Digital preemphasizer for transmission of PCM codes

A preemphasizer for reducing a bit error rate during transmission of pulse code modulator (PCM) code on a fixed transmission line, said preemphasizer comprising:

• a state detector for receiving the PCM serial input signal, operatively connected thereto, and detecting a Mark or Space of each portion of the input signal thereof;
• said detector means having a plurality of detector input address terminals and an equal number of detector output terminals;
• a controller for providing a plurality of control signals for controlling said preemphasizer, said controller having controller input terminals, equal in number to said detector output terminals of said state detector and operatively connected thereto, said controller having output terminals equal in number to said detector input terminals of said state detector and operatively connected thereto, said controller having a plurality of output control signals present thereon;
• multiplexer for receiving said output control signals on separate multiplexer input terminals, equal in number to the plurality of said output control signals from said controller, for mapping the plurality of possible states of the PCM controller signal into a preemphasized signal comprising an adjustable amplitude for each of said possible states, having said preemphasized signal as the output signal thereof;
• clock for generating a 2X clock signal, derived from and operating at twice a frequency of a clock signal of the PCM signal, operatively sending a 2X clock signal to both said controller and said multiplexer, for timing and synchronizing said mapping of the PCM signal;
• a level adjustment for generating a plurality of PCM state level adjustments, one level for each of said possible states, operatively connected to said multiplexer, for mitigating frequency dependent attenuation attendant to a fixed transmission line;
• and
• said preemphasizer signal, mapped from the PCM signal, thereon operatively connected to the input of a buffer amplifier, output of the buffer amplifier operatively connected to input of the transmission line, output of the transmission line operatively connected to a receiver, comprising a wide-band amplifier and a threshold detector thereof, the receiver producing as its output a replication of the PCM serial input signal, said preemphasizer reducing the bit error rate during transmission of the PCM serial input signal through the transmission line.

A digital preemphasizer comprising:

• a pulse code modulator (PCM) state detector for receiving a PCM input signal, operatively connected thereto, and detecting a Mark or Space state of each portion of the input signal, said detector having a plurality of detector input address terminals and an equal number of detector output terminals;
• a multiplexer controller for providing a plurality of control signals for controlling said preemphasizer, said controller having controller input terminals, equal in number to said detector output terminals of said state detector and operatively connected thereto, said controller having output terminals equal in number to said a detector input terminals of said state detector and operatively connected thereto, said controller having a plurality of output signals present thereon;
• a wide-band analog multiplexer receiving said output control signals on separate multiplexer input terminals, equal in number to the plurality of said output control signals from said controller, for mapping the plurality of possible states of said PCM signal into a preemphasizer signal of adjustable and variable amplitude for each of said possible states, having said preemphasized signal as an output signal thereof;
• a clock generating a 2X clock signal derived from and operating at twice a frequency of a clock signal of said PCM signal, operatively sending a 2X clock signal to both said controller and said multiplexer for timing and synchronizing said mapping of said PCM signal;
• a plurality of adjustments for the PCM state level, one level for each of said possible states, operatively connected to said multiplexer for compensating for frequency dependent attenuation attendant to a fixed transmission line;
• and
• said preemphasizer signal mapped from the PCM signal, thereupon operatively connected to the input of a buffer amplifier, output of the buffer amplifier operatively connected to the input of the transmission line, output of the transmission line operatively connected to a receiver, comprising a wide-band amplifier and a threshold detector thereof, the receiver producing as its output a replication of the PCM serial input signal, said preemphasizer reducing the bit error rate during the transmission of the PCM input signal.