[amsat-bb] Re: The Moon is our Future

[John B. Stephensen]

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 at yahoo.com>
To: <kg4zlb at gmail.com>; <amsat-bb at amsat.org>; "Jack K." <kd1pe.1 at 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 at gmail.com> wrote:
>
>> From: Jack K. <kd1pe.1 at gmail.com>
>> Subject: [amsat-bb]  Rebuttal -  Re: Unused sats
>> To: kg4zlb at gmail.com, amsat-bb at 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 at googlemail.com>
>> To: <amsat-bb at 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.
>>
>> _______________________________________________
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>
>
>
>
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