Fox-2 to have Mode J (145 to 435 MHz) transponder

AMSAT FOXTony Monterio AA2TX and the AMSAT News service (ANS) have released this update on the Fox CubeSat program.

The main point of Fox-2 is to develop and fly an advanced, software defined transponder (SDX.) An SDX can be programmed to be any kind of transponder. It will be a linear [SSB/CW], inverting mode-J [VHF uplink UHF downlink] transponder by default.

We would also like to try some new and interesting digital modes perhaps including digital voice which would be my personal favorite. That is the tremendous flexibility you get with an SDX. You can change the transponder in software.

ARISSat-1 was our first attempt at an SDX and it worked very well. It could only be programmed on the ground though. The SDX for Fox-2 will be programmable in orbit.

Fox-2 will be a 3U CubeSat (three times the size of Fox-1) providing a lot more power and space for the electronics.

The source of confusion may be because we are building four Fox-1 flight units. The idea is to have them available and ready to fly so we can easily team up with universities that want to fly science missions and get free launches. Building them all at once is also a much cheaper way to build satellites.

All four Fox-1 units will have the same hardware and avionics. The universities will supply their experiment cards and the software can be customized for each satellite as needed.

Once the Fox-1 flight models are built, the engineering team can begin working on Fox-2. That should start this year [2014].

The status of the Fox-1 satellites is as follows:

Fox-1 (Fox-1A) is scheduled to fly on NROL-55.

RadFxSat (Fox-1B) is a joint project with Vanderbilt University. It has already been accepted into the NASA ELaNa program but it has not been assigned a launch yet.

Fox-1C and Fox-1D are not currently assigned.

RIT AMSAT Fox-2 Maximum Power Point Tracker Time-Lapse and Final Presentation

AMSAT FOXA time-lapse video of the first of two Maximum Power Point Tracker channels being populated by the Rochester Institute of Technology senior design ground P13271.

The prototype maximum power point tracker used to optimize the power output of the solar panels on the amateur radio Fox-2 satellite was developed in this senior design project.

This time-lapse only shows one side being brought up for the first time, including initial testing and represents 13,739 images taken every 5 seconds by a GoPro HD Hero resulting in a 2.5 minute video showing 19 hours of work by P13271 team-members.

Watch the Time-Lapse video

Rochester Institute of Technology Multidisciplinary Senior Design program team P13271 consisting of electrical engineering students Bryce Salmi (KB1LQC), Brenton Salmi (KB1LQD), Ian MacKenzie (KB3OCF), and Dan Corriero conduct the final project review at the conclusion of Spring Quarter 2013. P13271 designed and built a 7 Watt Maximum Power Point Tracker prototype intended for use on the Radio Amateur Satellite Corporation (AMSAT) Fox-2 satellite, a 3U CubeSat.

Watch P13271 AMSAT Fox-2 MPPT RIT Senior Design Final Presentation

Fox-2 MPPT Team Selected In TI Design Contest

Fox-2 MPPT Team Selected In TI Design Contest

AMSAT FOXAMSAT sponsored a senior design project at the Rochester Institute of Technology (RIT) this academic year.

The students included senior EE majors:
Bryce Salmi KB1LQC
Brent Salmi KB1LQD
Ian MacKenzie KB3OCF
Dan Corriero

The project was to develop a Maximum power point tracking (MPPT) circuit which is used to maximize the power obtained from a solar panel by forcing the cells to operate at their most efficient voltage regardless of the voltage required by the payload. One can also think of this as an impedance match. This optimum voltage changes slightly with variations in solar irradiance but changes greatly due to variations in solar panel temperature.

The MPPT utilizes a Texas Instruments MSP430 microcontroller to communicate telemetry data with the Fox satellite Internal Housekeeping Unit (IHU) designed by AMSAT for transmission to Earth via ham radio. The senior design group consisting of Brenton Salmi (KB1LQD), Bryce Salmi (KB1LQC), Ian MacKenzie (KB3OCF), and Daniel Corriero successfully implemented an analog MPPT designed for use in orbit over the five year mission intended for Fox-2 providing the amateur radio community with a 3U CubeSat carrying amateur radio communications equipment.

The students completed a working prototype which was on display in the AMSAT engineering booth at Dayton in May.

The project was entered into Texas Instruments’ 2013 Analog Design Contest for university students.

The AMSAT MPPT project was selected as one of the top 10 semi-finalists and the students were invited on an all-expenses paid trip to TI’s contest summit to be held July 21-23 in Dallas where the final winners will be announced.

Congratulations to the Fox-2 RIT MPPT team!

Main Documentation:

Technical Document (8 pages of technical information HIGHLY recommended reading):

Theory of Operations (In-depth technical documentation):

PCB Picture:

MPPT Testing Operational Walk-through:


Thanks to Bryce Salmi KB1LQC, ANS and Tony AA2TX for the above information.