AO40 Whole Orbit Telemetry Retrieval Experiment

1
AO-40 Whole Orbit Telemetry Retrieval Experiment
Presented by Richard M. Hambly (W2GPS) For the
AO-40 Telemetry Improvement Team Previously
known as the 12-Meter Team
WB4APR Bob Bruninga W2GPS Rick Hambly N4HY Bob
McGwier
W3IWI Tom Clark KA9Q Phil Karn W3SIR Ron Parise
AMSAT-DC MEETING AND SPACE SEMINAR Maryland-DC
area AMSAT Meeting and Space Seminar Sunday,
April 1, 2001, 1300-1700 EDT NASA Goddard Space
Flight Center Greenbelt, Maryland
2
The Problem

• AO-40 sustained damage after the 400N rocket was
  fired. Telemetry ceased on Dec 13th recovered
  Dec 26th.
• Recovery depends on information but telemetry
  reception is limited due to the satellites
  orientation.
• We want to help but what can WE do?

Phase 3D was launched November 16, 2000 from the
European Spaceport in Kourou, French Guiana on
Flight 135, an Ariane 5 rocket. On reaching orbit
it became AMSAT OSCAR 40 or AO-40.
3
An Idea Emerges

• Bob WB4APR and Rick W2GPS met at the USNA
  Satellite facility on Wednesday, December 26,
  2000.
• It was noticed that the 12-meter dish was
  parked and was looking for a new mission.

4
A Possible Solution

• Individual Assets
• WB4APR has access to the largest available
  antenna in the world.
• WA4SIR announced the AO-40 telemetry meta-server
  at the NASA Goddard Spaceflight Center Amateur
  Radio Club on Dec 29th.
• N4HY and KA9Q are looking at DSP solutions to
  decoding the distorted (spin modulated)
  telemetry.
• W2GPS has networking and software assets plus
  project management experience.
• Solution - Combine our Assets!

5
AO-40 Telemetry Station
Latitude N 38.9908, N 38 59.4474', N 38 59'
26.8466" Longitude W 76.4902, W 76 29.4109', W
76 29' 24.6541" Altitude -45.81
Meters Coordinate System WGS-84
6
WB4APR at USNA

• Bob Bruninga (WB4APR) mans the station 5 days a
  week
• Improvements are being made so the station can be
  left operational even when unattended

7
WB4APR Tracking Software
Antenna Steering
Radio Control
8
More Control Room Features

• InstaTrack is used to show visitors the location
  of AO-40 and review the pass.
• The antenna feed is remote controlled from here.

9
Signal Processing

• W2GPS set up the telemetry decoding and
  networking software here.

• Here is where we record the 5-minute audio clips
  for analysis.

10
Completed Items

• WB4APR has the 12-Meter dish copying AO-40
  telemetry with good signal levels throughout the
  orbit. No other station in the world is doing
  this!
• WB4APR has R5000 Audio going to a second computer
  for simultaneous recording of 5-minute audio
  tracks.
• WA4SIRs Telemetry Server is making the 12-meter
  dish signals available to anyone in the world via
  the Internet.
• AE4JY updated AO40Rcv to allow UDP/IP connection.
  He also released the source code, which makes it
  an ideal platform for FEC development.
• W2GPS has been submitting telemetry files to
  AMSAT.
• W2GPS is now recognized by AO40 Command Team as
  Project Leader of the telemetry FEC project.

11
Action Items

• WB4APR to enhance antenna/Doppler tracking
  software to obtain full automation for unattended
  operation.
• WB4APR to execute tests suggested by W3IWI to
  validate antenna noise temp performance.
• WB4SIR to implement automatic logging and log
  delivery system.
• KA9Q, W3IWI and N4HY are working on an FEC and/or
  interleaving scheme to improve telemetry
  reception. W2GPS will implement the algorithms in
  the AO40Rcv program and its companion signal
  simulator. The results will be sent to the AO-40
  Command Team for review.

12
Antenna Performance Measurements

• Richard Allen, W5SXD did this solar plot of the
  noise performance of his 4 foot dish stepped
  through an array of 1 degree points at 1.7 GHz.
• This was a good idea so we want to do the same
  with the USNA 12-meter dish, but using the moon.

13
Audio Waveform Analysis

• Typical audio trace from 18-Jan-2001 shows
  repetitive envelope every 3.38 seconds. This
  suggests AO-40 is spinning at 17.75 rpm.
• Each revolution has 3-4 deep nulls. Each frame
  is about 11 seconds long so there is no way to
  correctly decode a frame even with solid signals!

