70 cm power on input of the earth receiver.....-134 dBm 70 cm Noise Floor of the earth receiver..........-144 dBm ------ S/N ratio at the output of 70 cm receiver.......+ 10 dB
COMMENT: Using a Lander transponder on the moon with 2 meters and 70 cm antenna's gain in the order of 5 dBi will not produce serious problems of pointing at the earth due of libration. If the Lander transponder is capable to develope 10 watt pep and the IF bandwidth is very narrow in the order of 2.5 KHz it is possible to accomodate one SSB QSO or 3 CW QSO just using the actually available TX and RX equipments for satellite communications i.e. For the uplink in 2 meters 100 watt pep and a 13 dBi antenna gain For the downlink in 70 cm a receiving system with an overall Noise Figure of 0.5 dB and antenna gain of 18 dBi The rate of change of the frequency due of doppler shift in 2 meters and 70 cm is very slow and easily manually compensated even into only a 2.5 KHz bandwidth The antenna polarization is very important because a linear signal transmitted from the earth or from the moon by stations located in different continents can be reversed from Vertical to Horizontal polarization so that at least on the earth circular RHCP and LHCP switchable polarization is recommended.
Best 73" de
i8CVS Domenico
_______________________________________________ Sent via AMSAT-BB@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
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A more meaningful appoach for an exercise like this is to start with DC power input for the entire package. Receivers consume power and transmitters (especially linear ones) are inefficient and the efficency goes down with increasing frequency. On the moon, you also have to heat the electronics at night to prevent failure.
Linear microwave power amplifiers have 20-35% efficiencies and VHF amplifiers might reach 50%. You can make more efficient amplifiers by converting the output signal into magnitude and phase or frequency components and using class C, D or E amplifiers. However, the added circuitry (whether analog or digital) also consumes power. FM makes sense for single channel transponers as the amplifiers can be nonlinear and you can get 80% efficiency at VHF. SSB amplifiers have a double inefficiency as you must design for peak power output which is 4-5 times the average power output. Amateur HEO satellites have used SSB for multichannel applications as you can count on the voice peaks for different users to occur at different times and design for the average power of all users. However, you need lots of users to reach this goal.
73,
John KD6OZH
----- Original Message ----- From: "i8cvs" domenico.i8cvs@tin.it To: "Joe" nss@mwt.net Cc: "Jack K." kd1pe.1@gmail.com; "AMSAT-BB" amsat-bb@amsat.org; kg4zlb@gmail.com Sent: Friday, July 03, 2009 14:41 UTC Subject: [amsat-bb] Re: The Moon is our Future
Hi Joe,
The specification given by Miles WF1F is for a Lander transmit power of 5 to 10 watt in 70 cm from the moon.My calculation shoves that a single SSB station to be received in 70 cm with a S/N ratio of 10 dB on the earth a power of 10 watt in 70 cm is necessary on the moon.
If you like an IF window 10 time greater i.e. 250 KHz to accomodate more stations at the same time than the Lander transponder must have the capability to get around 100 watt wich is out the WF1F specifications.
73" de
i8CVS Domenico ----- Original Message ----- From: Joe To: i8cvs Cc: MM ; kg4zlb@gmail.com ; AMSAT-BB ; Jack K. Sent: Friday, July 03, 2009 12:59 PM Subject: Re: [amsat-bb] Re: The Moon is our Future
This is all good except for one thing,
The IF window is 10 times too small.
Look at the mess the FM single channel birds are with their tiny surface foot print. Imagine now a whole hemisphere worth of people trying to use it at once. The thing would be useless
i8cvs wrote: ----- Original Message ----- From: "MM" ka1rrw@yahoo.com To: kg4zlb@gmail.com; amsat-bb@amsat.org; "Jack K." kd1pe.1@gmail.com Sent: Thursday, July 02, 2009 1:31 PM Subject: [amsat-bb] The Moon is our Future
We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Questions: What’s the link budget? How much gain will be needed on earth for such a setup? Can we build a working mockup in 1 year or less.
The Moon is within Reach. Let’s Go for IT.
