[SLS-CC] FW: S-band Proximity Hailing (A heads-up)

[Andrea Modenini]

Hi all,
Please see the information below provided by Faramaz, to be possibly taken into consideration when preparing S-Band proxy-1 related inputs for the C&S meeting jointly with SLP and RFM.

Regards

Ph.D. Andrea Modenini
TT&C Communications Systems Engineer
TT&C and PDT Systems & Techniques Section (TEC-EST)
RF Systems Division
European Space Agency, ESTEC
Keplerlaan 1, PO Box 299
NL-2200 AG Noordwijk, The Netherlands
andrea.modenini at esa.int<mailto:andrea.modenini at esa.int> | www.esa.int<http://www.esa.int/>
T +31 71 56 53439, M +31 6 484 56 527

From: Davarian, Faramaz (US 9700) <faramaz.davarian at jpl.nasa.gov>
Sent: 22 March 2023 19:40
To: Andrea Modenini <Andrea.Modenini at esa.int>; Kazz, Greg (US 312B) <greg.j.kazz at jpl.nasa.gov>; Lee, Dennis K (US 332G) <dennis.k.lee at jpl.nasa.gov>; Andrews, Kenneth S (US 332B) <kenneth.s.andrews at jpl.nasa.gov>
Cc: Fadl, Ahmed M. (GSFC-8500) <ahmed.m.fadl at nasa.gov>; Ben Schwarz <BSchwarz at sstl.co.uk>; Charles Cranstoun <CCranstoun at sstl.co.uk>; Ashvi Ilott <AIlott at sstl.co.uk>; Stuart Golden <sgolden at vulcanwireless.com>; Kevin Lynaugh <klynaugh at vulcanwireless.com>; Zack Nootens <znootens at vulcanwireless.com>
Subject: S-band Proximity Hailing (A heads-up)

Hi Andrea, Greg, Dennis, and Ken,

We (JPL/Vulcan) recently discovered that the Lunar Pathfinder (LPF) hailing channel as designed will not have adequate link performance to close the link most of the time. We brought this to the attention of SSTL, the developer of LPF. Consequently, SSTL agreed with the concern we had raised. We (JPL/Vulcan/SSTL) are now inclined to reduce the hailing channel rate from 8 kbps to 1 kbps and add rate 2/3 LDPC coding to it. This will increase the link performance substantially allowing the hailing channel to close at the most adverse situations, i.e, longest distances and lowest elevation angles of interest to us. Moreover, we would like to propose to CCSDS to consider a recommendation for the proximity link were the data rate is specified and channel coding is used. We can discuss this subject further during the CCSDS meeting in May at the joint meeting of your Study Groups. I would also like to acknowledge, Dr. Stuart Golden of Vulcan Wireless inc. for his discovery of the hailing channel problem.

The following table summarizes the proposed changes:

Proposed S-Band Proximity Hailing Channel Changes
Item
Current Parameter
Revised Parameter
Link Data rate
8 kbps
1 kbps
Coding
No coding
LDPC 2/3 coding

Looking forward to meeting you all in May,

Faramaz
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