A waveform adaptive
transmitter that conditions and / or modulates the phase, frequency, bandwidth, amplitude and / or attenuation of ultra-
wideband (UWB) pulses. The
transmitter confines or band-limits UWB signals within spectral limits for use in communication, positioning, and / or
radar applications. One embodiment comprises a low-level UWB source (e.g., an
impulse generator or time-gated oscillator (fixed or
voltage-controlled)), a waveform adapter (e.g., digital or analog filter,
pulse shaper, and / or
voltage variable attenuator), a power
amplifier, and an antenna to radiate a band-limited and / or modulated UWB or
wideband signals. In a special case where the oscillator has
zero frequency and outputs a
DC bias, a low-level
impulse generator impulse-excites a bandpass filter to produce an UWB
signal having an adjustable
center frequency and desired bandwidth based on a characteristic of the filter. In another embodiment, a low-level impulse
signal is approximated by a time-gated continuous-wave oscillator to produce an extremely wide bandwidth pulse with deterministic
center frequency and bandwidth characteristics. The UWB
signal may be modulated to carry multi-
megabit per second
digital data, or may be used in
object detection or for
ranging applications. Activation of the power
amplifier may be time-gated in
cadence with the UWB source thereby to reduce inter-pulse
power consumption. The UWB
transmitter is capable of extremely high pulse repetition frequencies (PRFs) and data rates in the hundreds of megabits per second or more,
frequency agility on a pulse-to-pulse basis allowing frequency hopping if desired, and
extensibility from below HF to
millimeter wave frequencies.