The function of an LPI radar is to prevent it's interception by an electronic support receiver. This objective is generally achived through the use of a radar waveform that is mismatched to those waveform for which an electronic support receiver is tuned. Consequently, a conventional electronic supprot receiver can only detect an LPI radar at very short range.

The LPI radar transmit a low power intra pulse modulated waveform so that the range of detected target can be determined with a good range resolution. This modulation may be phase or frequency modulated, or pseudo-random, noise like modulation. A typical LPI radar has a switchable pulse-power output of up to 1 watt. A conventional pulse radar need at least 10 Kw for a similar detection range of target. This allow the LPI radar to achieve a processing gain, with respect to an electronic support receiver, that is equal to the time-bandwidth product of the radar waveform. This processing gain allow the LPI radar and fourth-root dependence of the two way travel of electromagnetic wave, to overcome the range-squared advantage of the electronic support receiver in conventional situations.