Let’s talk 10GHz amateur receive station for lunar orbit (Gateway).
JAMSAT (and others!) would like to see a prototype by JAMSAT’s next Symposium. I volunteer to follow through on this, bring it to them, and to remove whatever roadblocks are in the way.
Let’s see what we all can do together to achieve this goal.
Working from what we know of the Gateway amateur radio station through ARISS presentations at AMSAT-NA Symposium, here is the (developing) link budget and the beginning of requirements and specifications.
I can’t think of a better community to provide feedback. I hope that this station could be fully SatNOGS compliant? This could help expand the frequency range to microwave, which I know is a goal.
Free space path loss to moon is 224.5dB at 10.45 GHz.
2m dish with 80% efficiency is 46dB gain.
100 Watts transmit power at Gateway (very preliminary number)
With no other gains or loss that is -128.5 dBm.
Typical received signal power from a GPS satellite is −127.5 dBm
Someone smarter than me please check the work.
Az/El antenna rotator hardware.
Capable of pointing a 2 meter dish with associated receiver electronics.
All open source.
When possible, standard, easily sourced components should be used.
Movement speed capable of tracking LEO satellites.
Appropriate enclosure for protection from weather and spray.
Quiet enough to not disturb neighbors.
Electrical Control System
Should interface with on/off, DC Drive, or Stepper motors (perhaps with optional hardware add-ons).
Should accept position feedback from analog sensors, homing switches, or encoders.
Capable of running open-loop or closed loop (preferred).
Optional capability for position sensing through IMU.
Optional GPS for location and time sync.
Supports control by hamlib, common serial rotor protocols, N1MM rotor protocol, and additional networked methods such as MQTT.
We expect to accommodate a 3 inch steel mast.
A 2m dish is expected to provide enough gain.
There is a raspberry pi hat rotor controller schematic in progress.
There is a rotor design in progress.
We expect to use an SDR with filters and GNU Radio to demonstrate.
Tests expected with the DL0SHF Moon Beacon at 10,368.025 MHz.
EME operators in the San Diego Microwave Group will be consulted today at their monthly meeting.
Stability and pointing are challenges, but given the number of successful 10GHz EME stations, these challenges can be overcome. Eventual goal is an open source kit.