CNCTRK – A LinuxCNC Based Satellite Tracking System
by Bob Freeman, KI4SBL
Hello, and thank you for visiting my CNCTRK project site. This site
information on the CNCTRK satellite tracking system and hardware. Included
here are discriptions of two antenna positioning systems, updated assembly
instructions and the latest information available
since the CNCTRK article was published in the May/June 2015 issue of the AMSAT Journal.
Background information on the CNCTRK system and hardware is on the original web page here. As a refresher, the
photograph below shows a ground station assembled using the CNCTRK
system with the Raspberry Pi as sytem controller. The AZ/EL
positioner is steering two small
DIY antennas, one on each side of the positioner. An Arduino Sketch is available that allows interfacing the RAZEL hardware to tracking
software such as SatPC32; see below for details.
RPi-Based Tracking System Using PREDICT and CNCTRK
UPDATE: 2018-01-30 CNCTRK Kits are SOLD
The CNCTRK Kits are no longer available on eBay as all kits have been sold.
Thank you to all who have participated in the project -- it has been a
fun project and, hopefully, several folks are outdoors making contacts
with the system. AMSAT has benefitted from the project, as well,
due to donations from some proceeds of sales. Project
documentation and Arduino Sketch will remain available on this
site. Feedback and questions about the CNCTRK project are still
welcome. Thanks again. 73, Bob
UPDATE: 2017-12-05 Updated CNCTRK Flyer including Arduino wiring diagram and 2m & 70cm antenna designs
A two page flyer
describes key features of the CNCTRK
system and provides web links to two tape Yagi-Uda antenna designs that
are a good fit for use with CNCTRK's RAZEL positioner. Also
included is wiring diagram for using an Arduino UNO with the
positioner, for use with SatPC32, GPredict, and etc. The updated
flyer is available here.
UPDATE: 2016-09-16 CNCTRK Kits will soon be available on eBay
The CNCTRK Kits will soon be available on eBay. Presently,
only the RAZEL Kit and RASPI Kit are offered. The project documentation and Arduino Sketch remain available on this site.
UPDATE: 2016-06-01 Handy-Dandy Flyer for CNCTRK System
A one page flyer describes key features of the CNCTRK
system, including non-CNC use with the Arduino; references are
included, as well. The flyer is available here.
UPDATE: 2016-05-25 Arduino-based Interface Developed For Use With SATPC32
An Arduino SKETCH has
been developed to allow interfacing the RAZEL hardware to any tracking
software; the Yaesu GS-232 protocol is used. This enables the
AZ/EL stepper motor based positioner to be used from SATPC32, GPredict, and others without using the CNC-based system on the Raspberry Pi or laptop. The Arduino Sketch is found here: RAZEL-duino_2016-05-28.ino. Pin connections are detailed in the Sketch; a drawing is located here: Arduino_to_CNCTRK_connections.pdf .
The CNCTRK has been included in the release of the hamlib 3.0.
It is no longer necessary to patch hamlib in order to use the CNCTRK
system. This is good news as it just makes life easier for folks
running GPredict or other software that uses hamlib. The "rotor
type" is changed from the example in the AMSAT article, however; the
new rotor type is initiated using "rotctl -m 1601" or "rotctld -m 1601," rather than the 1501 shown in the article.
UPDATE: 2015-11-28 CNCTRK Hardware Kits for Sale
Three kit offerings have been developed for sale to interested parties; these are described below.
UPDATE: 2015-12-11 CNCTRK Introduction Videos on YouTube
CNCTRK motion demonstration https://youtu.be/KIgcvlxFY7E
CNCTRK Raspberry Pi Tracking Process https://youtu.be/nOYwMzDjjIk
CNCTRK Raspberry Pi Hardware Overview (my version) https://youtu.be/VCj4ibacnYs
CNCTRK EL-over-AZ Positioner Alternative Configuration https://youtu.be/wZZcbhpLT8o
CNCTRK Hardware Kit Details
RAZEL Kit -- DIY AZ/EL (dual axis) Positioner Kit
Includes: CNC machined gearbox components (2 ea), gear kits (2 ea), stepper
motors (2 ea), configuration adapter, assembled motor driver
electronics (2 ea). and an Antenna Mounting Kit for two antennas.
Mechanical assembly of the gearbox is required. Photographs of the assembled prototype RAZEL Kit follow.
Note that since the gearbox units are modular, different configurations of the positioner can be achieved, as described in the Assembly Instructions.
Antenna Mounting Hardware images:
RASPI Kit -- Raspberry Pi-Based Tracking System Controller Kit
Raspberry Pi Model B+, MicroSD Card with working CNCTRK Image, DC-DC
Converter (12V-to-5V), Interface PCB and components (some SMD),
including pre-programmed PIC controller, needed to build the control
PCB assembly is required. Peripherals such as monitor, keyboard, mouse, Wi-Fi dongle, and enclosure are not provided in the kit. A photograph of the RASPI Kit controller (with a populated and assembled PCB) is shown below, for reference.
The RAZEL Kit can be controlled using the LinuxCNC on a suitable computer (i.e. with parallel port), using RASPI Kit, the Raspberry Pi based tracking system, or using an Arduino UNO. All Items operate on 12 VDC for portable use.
1. A limited number of kits are available for sale.
2. Stepper motors supplied in the RAZEL kits are "refurbished" or "like new" units.
3. Motor controllers accept Step and Direction inputs.
4. Alternate uses for the kits may be: Solar (PV) Tracking, or Pan/Tilt for Camera.All Items operate on 12 VDC for portable use.
5. The RASPI Kit should be able to serve as a controller for a stepper driven CNC machine, once assembled.
6. The RASPI Kit is available individually for those wanting a CNC controller.
7. The login information for the RASPI Kit is not normally needed for operation but these are listed below.
Finally, please note the images shown above are of the prototype/development hardware.
The kit hardware is essentially the same but refined for weight, cost,
and manufacturing. For example, the kits will include thinner aluminum
flat plate and the aluminum tube will have no filleted inside
corners. The kit parts contain rounded corners for safety; all
aluminum parts are unfinished.
Conditions of sale are available on the eBay listing.
A block diagram of a CNCTRK system using the RASPI Kit is contained in the original web page.
Antenna Range Note
If you become proficient in using the CNCTRK hardware and LinuxCNC,
then you may want to have a look at my antenna measurement system based
on these same systems. The measurement system is called EMCAR which stands for the Enhanced
Machine Controller Antenna Range and is found on the EMCAR site at Sourceforge. A detailed description of the EMCAR system may be found here, also on the Sourceforge site.
May/June 2015 AMSAT Journal article on CNCTRK is available here: CNCTRK Article in pdf form
Updated Assembly Instructions for the AZ/EL Antenna Positioning System (APS): APS Assembly Instructions
Source code for cnctrk.c, a PREDICT client program for Satellite/Sun/Moon tracking: cnctrk.c
Executable or binary for cnctrk.c to enable tracking: cnctrk
Updated PREDICT database containing new active amateur radio satellites as of October 2015: predict.tle
Updated script for updating two line elements in PREDICT database via network: update.script
Sample LinuxCNC .ini setup file for the AZ/EL APS: stepper_inch.ini
Home for the PICnc-V2 interface board used in the RASPI
Feedback on the above content is welcome - especially, if there are errors or omissions.
Please note that this CNCTRK project is (still) a fun hobby and not a
Thanks and 73,