公开(公告)号：DE2308634A1

公开(公告)日：1973-08-30

申请号：DE2308634

申请日：1973-02-21

Applicant: MOTOROLA INC

Inventor： SCHWENDEMAN ROBERT JOHN ,  D AMICO THOMAS VICTOR ,  PETRAKOS NICHOLAS

IPC: H04W88/18 ,  H04Q7/00

Abstract: A paging system includes a transmitter for transmitting a carrier frequency signal modulated by subaudible tone signals in response to audible tone signals coupled to the transmitter from a remote point. An encoder at the remote point develops the audible tone signals which are coupled to the transmitter over standard telephone channels. At the transmitter, a circuit converts the audible tone signals to first square wave signals having the same frequency as the audible tone signals. A divider circuit divides the first square wave signals by a particular number to develop second square wave signals having the same frequency as the desired subaudible tone signals. The second square wave signals are coupled to a low pass filter which attenuates all frequencies above the subaudible tone signal frequencies and develops a sine wave having the desired subaudible tone frequency.

公开(公告)号：CA978261A

公开(公告)日：1975-11-18

申请号：CA162373

申请日：1973-01-30

Applicant: MOTOROLA INC

Inventor： SCHWENDEMAN ROBERT J ,  D AMICO THOMAS V ,  PETRAKOS NICHOLAS

IPC: H04W88/18

Abstract: A paging system includes a transmitter for transmitting a carrier frequency signal modulated by subaudible tone signals in response to audible tone signals coupled to the transmitter from a remote point. An encoder at the remote point develops the audible tone signals which are coupled to the transmitter over standard telephone channels. At the transmitter, a circuit converts the audible tone signals to first square wave signals having the same frequency as the audible tone signals. A divider circuit divides the first square wave signals by a particular number to develop second square wave signals having the same frequency as the desired subaudible tone signals. The second square wave signals are coupled to a low pass filter which attenuates all frequencies above the subaudible tone signal frequencies and develops a sine wave having the desired subaudible tone frequency.

公开(公告)号：AU5215973A

公开(公告)日：1973-11-15

申请号：AU5215973

申请日：1973-02-14

Applicant: MOTOROLA INC

Inventor： SCHWENDEMAN ROBERT J ,  AMICO THOMAS V D ,  PETRAKOS NICHOLAS

IPC: H04W88/18 ,  H04M9/00 ,  H04Q7/00

Abstract: A paging system includes a transmitter for transmitting a carrier frequency signal modulated by subaudible tone signals in response to audible tone signals coupled to the transmitter from a remote point. An encoder at the remote point develops the audible tone signals which are coupled to the transmitter over standard telephone channels. At the transmitter, a circuit converts the audible tone signals to first square wave signals having the same frequency as the audible tone signals. A divider circuit divides the first square wave signals by a particular number to develop second square wave signals having the same frequency as the desired subaudible tone signals. The second square wave signals are coupled to a low pass filter which attenuates all frequencies above the subaudible tone signal frequencies and develops a sine wave having the desired subaudible tone frequency.