One area that I believe would welcome more experimentation is digital transponders and digital repeaters. I think there is a vast territory for experimentation (protocols, ground software, etc). With some careful engineering, a digital transponder could be operated on the same frequency using half-duplex. This would simplify the antenna system and ease the operation.
73, Edson PY2SDR
--- - We humans have the capability to do amazing things if we work together. - Nós seres humanos temos a capacidade de fazer coisas incríveis se trabalharmos juntos.
On Wed, Jun 29, 2016 at 9:28 AM, rsoifer1--- via AMSAT-BB < [email protected]> wrote:
I didn't say that AO-7, FO-29 and SO-50 are the only communication satellites, only that they are the most popular and useful.
Why is that? As you say, some of that has to do with altitude, which is largely beyond our control. Some has to do with low power output, which depends on satellite size. Some, too, has to do with operating schedule: is it always on?
73 Ray -----Original Message--- do From: Paul Stoetzer [email protected] is To: rsoifer1 [email protected] Cc: amsat-bb <[email protected] Sent: Tue, Jun 28, 2016 1:48 pm Subject: Re: [amsat-bb] Amateur communication satellites
The CW beacon on FO-29 does still function. We are definitely fortunate that FO-29 still works and works very well. It is clearly the most popular linear transponder satellite due to it's wide passband and high orbit.
I would note that we are not starved for linear transponders. There are 7 in orbit and active and 4 in orbit awaiting activation plus at least one more scheduled for launch this year (Nayif-1). As far as FM satellites, there are three in orbit with two of those available 24/7 and a third with an errattic schedule. However, between now and January, three more FM satellites are scheduled to launch (Fox-1Cliff, Fox-1D, and RadFxSat/Fox-1B).
The issue, of course, is the orbits of these satellite don't approach the 1460km apogee or 1330km apogee of FO-29. We can blame debris mitigation rules for that! Hopefully we will find a way to get some higher orbiting satellites up in the future (including GEO/HEO).
On Tue, Jun 28, 2016 at 4:28 PM, rsoifer1--- via AMSAT-BB [email protected] wrote:
This past weekend, I made three ARRL/AMSAT Field Day QSOs via FO-29
(JAS-2). Nothing noteworthy about that, except that FO-29 will be 20 years old on August 17th. We're very fortunate that its linear transponder still works. The CW beacon and digital transponders are no longer functioning.
Two more of the satellites carrying the bulk of amateur satellite
communication are well beyond their design lifetimes. SO-50, our main FM transponder satellite, will be 14 years old in December. Then, of course, there is AO-7, whose linear transponders miraculously are still functioning some of the time. In November it will be 42 years young.
Educational and research satellites are well and good, but amateur
satellite communication is still overly dependent on aging space hardware. To those who are building new amateur communication transponders, especially linear transponders in the UHF and VHF bands, best wishes for success. I wish there were more of you. Maybe there will be.
73 Ray W2RS
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Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb