#Light-duty two-axis Az/El rotor using portable "Carryout" satellite antenna.

Gabe Emerson / Saveitforparts 2024. Email: [email protected]

Video demo: (in progress)

Introduction:

This code controls a portable satellite antenna over RS-485 using serial commands. This is based roughly on my Carryout-Radio-Telescope project, adapted as a satellite tracking rotor.

The carryout_rotor.py program acts as an interface between a Winegard Carryout and Gpredict (or possibly other hamlib / rotctld compatible programs). Commands to get and set position are converted to Winegard firmware commands. Currently only "p", "P ", and "S" are implemented.

Please note that the author is not an expert in Python, Linux, satellites, or radio theory! This code is very experimental, amateur, and not optimized. It will likely void any warranty your Carryout antenna may have. There are probably better, faster, and more efficient ways to do some of the functions and calculations in the code. Please feel free to fix, improve, or add to anything (If you do, I'd love to hear what you did and how it worked!)

Applications:

• Manually aiming a Winegard Carryout antenna at specific coordinates
• Automatically tracking low-earth-orbit satellites with Gpredict
• Tracking satellites on different frequencies (replace stock Ku-band hardware)
• Tracking drones or aircraft (not tested)

Hardware Requirements:

This code has been developed and tested with a Winegard "Carryout" portable satellite antenna. Specifically, a 2003 version running HandEra HAL 1.00.065 firmware. There are other variations and versions of this hardware, such as the Carryout G2 and G3. I have not tested it with all models, but the firmware and commands are very similar across Winegard products.

You will need to remove the plastic radome from the top of the antenna to access the console port and change or modify the receiver feed.

In addition to the antenna, you will need an RS-232 to RS-485 adapter, custom RJ-25 cable, and USB-to-Serial adapter. I used a "DTECH RS232 to RS485" converter that includes screw terminals. The DB9 end is connected to my USB serial cable, and the wiring terminals are connected to an RJ-25 cable (6-conductor phone cord) as follows:

Looking at the bottom (pin side) of the RJ-25, with end of cable up, the wires from left to right are:

Pin 1: GND Pin 2: T/R- Pin 3: T/R+ Pin 4: RXD- Pin 5: RXD+ Pin 6: Not connected

(See cable1.jpb and cable2.jpg in the images folder)

Thanks to Kyle from Kismet Emergency Communications for providing the RS-485 info!

You will also need a new antenna feed if you plan to use this system with anything other than Ku band. I removed the reflector and LNB and replaced them with a 3D- printed helicone antenna for L-band (https://www.thingiverse.com/thing:6436342). The helicone is connected to a Nooelec SAWbird+GOES LNA, powered via RTL-SDR bias-tee.

The motors might be powerful enough to hold a small Yagi or other directional antenna, but I have not tested this. Adding too much weight or moving the center of balance too far from the mounting plate might damage the motors or gearing.

Notes on power supply and auto-scan behavior

The Winegard Carryout used for testing had a proprietary 12v DC jack, I replaced this with a standard barrel jack. The on-board DC could be stepped down to run an embedded system or SBC if desired. Power of at least 1A seems best.

When first powered on, the Carryout antenna goes through a series of calibration and automatic satellite search movements. This can take approximately 10-15 minutes to complete, depending on DIP switch settings on the control board. It may also produce some alarming grinding sounds from the stepper motors and gearing. Winegard apparently did not bother to install limit switches, and uses motor stall to determine drive limits.

Other users have reported that setting all DIP switches to "off" (up) disabled the search mode, but that did not work for me. There may be a setting in the firmware to disable the search, but I also have not found that (disabling tracking in the "nvs" firmware submenu also disables the position calibration, which we want to retain for accurate aiming).

Package Requirements:

carryout_rotor.py uses pyserial, regex, and socket. They can be installed individually or by running "pip install -r requirements.txt"

Setting up / testing Carryout console:

To connect to a Carryout antenna with RS-485, you will need the cable described above under Hardware Requirements.

To connect to the serial console on the antenna, run "screen /dev/ttyUSB0 57600" (or appropriate port) on Linux, or use a Windows serial terminal to connect to the usb device (typically com3 or similar). You will initially get a blank screen. Typing "?" should return a menu of available commands and submenus. Typing "q" exits the current submenu and returns to the root menu.

Some submenus of interest include: target: send antenna to desired azimuth / elevation coordinates motor: manual motor movements and settings dvb: Get signal info from the stock LNB (if installed) os: List and quit running processes, etc

You will probably want to increase the maximum elevation setting for use as a rotor. This can be found in the nvs submenu, index 102. Once in nvs, enter "e 102" to verify this is the max elevation setting. Then enter "e 102 90" to set the new max, and finally enter "s" to save.

Note that the console does not accept backspace, so if you make a mistake while typing, just hit enter to clear the console. If necessary, close the console or unplug the dish to avoid a motor overrun.

Positioning the antenna:

The Carryout antenna uses a 360-degree clockwise coordinate system, with the coax / F connector at approximately 135 degrees. You may have to run some serial console commands like "target", "g 0 22" to find the 0 or North position. I marked mine with sharpie once I determined this.

Generally I place the antenna with the "0" position facing due North.

Using as an Az/El rotor:

NOTE: If your USB device is other than ttyUSB0, edit line 16 of carryout_rotor.py

Once the dish is connected, powered, and ready on a serial port, run: "python3 carryout_rotor.py"

The code will attempt to connect to the serial port and open a socket on localhost, port 4533 (the default for Gpredict).

In Gpredict's rotor settings, you will want to create a new rotor at 127.0.0.1:4533, 0->180->360, with minimum elevation 22 and maximum elevation 90 (the Carryout can't physically drop below about 22 degrees elevation, other models may have different limitations). See the note in the "Setting Up / Testing" section about increasing the Carryout's default max elevation.

Use Gpredict as normal to track a satellite and click "Engage" to connect to carryout_rotor.py. Clicking "engage" a second time to disengage will close the socket, the serial connection, and exit the python script (otherwise Gpredict crashes).