software is always a demanding and painstaking process -- an exercise
in logic, clear expression, and almost fanatical attention to detail.
It requires intelligence, dedication, and an enormous amount of
hard work. However, a certain amount of unpredictable and often
unrepeatable inspiration is what usually makes the difference between
adequacy and excellence." (From the Unix "fortune" program.)
While most of the software I create is
done as a personal hobby, some is of enough general interest to
warrant release to the public.
The UoSAT Data Capture
and Display Program
My first commercial
software application was The UoSAT Data Capture And Display
Program, a telemetry and data capture program written for and
donated to AMSAT North America
in 1991. This program was designed in the late 1980s as part of
a low-cost satellite ground station designed around a
home computer to decode and analyze the "living conditions"
on-board the University of Surrey's OSCAR-9 and
satellites. The program was written entirely in hand assembled machine
language (6510 processor), and even decoded DCE (Digital Communication
Experiment) information frames transmitted by OSCAR-11. (OSCAR-11's DCE
was the precursor to later "Pacsat" satellites that employed
digital store-and-forward protocol transponders.)
The following is a small example of data
captured from the UoSAT-2/OSCAR-11 spacecraft using this software:
***UOSAT 2 COMPUTER STATUS INFORMATION***
COMMAND DIARY V4.6 IN OPERATION
UNIVERSAL TIME IS 15:18:15
AUTO MODE IS SELECTED
0A RAM ERRORS AT ACA0H
SPACECRAFT SPIN PERIOD IS -008BH SECONDS
LAST CMD SENT BY COMPUTER WAS 40H TO 1
LAST CMD RECD BY COMPUTER WAS 6DH TO 0 WITH DATA 00H
CURRENT WOD COMMENCED AT 00:00:00
SURVEY INCLUDES CHANS 01,02,03,61,
**** UoSAT-OSCAR-11 BULLETIN - 105 24 September 1987 ****
UoSAT MISSION CONTROL CENTRE,
University of Surrey, Guildford, Surrey, England
** UOSAT TEAM **
Reports, letters, queries and requests from the UoSAT
experimenter community arrive at UoS and you might be interested
to know who it is that you are 'talking' to! All the incoming
mail is first read by G3YJO, then coded and passed to the most
appropriate member of the UoSAT team to deal with in detail.
Requests for standard information sheets, booklets, slides etc.
are handled by Jackie Brooks, whilst technical queries by UoSAT
engineers who either reply by mail or via the Bulletin (when the
answer may be of general interest). The UoSAT team comprises:
Dr Martin Sweeting G3YJO Director, RF systems, telecommand
Dr Lui Mansi On-board data handling, telemetry
Stephen Hodgart Attitude Control, signal processing
Steve Holder On-board Computer software
Michael Meerman G0/PA3BHF Spacecraft Operations, CCD
Jacky Radbone G8WJN CCD, Particle-Wave, mission studies
Jeff Ward G0/K8KA DCE
Lionel Watkins Modulation schemes
Paul Wright Attitude Control
Hok Wong Spacecraft Power systems
Craig Underwood G1GTW Sats In Ed, Groundstation s/ware
Dinesh Patel Orbit studies
Mike Blewett G4VRN Spacecraft Power systems
Richard Clarke G8UNO Telemetry subsystems
Bob Doran G4VRC Mechanics, data collection
Martin Day Engineering
'Mac' Macbeth G8VLY Engineering
Brian Crosse Technician
Martin Nunn G6FNK Technician
Tim Setterfield Technician
Chris Payne G8VRL On-Board Data Handling Research Student
Hamid Mahde G1XWI On-Board Data Handling Research Student
Robert Edgell Space Radiation Effects Research Student
Jackie Brooks Secretary/PA/Administration
**UoSAT SPACECRAFT **
Several stations have enquired why the UO-9 VHF downlink appears
to be 'stronger' than UO-11 on similar passes. Firstly, the
UO-11 transmitter yields between 220 mW (eclipse) and 480 mW
(sunlit) RF output dependent on battery voltage (the power taken
by the VHF tx decreases as battery voltage decreases
deliberately to avoid excessive discharge). UO-9 generally
yields around 475 mW and is rarely in eclipse at present.
Secondly, UO-11 is at 698 km and UO-9 at 478 km thus, when
overhead, UO-9 is some 3.2 dB 'closer'! Consequently, but also
dependent on the groundstation antennas used, UO-9 can be up to
6 dB stronger than UO-11 under certain circumstances.
* UO-11 Operations *
As notified via the UO-11 Newsflash, spacecraft operations have
been interrupted periodically (whilst in range of the UK) since
Thursday 170987 to support the loading and evaluation of new,
updated DCE software - sorry for any inconvenience caused.
The new DCE software features include:
o multiple message 'kill' command.
o suppression of full kep data title frames during
o error detection/correction coding of 96k byte RAM unit.
o two new 16-bit error counters displayed in title no.0.
