Distributed Ground Station Network For CubeSat Communications

Radio amateur Zachary J. Leffke KJ4QLP has written a Masters Thesis which explores the concept of deploying a network of distributed ground station receiver nodes for the purposes of increasing access time to the spacecraft  

This increases the potential amount of data that can be transferred from orbit to the ground. The current trends in CubeSat communications are being analyzed and an argument made in favor of transitioning to more modern digital communications approaches for on orbit missions. Finally, a candidate ground station receiver node design is presented a possible design that could be used to deploy such a network.

Read the paper -  http://t.co/yQx2O0PPUF

AMSAT-UK - http://amsat-uk.org/

Solar activity delays CubeSat launch

High radiation levesl from recent solar eruptions has resulted in a planned launch of amateur radio CubeSats being postponed

“Early on Wednesday, January 8 the Antares launch team decided to scrub the launch attempt due to an unusually high level of space radiation that exceeded by a considerable margin the constraints imposed on the mission to ensure the rocket’s electronic systems are not impacted by a harsh radiation environment.”

— NASA's Wallops Flight Facility

The solar flux activity that occurred late yesterday afternoon has had the result of increasing the level of radiation beyond what the Antares engineering team was monitoring earlier in the day. Overnight, Orbital engineers who are experts in the field ran numerous models to ensure that all possibilities to preserve the launch were examined. However, due to significantly elevated flux levels, the Antares team decided to postpone the launch to spend the day further examining the potential effects of the space radiation on the rocket’s avionics suite.

During Wednesday, in consultation with NASA and outside experts in the field of “space weather,” Orbital will continue to monitor the levels of space radiation with a goal of setting a new launch date as soon as possible. If we are able to launch on Thursday, the launch targeted launch time would be 1:10 p.m. (EST), with Cygnus arriving at the ISS Sunday morning, January 12.

AMSAT-UK - http://amsat-uk.org/

SO-50's eleventh birthday

Now known as SO-50, Saudisat 1C is a Saudi Arabian picosatellite that was launched by a Dnepr rocket from Baikonur at 17:00 UT on 20 December 2002.

SO-50 features a "Mode J" FM amateur repeater operating on a 2M uplink and a 440 downlink.

“Most hams already own the necessary equipment to work SO-50,

It is preferable to work SO-50 in true, full-duplex mode - so you can hear the downlink as you transmit. This means - for most - using a second radio or the Kenwood TH-D72A and its true full-duplex capability. The new Puxing PX-UV973 is currently being tested in this mode, too, to see how it works on the satellites.”

— Clint Bradford, K6LCS

SO-50's repeater is available to amateurs worldwide, and it uses a 67.0 Hertz PL tone on the uplink. SO-50 also has a 10 minute timer that must be armed before use. If you know the satellite is there - but there is nothing heard - you may need to shoot it a PL tone of 74.4 to turn it ON!

The repeater consists of a miniature VHF receiver with sensitivity of -124dBm, with an IF bandwidth of 15 KHz. The receive antenna is a 1/4 wave vertical mounted in the top corner of the spacecraft. Its UHF transmitter is a mere 250 mW, and downlink antenna is a 1/4 wave mounted in the bottom corner of the spacecraft and canted at 45 degrees inward.

"Hams just with Technician licenses can work the satellite," Clint continues. "We are talking about weak signals from 500 miles away - so improving both your TX and RX antennas is critical for success on this satellite." Plans for making tape measure beams and other inexpensive, high-gain antennas are also on his Web site.

"Do not forget to accommodate for the Doppler phenomenon on the 440 receive side."

Complete details - including frequency chart and sources for knowing when the satellite will be over your area - http://www.work-sat.com