Tuesday, September 28, 2010

ARISSat-1: Transponders that don't transpond ?

Time after time after many thousands of amateurs worldwide equipped themselves for amateur satellites, we are subjected to the spectacle of a university, a government or both using the ham bands for a satellite that transmits only for their benefit. The ARRL and AMSAT have even taken to saying these are transponders. These are not transponders. They are looped transmitters.

From ARRL:

ARISSat-1/RadioSkaf V will have simultaneous 2-meter FM, CW, BPSK and transponder transmissions. These multiple transmissions are created by a new software-defined transponder (SDX) board. The FM transmissions will cycle between a voice ID, select telemetry values, 24 international greeting messages in 15 languages and live SSTV images. The CW transmissons will be callsign ID, select telemetry, and callsigns of people actively involved with the ARISS program. The BPSK transmissions will feature a new 1kBPSK protocol developed by Phil Karn, KA9Q, to be readable in low signal level conditions. The BPSK data will alternate betwen telemetry and Kursk experiment data. Free groundstation soundcard demodulator and display software will be available before launch for multiple platforms. There also is a 16 kHz wide Mode U/V (UHF uplink - VHF downlink) transponder between the BPSK and FM signals.

From the "Webster" Dictionary (who was Miriam to usurp Noah anyway ?):

tran·spon·der
noun \tran(t)-ˈspän-dər\
Definition of TRANSPONDER
: a radio or radar set that upon receiving a designated signal emits a radio signal of its own and that is used especially for the detection, identification, and location of objects and in satellites for relaying communications signals
Origin of TRANSPONDER
transmitter + responder
First Known Use: circa 1944

From Wisegeek:

A transponder is an electronic device used to wirelessly receive and transmit electrical signals. Fittingly, its name is equally derived from the words "transmitter" and "responder".

From Wikipedia:

In telecommunication, the term transponder (short-for Transmitter-responder and sometimes abbreviated to XPDR[1], XPNDR[2], TPDR[3] or TP[4]) has the following meanings:

They have made available ONE ... ONE ... bizarrely configured transponder:

There also is a 16 kHz wide Mode U/V (UHF uplink - VHF downlink) transponder between the BPSK and FM signals.

And, the rapidity with which this bird was built is nothing short of disgusting with the anguish that we are put through waiting for a replacement to AO-40 which was used by a government for target practice right before the Chinese openly fired a weapon at a test satellite and destroyed it.

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