Miles WF1F MarexMG.org
Hi Miles, WF1F
The gain of the 2 meters antenna on the Lander is 3 dBd = 5.14 dBi Assume that the Noise Figure of the 2 meter receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 2 meter Lander antenna looking at the earth is conservatively 290 kelvin but (probably more ). The isotropic path loss earth-moon in 2 meters at an average distance of 380.000 km is 187 dB You don't specify the IF bandwidth of your transponder so that for simplicity I will assume that only one QSO will be possible in SSB and 3 on CW in a total BW = 2.5 KHz With the above data the calculated Noise Floor (KTB) of the above 2 meter Lander receiver is -139 dBm We assume to use an earth 2 meters antenna with a gain of 13 dBi and a power of 100 watt pep in 2 meters.
UPLINK BUDGED:
Earth TX power 100 watt.............................+ 50 dBm Earth antenna gain............................. .............+ 13 dB ------ Earth EIRP.....................................................+ 63 dBm 2 m isotropic attenuation earth-moon..............-187 dB ------ Isoptropic power received on the moon .........- 124 dBm 2 meters Lander antenna gain.........................+ 5 dBi ------ Power applied to the 2 m Lander receiver......- 119 dBm Lander receiver 2 m Noise Floor...................- 139 dBm ------ S/N ratio available from the Lander receiver.. + 20 dB
COMMENT: With a 2 meter signal +20 dB above the noise floor the 70 cm TX on the Lander transponder is in condition to supply a noise-less power between 5 to 10 watt pep to the 70 cm TX antenna.
DOWNLINK BUDGED:
The gain of the 70 cm antenna on the Lander is 3 dBd = 5.14 dBi and the 70 cm power is 10 watt pep Assume that the Noise Figure of the 70 cm earth receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 70 cm antenna looking at the moon is 75 kelvin Assume that the antenna gain of the 70 cm earth receiver is 18 dBi The isotropic path loss earth-moon in 70 cm at an average distance of 380.000 km is 197 dB With the above data the calculated Noise Floor (KTB) of the 70 cm ground receiver is -144 dBm
Lander 70 cm TX power 10 watt...................+ 40 dBm Lander antenna gain.......................................+ 5 dBi ------ 70 cm EIRP from the moon...........................+ 45 dBm 70 cm moon-earth isotropic attenuation .........-197 dB ------ 70 cm power available in to isotropic antenna -152 dBm 70 cm earth receiving antenna gain..................+ 18 dBi ------ 70 cm power on input of the earth receiver.....-134 dBm 70 cm Noise Floor of the earth receiver..........-144 dBm ------ S/N ratio at the output of 70 cm receiver.......+ 10 dB
COMMENT: Using a Lander transponder on the moon with 2 meters and 70 cm antenna's gain in the order of 5 dBi will not produce serious problems of pointing at the earth due of libration. If the Lander transponder is capable to develope 10 watt pep and the IF bandwidth is very narrow in the order of 2.5 KHz it is possible to accomodate one SSB QSO or 3 CW QSO just using the actually available TX and RX equipments for satellite communications i.e. For the uplink in 2 meters 100 watt pep and a 13 dBi antenna gain For the downlink in 70 cm a receiving system with an overall Noise Figure of 0.5 dB and antenna gain of 18 dBi The rate of change of the frequency due of doppler shift in 2 meters and 70 cm is very slow and easily manually compensated even into only a 2.5 KHz bandwidth The antenna polarization is very important because a linear signal transmitted from the earth or from the moon by stations located in different continents can be reversed from Vertical to Horizontal polarization so that at least on the earth circular RHCP and LHCP switchable polarization is recommended.
Best 73" de
i8CVS Domenico
Sent via AMSAT-BB@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
No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.375 / Virus Database: 270.13.2/2215 - Release Date: 07/02/09 18:06:00
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Been Thinkin',
John B. Stephensen wrote:
A more meaningful appoach for an exercise like this is to start with DC power input for the entire package. Receivers consume power and transmitters (especially linear ones) are inefficient and the efficency goes down with increasing frequency. On the moon, you also have to heat the electronics at night to prevent failure.
What difference is there and why if there is any a difference of shadow cold on the moon, vs shadow in orbit? If anything i would think you would get some thermal radiation heating from the soil. wjereas in space you don't get this benefit.
