| 摘要 |
<p>PURPOSE: To recognize a signal surely even if the noise level is high by employing a pulse signal as the base signal for intelligence signal and transmitting a carrierless signal burst obtained by modulating with respect to the generation time. CONSTITUTION: Output from an oscillator 12 is applied, as a base signal, to a pulse position modulator 22, through a 1/4 frequency divider 14. The modulator 22 comprises a comparator 28 and the actual conduction level thereof is determined by an audio signal from a microphone 34. A monostable multivibrator 46 is triggered by the output from the modulator 28 and a transistor 52 is controlled by the output from the multivibrator 46. The transistor 52 has an emitter connected with a trigger transformer 60 which is connected, on the primary thereof, with respective transistors 66, 68 at a power output section 18. Output from the output section 18 is applied through a coaxial cable 88 to a discone antenna 90 and a wide band spectrum signal is transmitted.</p> |
