The paper describes a transistorized digital system for improving the signal/noise ratio of a search radar, by correlating the responses from several successive transmitted radar pulses. The main emphasis in the paper is on the circuit techniques employed.The radar information is first quantized into 2 levels of amplitude (‘0’ and ‘1’) and then into 1024 range elements each of ¼ nautical mile, i.e. 3.09 microsec. The correlation is achieved by counting the ‘1’s stored at each range for a number of consecutive radar p.r.f. periods and deciding whether or not the results are significant. The criteria chosen for this should enable the system to have an overall bearing accuracy somewhat better than the aerial beamwidth.Four separate correlation circuits are used, each handling every 4th range quantum. Thus the clock period is 12.4 microsec, which allows the use of standard magnetic-core-storage techniques.The machine is entirely transistorized and among the circuits described are (a) a precision 323 kc/s triggeredLCoscillator, (b) highspeed logical circuits using transistors and diodes, (c) a high-speed reversible counter and (d) parts of the storage system.