Radar Secrets Revealed - Newsreel Videos for Engineers
Half a century ago, radar was still a mystery to most people. Radio in general was still a mystery for that matter. Today, radio and radar are still mysteries to most people, it is just that today the devices are ubiquitous - even if the people do not realize what miracles of engineering they are. Radar played a crucial role in pushing back Axis forces during World War II. Not only did it afford advanced notice and estimation of air force sizes many miles in advance of their approaches, but it also warned of land and sea forces. Surprise attacks above the clouds or within fog and rain were no longer tactics that could be assumed to be successful.
In trademark form from the WWII era, this newsreel titled "Radar Secrets Revealed" presents a high level demonstration of how the early radars functioned, complete with motivational music and enthusiastic, deep-voiced narration. I almost felt an obligation to stand at attention while watching it.
As with any of the films of the era, if you are privy to the details of the featured technology, you have to be amazed at the ingenuity of the developers and the skill of the operators. Early radar scopes were not the nifty large, round, color-coded displays we are familiar with today. Rather, they were small, basic cathode ray tubes (CRTs - remember them?), with a low-tech trace that plotted signal strength against the time scale. Operators would compare signal strength to the distance (time) and try to discern whether it represents a single large craft or multiple smaller craft; i.e., a bomber with a couple escorts, or an entire squadron of attack planes. The relatively low frequencies where the radars operated limited spatial resolution.
Modern radars are able to exploit many techniques for target optimization, including frequency agility, target tracking, and sophisticated signal processing that in many cases can identify the type of object being detected.