Category Archives: Operating

WB4SON Reports QSO Success with AO-73

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After three failed pass attempts, Bob, WB4SON, was successful in making his first CW contact through AO-73 this evening.  While the Downlink signal levels were high, Bob was unable to hear his own signal in the Downlink.  The mystery was solved, when a much larger than normal Uplink Correction of +8500 Hz was added on top of the DL/UL Doppler corrections.  So while the normal published DL/UL would have been 145.955/435.145, in reality the actual DL/UL was closer to 145.955/435.155.

That Uplink Correction takes into account any frequency inaccuracies in both the earth station as well as the satellite itself (which is subject to wildly fluctuating temperatures in space).

Bob also notes that the Uplink Correction was varying during the pass, from about +8500 Hz to +10500 Hz.  This is an indication that the orbital elements (TLE) have not been refined well enough this early in the satellite’s life, to be an very accurate predictor of its location in orbit — therefore the Doppler corrections, applied automatically, are not as accurate as they could be.

AO-73 (Funcube-1) Reaches Orbit Today!

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Funcube-1, a product of AMSAT-UK and AMSAT-NL, has reached orbit this morning along with 31 other satellites.  The satellite appears to be functioning as expected.  One of the exciting things about this satellite is that it includes a U/V linear transponder that will be available during the night hours for ham radio use.  In addition an extensive educational program is provided, along with some impressive windows based software for decoding telemetry.  Current telemetry values can be viewed in the “Data Warehouse”, as this information is constantly updated.

Signals were heard loud and clear in Rhode Island during a pass that lasted from 16:58 UTC until 17:05 UTC.  The downlink beacon is pretty distinct with a beep that happens every 5 seconds followed by digital data (sounds like noise).  Signals were peaking at least 4 S units above the noise floor using a turnstile antenna.  The Beacon Frequency ranged from 145.937.5 to 145.933.0, putting the midpoint at about 145.935 — spot on according to the pre-launch values.

Funcube-1 is based on a small “cube” satellite factor (about 4x4x4 inches). The idea is by basing the designs on a standardized form-factor, inexpensive launch opportunities can be provided.  As another example of this, yesterday, a US-based launch put 28 cubesats into orbit.

WB4SON has a small post on his first telemetry decodes/uploads that happened on the first day of launch.