Aircraft detection before radar

[Bernie Brule]

Sent ot me by a good friend, these show amazing early devices created to detect aircraft from a distance.

[Bernie Brule]

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[bsmith56]

Oh wow, those are wacky. The 2nd and 3rd are my favorite... Wouldn't want someone to walk up and yell into one of those!

[byterock]

The have one at the CWM here in ottawa. Next time I am there Iwill grap a pic.

It seems you could yell in them as they were designed to tune in only a certain range of frequency some could even dial up the type of aircraft being sought after. A very primitive version of IFF