Pulse compression can be performed in noncoherent radars by using coded on-off keying (OOK). We show how any bipolar pulse-compression code (e.g., Barker) can be modified into unipolar OOK through Manchester coding. The resulted transmitted signal is a burst of dense subpulses, with pulse position modulation. In the receiver, the envelope-detected signal is aperiodically cross-correlated with a mismatched bipolar reference signal, yielding noncoherent integration with a low-sidelobe response. The concept can be used in simple radars where Doppler information is not required, in direct-detection laser radars and in ultrawideband (UWB) radars. Examples are given with bursts of 13 and 70 subpulses. Detection probabilities dependence on SNR is studied and compared with coherent processing.