Signal discriminator

Abstract

Abstract PURPOSE:To easily demodulate a modulation signal produced by an ASK modulation system without using a specific device, by deciding the level, H or L, of an input signal by the number of the waves of carriers in which the modulation signal is inputted directly to a counter, and is counted within a time considerably shorter than the length of one bit. CONSTITUTION:The modulation signal transmitted by a signal line 1 is amplified at a CMOS inverter 4 through a coupling coil 2 and a capacitor 3, and its output wave is voltage-shifted by resistors 6 and 6A, and is inputted to the clock input of a counter 7. The output of the counter 7 is inputted to a control circuit 8. The control circuit 8 resets the counter 7 just before deciding the H or L of the input signal, and sets a timer for a constant time considerably shorter than the length of one bit of the signal sent following the input signal, and waits. When a time set in the timer elapses, the reading of a counter value is started, and it is compared with a reference value, and the signal is discriminated. The discrimination of the signal is performed in such a way that the level is decided as an L level when the counter value is less than a prescribed value considering the influence of noise, etc., and as an H level when it is the value around the reference value, and as a noise component when it is the value other than the above values.

Inventors

• 👤 Sunao Fujishiro
• 👤 直 藤城

Bibliographic Details