System for the transmission of signals by pulse code modulation

Claim 1

A system for the transmission in a given transmission band, continuously varying information signals by means of companded delta modulation, said system being of the type comprising a transmitter and a receiver, the transmitter comprising a delta modulation and a receiver, the transmitter comprising a delta modulation compressor; a ringing generator for generating a ringing signal having a frequency within said transmission band, being transmitted to said receiver; a clock pulse generator, a pulse code modulator connected to said clock pulse generator for producing output pulses, means for transmitting the output pulses to the cooperating receiver and which are also applied to a local receiver provided with an integrating network, said network producing a comparison signal; a difference producer, said comparison signal and said information signal being applied thereto, said difference producer producing a difference signal controlling the pulse code modulator; said receiver comprising a deltamoduation expander, a pulse pattern analyzer and a ringing signal detector, said delTamodulation compressor and said expander each comprising a dynamic control device which is controlled by a dynamic control voltage generated by said pulse pattern analyzer, said pulse pattern analyzer being provided with a shift register coupled to the output of the pulse code modulator and comprising at least three shift register elements whose contents is shifted in synchronism with the pulses originating from the clock pulse generator, the improvement wherein the ringing signal generator in the transmitter comprises a pulse pattern generator controlled by said clock pulse generator for generating a periodic pulse pattern within which the pulses assume a first and a second of two binary values, occur in an irregular alternation and coincide with the successive pulses generated by the clock pulse generator, said pulse pattern generator being constituted by a cascade arrangement of at least one modulo-2-adder and at least one additional shift register element connected to the output of one of the shift register elements of the shift register associated with said pulse pattern analyzer in the transmitter, a switching device having a shift register input terminal coupled to the output of the pulse code modulator and a pulse pattern generator input terminal connected to the output of the cascade arrangement, the input of said pulse pattern generator being connected to said switching device said output of the cascade arrangement being likewise connected to a second input of the modulo-2-adder, the pulses to be transmitted in said transmitter being derived from one of the shift register elements associated with both the said shift register of said pulse pattern analyzer and with said pulse pattern generator, the transmitted signals in the reciever of said transmission system being applied to the ringing signal detector which generates a series of pulses in accordance with the received ringing signal.

Claim 2

A system for the transmission in a given transmission band, continuously varying information signals by means of companded delta modulation, said system being of the type comprising a transmitter and a receiver, the transmitter comprising a delta modulation and a receiver, the transmitter comprising a delta modulation compressor; a ringing generator for generating a ringing signal having a frequency within said transmission band, being transmitted to said receiver; a clock pulse generator, a pulse code modulator connected to said clock pulse generator for producing output pulses, means for transmitting the output pulses to the cooperating receiver and which are also applied to a local receiver provided with an integrating network, said network producing a comparison signal; a difference producer, said comparison signal and said information signal being applied thereto, said difference producer producing a difference signal controlling the pulse code modulator; said receiver comprising a deltamoduation expander, a pulse pattern analyzer and a ringing signal detector, said delTamodulation compressor and said expander each comprising a dynamic control device which is controlled by a dynamic control voltage generated by said pulse pattern analyzer, said pulse pattern analyzer being provided with a shift register coupled to the output of the pulse code modulator and comprising at least three shift register elements whose contents is shifted in synchronism with the pulses originating from the clock pulse generator, the improvement wherein the ringing signal generator in the transmitter comprises a pulse pattern generator controlled by said clock pulse generator for generating a periodic pulse pattern within which the pulses assume a first and a second of two binary values, occur in an irregular alternation and coincide with the successive pulses generated by the clock pulse generator, said pulse pattern generator being constituted by a cascade arrangement of at least one modulo-2-adder and at least one additional shift register element connected to the output of one of the shift register elements of the shift register associated with said pulse pattern analyzer in the transmitter, a switching device having a shift register input terminal coupled to the output of the pulse code modulator and a pulse pattern generator input terminal connected to the output of the cascade arrangement, the input of said pulse pattern generator being connected to said switching device said output of the cascade arrangement being likewise connected to a second input of the modulo-2-adder, the pulses to be transmitted in said transmitter being derived from one of the shift register elements associated with both the said shift register of said pulse pattern analyzer and with said pulse pattern generator, the transmitted signals in the reciever of said transmission system being applied to the ringing signal detector which generates a series of pulses in accordance with the received ringing signal.