| 摘要 |
<p>Low -frequency interference components produced by a time division multiple access (TDMA) portable radio transmitter that might potentially interfere with devices sensitive to low frequencies, such as cardiac pacemakers, are substantially reduced. In those TDMA frames in which a protocol calls for either a burst of an information-bearing signal to not be transmitted in its designated time slot, or transmitted at a reduced power level, or for a shorter duration, an interference-compensating signal at a compensation frequency other than the transmitter's carrier frequency is transmitted. The interference-compensating signal is transmitted in the time slot in which the transmitter normally transmits the burst at a power level equal to the power level of the burst. If the protocol calls for a reduced power burst, the interference-compensating signal is transmitted within an adjacent time slot at a power level that compensates for the reduced burst power level. If the protocol calls for a shorter burst length, the interference-compensating signal is transmitted within the same time slot to extend the burst to the length of the time slot. The interference caused by the compensating signal is substantially the same as would have been caused by the information-bearing signal, so that the interference pattern remains unchanged. This eliminates low-frequency variations in the interference pattern. <IMAGE></p> |
