Emergency locating transmitter
First Claim
1. A distress transmitter comprising:
- means for generating a radio frequency carrier;
means for generating a first audio signal to indicate a distress condition;
means for generating a second audio signal, which differs from said first audio signal,means for modulating said radio frequency carrier with said first and second audio signals as well as for providing a period during which said radio frequency carrier is unmodulated; and
means for sequentially transmitting a periodic signal containing said first audio signal modulated carrier, said second audio signal modulated carrier and said unmodulated carrier, each with predetermined durations.
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Accused Products
Abstract
A transmitter generates three signals for sequential transmission. These signals are an unmodulated r.f. carrier, an r.f. carrier amplitude modulated by a first audio frequency waveform and an r.f. carrier amplitude modulated by a second audio frequency waveform which is distinguishable from the first and which may be employed as a means for identifying a particular transmitter. The composite, sequentially transmitted signal may be varied in terms of the individual signal transmission sequence, the duration of the individual signals, overall composite signal repetition rate and the frequency of the second audio waveform. Various combinations of signal variations may be employed to transmit different information.
20 Citations
10 Claims
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1. A distress transmitter comprising:
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means for generating a radio frequency carrier; means for generating a first audio signal to indicate a distress condition; means for generating a second audio signal, which differs from said first audio signal, means for modulating said radio frequency carrier with said first and second audio signals as well as for providing a period during which said radio frequency carrier is unmodulated; and means for sequentially transmitting a periodic signal containing said first audio signal modulated carrier, said second audio signal modulated carrier and said unmodulated carrier, each with predetermined durations. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A transmitter comprising:
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means for generating a radio frequency carrier; means for generating an audio signal to identify said transmitter among a plurality of transmitters operating on the same frequency; means for amplitude modulating said radio frequency carrier with said audio signal as well as for providing a period during which said radio frequency carrier is unmodulated; and means for sequentially transmitting a periodic signal containing said audio signal modulated carrier and unmodulated carrier, each with predetermined durations. - View Dependent Claims (9, 10)
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Specification