Abstract: A method and apparatus for mitigating error in a received communications signal includes an error mitigator (35) of a communication unit (12) which receives and performs mitigation based on an error indication. In a first embodiment the error indication is a phase or non-used data symbol indicating error in ADPCM data, and mitigation includes changing certain nibble values to different predetermined values. In a second embodiment the error indication may include other parameters, e.g., a CRC frame error indicator, and an error estimator (34) determines a level of corruption in the ADPCM data. The error mitigator (35) applies a predetermined set of replacement values based on the indicated level of corruption and the mitigated data is subsequently decoded in an ADPCM decoder (26).

Abstract: An audio ramping technique (200) reduces acoustic shock in radio (100) that has multiple operating modes each having a different nominal audio speaker level. The ramping technique (200) sets the audio speaker level to the same initial sound pressure level (SPL) (208) regardless of the mode of radio operation and then ramps the audio level (216) until either a user initiated control signal (212) is received or the audio level reaches a maximum threshold level (210).

Abstract: Noise in an ADPCM signal is muted or suppressed by modifying the magnitude of the ADPCM information during noisy conditions. In one method, the ADPCM data is changed to a predetermined magnitude value. In another method, the magnitude is reduced by a predetermined amount.

Abstract: The present invention comprises a method and apparatus for selecting one of at least two antennas (202, 204) in a communication unit (200) for use in a wireless communication system (100). A signal is received by a radio frequency receiver during a receiving period from one of the at least two antennas (202, 204) currently selected by an antenna switch (206), the signal transmitted in a digital communications format comprising a plurality of bits. The quality of the receive signal is determined by a switch diversity algorithm programmed into a microcomputer (212) that bases the decision to switch antennas on predetermined thresholds established for each of: a received signal strength indicator, a phase error signal, and a recovered clock signal.

Abstract: A method for providing two-way calling between first and second handsets (402, 404) using a base station (406) and a paging terminal (412). The method for making the call includes storing a base line phone number for each line within the base station (406). A communication link is established between the first handset (402) and the base station (406) and between the base station (406) and the paging terminal (412). The paging terminal (412) prompts the caller for information to be sent to the second handset and the caller responds by entering a sequence that allows the base station itself to forward the base line phone number and an alias code, representing the identification of the first handset, to the paging terminal (412). The paging terminal (412) then pages the second handset (404) with the base line phone number and the alias code.

Abstract: A nested digital phase lock loop (DPLL) circuit (400) provides center bit sampling for incoming recovered data (406). Included in the nested DPLL circuit (400) are a narrow bandwidth DPLL (402) and a wide bandwidth DPLL (404) which generate first (410) and second (428) recovered clock signals respectively. Initially the first recovered clock signal (410) is used to clock in the recovered data (406) until the narrowband DPLL (402) is stabilized. Once the narrowband DPLL (402) is stabilized, the second recovered clock signal (428) generated from the wideband DPLL (404) is switched in by a multiplexer (424). If for any reason the center bit sampled data becomes corrupted, a RESET occurs in the wideband loop (404) to zero out the phase shift of the second recovered clock signal (428) to match that of the narrow loop. Thus, when a RESET occurs, the wideband loop is tracking at exactly the same clock rate as the narrowband loop.

Abstract: The present invention comprises a method and apparatus for selecting one of at least two antennas (202, 204) in a communication unit (200) for use in a wireless communication system (100). A signal is received by a radio frequency receiver during a receiving period from one of the at least two antennas (202,204) currently selected by an antenna switch (206), the signal having a plurality of bits. The receiver is capable of determining the quality of the receive signal by determining if the incoming bits transition periods fall within a predetermined time window. If it is determined by the receiver that the quality of the receive signal is below a predetermined threshold the currently selected antenna (202 or 204) is switched. The currently selected antenna remains selected when the currently selected antenna has been selected within a predetermined amount of time.

Abstract: A base site (200) capable of being remotely calibrated includes a receiver (206) and transmitter (210). The base site (200) further includes a controller (208) for controlling the base site and for measuring a transmission parameter related to the received transmission message from handset (120). Once an update message is received from handset (120) controller (208) updates the operating parameter of the base site (200).

Abstract: A base site circuit (38) for operating in a communication system (10) having a plurality of base sites capable of allocating a communication channel for use by a communication unit (16) in response to a communication channel request from the communication unit. The base site circuit includes a receiver (34) that operates in a low sensitivity mode when there are no communication channel requests received, and that operates in a high sensitivity mode which is activated by a control signal. The base site further includes a transmitter (34) which is activated by the control signal and a control circuit (32) coupled to both the receiver and the transmitter, for controlling the receiver and the transmitter. The control circuit (32) provides the control signal to the transmitter and to the receiver, in response to a communication channel request.

Abstract: A method for re-establishing a communication link that has been lost between a portable unit (406) and a fixed unit or base station (402) provides for a way of quickly re-establishing the lost communication link, on the previously used RF channel. The method is begun by transmitting a link re-establishment code word (900) using MUX 1 after determining that synchronization has been lost (502) for a predetermined period of time (504). This is followed by automatically switching the portable unit (406) from MUX 1 to MUX 3 communication protocol. Followed by re-establishing communication (re-establish synchronization) between the portable (406) and base station (402) in MUX 3 and switching the two communication devices (402 and 406) back to MUX 1 after the communication link has been re-established. The same steps can be followed by base site (402) if it had been the first to detect loss of the communication link.

Abstract: A base station allocates radio channels to radio telephone handsets in a second generation cordless telephone (CT2) communication systems by scanning each channel in a first band, and scanning each channel in a second band to measure an RSS level for each channel scanned. The base station scans the second band at a rate that is substantially faster than the rate at which it scans the first band. If a link request is received on a first channel within the first band, from a calling radio telephone, the base station determines whether the first channel has an RSS level above a predetermined threshold. If the RSS level of the first channel is above the threshold, and the calling radio telephone handset is capable of operating on the second band, the base station re-assigns a second channel, that is within the second band, to the calling radio telephone handset.

Abstract: A method and apparatus for choosing the most optimum communication channel in a system (100) having a plurality of communication channels provides for reduced interference and increased system capacity. By establishing a set of threshold levels and comparing these threshold levels to receive signal strength level measurements for each of the communication channels, a communication device originating a call can be guaranteed of establishing communication using the communication channel with the least chance of being affected by interference or of affecting other channels already in use.