[Sls-slp] 答复: Questions about Proximity -1 space data link protocol
Kazz, Greg J (312B)
greg.j.kazz at jpl.nasa.gov
Wed Sep 28 19:17:03 UTC 2016
Dear Xiongwen He,
I have included both the SLP WG as well as the RF&Modulation WG for comment on your questions below.
The Physical Layer of Proximity-1 was originally part of one blue book which also incorporated the synchronization and channel coding aspects as well.
From a historical perspective, I can answer your questions. However, for the physical layer issues/questions please contact Enrico Vassallo who is the RFM WG chairman. For synchronization and channel coding issues/questions please contact Massimo Bertinelli, who is the Coding & Synchronization (C&S) WG chairman.
From: he xiongwen <hexw501 at hotmail.com<mailto:hexw501 at hotmail.com>>
Date: Wednesday, September 28, 2016 at 7:20 AM
To: "Kazz, Greg J (313B)" <greg.j.kazz at jpl.nasa.gov<mailto:greg.j.kazz at jpl.nasa.gov>>
Subject: 答复: Questions about Proximity -1 space data link protocol
Dear Mr. Greg Kazz,
I have some other questions about Proximity -1 space data link protocol-Physical layer. I hope you can help me.
a) In 3.2.1 Table3-1
Why the modulation of E2d devices is different? What are microprobes？
** From a historical perspective, the prototypical E2d device we had in mind was a micro-probe. NASA sent a micro-probe to Mars called Deep Space 2 (DS-2), deployed from the Mars Polar Lander in 2000, which unfortunately failed to communicate. **
b) In 22.214.171.124.1
" The following three additional channels (fixed single forward and return frequency pairs) are defined for Proximity-1 operations: "
Why is "additional" used? ** The first channel, channel 1 defined in the specification is the hailing channel. Additional means after this first channel, I.e., channels 0, 2, 3 in this case **
What's the use case for channel 4~7 and channel 8~15？** It is the job of the program or project to define these. Currently, no agency has found a need to provide a frequency assignment for these channels yet **
c) In 126.96.36.199
NOTES 1 The Doppler frequency rate does not include the Doppler rate required for tracking canister or worst-case spacecraft-to-spacecraft cases.
Why doesn't The Doppler frequency rate include the two cases？** From a historical perspective, the Doppler freq. rate requirement was very generic and was assumed to meet most of the user’s use cases expect for very demanding performance cases such as tracking a canister or worst-case spacecraft-to-spacecraft tracking scenarios **
I would appreciated it if you could reply and help me clarify the questions.
China Academy of Space Technology(CAST)
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