Matches 251 - 300 out of 359 < 1 2 3 4 5 6 7 8 >
Match Document Document Title
4751729 Ring code recorder  
A telephone accessory for detecting and recording and optionally displaying the number of rings sounded by a telephone which is ringing is disclosed. The accessory includes detecting means to...
4747131 Dial tone detector  
A method for detecting the presence of a predetermined dual tone signal on a conductor including steps of performing threshold detection on the conductor for detecting the presence of signals...
4737984 Dial tone detector  
A dial tone detector is provided possessing a precise definition of a passband. In one example, virtually infinite roll off is achieved in less than 5 hertz. An incoming analog signal of at least a...
4712233 Monolithic telephone subscriber line interface circuit  
The present invention is an improved subscriber line interface circuit which allows fast detection of an off-hook signal in the presence of a ringing signal during an answer mode while also...
4696031 Signal detection and discrimination using waveform peak factor  
Apparatus and method for detecting and discriminating among various signals indicative of progress while making a telephone connection. A particular waveform parameter known as peak factor is...
4689760 Digital tone decoder and method of decoding tones using linear prediction coding  
An all digital feature based pattern recognition tone detection system distinguishes one or more tones from speech or other background noise and provides extremely reliable, low cost DTMF tone...
4686699 Call progress monitor for a computer telephone interface  
A call progress monitor for a computer telephone interface system. Energy detectors are connected to receive signals from a telephone line. A bandpass filter is connected to the telephone line,...
4686696 Transmission line signal sensing circuit employing means for conserving power, especially for use with a telephone disconnect circuit, and associated method  
An apparatus and method for sensing a predetermined tone signal transmitted on a transmission line, such as a telephone transmission line, and for generating a signal indicating the presence of the...
4677665 Method and apparatus for electronically detecting speech and tone  
A method and apparatus for detecting the presence of speech telecommunications tones on a communication line includes a voltage divider for ranging signals received from a communication line, a...
4675898 Single tone telephone receiver  
A single-tone receiver for a device which only needs simple data which can be encoded in the seven or eight single tones which can be generated by an ordinary pushbutton telephone is provided. A...
4674115 Programmable telephone switcher  
The programmable telephone screening device routes an incoming call to a selected telephone device, depending on preestablished device priorities and upon access codes dialed by the caller. The...
4659877 Verbal computer terminal system  
A telephonic data communications system provides verbal communication of data in remote computer systems. The major components of the systems are a plurality of channels and a data processor. Each...
4653093 Frequency selective ringer circuit  
A frequency selective ringer circuit which utilizes a constant current source in conjunction with an array of resistors and switches for developing a frequency selective window with which to detect...
4640989 Communications unit for executive work station  
A communications unit for an executive workstation which provides a switching arrangement for interconnecting voice and data lines with a computer and a telephone instrument. The communications...
4639552 Apparatus for converting a standard telephone to an unlisted number telephone  
The apparatus of this invention is a system which is attached to a standard telephone instrument at a receiving station. When a call comes from a transmitting station through a switching station,...
4639553 Call signal detecting device  
In a facsimile communication system, a call signal detecting device for identifying call signals which are received over a network. Both an unsounding call signal and a sounding call signal are...
4636590 Method and apparatus for converting frequency signals representing characters to binary code  
A frequency analyzing circuit for converting multifrequencies representing characters into selected signals for writing data into a plurality of channels adapted to effect enabling and disabling...
4634811 Call screening system  
A call screening system to be added onto and used with a PBX or Centrex telephone system having an attendant answering console. The call screening system enables incoming calls for various...
4626629 Digital multifrequency signal receiver  
A digital multifrequency receiver circuit of the type employed between telephone system central offices, arranged to provide a faster response to received signals by processing the received signal...
4626628 Telephone line circuit having time-shared DTMF receivers  
The invention provides a circuit and method for the time-sharing of a DTMF tone receiver. A DTMF receiver has its input terminal connected to a common output terminal of a pair of transmission...
4618742 Method and apparatus for decoding audiofrequency information sent through rotary dialing  
The present invention provides a method and apparatus for decoding audiofrequency information sent through rotary dialing from a calling phone set or through any other phone dialing generating...
4614909 Apparatus for identifying digital multi-frequency signals  
An apparatus for identifying multi-frequency signals, the received signals being processed in selective receivers after having passed through a digital bandpass filter. The input signal to the...
4611325 DTMF receiver sense and control arrangement  
The DTMF receiver sense and control arrangement collects and stores multiple customer originated data for determination of customer identification, validity and billing purposes. This arrangement...
4611098 Coded telephone access system  
A telephone access system provides to the caller connection to an output upon receipt of a coded signal from the caller. Units are connected in sequence for receipt of each member of the coded...
4604755 Feed forward dual channel automatic level control for dual tone multi-frequency receivers  
A dual tone multi-frequency receiver having an improved automatic level control is described. The level control is performed after the filtering operation instead of before the filtering operation...
