Modulation frequency and orientation tuning of second-order mechanisms underlying the detection of modulation in local spatial-frequency information are assessed by using an oblique-masking paradigm. Stimuli were Gabor-filtered noise patterns in which the local carrier spatial frequency was modulated about an average value of 4.7 cycles per degree (cpd) according to sinusoidal function. Thresho...

The conventional frequency diversity array (FDA) can generate arcsine form of continuous direction modulation (DM) waveforms which automatically scan the entire space range. However, single waveform and time varying phase FDA cannot meet requirements practical security communication application scenarios. Thus, a new transmit technique, called (TFDM), is proposed to improve azimuth security. In...

Doppler effect plays a vital role and cannot be neglected for high velocity radars. When the velocity between the target and radar is very high compared to the velocity of transmitted waveform, then the received signal suffers Doppler distortion and will not match with the matched filter. Due to this, linear frequency modulation waveform suffers from a considerable signal loss. Use of hyperboli...

We report the characteristics of current induced frequency modulation (FM) for two continuous-wave quantum cascade lasers (QCLs) at 9.06 μm. Both the frequency tuning rate and the phase shift between intensity modulation and FM are measured at different modulation frequencies from 10 Hz to 200 kHz. The frequency tuning rate of the QCLs depends on both the modulation frequency and amplitude. The...