Linear microwave power amplifiers have 20-35% efficiencies and VHF amplifiers might reach 50%. You can make more efficient amplifiers by converting the output signal into magnitude and phase or frequency components and using class C, D or E amplifiers. However, the added circuitry (whether analog or digital) also consumes power. FM makes sense for single channel transponers as the amplifiers can be nonlinear and you can get 80% efficiency at VHF. SSB amplifiers have a double inefficiency as you must design for peak power output which is 4-5 times the average power output. Amateur HEO satellites have used SSB for multichannel applications as you can count on the voice peaks for different users to occur at different times and design for the average power of all users. However, you need lots of users to reach this goal.
73,
John KD6OZH
----- Original Message ----- From: "i8cvs" domenico.i8cvs@tin.it To: "Joe" nss@mwt.net Cc: "Jack K." kd1pe.1@gmail.com; "AMSAT-BB" amsat-bb@amsat.org; kg4zlb@gmail.com Sent: Friday, July 03, 2009 14:41 UTC Subject: [amsat-bb] Re: The Moon is our Future
Hi Joe,
The specification given by Miles WF1F is for a Lander transmit power of 5 to 10 watt in 70 cm from the moon.My calculation shoves that a single SSB station to be received in 70 cm with a S/N ratio of 10 dB on the earth a power of 10 watt in 70 cm is necessary on the moon.
If you like an IF window 10 time greater i.e. 250 KHz to accomodate more stations at the same time than the Lander transponder must have the capability to get around 100 watt wich is out the WF1F specifications.
73" de
i8CVS Domenico ----- Original Message ----- From: Joe To: i8cvs Cc: MM ; kg4zlb@gmail.com ; AMSAT-BB ; Jack K. Sent: Friday, July 03, 2009 12:59 PM Subject: Re: [amsat-bb] Re: The Moon is our Future
This is all good except for one thing,
The IF window is 10 times too small.
Look at the mess the FM single channel birds are with their tiny surface foot print. Imagine now a whole hemisphere worth of people trying to use it at once. The thing would be useless
i8cvs wrote: ----- Original Message ----- From: "MM" ka1rrw@yahoo.com To: kg4zlb@gmail.com; amsat-bb@amsat.org; "Jack K." kd1pe.1@gmail.com Sent: Thursday, July 02, 2009 1:31 PM Subject: [amsat-bb] The Moon is our Future
We need a simple Mode-J transponder (2-meters up, 440 down). Low power consumption. Assume minimal antenna gain from the Lander (3 dBd on each antenna) Assume transmitter power 5-10 watts.
Questions: What’s the link budget? How much gain will be needed on earth for such a setup? Can we build a working mockup in 1 year or less.
The Moon is within Reach. Let’s Go for IT.
Miles WF1F MarexMG.org
Hi Miles, WF1F
The gain of the 2 meters antenna on the Lander is 3 dBd = 5.14 dBi Assume that the Noise Figure of the 2 meter receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 2 meter Lander antenna looking at the earth is conservatively 290 kelvin but (probably more ). The isotropic path loss earth-moon in 2 meters at an average distance of 380.000 km is 187 dB You don't specify the IF bandwidth of your transponder so that for simplicity I will assume that only one QSO will be possible in SSB and 3 on CW in a total BW = 2.5 KHz With the above data the calculated Noise Floor (KTB) of the above 2 meter Lander receiver is -139 dBm We assume to use an earth 2 meters antenna with a gain of 13 dBi and a power of 100 watt pep in 2 meters.
UPLINK BUDGED:
Earth TX power 100 watt.............................+ 50 dBm Earth antenna gain............................. .............+ 13 dB ------ Earth EIRP.....................................................+ 63 dBm 2 m isotropic attenuation earth-moon..............-187 dB ------ Isoptropic power received on the moon .........- 124 dBm 2 meters Lander antenna gain.........................+ 5 dBi ------ Power applied to the 2 m Lander receiver......- 119 dBm Lander receiver 2 m Noise Floor...................- 139 dBm ------ S/N ratio available from the Lander receiver.. + 20 dB
COMMENT: With a 2 meter signal +20 dB above the noise floor the 70 cm TX on the Lander transponder is in condition to supply a noise-less power between 5 to 10 watt pep to the 70 cm TX antenna.
