We’ve been having a lot of fun with the Greencube (IO-117) satellite, so I decided to put together a portable ground station for activating grid squares. I wanted a station that –
- Has adequate antenna gain and power for reliable Greencube operation
- Uses solar-battery power so that it is quiet when operating in public places
- Uses computer management for Doppler correction
- Can provide accurate grid locator information via a GPS receiver
- Is easy to set up in the field in less than 30 minutes
We already have a solar-battery power system that we build for portable operation with a 100w transceiver as well as an IC-9700 transceiver that we use as part of our transportable satellite ground station. We also have Windows and Mac laptop computers that we can use as part of our Greencube (IO-117) portable ground station. With these components in mind, here are the hardware components that we are using as part of our Greencube portable station –
- Icom IC-9700 Transceiver (70 watts output on 70cm).
- M2 Antenna Systems 440-11X Antenna mounted on a heavy-duty video camera tripod.
- Advanced Receiver Research coax-powered LNA.
- A portable solar-battery power system capable of producing up to 180 watts of power.
- MacDoppler software running on a MacBook Air Laptop.
- Greencube digital client and logging software running on a Windows Computer.
- A GPS Dongle and Client Software is running on a Windows Computer to accurately determine the grid locator we are operating from.
- A Verizon Jetpack 4G Wireless Modem for Internet Access.
We are using the following software for our portable Greencube (IO-117) ground station:
- UZ7HO’s Greencube Soundmodem (download greentnc.zip).
- OZ9AAR’s Greencube Terminal Software.
- DK3WN’s Greencube Telemetry Decoder.
- MacDoppler to determine antenna pointing and to provide automatic Doppler correction on the IC-9700.
- N3FJP’s ACLog for logging contacts.
- NMEATime 2 Client Software to accurately determine the grid locator that we are operating from.
We also purchased a case (Pelican Air 1555) to package the transceiver and accessories.
We choose the M2 Antenna Systems 440-11X Antenna for our portable ground station. This antenna has more than adequate gain for use with Greencube, and its lightweight rear-mounted design makes it ideal for use with our heavy-duty video camera tripod.
The antenna is attached to the tripod using a Camera Tripod Ball Mount, a Handlebar Ball Mount Clamp, and a Double Socket Ball Arm. The Handlebar Clamp grips that antenna’s rear extension and allows the antenna to be easily rotated to align its polarity with Greencube’s antenna during a pass. A short section of water pipe with a cap, hook, and a 1,000-gram weight provides a counterweight to balance the antenna on the tripod.
A Magnetic Digital Angle Guage is used to adjust the elevation angle of the antenna.
A coax-powered LNA from Advanced Receiver Research (an available alternative is the SSB Electronic SP 70 preamp) is attached to one of the legs of the tripod and is connected to the antenna with a short LMR-240uF coax cable. a 20′ length of LMR-400uF coax connects the antenna system to the transceiver. N-connectors are used throughout the feedline system.
Radio, Computers, and Software
The Windows computer runs the following software programs to provide the client terminal, modem, and logging functions required to operate with Greencube –
- UZ7HO’s Greencube Soundmodem (download greentnc.zip)
- OZ9AAR’s Greencube Terminal Software
- DK3WN’s Greencube Telemetry Decoder
The Windows laptop also runs the NMEATime application and uses a USB GPS Dongle to accurately determine the grid locator where we are operating from. The grid locator from NMEATime is used to configure MacDoppler to ensure accurate tracking information for aiming our antenna.
The MacBook Air laptop runs MacDoopler. MacDoppler is connected to the IC-9700 transceiver via a CI-V cable and controls the IC-9700’s uplink and downlink frequencies to provide Doppler correction. MacDoppler is also used to determine the azimuth and elevation of Greencube to enable manual pointing of our antenna.
Powering a 100-watt transceiver in a portable application during extended operating sessions can present a challenge. I also wanted a setup that was quiet as we often operate portable in public locations. For these reasons, I decided to put together a solar-battery setup that consists of the following components:
- Two 90-watt foldable solar panels from PowerFilm (current model is 120W)
- Two A123 4S4P 10.0 Ah LiPo batteries from Buddipole
- An MPPT Charge Controller
- A RigRunner Power Distribution Panel
The solar panels are wired in series and provide about 34 Vdc in bright sunlight.
The MPPT Charge Controller automatically determines the best balance between cell voltage and current to provide maximum power transfer to charge the batteries. The batteries provide the extra power capacity needed when transmitting. The resulting power setup can sustain the full power operation of our portable station, even on cloud days.
The laptops run on their internal batteries and are changed via automotive lighter socket power adapters between operating sessions.
Operating Using Greencube
My initial tests of the portable station were done using the station to receive Telemetry from Greencube. This allowed me to learn to steer the antenna and adjust it for the best polarity during passes. The station had no trouble hearing and decoding Greencube’s telemetry transmission from horizon to horizon.
It was relatively easy to point the antenna based on the azimuth and elevation information from MacDoppler. I used a compass app on my iPhone to set the antenna’s azimuth heading and the Digital Angle Guage to set the antenna’s elevation. Pointing the antenna to within +/- 10 degrees of accuracy was adequate for reliable operation with Greencube.
I turned the speaker volume on the radio high enough so I could hear Greencube’s signal while adjusting the antenna polarity. Finding the polarity that caused Greencube’s signal to be weakest and then rotating the antenna 90 degrees from this point worked well.
I was able to make 15-20 contacts on each Greencube pass with our portable ground station. The RSSI graph in the Greencube terminal is a good indicator to determine when to adjust the antenna’s heading and polarity to track Greencube during a pass. It’s best to have a helper with one person making contacts and the other adjusting the antenna, but it’s possible for a single operator to do both jobs and still make many contacts during a pass.
More Fun With Greencube
I am quite pleased with the performance of our new portable ground station for Greencube (IO-117). Anita and I are planning a portable grid square activation trip for later in the fall to make use of the station.
This article is the fifth in a series that we are working on. You view the other articles via the links below. This is a work in progress, and we’ll be creating additional Greencube-related posts in the near future:
- Greencube (IO-117) – A New Satellite for DX!
- Greencube (IO-117) – Station Setup, Software, and Operation
- Greencube (IO-117) – Completing a Satellite Worked All States
- Greencube (IO-117) – M2 Antenna Systems LEO Pack – Will It Work?
- Greencube (IO-117) – The Road to a Satellite DXCC?
You can also read more about our Satellite Ground stations here.