304UM0001 Rev 00
PD160 Enhanced Series User Manual
Page: 16 of 39
The noise sub-menu shows the instantaneous noise measured over
a short period of time. Due to the sporadic nature of noise, it is
difficult to determine the difference between true noise and faster
moving vehicles which produce large detect levels. As such, the max
value may show a larger number as a function of some vehicle detect
properties. Simply reset the statistics and monitor the max without
vehicles passing over the loop to get a better indication.
The signal sub-menu shows the percentage of the maximum signal
strength able to be processed by the microprocessor. While the
signal should reflect 100% across the inductance range, it is normal
for it to start to drop slightly at very low inductances towards the edge
of the range. If the feeder cable is too long or the series resistance is
too high, the signal level will be seen to drop further. The detector
does not allow a loop to tune if the signal strength is below 35%.
The channel count sub-menu shows the number of vehicle detects as
a function of sensitivity and presence. It should be noted to prevent
confusion that this is NOT necessarily the same as the number of
relay output events, depending on your output settings. For example,
fault outputs would yield a different total output count from the
number of vehicles detected.
Where the current value is shown (as opposed to max and min) and the channel is in fault, the current
fault will be displayed. The possible fault displays are:
Short circuit
The loop is showing short circuit properties. These include, but are not limited
to, very low signal level or very high frequency.
Open circuit
The loop is showing open circuit properties. This is seen at very low
frequencies and in some cases at low signal level. From frequency shift
setting 5 and upwards, an open circuit does not oscillate and looks like a
short circuit. Manually select frequency 1 to confirm an open circuit condition.
Signal
In trying to retune, the loop signal level was found to be too low to measure
reliably. This could be due to, but is not limited to, very low inductance or high
feeder cable resistance.
Noise
In trying to retune, the detector found large movements determined to be
noise. This could be due to, but is not limited to, crosstalk from other loops or
vehicles driving over the loop during tuning.
Drift
In trying to retune, the detector found unidirectional movements (either up or
down in frequency) which exceed the sensitivity. This could be due to start-up
conditions but is also noted at higher sensitivity levels at the extreme high and
low inductances.
