Adaptive bandwidth, multi-channel digital modulation

An RF system constructed for spread spectrum operation, comprising:

• executable program instructions stored on a non-transitory computer readable medium;
• and
• a controller that accesses and executes the executable program instructions stored on the non-transitory computer readable medium to control system operation, such that when a bandwidth of an RF signal portion is less than 500 kHz, the controller divides a channel to form at least two sub-channels, each sub-channel having a bandwidth less than 500 kHz, sets the bandwidth of the RF signal portion to be substantially equal to the sub-channel bandwidth, modulates the RF signal portion in the at least two sub-channels, varies the modulation as a function of time, and causes transmission of the RF signal portion in the at least two sub-channels,
• wherein the controller varies the RF signal portion over time so that power spectral density is not greater than 8 dBm in any 3 kHz band during a time interval of continuous transmission,
• wherein the function of time includes time multiplexing, and
• wherein setting the bandwidth of the RF signal portion to be substantially equal to the sub-channel bandwidth includes reducing a bandwidth of a transceiver to be substantially equal to the bandwidth of the sub-channels.

A wireless product for wireless communication constructed for spread spectrum operation, comprising:

• executable program instructions stored on a non-transitory computer readable medium;
• and
• a controller that accesses and executes the executable program instructions stored on the non-transitory computer medium readable medium to control system operation, such that when a bandwidth of an RF signal portion is less than a channel bandwidth, the controller divides the channel to form at least two sub-channels, each sub-channel having a bandwidth less than 500 kHz, sets the bandwidth of the RF signal portion to be substantially equal to the sub-channel bandwidth, modulates the RF signal portion in the at least two sub-channels, varies the modulation as a function of time, and causes transmission of the RF signal portion in the at least two sub-channels,
• wherein the controller varies the RF signal portion over time so that power spectral density is not greater than 8 dBm in any 3 kHz band during a time interval of continuous transmission,
• wherein the function of time includes time multiplexing, and
• wherein setting the bandwidth of the RF signal portion to be substantially equal to the sub-channel bandwidth includes reducing a bandwidth of a transceiver to be substantially equal to the bandwidth of the sub-channels.

A method for operating a wireless system comprising the steps of:

• determining a bandwidth required for transmission of a baseband signal;
• when the bandwidth required for transmission of the baseband in a channel is less than 500 kHz, dividing the channel into N sub-channels, selecting sub-channel frequencies of a carrier signal for the N sub-channels, modulating the baseband signal in the N sub-channels, each sub-channel having a bandwidth less than 500 kHz, varying the modulation as a function of time, and transmitting the baseband signal on the sub-channel frequencies, where N is an integer greater than one;
• and
• controlling the RF signal portion over time so that power spectral density is not greater than 8 dBm in any 3 kHz band during a time interval of continuous transmission,
• wherein the step of selecting includes reducing a bandwidth of a transceiver transmitting the baseband signal to be substantially equal to the bandwidth of the sub-channels, and
• wherein the function of time includes time multiplexing.