Ambient Controller - ACC 501 - Manual (Page 16)

ACC501
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14
4.7 TUNE menu
This menu is used to tune (calibrate) other Clockit devices or for the Controller to calibrate
its reference oscillator to an external source.
The internal reference can be tuned to + - 10ppm with a resolution of 0.15 ppm per digit.
The tuning number DAC is shown on the display as well as recent tuning history. The tuning
process may have to be carried out several times if the tuning error is large (over 4ppm). The
tune values are estimated and the final value approached and met after up to 5 tune
processes.
Please note:
Always make sure that the time code output is turned off when tuning intern
or extern to avoid re-jamming a ACL202CT (up to firmware 8.2 it will rejam
every 5 seconds and thus cause false readings when the oscillator is not tuned
in yet) or crosstalk from the time code signal. If time code out is “on”, you will
get a warning message to turn it off first.
Press 1, Tune extern: The device connected can be tuned to the Controller.
Please make sure “tune signal out” is off, i.e. no wave symbol displayed next to “INT”
(see command # 3).
Press 1, Ref: The tuning reference signal of the external device is scanned and
compared to the internal clock. This is the most used mode as the controller is
master in most cases.
After scanning, the DAC value of the external device is read out and a new DAC or
“tune value” proposed. You will be asked to "confirm or edit new tune value". To
confirm, press "Enter". To change values, use the "Up" or "Down" Keys.
Repeat tuning until difference is not more than 0.1 ppm.
Press 2, Man: The tune steps can be entered manually. (1 DAC value
difference equals 0.15ppm)