DOWNLINK BUDGED:
The gain of the 70 cm antenna on the Lander is 3 dBd = 5.14 dBi and the 70 cm power is 10 watt pep Assume that the Noise Figure of the 70 cm earth receiver is 0.5 dB = 35 kelvin and the sky temperature as seen by the 70 cm antenna looking at the moon is 75 kelvin Assume that the antenna gain of the 70 cm earth receiver is 18 dBi The isotropic path loss earth-moon in 70 cm at an average distance of 380.000 km is 197 dB With the above data the calculated Noise Floor (KTB) of the 70 cm ground receiver is -144 dBm
Lander 70 cm TX power 10 watt...................+ 40 dBm Lander antenna gain.......................................+ 5 dBi ------ 70 cm EIRP from the moon...........................+ 45 dBm 70 cm moon-earth isotropic attenuation .........-197 dB ------ 70 cm power available in to isotropic antenna -152 dBm 70 cm earth receiving antenna gain..................+ 18 dBi ------ 70 cm power on input of the earth receiver.....-134 dBm 70 cm Noise Floor of the earth receiver..........-144 dBm ------ S/N ratio at the output of 70 cm receiver.......+ 10 dB
COMMENT: Using a Lander transponder on the moon with 2 meters and 70 cm antenna's gain in the order of 5 dBi will not produce serious problems of pointing at the earth due of libration. If the Lander transponder is capable to develope 10 watt pep and the IF bandwidth is very narrow in the order of 2.5 KHz it is possible to accomodate one SSB QSO or 3 CW QSO just using the actually available TX and RX equipments for satellite communications i.e. For the uplink in 2 meters 100 watt pep and a 13 dBi antenna gain For the downlink in 70 cm a receiving system with an overall Noise Figure of 0.5 dB and antenna gain of 18 dBi The rate of change of the frequency due of doppler shift in 2 meters and 70 cm is very slow and easily manually compensated even into only a 2.5 KHz bandwidth The antenna polarization is very important because a linear signal transmitted from the earth or from the moon by stations located in different continents can be reversed from Vertical to Horizontal polarization so that at least on the earth circular RHCP and LHCP switchable polarization is recommended.
Best 73" de
i8CVS Domenico
Sent via AMSAT-BB@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
No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.375 / Virus Database: 270.13.2/2215 - Release Date: 07/02/09 18:06:00
Sent via AMSAT-BB@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@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
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HEOs are illuminated 99% of the time and LEOs are illuminated 50% or more of the time with eclipses by the earth lasting only 45 minutes. Thermal inertia can keep the temperature from swinging too far in either direction. Since the satellite is in a vacuum, heat can only be radiated away as in a Dewar flask. On the moon, the eclipse lasts for 2 weeks so more cooling occurs. During the other 2 weeks, heat from the electronics and solar illumination must be radiated away. Every lander that I have seen has a few spindly legs so there won't be much heat conduction to the moon's surface.
However, I'm not an expert on thermal design. When I was designing a 70 cm receiver for AMSAT, others did the thermal analysis. Nothing behaves in space as it does on Earth as there is no convection cooling.
Building a prototype that works on Earth for project like this is only a few percent of the effort required. Treating it as a radio club project won't be effective as people need to sign up for a 5-year project. If your making an add-on to a NASA project you have to fit into their shedule, design to their specifications, produce the documentation that they need, travel to their test facilities and pass their tests. There are also legal requirements (ITAR) when working on space-related projects.
73,
John KD6OZH ----- Original Message ----- From: Joe To: John B. Stephensen Cc: i8cvs ; Jack K. ; AMSAT-BB ; kg4zlb@gmail.com Sent: Friday, July 03, 2009 19:57 UTC Subject: Re: [amsat-bb] Re: The Moon is our Future
Been Thinkin',
John B. Stephensen wrote:
A more meaningful appoach for an exercise like this is to start with DC power input for the entire package. Receivers consume power and transmitters (especially linear ones) are inefficient and the efficency goes down with increasing frequency. On the moon, you also have to heat the electronics at night to prevent failure. What difference is there and why if there is any a difference of shadow cold on the moon, vs shadow in orbit? If anything i would think you would get some thermal radiation heating from the soil. wjereas in space you don't get this benefit.
participants (12)
-
David Moisan -
Gary "Joe" Mayfield -
Glenn AA5PK -
Gordon JC Pearce -
Gregg Wonderly -
i8cvs -
Jack K. -
Joe -
John B. Stephensen -
MM -
Nigel Gunn G8IFF/W8IFF -
Robert Bruninga