The Cal Poly Earth Stations have evolved over the years to adapt to different satellite configurations and needs. Originally, since our first two CubeSats were launching at the same time, we decided to build two stations to operate them simultaneously. Having multiple stations also provides redundancy in case one needs to be taken offline for maintenance. Despite the changes the stations have undergone over the years, the basic principles are still the same. The primary unchanging difference between the stations is the antenna configuration. Otherwise, the stations can be configured as needed to support different missions.
Hertz was our first Earth Station, built mostly by Trent AE6HD to talk to CP1. Marconi was built next to communicate with CP2, since CP1 and CP2 were manifested for the same launch which unfortunately didn’t make it to orbit. These two stations would both be used the following year to successfully support the launch and operations of CP3 and CP4.
Friis, our third station, was built most recently in an attempt to maximize link margin and experiment with higher data rates using our new space-segment AXSEM transceiver on the ground-segment as well. This is still in the experimentation phase, so Friis, as well as the other two stations, tend to swap equipment as needed. The original design used the same Yaesu G-5500 rotor as the other two stations, however the increased weight of the quad-phased yagi array proved to be too massive for smooth pointing.
In the table below are the default configurations for each station.
|Tower||Rohn JRM23810 non-penetrating roof mount 5' x 5' base, 10' tall|
|Rotor||Yaesu G-5500||SPID BIG-RAS/HR|
|Rotor Controller||Yaesu GS-232a||Yaesu GS-232b||Green Heron RT-21|
|Pre-amplifier||SSB SP-7000||Microset PR430A|
|Hardware Radio||Icom-910H||Yaesu FT-847||Kenwood TS-2000,
PolySat Intrepid System Board with AXSEM Transceiver
|Software-Defined Radios||FUNcube Dongle Pro+, RTL-2832, HackRF One|
|TNC||Kantronics KPC-9612+ (hardware)||MixW3 (software)|
|Coax||LMR-400, antenna to preamp, 5/8'' Heliax 50' from preamp to radio||LMR-400 phasing cables (M2 UHF-50) antenna to preamp, LMR-1200 50 ft preamp to station||LMR-400, phasing cables, LMR-900 Pre-amp to cabinet|
|Control Systems||Raspberry Pi 2 running custom Satcom software|
|Windows 7 PC (shared) running SDR-Console/Server, remote accessible via VNC||Windows 7 PC (dedicated) running SDR-Console/Server, remote accessible via VNC|
|Two Mac Mini's located in the main lab act as control terminals. Each Mac Mini is running MacDoppler software which can connect to any of the three stations over the network to control radio tuning and antenna positioning if desired for more user-interactive control.|
|Remote Control and Automation||All stations can be remotely controlled via SSH to the Raspberry Pi's, or remote desktop (VNC) to the Windows 7 PC's or Mac Mini's.
The Raspberry Pi's also call home to a primary Satcom server which handles pass scheduling and automated commanding and downlink from our latest generation of satellites, independent from the Windows 7 PC's or Mac Mini's. The Satcom server can be tasked using a custom iPhone app.