Oscillator circuit schematic

Posted on Feb 7, 2014

This web page describes the radio transmitter unit that flew aboard the Cirrus One rocket in April 2001. The intent of including the transmitter as payload was to: As the Cirrus One rocket was expected to achieve an altitude that would be well out of visual range at 10, 000 feet (3 km. ), it was felt that there could be recovery difficulties if the

Oscillator circuit schematic
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wind (if present at launch) would carry the rocket far downrange. Since the altimeter that also flew with the rocket was expected to generate a continous audible "beeping" code once peak altitude was achieved, this sound could be picked up by the transmitter and effectively act as a homing beacon*. Although of secondary importance, it was felt that it might be advantageous to receive the altimeter signal of peak altitude while the rocket was still in flight. just in case the recovery system should fail to function properly, or if the rocket was to be otherwise lost. This was my first try at having a transmitter as payload, and I felt that an FRS radio might be a practical, simple, and inexpensive solution that could be implemented within the short timeframe that was available prior to the launch event. * As it turned out, a software bug dictated last-minute replacement of the altimeter`s PIC chip with one with updated software, which, unfortunately, provided for only a one time, rather than continous, audible broadcast of the coded peak altitude. The transmitter unit was an essentially unaltered FRS radio transceiver. These inexpensive units, which operate at a frequency band of, 462. 5625 MHz to 467. 7125 MHz, have an advertised range of 2 miles (3. 2 km. ). The unit that I used was a Panasonic "Talkabout FR50", with 14 channels, and cost about $30 CAD. The only modifications to the unit involved stripping away the case...

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