SMPTE/DIN IMD The most common IMD measurement. SMPTE standard RP120-1994 and DIN standard 45403 are similar. Both specify a two-sine wave test signal consisting of a large amplitude low-frequency tone linearly mixed with a high-frequency tone at ¼ the amplitude of the low frequency tone. SMPTE specifies 60 Hz and 7 kHz mixed 4:1. The DIN specification allows several choices in both frequencies, with
250 Hz and 8 kHz being the most common.
ITU-R (
old CCIF)
, Twin-Tone, or
Difference-Tone IMD, or
Difference Frequency Distortion (DFD) All these terms refer to the same test and are used interchangeably. The test specifies two equal-amplitude closely spaced high frequency signals. Common test tones are 19 kHz and 20 kHz for full audio bandwidth units. While all combinations of IM distortion products are possible,
this test usually measures only the low-frequency second-order product falling at f2-f1, i.e., at 1 kHz. The principal standard is IEC 60268-3.
Это дву цитаты вот отсюда
https://aes.org/publications/par/i/#IM -
https://aes.org/wp-content/uploads/2021/05/AES-Logo-R.png
Токо вы ж с оксаной метролухи, умнее всех, мировых стандартов не признаёте.