Bi-phase modulator/demodulator
AssigneeHoneywell Inc.
InventorHarryF. Stillwell
Life of this patent
Estimating the term…
Abstract
A bi-phase modulator/demodulator circuit for converting uni-polar to bi-polar signals. The circuit can be used to bi-phase modulate a continuous wave (CW) input signal or to demodulate a bi-phase coded input signal by use of transistor-transistor logic (TTL) control signals. A tri-state logic gate is used to convert two digital signals to an unbiased AC signal which is applied to one of two inputs of a double balanced mixer. The other input of the mixer is adapted to receive a continuous wave signal for bi-phase modulation, or a bi-phase coded signal for demodulation.
Claims2
A bi-phase modulator-demodulator circuit for converting uni-polar to bi-polar signals, comprising:
- a tri-state logic gate having first and second inputs for receiving first and second digital signals and having an output;
- a first amplifier stage including a first transistor having a base electrode connected to receive the signal from the output of said tri-state logic gate and having an emitter electrode and a collector electrode;
- impedance means for interconnecting said electrodes of said first transistor between sources of first and second potential so as to allow the signal at the collector electrode to swing linearly by a predetermined voltage amount in either direction from a reference potential;
- means for providing DC isolation between the output of said tri-state logic gate and the base electrode of said first transistor
- a second amplifier stage including second and third complementary transistors connected to receive an input signal at a common junction joining their respective base electrodes, and to provide an output at a common junction joining their respective emitter electrodes, and further having their collectors respectively connected to sources of positive and negative potential;
- means for providing DC isolation between the output of said first amplifier stage and the input of said second amplifier stage;
- means for limiting the voltage swing at the output of said second amplifier stage between predetermined positive and negative voltage levels;
- and
- a double balanced mixer having a first input connected to receive the signal from the output of said second amplifier stage and having a second input and an output.
Dependencies are inferred from the claim text.