User`s manual

Page 22
5.10.1 Locked Standalone Behavior after PC Programming
After PC programming, the unit will power up in the locked state. As long as the
unit is never manually unlocked, it will power up in the locked state each time
power is cycled, and it will always run at the programmed settings.
Note that the INPUT LEVELS controls, INPUT SELECT, and headphone controls
are NOT programmed, and their controls remain fully functional even when the
unit is locked.
5.10.2 Unlocked Standalone Behavior after PC Programming
If a programmed unit is unlocked, it will continue to use the programmed settings
to whatever extent is sensible, but it will choose default values where necessary.
BW Changes
If only the BW (Bandwidth) setting is changed, then the filter behavior is
preserved as closely as possible. For the adaptive filters, three of the settings
are time-dependent and therefore scaled for bandwidth changes; these are the
filter length, the adapt rate, and the delay. When the bandwidth is changed, the
filter length and delay are changed proportionally, and the adapt rate is changed
inverse-proportionally. These scalings preserve filter behavior in relation to time
(if your delay at 10 kHz bandwidth was 5 ms, then your delay at 20 kHz
bandwidth should also be 5 ms, which now requires twice as many delay taps.)
These scalings are subject to the maximum and minimum possible settings for a
given bandwidth, so after a bandwidth change the settings may not be able to be
perfectly scaled. For instance, consider the case where the user programs a
maximum-length filter at 5 kHz bandwidth. If the unit is later unlocked and the
bandwidth is changed to 10 kHz, then the hardware will not be capable of
running twice as many taps to achieve the same effective filter duration. The unit
will run at its maximum filter length, but this will correspond to a shorter time in
milliseconds than the 5 kHz setting.
MONO/STEREO Changes
If the MONO/STEREO setting is changed, then again the filter behavior is
preserved as closely as possible. The 1CH adaptive filter, highpass filter, and
AGC will continue unchanged. However, if a reference canceller is running, the
maximum possible filter size will change. If the change is from stereo to mono,
the ceiling is actually increased, so the filter will continue running at the
programmed settings. If the change is from mono to stereo, however, the ceiling
is decreased and the length of the filter will be shortened as necessary.
Filter In/Out Changes
If the HPF or AGC setting is changed, then the filters will continue to run at their
programmed settings when they are “in,” and the filters will not be applied when