Abstract: Some embodiments of an emergency radio frequency (RF) repeater system includes a remotely adjustable conveyance characteristic between multiple antenna nodes and a repeater. Optionally, the characteristic may be adjusted independently for each node. Optionally, adjusting the conveyance characteristic after installation of system hardware simplifies system installation and/or facilitates precise balancing of conveyance and/or improves system performance. A conductive riser cable optionally carries multiple channels, for example including an RF signal and/or a communication/control signal and/or data and/or electrical power between system components. For example, the riser may carry a command to the adjustable coupler, to adjust a coupling factor between an antenna node and the riser. Optionally the riser includes a coaxial cable and/or is fire resistant. Optionally, portable transmitter location is estimated from received signal characteristics measured at nodes at different locations.

Abstract: Some embodiments of an emergency radio frequency (RF) repeater system includes a remotely adjustable conveyance characteristic between multiple antenna nodes and a repeater. Optionally, the characteristic may be adjusted independently for each node. Optionally, adjusting the conveyance characteristic after installation of system hardware simplifies system installation and/or facilitates precise balancing of conveyance and/or improves system performance. A conductive riser cable optionally carries multiple channels, for example including an RF signal and/or a communication/control signal and/or data and/or electrical power between system components. For example, the riser may carry a command to the adjustable coupler, to adjust a coupling factor between an antenna node and the riser. Optionally the riser includes a coaxial cable and/or is fire resistant. Optionally, portable transmitter location is estimated from received signal characteristics measured at nodes at different locations.

Abstract: A terminal (200) and method for operation thereof for use in a wireless communication system (100), the terminal including a plurality of antennas (215, 235, 255) and a plurality of receiver chains (217, 237, 257) each including an associated one of the antennas, the terminal being operable to receive a signal including a plurality of time divided portions including a first portion (303) and a second portion (304), characterized in that the terminal is operable in a manner such each of the plurality of receiver chains is active when the first portion of the signal is being received and at least one of the receiver chains is inactive when the second portion of the signal is being received.

Abstract: A terminal (200) and method for operation thereof for use in a wireless communication system (100), the terminal including a plurality of antennas (215, 235, 255) and a plurality of receiver chains (217, 237, 257) each including an associated one of the antennas, the terminal being operable to receive a signal including a plurality of time divided portions including a first portion (303) and a second portion (304), characterised in that the terminal is operable in a manner such each of the plurality of receiver chains is active when the first portion of the signal is being received and at least one of the receiver chains is inactive when the second portion of the signal is being received.

Abstract: A frequency synthesiser circuit for use in wireless communications including a phase locked loop including a VCO (voltage controlled oscillator), wherein the synthesiser circuit includes a further oscillator which in operation is a free running oscillator at a frequency higher than the VCO and a mixer connected to receive input signals from the VCO and from the further oscillator and to combine such signals. Also described is a wireless communications transmitter or receiver incorporating the frequency synthesiser circuit.

Abstract: A demodulator (100), includes an input signal path (101) for delivering an RF input signal, a local oscillator (111), connected to the input signal path a first mixer (107) for mixing an output reference signal from the local oscillator with an RF input signal to produce an in-phase component of the input received signal, a phase shifter (113), connected to the input signal path a second mixer (109) for mixing an output reference signal from the local oscillator via the phase shifter with the RF input signal to produce a quadrature component of the RF input signal; and an output signal processor (119) for producing an output demodulated information signal by producing a function of the in-phase and quadrature components; and wherein the demodulator is periodically operable in a quadrature phase error determination mode.

Abstract: A circuit and method for reducing local oscillator frequency transmission in a homodyne, or direct conversion, radio transceiver using I/Q modulation/demodulation minimizes local oscillator leakage to the antenna and its subsequent reception by the receiver by interfacing I/Q input signals to the modulator in a controlled manner so as to increase isolation during reception by presenting high impedance states to the I/Q modulator input terminals during reception thereby nulling the carrier during reception.

Abstract: A circuit and method for reducing local oscillator frequency transmission in a homodyne, or direct conversion, radio transceiver using I/Q modulation/demodulation minimizes local oscillator leakage to the antenna and its subsequent reception by the receiver by interfacing I/Q input signals to the modulator in a controlled manner so as to increase isolation during reception by presenting high impedance states to the I/Q modulator input terminals during reception thereby nulling the carrier during reception.

Abstract: A circuit for use in a radio transceiver (100), the circuit comprising modulator means (114) for receiving digital signals (IT,QT) for application in combination to control the phase of a carrier to produce a transmission signal for transmission by the transceiver during a transmission mode; demodulator means (126) for demodulating a received signal during a reception mode to recover from the received signal digital signals (IR,QR) representing components of the phase thereof; wherein the demodulator means is coupled to the modulator means to receive therefrom in operation during the reception mode a reference signal indicating the phase of the transmission signal whereby there can be recognized from the received signal which is demodulated the phase applied in the transmission mode thereby to facilitate separation of signal from noise.

Abstract: An antenna is described having a generally elongate radiating part (10) and a reflective plane (11)juxtaposed and generally parallel to the elongate radiating part. The radiating part has a free end (15), a ground connection (13) remote from the free end and a feed connection (16) between the free end and the ground connection. The ground connection is mounted on the reflective plane (11), giving electrical ground connection and mechanical support. A method of manufacture of an antenna is also described involving breaking off an extension portion to suit the required frequency of operation.

Abstract: A communications system (10) comprising a base station (12) for controlling a control channel signal and a plurality of traffic channels and a communications device (17) responsive to the control channel signal (16) and receptive to the plurality of traffic channels. The communications device comprises a tuneable filter (48), having an adjustable characteristic, which substantially filters all but a selected traffic channel of the plurality of traffic channels. The communications device further comprises a tuning circuit (24, 38, 40, 44, 46, 52) for adjusting the filter characteristic. The tuning circuit (24, 38, 40, 44, 46, 52) uses the control channel signal (16) as an accurate central frequency (F.sub.o) for a passband of the tuneable filter (48) and adjusts the filter characteristic to substantially a minimum insertion loss at the accurate central frequency, thereby substantially optimizing selectivity and sensitivity for the communications device (17).

Abstract: FIGS. 2 and 3 illustrate communications devices (30) that are operable in both a radio dispatch mode and a telephone interconnect mode. To mitigate the problem of a relatively high level audio signal from being unexpected broadcast from an ear-piece of the device (30) when the ear-piece is proximally located with an ear of a user of the device, the communications device (30) is arranged to ensure that, at least during an initial period of operation in either of the two operating modes, audio signals of relatively high level do not originate from the ear-piece, thereby preventing a change in audio power output from the ear-piece that may potentially cause damage to the hearing of a user of the radio communications device.

Abstract: A phase lock loop comprises a phase detector (11), a frequency adjuster (13, 15) for adjusting and cancelling phase differences detected by said phase detector (11) and responsive thereto, and a filter (12) coupled between said phase comparator (11) and said frequency adjuster (13, 15). The phase lock loop has a first and a second operating mode (FIG. 5). Operation in said first operating mode is used to establish an initial lock acquisition to a desired output signal f.sub.out and uses a relatively wide bandwidth within the filter (12). At a transition from said first operating mode to said second operating mode, initial lock acquisition is lost, whereafter said second operating mode is used to re-establish final lock acquisition to the desired output frequency f.sub.out. A gain adjuster (15) commences the controlled adjustment of the gain of said phase comparator (11) at a transition between said first and said second operating modes.