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SARCTRAC History, Credits and Features

Published by Julie & Joe in SARCTRAC · 24 August 2019
The purpose of this Forum is to inform readers of SARCTRAC software release version history; to credit the authors of any contributing software and to provide user's discussion on new features.

SARCTRAC Software Version History:

Release 1.0 - 8 April 2019: Original Release.

This is the initial release of SARCTRAC after 15 months of solid development effort. SARCTRAC is written in Python. The distributed version is cross-compiled into C++.

SARCTRAC does the all the satellite tracking, antenna steering and transceiver (rig) control automatically, so that students can just enjoy working satellites!
  • It is best suited to portable operation, mounted on a sturdy tripod and attached to a small hand-held, dual-band satellite antenna.
  • It can be set up quickly in the school playground and runs off the same power supply (13.8VDC) as the rig.
  • It uses 3D sensors and DC motors to point the antenna at the selected satellite and does not require any on-site calibration.
  • It has a built-in GPS receiver, to get accurate time and location information.
  • It has a built-in World Magnetic Model, to get the local magnetic inclination and declination.
  • It has a built-in WiFi web server, so students can control it via a web browser on their mobile devices.
  • It has a built-in satellite transponder / beacon database, so students can select the correct satellite frequency and mode.
  • It uses the latest orbital prediction models to accurately track selected satellites.
  • It can automatically download the latest satellite orbital elements from the Internet, using a personal WiFi hotspot on the mobile device.
  • It allows students to select the satellites they want to track.
  • It displays the system status and the next pass of each satellite.
  • It automatically schedules the tracking of each selected satellite in turn.
  • It controls the frequency and mode(including manual fine tuning) of an Amateur Radio transceiver via a USB cable.

Version 1.01 - 28 April 2019: This is a mandatory safety update. So please install it before using SARCTRAC!

WARNING: Safety Issue with SARCTRAC Version 1.0.
SARCTRAC was originally designed to power up and just start tracking. However, if something goes wrong your setup (e.g. if the 3D Sensor was mounted incorrectly), the rotator could move in an unexpected way on power-up, potentially causing damage or harm. By the time you open the SARCTRAC SELECTION page and press the STOP button, it may be too late! To avert this scenario, SARCTRAC Version 1.01 now powers up with the motors stopped. There are also some other important changes in this update as well:

Software changes:
  • Fixed some issues with calibration not always beeping and Doppler frequency tracking.
  • Substantially reduced RFI from I2C bus by reducing the 3D Sensor baudrate.
  • Some DC Motor PID and 3D Sensor LPF changes for smoother operation and easier calibration.
  • Added 3D Sensor auto-reset function, as the 3D Sensor can be affected by stray RF.

Hardware changes:
  • Recommend using overall-shielded cable for the 3D Sensor. However we have not found a suitably-thin cable yet.
  • Recommend soldering 0.1uF capacitors from the motor terminals to the chassis to reduce commutator noise.

Please see the SARCTRAC Manual Version 1.01 for details of the software update process and the new hardware modifications.

Credit and thanks for included free, open-source software (Please see the following websites for copyright notices and original source code):

New Features:
The following new features, improvements and fixes are being considered for future versions of SARCTRAC:

  1. Brandon Rhodes has depricated pyEphem - although it will still be available on PyPI. Oh well... We wrote our original orbital element propegator in 1985 by translating the "Spacetrack Report #3" FORTRAN-IV code into Pascal. That was fun! Recently we have been thinking of using the C code from "Spacetrack Report #3 Revisited", but it does not include Brandon's future-pass algorithm, which is pretty cool. We have also noticed some Doppler frequency anomalies, which must be based on erroneous range-rate calculations. We were thinking an update may fix this.
  2. SARCTRAC currently supports only the Yaesu FT-817/818/857/859 all mode all band amateur radio transceivers. We considered using HAMLIB, but that is overkill and has its own problems. So we intend to provide more generic support for the following radios:
    1. ICOM CI-V control.
    2. YAESU CAT control.
  3. We are working on a USB WiFi dongle to provide a wireless interface to the radio.
  4. We are working on a higher-gain, dual band, RHCP Yagi specifically designed for SARCTRAC.

1 comment
Matt Howard
2020-06-24 00:46:43
9V1MH here
Really great stuff - love the concept. I have been working with the Scouts here and this would be a great thing for the annual JOTA gathering.
Portable ops is our best way to get satellites here as most of us have no land/roof to work with.
Most of the team here have ICOM radios - is there any timeline on CI-V interface?

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