Peak Programme Meter

From IBS_FAQ

The Peak Programme Meter or PPM was originally developed by the BBC in the 1930s to monitor programme levels in radio. See the article on Metering in the Audio Compendium. Its specification is defined in an EBU Technical Document 3205.

BBC Scale PPM, courtesy Sifam Instruments Limited

PPMs may have mechanical (moving needle or pointer) or electrical (LEDs, LCD, VFD bargraph) displays. The mechanical type is characterised by a scale of white numbers on a black background. The "classic" BBC type has a scale from 1 to 7. Other broadcasters use different markings. See the Level Meter entry in these FAQs.