Sometime on or about May 20, the next US Naval Academy satellites and Brno University PSK31 transponders head into space from Cape Canaveral on an Atlas 5 launcher and into an approximately 50° orbit. The launch will include the Psat APRS satellite — a pair of identical 1.5 U cubesats (A and B) — as well as the BRICsat and USS Langley (Unix Space Server Langley) nanosatellites.
“Psat is a Naval Academy student satellite project named in honor of one of our graduates, Bradford Parkinson, of GPS fame, which contains an APRS transponder for relaying remote telemetry, sensor, and user data from remote users and Amateur Radio environmental experiments or other data sources back to Amateur Radio experimenters via a global network of Internet-linked ground stations,” explained APRS developer Bob Bruninga, WB4APR. In addition to the data transponder, a secondary Brno University transponder will support multi-user PSK31 text messaging. The APRS downlink will be 145.825 MHz (1200 baud AX.25 APRS).
“We welcome radio amateurs worldwide to tune into the downlinks and either IGate packets into the global APRS-IS system or to e-mail me,” Bruninga said. “After launch, the next several orbits will be over USA and Europe.” Bruninga said PSAT, including the PSK31 transponder, would not be available for use until all on-orbit checks are complete, a process he said could take “many, many days.” He also requested reports on any PSK31 (FM) heard on 435.350 MHz (the PSK31 uplink is 28.120 MHz).
The PSK31 multi-user FDMA transponder experiment on Psat, BRICsat and USS Langley is similar to the one on RAFT and PCSAT2. It will allow messaging among up to 30 modest ground stations simultaneously, Bruninga said.
Psat is one of five APRS-networked Amateur Radio satellites that will be in orbit during 2015, and all will appear on the live APRS downlink page. The others include PCsat-1, in orbit since 2001, QIKcom-1, set to launch in September, QIKcom-2, set to launch in December, and the ARISS packet radio system on board the International Space Station since 2007.
According to AMSAT-UK, BRICsat will carry an APRS constellation transponder with a downlink of 437.975 MHz and an uplink on 145.825 MHz (1200 and 9600 baud AX25) plus a PSK31 transponder with a 28.120 MHz uplink (2.5 kHz bandwidth) and a UHF FM downlink on 435.350 MHz. Gunter’s Space Page describes USS Langley as “a proof-of-concept mission for providing global internet access via a nanosatellite constellation.” The satellite will act as a web server and router in space, using Internet Protocol and Linux. Downlinks 437.475 MHz (9600 baud AX.25 packet telemetry) with uplink at 145.825 MHz. The PSK31 transponder also will uplink at 28.120 MHz and downlink 435.350 MHz. The IARU coordination page said that while 28.120 MHz is not in the band plan as a satellite frequency, “the panel considered the motivation for this frequency as to give lower class license holders in the US the opportunity to participate in the project.”
Bruninga said satellite experiments such as Psat “serve our educational and outreach goals for student projects encouraging young people to be interested in Science, Technology, Engineering and Math.” He said he hopes other schools will build either additional 145.825 MHz relay satellites or experimental sensors. “We hope that Psat will be the ‘egg’ in this chicken-egg conundrum,” he added.