[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: lower frequency downlinks cont.


Having the technical ability of building a satellite is one thing.
Having the ability, contacts and funds to launch is another....
So, I assume, since you don't know how to build one, you have a couple 
dollars laying around to launch one?

Step one is to at least have a ground station capable of "communicating" 
with the bird.
That is the "easy" part!

As for HF and LEO/HEO satellites, 10 and 15 meters can be a problem with LEO 
and difficult at best for a HEO scenario. The RS series of satellites were 
primitive, but useful.

Did you ever take an Amateur exam where they talk about propagation?
The invisible D to F2 layers? When there "is" propagation on these bands,
that means the signals are not going out into space anymore, and thus 
back to earth. Some call it DX. So, when there is propagation, signals from 
space may not
make it to earth, bounce around or killed with QRM. With "weak" signals 
(QRP) from a spacecraft,
one needs to have a decent antenna and receiver. Remember.. it's all in the 
Amps/preamps help.

Oh... I just threw KISS out of the equation.
Cans and a string would only work for a limited amount of orbits.

Back to the drawing board...

73, Scott

----- Original Message ----- 
From: "John B. Stephensen" <kd6ozh@comcast.net>
To: "T. P. McGrane" <n2oeq@netzero.net>; <amsat-bb@amsat.org>
Sent: Tuesday, January 31, 2006 11:02 AM
Subject: Re: [amsat-bb] lower frequency downlinks cont.

> I'm not aware that there have ever been any HF downlinks on amateur HEO
> satellites. I assume that your experience is with LEOs which have been 
> 40-60
> times lower in altitude than HEOs and therefore have 32-36 dB lower path
> loss (appx. 5-6 S-units). This started out as a discussion of lower
> frequency downlinks on HEOs and the two shouldn't be mixed up as LEOs are
> usually much easier to receive, regardless of frequency.
> 73,
> John
> ----- Original Message -----
> From: "T. P. McGrane" <n2oeq@netzero.net>
> To: <amsat-bb@amsat.org>
> Sent: Tuesday, January 31, 2006 16:59 UTC
> Subject: [amsat-bb] lower frequency downlinks cont.
> > Hello again, de pat n2oeq
> >
> > Thanks for the technical info and noise graph.
> >
> > My real world experience is that I hear HF downlinks better than VHF and
> especially UHF.
> >
> > And I'm using a 12 element X beam for UHF and have marginal reception.
> >
> > I would love to build and launch a satellite but I dont have the 
> > expertise
> to do so. That is why I propose it to the group.
> > I'm happy to donate to amsat for a universally usable satellite but not 
> > to
> further the interests of a select few.
> >
> > Agree with the idea or reject it. If amsat is not interested, perhaps 
> > they
> could share it with other groups who might be interested.
> >
> > Many thanks to all the amsat volunteers for echo and eagle. Just think
> about lower frequency downlinks in the future and PLEASE raise the Echo
> downlink power on UHF PHONE now and then.
> >
> > K.I.S.S.  73, pat 
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org