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Headroom Overhead or Margin in a electronics system


headroom is the amount by which linear signal capabilities exceed actual signal level. In digital audio, headroom is defined as the amount that full scale (FS) exceeds the permitted maximum level (PML) in dB (decibels).

Typically, nominal (alignment) level is 0 dB, corresponding to an analog sine wave voltage of +4 dBu, corresponding to an RMS voltage of 1.23 V, or an amplitude of 1.74 V. In the digital realm, alignment level is −18 dBFS. An alternative EBU recommendation allows 24 dB of headroom, which might be used for 24-bit master recordings, where it is useful to allow more room for unexpected peaks during live recording.

Headroom (also called Overhead or Margin) The number of decibels by which a system exceeds the

minimum defined requirements. The benefit of headroom is that it reduces the bit-error rate (BER),

and provides a performance ‘safety net’ to help ensure that current and future high speed

applications will run at peak accuracy, efficiency and through-put.IT IS Used in conjunction with

series pass regulators, and is the difference between the input and output voltages.
how much power you have available above and beyond what you are using at any particular point in time. Assume you have a 100 watt amp and you are using 50 watts; that means you have 3dB of headroom. That’s not much. It’s recommended that you have 6 to 10dB of available headroom so that you won’t eat it all up on transients; that means having four to ten times the power available than your average power draw. Knowing how much your average draw is without measuring equipment isn’t possible, but if you get distortion on hard transients then whatever you’ve got isn’t enough.

Attenuation-to-crosstalk ratio (ACR), also called headroom, is the difference, expressed as a figure in decibels (dB), between the signal attenuation produced by a wire or cable transmission medium and the near-end crosstalk (NEXT).
In order for a signal to be received with an acceptable bit error rate, the attenuation and the crosstalk must both be minimized. In practice, the attenuation depends on the length and gauge of the wire or cable transmission medium, and is a fixed quantity. However, crosstalk can be reduced by ensuring that twisted-pair wiring is tightly twisted and is not crushed, and by ensuring that connectors between wire and cable media are properly rated and installed. Crosstalk can sometimes be reduced by replacing unshielded twisted pair (UTP) wiring with shielded twisted pair (STP) wiring.

The ACR is a quantitative indicator of how much stronger the attenuated signal is than the crosstalk at the destination (receiving) end of a communications circuit. The ACR figure must be at least several decibels for proper performance. If the ACR is not large enough, errors will be frequent. In many cases, even a small improvement in ACR can cause a dramatic reduction in the bit error rate.

In a digital and analog audio systems, headroom is the amount by which linear signal capabilities exceed actual signal level. In digital audio, headroom is defined as the amount that full scale (FS) exceeds the permitted maximum level (PML) in dB (decibels).

The European Broadcasting Union (EBU) specifies a PML of 9 dB below 0 dBFS (-9 dBFS), thus giving 9 dB of headroom. In analog audio, headroom can stand for low-level signal capabilities as well as for the amount of extra power reserve available within the power amplifiers that drive the loudspeakers.

Alignment level is an ‘anchor’ point, a reference level which exists throughout the system or broadcast chain, though it may have different actual voltage levels at different points in the analog chain.

Typically, nominal (alignment) level is 0 dB, corresponding to an analog sine wave voltage of +4 dBu, corresponding to an RMS voltage of 1.23 V, or an amplitude of 1.74 V. In the digital realm, alignment level is −18 dBFS. An alternative EBU recommendation allows 24 dB of headroom, which might be used for 24-bit master recordings, where it is useful to allow more room for unexpected peaks during live recording.





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