I also remember 2 SDX payloads, but this will be useless without redundancy elsewhere.
Given the use of UV for both class 0 and class 1 users, and the fact that an L uplink won't support small fixed ground station antennas for class 1, I think that using the L receiver as a backup for the U receiver isn't sufficient. We need 2 U receivers in case one receiver fails or in case the omni/gain antenna relay fails. We also need 2 V transmitters for the same reason.
If we end up with a digital uplink on L-band, the SDX could be given an output from that receiver. If not, a separate L receiver could be added or the U receiver designed for band switching with 2 RF amplifiers, 2 first LOs, 2 mixers and a switch in each receiver. Any S-band transmitter should be a separate module.
I've attached two block diagrams showing the proposed architecture for U/V only and for UL/VS.
73,
John KD6OZH
----- Original Message ----- From: "Lyle Johnson" kk7p@wavecable.com To: "Matt Ettus" matt@ettus.com Cc: "EAGLE" eagle@amsat.org Sent: Tuesday, September 12, 2006 01:38 UTC Subject: [eagle] Re: Team Speak tomorrow night
We offer that anyone willing can develop and submit fortesting and qualification a stand-alone L/S transponder to fly in one
of
the TSFR slots, using fixed antennas. It would be usable at/near Apogee, like the microwave packages on AO-13 and A)-40. What do you think? Les's discuss this.
Bad idea. We discussed having ONE SDX transponder and ONE digital communications payload. If for some reason it is decided that the DCP is on neither S1 nor L (which itself would be a bad idea...), AND it was decided that there was a desire for old-style transponders on L/S, then it makes sense to build it as part of the SDX, and not have a THIRD
payload.
Like Matt, I am not in favor of this. We need to design the system for services, not design the spacecraft as a bus for a collection of modules.
I recall two SDX payloads, but I'm old and my memory is failing. The Eagle block diagram from Oct 2005 shows a pair of SDX modules, and the SDX block diagram shows a U and an L uplink, an S1 and a V downlink. Of course, at that time the digital payload was to be C/C.
Did we decide to kill the L uplink for SDX/analog use in San Diego? I recall that we decided to not use an L uplink for the digital system.
73,
Lyle KK7P
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