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

Re: Satellite-to-Satellite communications



Are the planned orbits of the two spacecraft different enough that a  
cross-link would increase ground coverage?

And asking that question makes me wonder if the orbits are similar  
enough to even permit an economical cross-link, even for a few hours  
a day during several months...

Thanks,

Dave
N0TGD


On Jan 8, 2006, at 6:56 PM, John B. Stephensen wrote:

> The characteristics of any digital transponder on Eagle haven't been
> finalized. HEO digital communications are power limited because of  
> the 35,000
> km altitude so speeds may be closer to dial-up than DSL. HEOs are  
> 45 times
> further out than LEOs so communications requires 2000 times more  
> radiated
> power. The digital links used on LEOs are not very power efficient  
> so some of
> this loss can be recovered.
>
> You could link analog transponders by repeating a portion of one  
> downlink onto
> another uplink. If the antennas used in the repeater have 6 dB more  
> gain than
> the users' antennas, there will be a dB or two of degradation, but  
> it will
> work.
>
> 73,
>
> John
> KD6OZH
>   ----- Original Message -----
>   From: Christensen, Eric
>   To: Andrew Glasbrenner ; John B. Stephensen ; amsat-bb@amsat.org
>   Sent: Monday, January 09, 2006 01:34 UTC
>   Subject: RE: [amsat-bb] Satellite-to-Satellite communications
>
>
>   Thinking it over with the good information that has been  
> presented I agree
> where if we are not in geosync orbit it would be difficult, but not
> impossible, to track another HEO.  I think ground stations relaying  
> to other
> stations that have view of the other HEO is very workable.
>
>   It could be very workable if everything is digital.  I'm still  
> trying to
> figure out the digital capabilities of the two new birds.  Maybe  
> digital voice
> as well???
>
>   So maybe we should identify stations that have reliable satellite  
> stations
> and reliable Internet connectivity with 2Mb(???) connectivity or more.
>
>   73s,
>   Eric KF4OTN
>
>
>
> ---------------------------------------------------------------------- 
> -------
> -
>
>   From: Andrew Glasbrenner
>   Sent: Sun 08-Jan-06 19:50
>   To: John B. Stephensen; Christensen,Eric; amsat-bb@amsat.org
>   Subject: Re: [amsat-bb] Satellite-to-Satellite communications
>
>
> Not to mention how would you point the link antennas, and to where?  
> We aren't
> going to be in a fixed geosynch type orbit....
>
> Now....ground based relays would be uber-cool. Imagine a 10-20 khz  
> wide
> transponder on the ground linking 2 HEOS on opposite sides of the  
> planet.
> You'd need a pretty fat pipe between groundstations, and a healthy  
> uplink, but
> wow...that would be an innovation (for us hams at least).
>
> 73, Drew KO4MA
>
> -----Original Message-----
>> From: "John B. Stephensen" <kd6ozh@comcast.net>
>> Sent: Jan 8, 2006 7:26 PM
>> To: "Christensen, Eric" <CHRISTENSENE@MAIL.ECU.EDU>, amsat- 
>> bb@amsat.org
>> Subject: Re: [amsat-bb] Satellite-to-Satellite communications
>>
>> No intersatellite communications is planned. Intersatellite links  
>> would
>> require just as much power as the satellite-to-ground links. The  
>> satellite
>> would also have to be 3-axis stabilized to point the intersatellite
>> antennas. The additional power and fuel would double or triple the  
>> weight
>> and launch cost. The majority of AMSAT membership has been very  
>> clear that
>> it wants simpler, cheaper HEO satellites so that more can be  
>> launched.
>>
>> When 2 or more HEO satellites are in orbit, Earth-based  
>> intersatellite links
>> will be possible at a fraction of the cost of space-based links.
>>
>> 73,
>>
>> John
>> KD6OZH
>>
>> ----- Original Message -----
>> From: "Christensen, Eric" <CHRISTENSENE@MAIL.ECU.EDU>
>> To: <amsat-bb@amsat.org>
>> Sent: Sunday, January 08, 2006 18:05 UTC
>> Subject: [amsat-bb] Satellite-to-Satellite communications
>>
>>
>>> I was sitting here reading the Nov/Dec AMSAT Journal thinking  
>>> about Eagle
>> and
>>> P3E when it hit me.  Are their any sat-to-sat circuits being  
>>> built into
>> these
>>> satellites?  If we are going to have daily coverage of a HEO by  
>>> 2009 and
>>> continuous coverage by 2012 I think having the additional sat-to-sat
>> circuits
>>> would be very useful for providing worldwide coverage.
>>>
>>> Uncle Sam finally figured that out with the new MilStar sats.   
>>> Otherwise
>> data
>>> had to be relayed by ground stations between satellites to cover  
>>> the area.
>>>
>>> Any ideas???
>>>
>>> 73s,
>>> Eric KF4OTN
>>> ----
>>> 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
>> ----
>> 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
> ----
> 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

Dave Hartzell
hartzell@gmail.com
----
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



AMSAT Top AMSAT Home