Quindar tones were used by NASA, for example in the Apollo missions, to enable and disable the radio transmitters on the ground, in a push-to-talk-like system operated by the CapCom. These are iconic and recognizable sounds present in original recordings as well as movies etc.
There are two tones, each lasting for 250 ms. The first, higher one (2525 Hz) enables the transmitter, the second, lower one (2475 Hz) disables it after speaking. This sample contains the higher one.
The file has been optimized for size, which is why it's not using a higher sample rate than required for reproducing the sound. Also, the file is slightly longer than 250 ms in order to end near zero after a complete sine phase. It can be looped, if you want to.
Generated from scratch in Audacity.
Type
Wave (.wav)
Duration
0:00.251
File size
5.5 KB
Sample rate
11025.0 Hz
Bit depth
16 bit
Channels
Mono
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