New ARISSat-1 FM operating mode

New ARISSat-1 FM operating mode

ARISSat-1/KEDR Project Manager Gould Smith, WA4SXM reported on this week’s status of the satellite.

Gould noted that while the battery performed as expected during the first week of operation. Lower voltages during eclipse began to show up in the telemetry on 10 Aug 2011.

The voltages during eclipse have continued to decline causing the satellite to reset and occasionally go into Emergency power mode.

Gould explained the changes noted on the 145.950 MHz FM downlink that were heard this week:

• A Male voice for the spoken telemetry means that the female voice files on the SD card could not be read.

• If no greetings are transmitted this means that these message stored on the SD card could not be read.

• A short Mission-Elapsed-Time (minutes to hours) has been noted while the satellite was still in a long period of sunlight indicating that satellite must have reset during sunlight.

Reports received on later orbits indicated that the female voiced
telemetry and the greetings messages had returned to normal operation once the solar panels had recharged the battery.

After each reset the satellite MET (Mission Elapsed Timer) goes to 000, waits during the 15 minute TX delay, the power management software checks the current voltage and power values and determines what power mode to operate the satellite. The power mode is re-determined at fixed intervals, especially during illuminated periods to provide the most transmitted signals while protecting the battery.

High power mode provides continuous transmission when sunlight is charging the battery. If the satellite has entered low power mode it will transmit for 40 seconds and remain idle for 2 minutes when in eclipse, or when the battery voltage is low.

The ARISSat-1 team is closely monitoring the situation and is pleased with how well the power management software is controlling the battery usage to prolong the lifetime of the battery and the satellite as much as possible.

Please send your BPSK telemetry into the server arissattlm.org.

Gould Smith, WA4SXM
ARISSat-1/KEDR Project Manager

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