| 摘要 |
An electronic diving apparatus detects pressure by means of a bellows transducer (12). A variable frequency oscillator (10) produces a variable frequency output in proportion to the pressure applied to the transducer (12). A local oscillator (16) produces a fixed frequency signal which is mixed with the variable frequency signal in a mixer-demodulator (14) to produce an audio depth signal. The audio depth signal is provided to up/down counters (30). A time base and synchronizer circuit (24) sequences the counters (30) for an up frequency count and a down frequency count of the audio depth signal. When the difference count exceeds a preset limit, a maximum rate of depth change circuit (34) produces an alarm signal which is transmitted through a beep timer circuit (36) to activate an audio driver and output circuit (28) which produces alarm signal at an audio disk (38). This gives a warning of too rapid of an ascent or descent by the diver. The maximum depth circuit (32) detects the maximum up-count produced by the counters (30 ) and if the count is above a preset limit, an alarm is output through the audio driver and output circuit (28) to the audio disk (38) to warn the diver of an excessive depth. The electronic diving apparatus produces a periodic tone which has a frequency proportional to depth. Warning signals are indicated by modulating the tone or by increasing the duty cycle. Further aspects of the invention include a preset depth indicator, digital tone indications of depth and synthesized speech output to provide voice messages for each of the above alarms and indications.
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