초록 ▼

A transmitter includes a modulator, a power amplifier and a controller to reduce the effects of phase cancellation in a simulcast paging system. The modulator is digitally configurable to modulate according to at least two protocols. The controller configures the modulator for a first protocol and p

A transmitter includes a modulator, a power amplifier and a controller to reduce the effects of phase cancellation in a simulcast paging system. The modulator is digitally configurable to modulate according to at least two protocols. The controller configures the modulator for a first protocol and provides to the modulator a signal to be broadcast. The modulator then modulates this signal according to the first protocol and causes the modulator to introduce a random frequency offset within a frequency range predetermined to optimally reduce phase cancellation for the first protocol. When the controller provides a signal to be broadcast according to a second protocol, the controller reconfigures the modulator for the second protocol. In addition the controller causes the modulator to introduce a random frequency offset within a predetermined range to optimally reduce phase cancellation for the second protocol. Because the controller can change the frequency offset on a protocol basis, phase cancellation errors can be optimally reduced for both protocols. In addition, the transmitter can easily be reconfigured to support new protocols as they are developed without changing the existing transmitter hardware. Still further, the randomly changing offsets dispense with the need to maintain records of the offsets for each transmitter in the simulcast paging system.

대표청구항 ▼

[ The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:] [1.] A radio frequency transmitter for use in a simulcast environment, said transmitter comprising:an input terminal coupled to receive an input signal;a modulator having an input lead

[ The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:] [1.] A radio frequency transmitter for use in a simulcast environment, said transmitter comprising:an input terminal coupled to receive an input signal;a modulator having an input lead and an output lead, said input lead of said modulator coupled to said input terminal, said modulator being configured to perform a modulation process on a carrier signal using a signal received at said input lead of said modulator, wherein said modulator is configurable to introduce a first frequency offset, a second frequency offset and a third frequency offset to said carrier signal, said first and third frequency offsets being different from each other;a power amplifier having an input lead coupled to said output lead of said modulator, said power amplifier configured to output an amplified signal dependent on a signal received at said input lead of said power amplifier; anda controller coupled to said modulator, said controller being configured to selectively configure said modulator to introduce said first frequency offset or said third frequency offset to said carrier signal when said transmitter is transmitting signals according to a first protocol, and wherein said controller is confirmed to selectively configure said modulator to introduce said second frequency offset when said transmitter is transmitting signals according to a second protocol, said first frequency offset being predetermined and optimized to minimize the phase cancellation data reception errors for signals transmitted according to said first protocol, and said second frequency offset being predetermined and optimized to minimize the phase cancellation data reception errors for signals transmitted according to said second protocol.