1. A method for determining angle and frequency of transmission from a transmitter, the method comprising: receiving during a current coherent dwell, sensor data comprising a first plurality of samples, the first plurality of samples comprising N samples collected at a sensor array comprising D sensors, a spacing between a pair of adjacent sensors being Δ; selecting a second plurality of M samples from the first plurality of samples, M being less than N times D; determining angle and frequency of transmission of a transmitter located at a range R and an angle θ relative to a plane of the sensor array and transmitting a signal at a frequency f, by minimizing using a solver, an l 1 norm of a product of: (i) a phase functional representing a mapping between time-distance and angle-frequency representations of sensor samples and (ii) the second plurality of M samples, the time-distance representation being based on the spacing Δ, and the angle-frequency representation being based on θ and f.