← Sunil Khorwal

Space Engineering & Projects

I operate a SatNOGS ground station (Station 4763: Mumbai-RTL-1) and contribute to open-source satellite communications. My work involves ground station infrastructure, telemetry decoding, and satellite protocol analysis. Here are some of my key space projects:

UWE-3 Satellite Decoding

Real UWE-3 Satellite

My primary focus has been decoding telemetry frames from the UWE-3 satellite (NORAD 39446) and parsing raw data into readable values.

Raw Telemetry Frames (41 Bytes)

Frame #1 (Valid Housekeeping)
86 A2 40 40 40 40 60 86 A2 40 40 40 40 61 03 F0 35 53 20 64 64 00 21 21 02 00 3C 15 00 00 00 00 00 12 42 63 60 0F E5 11 0B 52
Frame #2 (Valid Housekeeping)
86 A2 40 40 40 40 60 86 A2 40 40 40 40 61 03 F0 36 53 20 64 64 00 21 21 02 00 3C 1F 00 00 00 00 00 D9 C2 33 55 0D E0 FF 08 2A

Kaitai Struct Decoder (uwe3.ksy)

Here is an excerpt from the telemetry payload mapping I contributed to the SatNOGS decoders repository:

Payload Definition
hskp_payload: seq: - id: beacon_payload_command type: u1 doc: 'Housekeeping command byte, always 2 (0x02)' - id: beacon_payload_vals_out_of_range type: u1 doc: 'Count of sensor readings outside valid range' - id: beacon_payload_beacon_rate type: u1 doc: '[s] Beacon transmission interval' - id: beacon_payload_uptime_raw type: u1 repeat: expr repeat-expr: 3 doc: '24-bit uptime counter' - id: beacon_payload_obc_temp type: s1 doc: '[degC] On-board computer temperature' - id: beacon_payload_batt_a_voltage type: u2le doc: '[mV] Battery A voltage' - id: beacon_payload_batt_a_current type: s2le doc: '[mA] Battery A current'

This decoding pipeline processes raw bytes, extracts fields, and converts them into telemetry values. I recently contributed a telemetry decoder for UWE-3 (NORAD 39446) to the SatNOGS decoders repository (PR !515). The decoder processes 41-byte frames extracted from ~129k SatNOGS packets, reconstructing over 270 valid frames.

Read the full technical discussion and protocol specification process on the Libre Space Community Forum.

Implemented using Kaitai Struct, the full payload mapping includes decoding of:

  • Battery voltage and current
  • State of charge and power consumption
  • OBC, exterior, and panel temperatures
  • Subsystem status fields