There will be continued DCE activity during this development and
test period which may further interrupt the UO-11 schedule when
in range of the UK.
CCD image tests have re-commenced on UO-11 this week with an
image taken on 240987 over the northern UK. This data will be
transmitted on 435 MHz at 4800 bps whilst in range of UoS and
during the normal 435 MHz transmissions scheduled by the DIARY
each Sunday from 0000-1200 gmt.
The following WOD surveys are scheduled on UO-11:
* UO-9 Operations *
A CCD image was taken by the UO-9 camera on 230987 and
transmitted at 1200 bps on 145.825 MHz. CCD transmissions will
take place each Wednesday.
** FO-12 SPACECRAFT **
Following the interruption to the FO-12 operating schedule due
to poor power budget, reports indicate that the original
schedule is being pursued once more:
Date Time Date Time Mode
September 26 03:27 27 04:35 JD
29 02:46 30 03:54 JA
October 01 03:00 02 04:08 JA
03 03:14 05 01:26 JA
07 01:39 08 02:47 JD
09 01:53 10 01:00 JD
The transponders will be off at others times. The schedule may
be changed at any time due to unexpected power situations.
** Thanks for Reports **
G4JJ - thanks for the reports, graphs etc. Jack de G3YJO
Renee Beer - information on its way, please let us know how
you get on with your project.
WB3JFS - thanks for the report on UO-9 21 MHz beacon
KD2BD - keep us posted concerning your demodulator!
Archives of satellite
telemetry and digital news broadcasts received from OSCAR-9 and
OSCAR-11 satellites using this software are available toward the
bottom of the
News Archive Page authored by Clive Wallis, G3CWV.
The funds received from the sale of this and
other AMSAT-NA software are applied directly toward the construction
of amateur radio communication satellites, and benefit the advancement
of the amateur space program.
PREDICT is a
very popular satellite tracking/orbital prediction program
developed for the Linux operating system. PREDICT permits
users to track satellites in real-time, or make orbital
predictions in advance of their arrival. A unique voice mode allows azimuth and elevation
bearings of a satellite to be articulated via a soundcard to aid
a ground-based observer in locating and identifying satellites
through visual means. PREDICT also provides live bearings
of the Sun and Moon, as well as solar illumination conditions
onboard satellites. Doppler shift, squint angle, and path loss
information is also provided for characterizing radio
communication paths between satellites and earth-based ground
stations. PREDICT supports the PIC/TRACK and FODTrack
automatic antenna tracking systems, and includes a UDP
socket-based interface that allows real-time tracking data to be
exported to any number of client applications running locally or
remotely via a network connection. Several socket-based graphical
satellite tracking display applications are included in the
latest release of PREDICT.
PREDICT is currently used
for satellite tracking applications at the NASA/Goddard Spaceflight
Center, the U.S. Naval Research Laboratory, Stanford University, and
the European Space Agency. The latest version may be downloaded via
the Internet for either Linux or DOS-based operating systems. See the
PREDICT Website for more information on
PacsatTools is a
collection of utilities for the Linux operating system that are
designed for integration into a "Pacsat" satellite groundstation.
Included are utilities that prepare files for upload to Pacsat
satellites, tag files for download, process downloaded files, and
display satellite directory information. Also included is a utility
to process narrow-angle CCD Earth Imaging Camera images taken by
the UoSAT-OSCAR-22 and KITSAT-OSCAR-25 satellites, and convert
them to PGM (Portable Gray Map) formatted images.
PacsatTools is an excellent
addition to the PB/PG Pacsat communication suite by Bent Bagger,
OZ6BL, and may be downloaded from
SPLAT! is a
Signal Propagation, Loss, And
Terrain analysis utility for the spectrum between 20 MHz
and 20 GHz. It is designed to operate under the Linux (or Unix)
SPLAT! provides site engineering
data such as the great circle distances and bearings between
sites, antenna elevation angles (uptilt), depression angles
(downtilt), antenna height above mean sea level, antenna height
above average terrain, bearings and distances to known
obstructions, path loss and received signal strength based on
the Longley-Rice Irregular Terrain Model, and minimum antenna
height requirements needed to establish line-of-sight communication
paths absent of obstructions due to terrain.
SPLAT! produces reports, graphs,
and highly detailed and carefully annotated topographic maps
depicting line-of-sight paths, path loss, and expected coverage
areas of transmitters and repeater systems. When performing
line-of-sight analysis in situations where multiple transmitter
or repeater sites are employed, SPLAT! determines
individual and mutual areas of coverage within the network
Applications of SPLAT! include
site engineering, wireless network design, amateur radio
communications, frequency coordination, communication system
design, and terrestrial television and radio
Please visit the SPLAT! Website
for additional information.