Hi Hovie,AB2S
You are correct but there is another reason that make very difficult to use a commercial satellites for amateur communications.
The Amateur Satellites and our ground stations are FDMA i.e Frequency Division Multiple Access in wich the satellite passband is shared at the same Time by all ground users depending on the frequency that they chouses for the uplink and downlink.
On the other side the Commercial Satellites are mostly TDMA i.e. Time Division Multiple Access in wich a master Ground Stations send to the satellite transponder the sincronization pulses to switch the onboard multiplexer at very high speed and specific Time between all client ground stations as explained in the following web page.
http://www.satsig.net/vsat-equipment/tdma-explanation.htm
In simple word the TDMA often called "switcher" operate as a citizen Telephone Central Station that is not on earth but on board of the satellite.
73" de
i8CVS Domenico
----- Original Message ----- From: "Howie DeFelice" howied231@hotmail.com To: w7lrd@comcast.net Cc: amsat-bb@amsat.org Sent: Friday, June 15, 2012 11:31 PM Subject: [amsat-bb] Re: perfect groundtrack contest
Unfortunately the hardware on board isn't programmable. The shared antenna's are connected to very frequency specific bandpass filters that form the multiplexer, the frequency translators are fixed and if the HPA is a TWTA it is also very frequency dependent. By the time the commercial operators are done squeezing every last penny out of them, there isn't much left over to use anyway :)
- Howie AB2S
Date: Fri, 15 Jun 2012 21:18:46 +0000 From: w7lrd@comcast.net To: howied231@hotmail.com CC: amsat-bb@amsat.org; tomdoyle1948@gmail.com Subject: Re: [amsat-bb] perfect groundtrack contest
I have also "wondered" if any of the older commercial surplus satellites can be "reprogrammed" for our use. I realized that idea is no doubt an over simplification. Today's speculation can be tomorrows reality. 73 Bob W7LRD
From: "Howie DeFelice" howied231@hotmail.com To: amsat-bb@amsat.org, tomdoyle1948@gmail.com Sent: Thursday, June 14, 2012 12:48:06 PM Subject: [amsat-bb] perfect groundtrack contest
I vote for Intelsat G-11 at 304.5 deg E. This is a Ku band only bird, however, the semi-retired Intelsat 805, which is co-located with this sat has a global C band beam with a downlink that extends into the amateur 9cm satellite band (3400-3410 MHz). I often wondered if Intelsat would consider "donating" a few Khz to AMSAT. We could then tie a single, commercially licensed uplink station via echolink and hear it on the 9cm downlink. At least it would be a reason for people to use the 9cm band before it's taken away for the latest mobile broadband gizmo.
Howie AB2S