4602131 Touch tone decoder  
A programmable tone decoder for standard bell system DTMF tone pairs is presented which comprises an integrated DTMF receiver and a means for programming a sequence of digits which are compared to...
4599495 Apparatus for multifrequency signalling tone detection  
Apparatus for detection of the presence of signalling tones in telephony is provided wherein the output levels for four band-pass filters in the VF band are processed by means of logic circuits to...
4570235 Digital receiver of multifrequency signals with frequency recognition device  
The present invention relates to a digital frequency recognition device for a receiver of multifrequency PCM signals, and consists essentially in forming characteristic values V(f i ) for each...
4568802 VF Line fault isolation and diagnostic apparatus and method  
An addressed transmission line test system having bidirectional input and output lines with through connections in a quiescent state which is capable of recognizing properly addressed signals at...
4567328 Energy detection circuit for a facsimile system controller  
Disclosed is an energy detection circuit for use in a facsimile system autodialer/controller. The circuit monitors a telephone line and nulls out transmit tones leaving only receive signals. The...
4559416 Telephone line activity monitor  
A line activity monitor for a plurality of telephone lines operates to record a log for each call indicative of the time at which the telephone line entered each of a plurality of states during the...
4544808 Telephone indicator  
An indicator for use with a multiline telephone, which displays the status of both a local and called telephone set. The status indicator is comprised of a first indicator enclosed within a second...
4540851 Remote control device using telephone circuit of electric apparatus  
A remote control device using a telephone circuit of an electric apparatus to remote-control the electric apparatus from a remote location. The electric apparatus is held operative by a loop means...
4540855 Detecting signals within a passband on a telephone line  
An improved combination of a hardware and digital signal processing filter for detecting pick-up of a telephone call, solely through audio information on the telephone line. The apparatus employs a...
4539692 Digital automatic gain control circuit for PCM signals  
A digital tone detector circuit characterizes the received PCM encoded signals as one of a plurality of call progress tones, voice signals or silence. The PCM signal is linearized and normalized to...
4536614 Supervision and dial pulse detection circuit for a telephone subscriber line  
A floating battery feed circuit employs a single primary winding, a pulse width control circuit and a peak detector for providing a controlled current to a subscriber loop. The amplitude of the...
4536619 Ringing signal detection circuit  
A ringing signal detection circuit for a subscriber's apparatus which is connected to a telephone office line together with an attached telephone set. An incoming signal on the telephone line is...
4536618 Telephone line interface  
A telephone line interface for direct connect telephone line connections characterized by low cost and minimal package size requirements. The telephone line interface utilizes a small signal...
4534041 Digital circuit for determining the envelope frequency of PCM encoded call progress tones in a telephone system  
A digital tone detector circuit characterizes the received PCM encoded signals as one of a plurality of call progress tones, voice signals or silence. The PCM signal is linearized and normalized to...
4528664 Call progress signal monitor and method for telephone systems  
A call progress signal monitor includes a translation circuit for generating data signals indicative of predetermined signal characteristics in a TDM PCM signal channel. A processor implemented...
4527015 Security listening system  
A security listening system activated by and transmitting over telephone lines to allow listening for sounds at a remote location over a standard telephone line using a standard telephone...
4521647 Tone detection system and method  
Tone detection apparatus and a corresponding method is disclosed. The improved tone detector and method is for use in a preferred embodiment in a voice message answering system to provide for...
4519072 Answer supervision system  
This disclosure depicts a telecommunication supervision system, such as a supervisory progress signal detector, for evaluating the status of an input signal from a communication channel. An output...
4510601 Digital frequency receiver  
A digital frequency receiver connected to a processor for the recognition of multifrequency code signals received in signalling time slots and transmitted to the receiver in digital form by at...
4502049 Universal signalling tone receiver  
An inexpensive universal telephone signalling tone receiver employs switched capacitor filters to provide selective tone reception in accordance with pre-selected clock signal frequencies. The...
4489438 Audio response system  
The system receives line signals including tone coded information request messages from a telephone line and transmits synthesized human voice response messages along the same line. The system...
4479188 Digital detector for a multi-frequency code in an analog signal  
This disclosure concerns a system for digitally detecting one or more of a plurality of fixed frequencies in an analog signal according to a correlation method, the fixed frequencies occurring in a...
RE31643 Hold circuit for telephone system  
A single master unit hold circuit which can be utilized for a single or a group of telephone instruments connected to a common telephone line. A single latching circuit is coupled to the telephone...
4460806 Dual tone multifrequency and dial pulse receiver  
A dual tone multifrequency and dial pulse receiver that receives 8000 digital data words per second, each of the data words including eight PCM bits representing the analog signal transmitted from...
4442319 Telephone accessible appliance control system  
A control system is disclosed for switching on or off appliances or other electrical devices at predetermined or preselected times. The timing or sequencing of switching on or switching off any...
Matches 251 - 300 out of 359 < 1 2 3 4 5 6 7 8 >