The phase term of the output of the matched filter is determined by the difference between the bistatic transmitter-target-receiver range and the direct transmitter-receiver range.
The technique can also be usefully applied to wider vertically directed transmitter beams to determine the mean angle of arrival.
By assuming M direct paths from transmitters to a specific receiver and N reflection paths to the same receiver, the total power of the received optical signals, P T, is thereby calculated as: P T = ∑ i M P d, i + ∑ j N P r, j (5).
Up to now, such fish have been tracked remotely using two principal methods: direct positioning of transmitters by Argos polar-orbiting satellites, and satellite relay of tag-derived light-level data for post hoc track reconstruction.
A beamforming scheme based on the channel estimates obtained from contaminated pilots results in interferences directed to those transmitters using the same pilot [48].
Because the direct signature (from transmitter to receiver directly) is far stronger than the moving target signature, using the envelope detector or phase detector, we can extract the signature of moving target (beat frequency).
For a wireless link where the direct path between transmitter and receiver has length d, the n th Fresnel zone is the region inside an ellipsoid with circular cross-section.
As for the synchronization, the easy to realize and commonly used strategy is using an additional antenna to receive the direct pulses from transmitter, and then using these directly received pulses as a reference for range compression.
This model is a compromise between semi-empirical models only considering the "direct" ray between transmitter Tx and receiver Rx (e.g., Motley-Keenan multi-wall model [29]) and ray-tracing models where hundreds of rays and their interactions with the environment are investigated.
The well-known Motley-Keenan multi-wall model [29] in contrast to our model, calculates the loss experienced along the direct ray between transmitter and receiver: it is indeed clear that an increasing distance and a higher number of walls between Tx and Rx (first two factors of Equation (1)) lead to a higher path loss, but this model is not realistic for all situations.
