To sort out the radar return from various objects according to doppler frequency, the receiver output is applied to a bank of narrowband filters. If sorting by range is also desired, a separate bank is provided for each range increment. The width of the passband of a narrowband filter is primarily determined by the filter's integration time but is increased by losses. So that return will not be lost when a target straddles two filters, the passbands are made to overlap. So that only one line of a target's spectrum will fall within the band of frequencies bracketed by the bank, the passband of the bank is made no greater than the PRF.