Abstract: The telephone system of the present invention is realized by a unique dynamic time slice architecture which allows for up to 480 transfers of data. A dual port RAM is utilized in which are stored two pages of data, containing time slice information identifying the sending and receiving devices for each time slice slot within the frame. The time slice configuration can be easily modified to accommodate a change in the current system configuration, for example, a handset connecting or disconnecting from a central office line, or the initiation of a conference call. The time slice configuration is modified by updating the second page and swapping the two pages at the beginning of the next frame so that the time slice controller accesses the second page and the configurations specified therein. Thus the system can be updated and controlled in real time with no delays to the users of the telephone system.

Abstract: A phase locked loop is augmented by an additional mechanism which permits the closed loop cancellation of the frequency perturbing effects on the oscillator by repetitive signals well beyond the bandwidth of the phase locked loop. Successful implementation requires that the perturbations be repetitive and that the perturbing signal be available as a reference, conditions which are commonly the case. This compound loop can effectively cancel perturbations whose dynamics change only slowly compared to the speed of the added synchronous loop.

Abstract: A comparator-based digital data separator is modified to operate in noisy signal environments, with signals characterized by extreme duty cycle. A demodulated binary signal is passed through a pair of diodes which produce a slack voltage. The signal is then passed through an RC low-pass filter, and is finally connected to an input of the comparator as the reference voltage. The low-pass filter, which provides the D.C. averaged voltage to the threshold comparator, receives current into its own input only when the demodulated signal excursions exceed the existing threshold voltage by more than the slack voltage. Consequently, assuming there exists a sufficiently large recovered signal, the voltage being used as the decision threshold will remain separated from the recovered signal excursion peaks by at least the amount of slack voltage. In so doing, the binary data separation is given improved noise immunity and reduced sensitivity to duty cycle variations.

Abstract: The telephone system of the present invention is realized by a unique dynamic time slice architecture which allows for up to 480 transfers of data. A dual port RAM is utilized in which are stored two pages of data, containing time slice information identifying the sending and receiving devices for each time slice slot within the frame. The time slice configuration can be easily modified to accommodate a change in the current system configuration, for example, a handset connecting or disconnecting from a central office line, or the initiation of a conference call. The time slice configuration is modified by updating the second page and swapping the two pages at the beginning of the next frame so that the time slice controller accesses the second page and the configurations specified therein. Thus the system can be updated and controlled in real time with no delays to the users of the telephone system.

Abstract: An improved proximal cable-less communications system using at least two receivers is described. The system is significantly improved by eliminating the sidetone which can occur in full duplex systems. Components are placed in the receivers, between the mixer components and the components which detect the information encoded in the signal at the intermediate frequency, which function to cancel out the detrimental affect of those signals containing information derived from the modulation of the local oscillator of the receiver device.

Abstract: In the secure radio transmission system of the present invention the sign bit for each byte of audio digital data is scrambled to generate a scrambled sign bit. By altering the sign bit, the resultant sound is significantly affected regardless of the amplitude range of the source audio. A key is stored in each authorized radio transmitter/receiver telephone. The key is used to select the bits of the digital voice data to be transmitted which are used to scramble the sign bit. The selected bits of the voice data are then used to scramble the sign bit and the voice data with the scrambled sign bit are transmitted to the receiving device. The receiving device executes the reverse process wherein the receiving device selects predetermined bits of the received voice data according to the key stored in the receiving device and scrambles the scrambled sign bit using the same algorithm in accordance with the data bits selected.

Abstract: A hybrid network including a four port directional coupler with the terminating impedance of one port being intentionally mismatched with the characteristic impedance of the coupler. Such an intentionally mismatched port will cause the transfer signal of an input signal from an adjacent port to be reflected to another adjacent port and to be combined with the transfer signal of a second input signal, which is from an input port not isolated from the first input port. Placing the two input ports adjacent to one another also allows one input to radiate out of another adjacent input port. Alternately, a hybrid network is provided including a four port directional coupler with all ports properly terminated at the characteristic impedance of the coupler. An external combiner for signals from one port and its adjacent port allows the combining of two input transfer signals generated from the other two non-isolated input ports.