
DSP-19 User Manual
Page 10 of 24
DSP19_MAN_A
Frequency (DIP Switches 1 and 2)
When loops are installed sufficiently far apart, any two loops will not interfere with each other. However, if two
loops are fairly close together, say two to four feet apart, the inductive fields may couple together and may
interact causing intermittent false detections. The main variables for inductive coupling are loop size, distance
between loops, and the loop frequency. To aid in mitigating inductive coupling, each DSP-19 unit comes with two
frequency switches. They are binary coded allowing up to four different operating frequencies.
If there are suspicions that loops are interacting, change one of the
detector’s frequency settings so that their
inherent frequencies are sufficiently different as to no longer interact. If the loops are the same size and number
of turns, setting one detector to high and the other detector to low will provide the maximum frequency
separation.
DIP Switch
Frequency
1
2
OFF
OFF
High
Factory Default
OFF
ON
Medium Low
ON
OFF
Medium High
ON
ON
Low
Loop / Magnetometer (DIP Switch 3)
The DSP-19 is capable of operating with either a standard inductive loop in the presence mode or the new mini-
loop (magnetometer) in the pulse on entry mode. In the magnetometer mode of operation the detector will only
hold a detection for 2 seconds. Therefore, if a vehicle stays over the sensor for more than 2 seconds it may
generate additional pulses for the same vehicle. The factory default is the inductive loop mode.
DIP
Switch 8
Loop Type
OFF
Inductive Loop
Factory Default
ON
Mini-Loop
NOTE: The magnetometer mode of operation can not be used if the detector will function as a safety loop as
the mini-loop is not capable of presence detection.
Normal / Extended Presence (DIP Switch 4)
After four minutes of continuous detection, the detector will begin to slowly retune the detector with the goal of
tuning out the vehicle that stalled or parked on the loop over a relatively long time. For those instances where a
longer hold period is desired, extended presence is available.
The time it takes to complete the retuning process is dependent on the strength of the call being induced by the
vehicle. In the Normal Presence mode (DIP switch 4 off) this usually takes between 15 minutes and about 4 hours.
In the Extended Presence mode (DIP switch 4 on) the retuning process may take considerably longer, perhaps
over a day or so.