Fig. 3 | Nature Communications

Fig. 3

From: Partially coherent radar unties range resolution from bandwidth limitations

Fig. 3

Simulation results and schematics. a Schematic representation of the partially coherent radar operation. A continuous wave signal is generated with N phase jumps that are randomly produced to provide a constant (controllable) coherence time τm (time between phase switching events). Each pulse has a random phase (\({{\varphi }}_{\boldsymbol{n}}\) or vector \({\bar{\varphi }}\)), which is kept constant for the pulse duration. The signal reflects from a target that is situated at a distance related to the delay, attenuated by a factor A and received along with additive white noise. The output of the receiver is mixed with the still transmitting signal and averaged over the duration of the transmission time \({{N\tau }}_{{m}}\) (the averaging starts at the same time as the signal begins transmitting). The result of the integration is multiplied by the coherence time τm. The result is termed the cross-correlation and denoted as \({\tilde{ C}}_{\boldsymbol{m}}\). The process is repeated for M coherence points (lengths of constant coherence). M and N define the performances of the system (range resolution and range accuracy). Monte Carlo simulations in high SNR (30 dB) scenarios: b Cross-correlation as a function of coherence length for a single target located 25  away, drawn for different carrier frequencies using Eq. (4). c Cross-correlation for two targets located at coherence lengths of 23.6 and 25.4  corresponding to Eq. (9). d Cross-correlation of a single target moving at different velocities along the line of sight, corresponding to Eq. (14)

Back to article page