Multiple frequency communication device

DETAILED DESCRIPTION The present invention encompasses a multiple band radio that can transmit and receive multiple frequency signals simultaneously.
The radio has a transmit path and a receive path.
The transmit path is comprised of a plurality of mixing paths.
Each mixing path has an amplifier whose input is coupled to the signal to be transmitted.
The output of each amplifier is coupled to an input of a mixer.
Another input of the mixers is coupled to an output of a frequency synthesizer.
The resulting signals from the mixers are summed by a summer.
The sum signal is input to a power amplifier which inputs the signal to an antenna to be radiated.
The receive path is comprised of an amplifier coupled to the antenna for amplifying received signals.
The output of the amplifier is input to a plurality of down converting paths.
Each down converting path has a mixer coupled to the amplified signal.
Another input of each mixer is coupled to the frequency synthesizers.
The resulting down converted signals are input to filters.
The output of each filters is input to a variable gain amplifier.
The amplified signals from the down converting paths are input to a summer.
The sum signal is then input to a common filter that generates a signal for use by the rest of the radio.
The multiple frequency synthesizers in combination with the multiple transmit and receive paths enables the apparatus of the present invention to transmit and receive on multiple frequencies simultaneously, communicate on one frequency while searching others, and to perform a soft hand-off between frequencies.
This alleviates the problem of the prior art of settling time of a frequency synthesizer since the frequency synthesizers do not have to change frequencies as rapidly and as frequently as previously required.
It also avoids an interruption in communications, as normally results from monitoring one frequency at a time.