Pulse train carrier-less modulator using SAW filters
View Patent ↗A system and method of carrier-less modulation is described in this disclosure that uses SAW filters as a modulator in addition to their conventional use as filters for band limiting an UWB system. This system and method is primarily designed to be used with any integer cycle, ultra-wide band or impulse type modulation and more particularly is designed to work with a method of modulation named xG Flash Signaling. This technique exploits the impulse response of the SAW filter by exciting the filter with a narrow pulse train producing a carrier-less impulse radio system with limited bandwidth, low average power, but high peak power.
1. A modulator used to generate a pulse train carrier-less impulse modulated Radio Frequency signal from a data source comprising:
A Band Pass Filter having a fundamental frequency;
a pulse train generator in electrical communication with a data source;
said pulse train generator capable of producing a pulse train of selected pulse numbers, pulse periods, and pulse amplitudes indicating a modulation event when receiving data from said data source;
an input impedance matching network;
said input impedance matching network in electrical communication with said pulse train generator and said Band Pass Filter;
said input impedance matching network configured such that said input impedance matching network transforms the output impedance of said pulse train generator to the input impedance of said Band Pass Filter such that a pulse train indicating a modulation event generated by said pulse train generator is supplied to said Band Pass Filter causing said Band Pass Filter to ring at the fundamental frequency of said Band Pass Filter generating a carrier-less impulse modulated Radio Frequency signal at the output of said Band Pass Filter;
an output impedance matching network; and,
said output impedance matching network in electrical communication with the output of said Band Pass Filter and configured such that said output impedance matching network transforms the output impedance of said Band Pass Filter to match input impedances of other stages of a radio system used to broadcast said pulse train carrier-less impulse modulated Radio Frequency signal.
2. The modulator of claim 1 wherein said Band Pass Filter is a Surface Acoustic Wave Filter.
3. A method of generating a pulse train carrier-less impulse modulated Radio Frequency signal comprising:
Generating a pulse train of selected pulse numbers, pulse periods, and pulse amplitudes indicating a modulation event using a pulse train generator in electrical communication with and receiving a digital signal from a data source;
transforming the impedance of said pulse train generator to match the input impedance of a Band Pass Filter having a fundamental frequency;
applying said pulse train to the input of said Band Pass Filter such that said Band Pass Filter rings at the fundamental frequency and a pulse train carrier-less impulse modulated Radio Frequency signal is generated at the output of said Band Pass Filter; and,
transforming the impedance of the output of said Band Pass Filter to match input impedances of other stages of a radio system used to broadcast said pulse train carrier-less impulse modulated Radio Frequency signal.
4. The method of generating a pulse train carrier-less impulse modulated Radio Frequency signal of claim 3 wherein said Band Pass Filter is a Surface Acoustic Wave Filter.