Abstract: In the broadcast band having a plurality of channels allocated therein, by using high-side injection and low-side injection as described herein, the noise introduced into the channel by the local oscillator signal can be minimized. The local oscillator signal in combination with the intermediate frequency determines the frequency of the channel signal being produced by the transmitter. The selected high-or low-side injection determines whether the bulk of the power is introduced into the combination frequency signal (i.e., the channel) above or below the local oscillator frequency, thereby moving the local oscillator frequency outside the broadcast band. The non-selected sideband is even further outside broadcast band.

Abstract: In order to reduce the noise components in a multiplexed communication system, noise components generally referred to as splatter that from the rapid transition between the transmitting state and the non-transmitting state, this power transition in the transmitted signal is provided with a ramped envelope. In the preferred embodiment, the ramped power transition is the result of a ramped enabling signal applied to the power amplifier generating the transmitted signal. The use of a ramped power transition reduces the noise introduced as a result of an abrupt power transition. In addition, the transmitted signal is provided with a preamble so that no data is transmitted during the transition period.