Magnetron does not lend itself to pulse-compression. To achieve narrow range resolution it must transmit short pulses. For given peak-power, antenna-gain and rotation-rate, increasing energy-on-target can be achieved by increasing the pulse repetition frequency (PRF), which is ordinarily limited by the specified unambiguous range. The proposed pulse-train waveform unties the two. Transmitting the first or second out of each pair of pulses of a uniform pulse-train, according to a periodic code, can extend the unambiguous range considerably beyond what the original PRF determines. In the receiver the envelope-detected return-pulses are correlated with a corresponding mismatched bipolar pulse-train. In addition to extending the unambiguous range, this detection concept performs Marcum's alternative integration scheme of "(signal + noise) - noise", exploiting its benefits. Successful coastal trials with modified civil marine magnetron radar are described.