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AO-40 Telemetry Waveform AnalysisOne Block is
518 bytes _at_ 400 bits/sec 10.36 seconds
3.38 sec -gt 17.75 rpm
15
AO-40 Telemetry Waveform AnalysisOne Block is
518 bytes _at_ 400 bits/sec 10.36 seconds
13.193 sec -gt 4.55 rpm

• Audio from 16-Mar-2001 while near apogee shows a
  significant reduction in spin rate.
• Each revolution has many deep nulls. There is
  still no way to correctly decode a frame even
  with solid signals!

16
Telemetry Quality
17
What does the command team Think?
-----Original Message----- From Stacey E. Mills,
M.D. mailtow4sm_at_cstone.net Sent Tuesday,
March 20, 2001 149 PM To James R Miller
paul.willmott_at_omsl.bm Cc W2GPS_at_amsat.org Subject
Re FW AO40 Telemetry from the USNA 40-foot
dish At 0640 PM 3/20/2001 0000, James R
Miller wrote gtDear All, gt gt gt Here is today's
telemetry files from the "AO-40 Telemetry
Improvement gt gt Team" using 12-meter (40-foot)
dish at the US Naval Academy. gt gt gt gt This data
is a service from Bob WB4APR, Ron WA4SIR and
myself, Rick gt gt W2GPS. gt gt My ltdeitygt that is
impressive! I can't even /hear/ the beacon one
hour gt after AOS, and neither can the DFT (FFT)
programs. gt I agree... amazing!!! There's no
substitute for a good antenna!! Because of the
lower spin rate, some of the blocks are only
minimally corrupted!!!
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What does the Telemetry Archive Manager Think?
-----Original Message----- From Paul Willmott
mailtopwillmott_at_northrock.bm Sent Wednesday,
March 28, 2001 838 PM To Richard M.
Hambly Subject Bit-Merged WOD from the big
dish! Hi Rick, Many thanks for the telem, it
was very useful!!! Please find attached the
first "live" run of the WOD bit merge software,
... this was built from your data! Please keep
it coming, ... it allows me to get good WOD data
(and D-blocks when transmitting) to the command
stations about 12 hours earlier than would
normally be possible, ... which really makes a
difference! In each file The first block, is
the best CRCC OK block to date in archive The
remaining blocks are bit-merged blocks most
up-to-date first I've flagged the bit-merged
blocks as though they came from a 512 byte modem,
i.e. we don't know if they are CRCC OK or
not. The bit-merged WOD files will now be a
regular part of the archive zip files, ... the K
L files will be phased out. Cheers Paul
--------------------------------------------------
--------------------- Paul C. L. Willmott,
VP9MU, G6KCV AO-40 Telemetry Archive Please
zip and send all telemetry you capture from AO-40
to ao40-archive_at_amsat.org --------------------
--------------------------------------------------
-
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AO-40 Telemetry FEC Upgrade
256 Bytes
256 Bytes
256 Bytes
LS Byte
MS Byte
0x702 0x701 0x700 0x6FF
0x7FF
0x5FF

• 0x500
• 0x4FD
• 0x4FF
• 0x4FE
• 0x4FC
• 0x4FB - 0x50 inter-block idle character

CRCC
32-bit sync vector
254 byte CW and RTTY look-up tables (not used!!!)
512 bytes information, e.g. A block, M block etc

• Any FEC requires additional bits we have at
  least 254 unused bytes in the IHU1 telemetry
  buffer.
• Backward compatibility requires any new data to
  be in this upper 254 bytes.
• One proposal is a byte oriented Reed-Solomon
  (255,172) code that corrects up to
  int((255-172)/2) 41 errors in every 255 byte
  code word. Each A block has 514 bytes that can
  be coded in three 172-byte frames. With FEC we
  generate 3(255-172)249 bytes of parity data.
  We still have a couple bytes to spare!
• Another alternative is to send these parity bytes
  in a separate frame. We can fit two copies of the
  parity bytes in this new frame providing two
  chances to decode.

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Goddard Geophysical Astronomical Observatory
(GGAO)
VLBI Antenna
VLBI Trailer H-Maser
GPS Trailer
GODE GPS Antenna
Our Next Telemetry Tracking Site?
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Protect the Big Dish!
Weve got it so lets defend it!
12-meter dish
Rick W2GPS
US Naval Academy
Rick W2GPS and friends in Bill Wilsons 1944 M20
APC, August 1998