[SLS-DC] DCWG SAR Compression Meeting notes and actions

Tue Jun 3 14:31:03 UTC 2025

Please see below for the SAR Compression meeting notes and drafted action items.
Let me know if anything is not clear or something you want to change.

Best,
Mark
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Raw SAR Compression CCSDS-125.0-B
The working group met virtually on June 2, 2025, to accommodate most members' schedules. During the meeting, NASA GSFC (Wong) reconfirmed that the BAQ standard had expired in 2019 and can now be standardized without legal concerns. CNES (Bruno) provided system parameters for CNES-simulated SAR data, available in [1]. In addition, DLR (Martone) submitted an updated generic BAQ write-up [2] along with the corresponding published document [3]. SAR synthesis data was also uploaded to [4]. UAB (Hernández-Cabronero) presented an analysis of entropy coder performance, highlighting some notable findings. It appears that lower compression rates significantly benefit from using a non-uniform Max-Lloyd entropy coder.
There was a discussion on analog-to-digital conversion (ADC), which is essential for reconstructing the SAR signal. A higher-level description of this process is still needed. Additionally, certain parameters must be defined for the standard, such as bit-depth, ideally standardized in a range between 1 to 32-bit. The group also noted the need to address mid-rise and mid-tread quantization schemes.
The working group will examine whether it makes sense to output the reconstructed signal from the BAQ or to transmit only the mantissa (Mbaq) as input to the entropy coder. Several parameters are intended to be generalized, including the bias constant C, the maximum exponent value E, and the maximum mantissa value M, each corresponding to the desired compression rate Nb. Furthermore, there is a recognized need to establish a standard packet format. Finally, the working group agreed to reconvene around August 2025, one month prior to the Fall 2025 meeting. GTRI (McGuinness and Storm) volunteered to present their SAR compression study during this auxiliary meeting.
Before the 2025 Fall meeting, the working group has agreed to meet in advance to discuss some the following activities:

Action Item No.
Description
Actionee
Due Date
DC-A-2025-1
Investigate non-uniform quantizer, Lloyd-Max quantizer for lower compression rate.
UAB and DLR
August 2025 AUX meeting
DC-A-2025-2
Report on (a) generalization on ADC description on ADC, (b) BAQ output (reconstructed I/Q or Mantissa) to be encoded and (c) how to generalized BAQ input parameters, C, E and M.

DLR
August 2025 AUX meeting
DC-A-2025-3

(a)   Working group to provide additional feedback on the BAQ writeup provided by DLR and

(b)   Update section to the current red-book based on feedbacks

(a)   All

(b)   NASA-GSFC and DLR

(a)   Prior to August 2025 AUX meeting

(b)   CCSDS Fall 2025 Meeting

---------------------------------------------------------------------------------------
Mark Wong, Ph.D.
NASA/Goddard Space Flight Center
Flight Microwave & Telecommunication Systems Branch/Code 567
Greenbelt, MD 20771
B19 Rm S030
Phone: 1-301-286-6549
----------------------------------------------------------------------------------------

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ccsds.org/pipermail/sls-dc/attachments/20250603/536a6fec/attachment-0001.htm>