From ANS-236:
The Japan Amateur Satellite Association (JAMSAT) has announced the launch of the “Blueberry JAM” initiative, a new project to design and build an open-source multi-mode transponder for CubeSats. A kickoff meeting was held on May 3 with 15 participants, marking the start of what is envisioned as a flagship development effort for the organization.
The Blueberry JAM project centers on creating a versatile linear transponder that can be integrated into 1U CubeSats, while also being scalable to larger 3U and 6U platforms. The design is intended to support both traditional linear operation and potential digital enhancements, such as delay modes and data handling. The first demonstration unit—an engineering model—is targeted for completion by mid-2026 and will be offered to universities and satellite developers for potential flight opportunities.
Jerry Buxton, N0JY, AMSAT VP-Engineering commented, “AMSAT-NA is excited to see the Japan Amateur Satellite Association’s commitment to open-source development and collaboration with amateur satellite organizations around the world with their Blueberry JAM initiative.
“We are pleased to offer our help in this collective effort by providing JAMSAT with any schematics and documentation from AMSAT’s open-source/open-access projects developed to date as well as those being introduced this year.
“This includes our flight-proven LTM-2 Linear Transponder Module that has flown successfully on satellites deployed by two world-class universities and currently still operating on MO-122 and MESAT1. LTM provides telemetry downlink support for the host science missions and satellite health, as well as direct control of the LTM amateur radio usage. A third university is set to carry the latest version of LTM, which will fly on GOLF-TEE and Fox-Plus, on their upcoming mission that is currently under construction.”
A core philosophy of the project is openness. JAMSAT has pledged to make the development process, design documents, and results available to the amateur community. Hardware costs are expected to be covered by JAMSAT, while individual participants will bear their own incidental expenses. By sharing the design broadly, the group hopes to encourage adoption by multiple satellite missions, with a goal of eventually deploying the transponder on as many as 10 spacecraft.
Technical discussions during the kickoff highlighted the demand for new linear transponder capability in amateur satellites, as well as recognition that digital features will be important for future operations. Considerations include dual-channel command and data handling, efficient microcontroller use, and antenna and power system constraints inherent to CubeSats. The team also noted the potential to establish a ground-based test station to exercise the transponder under realistic conditions before flight.
Buxton also said, “We are also very happy to share AMSAT’s work on its upcoming SDR GEN-2, an SDR that provides all-mode functionality and continuous coverage from 144 MHz to 6 GHz providing “Five & Dime” capability in a format to fit 1U or larger CubeSats.
“We look forward to supporting JAMSAT in promoting more international collaborations that continue to Keep Amateur Radio in Space!”
Coordination for the project will be managed initially through mailing lists, with Slack and other online tools supporting more detailed technical exchanges. Meetings will be held on an ad-hoc basis until a regular schedule is established. Participants also suggested supplementary seminars to review background information and prior work for the benefit of newer contributors.
By positioning Blueberry JAM as a fully open-source design, JAMSAT hopes to strengthen international collaboration and demonstrate Japan’s continued leadership in the amateur satellite community. With a development horizon stretching into 2026 and beyond, the project has the potential to become a cornerstone payload for future CubeSat missions and to provide valuable new communication opportunities for amateur operators worldwide.
[ANS thanks JAMSAT and Jerry Buxton, NØJY, AMSAT VP-Engineering for the above information]