Spectralink Corporation

Spectralink Corproation

Gary L Bliss

Graeme S Paterson

Bruce M Holland

Mark R Boyd

Bryan Edwards

A wireless telephone using an RF receiver unit and an RF transmitter unit and having a removable headset, the telephone and headset particularly suitable for applications where the RF transmitter unit is switched on and off at a frequency less than twenty kilohertz. The wireless telephone is coupled to the headset using a conventional stereo plug and jack. A headset detect logic signal is generated from the speaker audio line. A microphone current detect logic signal is generated from the microphone audio line. A digital logic circuit, preferably including a microprocessor, monitors the headset detect logic signal and microphone current detect logic signals and generates a programmed response to the headset detect logic signal. The programmed response reduces audible noise to the headset user, generates a ringing signal on the speaker audio line when an incoming call is received and allows the headset user to answer incoming calls, and place outgoing calls while touching only the headset. The wireless telephone and headset include circuitry to reject RF noise and circuitry to attenuate RF noise passed into the wireless telephone by a long multi-conductor wire coupling the headset to the wireless telephone.

Headset for hands-free wireless telephone

A method and system for verifying that each remote cell unit in a cellular phone system is operational. The system and method in accordance with the present invention use the receiver equipment of each cell unit to listen to or monitor transmissions by other cell units. Each cell unit is independently placed in a listen verification mode in which it measures communication quality of other cell units that it can hear. The selected cell unit reports the communication quality results to a master control unit. The master control unit stores the result information to allow a comparison of communication quality over time. If communication quality has degraded over time by a significant amount, the master control unit signals an alarm. In another aspect of the present invention, the listen verification mode can be used during installation of the cellular system to verify performance of the system and adjust the system for optimal performance.

Listen verification method and system for cellular phones

A method, system, and apparatus for communication and handoff in a cellular phone system in which candidate cell units which can support communication with a mobile phone are identified. Neighbor cell units which have recently supported communication with the mobile phone are also identified. Handoff threshold values for each candidate cell are determined based on the existing communication quality and whether the candidate cell is also a neighbor cell such that the handoff threshold is higher when the candidate cell is a neighbor cell. A decision to handoff is made when the improvement offered by candidate cell is greater than the handoff threshold.

Handoff method for indoor cellular phone system

A unique method and system is disclosed for generating digital clock timing in a receiver for use in direct-sequence spread-spectrum digital communication systems wherein spread data is delivered from a transmitter to a receiver. The present invention provides at the transmitter frames of digital communication data with each frame having a plurality of time slots and with each time slot having a plurality of digital bits. The transmitter utilizes direct-sequence spreading codes for spreading the digital bits in the time frame. The direct sequence spreading codes each have the same fixed sequence length of M chips and, furthermore, the number of chips per bit CB to spread each digital bit is constant and fully aligned with each digital bit. The ration of M:CB is an integer and the ratio of time of each time slot to the time of the M chips also equals an integer. The spread frames of digital information are despread at the receiver with receiver provided identical direct-sequence codes. The digital clock timing is generated from the receiver's pseudo random sequence generator. Bit timing equals CB*8, nibble timing equals 4*CB, and byte timing equals CB.

Digital clock timing generation in a spread-spectrum digital

A system and method of driect-sequence spread-spectrum TDMA (or TDD) digital communication, wherein acquisition and tracking occurs for a plurality of frames having a predetermined number of time slots. One of the predetermined number of time slots in each frame is assigned for acquisition purposes and carries acquisition and sync digital information. The remaining time slots in each frame have assigned header bytes for tracking purposes. The assigned acquisition time slot is spread with an acquisition direct-sequence spreading code. The remaining time slots are spread with a communication direct-sequence spreading code. During acquisition, the signal strength in each successive time slot for each spread frame is measured for a given number of time frames. The peak is located within the given number of time frames through a major acquistion sweep and a refinement sweep. The major acquisition sweep and refinement acquisition sweep locate the frame and time slot boundaries of the transmitted signal. Once acquired, tracking occurs during the header bytes of each successive remaining time slot. Acquisition, tracking and demodulation of the digital data is performed with the same circuitry.

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Westminster, CO, United States of America

Gary L Bliss