Display Ranges and Display Formats
This section describes all the ranges and their formats in detail.
First we would like to add some comments on pulse probes. We decided to display the unit »pulses per
«, because other representations like »cps«, »Imp/s«, or »c/s« are not in common
international use and would take much of the LCD’s space. Large pulse rates are represented as »ks
where »k« stands for the prefix »kilo«. 1 ks
means 1000 pulses per second. This is not quite correct,
means »per centimetre«, that is 1/(cm), ks
would mean »per kilosecond«, that is
would mean 1 pulse per 1000 seconds. Strictly speaking one would have to represent
1000 pulses per second as one pulse per millisecond, that is 1 ms
. However, we thought that this
representation would be more difficult to understand, especially for users not very familiar with
mathematical notations. Therefore we decided to use ks
as a unit for large pulse rates. The risk, that ks
will be wrongly read as 1/(ks), is low, because firstly kiloseconds are not a common unit, and secondly
the 6150AD represents the letter »s« as a capital letter: »kS
«. Conclusion: If the 6150AD indicates
, this means 1000 pulses per second.
There are eight dose rate ranges that cover two decades each. Two adjacent ranges always overlap by one
decade. Although it has a total of four digits, the display contains at most three significant digits
(non-zero digits). Those three digits are the lower three ones in the lower decade of a range, and the upper
three ones in the upper decade. This allows the decimal point to maintain its position within a range,
which makes reading easier.
The levels to switch up to the next range and to switch down to the previous range are not equal, they
have a ratio of 10:2 (also known as »hysteresis«). For example, when dose rates exceeds 100 µSv/h, the
6150AD switches to the next range, but will not switch back to the lower range until dose rate drops
below 20 µSv/h. If those two levels were equal, and dose rate would be close to that level, the instrument
would keep switching between the two ranges, which would make the instrument quite difficult to read.
The 6150AD automatically selects the lowest and the highest range for each detector (internal tube or
probe). The table on the next page shows the eight dose rate ranges and their assignment to the individual
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