Resources Contact Us Home
Digital FSK demodulator

Image Number 14 for United States Patent #4825452.

The present invention provides a digital frequency shift keying (FSK) demodulator circuit which receives a hard-limited FSK input signal and recovers the modulating baseband signal at 300 baud or less. The FSK demodulator includes a digital phase locked loop demodulator section which receives the FSK input signal and generates a pulse width modulated output the frequency of which is a function of the input signal frequency. The output of the PLL demodulator section is provided to a quantizer which generates a set of parallel numbers. A translating means, for example a code linearizer, converts the parallel numbers into corresponding parallel outputs which are representative of the frequency of the FSK input signal. The parallel outputs are processed by a digital filter which emulates a second-order, low-pass filter. The filter processes the parallel outputs utilizing pulse density modulation. A deglitcher removes noise from the filter output to provide the demodulated data output.

  Recently Added Patents
Diaphragm valve for printhead
Baby swing and bouncer
Load supporting belt
Transistor device with reduced gate resistance
Renewable energy system
Usage of measurement antenna transmitting communication signal for power adjustment in wireless device
System and method for interfacing sensors to a sterile flow stream
  Randomly Featured Patents
Multi-part wire rope fabric assembly
Apparatus for mounting ski bindings
Adjustment method for spark plug and apparatus therefor
Sports shade
Solar powered radio
Head stack-level load/unload mechanism for rigid disk drives
Device and method for identifying, locating and tracking objects on laboratory equipment
Audio signal signal-to-mask ratio processor for subband coding
Crib structure with slidable steps providing storage compartments
Coin feed device for vending machines