
DSP-22-2 User Manual
Page 11 of 25
DSP-22-2_MAN_E
When Channel 2 is in the pulse mode of operation, the pulse generated by the output will be 250 milliseconds
long. There are slight differences between the probe pulse mode (DIP switch 8 ON) and the pulse mode (DIP
switch 7 ON). So, they will be explained individually.
If DIP switch 7 is ON and DIP switch 8 is OFF, the way the pulse mode operates is commonly referred to as Pulse
on Entry. In Pulse on Entry mode, the Channel 2 Output will pulse when a vehicle first enters the loop. The output
will not pulse again until the vehicle has vacated the loop. After the pulse has been output, the Detect 2 LED will
flicker (a very fast flash that is not at full brightness). This is a visual indication that the pulse has already been
output but the loop is still occupied, and no further pulses can be output until the loop is no longer occupied.
If DIP switch 8 is ON, the way the pulse mode operates is commonly referred to as Pulse with a 1 second retune.
In this mode, the Channel 2 Output will pulse when a vehicle first enters the loop. The channel will then wait 1
seconds and retune (reset) that channel. In the probe mode of operation, the detector will only hold a detection
for 1 second. Therefore, if a vehicle stays over the probe for more than 1 second it may generate additional pulses
for the same vehicle.
DIP
Switch 7
Function
OFF
Channel 2 Presence Mode
ON
Channel 2 Pulse Mode
Channel 2
–
Loop / Probe (DIP Switch 8)
The DSP-22-2 is capable of operating with either a standard inductive loop or the new mini-loop (magnetometer).
As usual, the inductive loop operates in both presence and pulse modes. However, the mini-loop (magnetometer)
can only operate in pulse mode and will automatically override any settings to the contrary. The factory default
is the inductive loop mode.
DIP
Switch 8
Sensor Type
OFF
Channel 2 Inductive Loop
ON
Channel 2 Free-Exit Probe
NOTE:
In the probe mode of operation the Channel 2 will only hold a detection for 1 second. Therefore, if a vehicle
stays over the sensor for more than 1 second it may generate additional pulses for the same vehicle.
Channel 2
–
Frequency (S3 DIP Switches 3 and 4)
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. Loops that are connected to the same DSP-22-2 detector can not interfere
with each other, as the detector will only turn on one of the loops at any point in time (this is referred to as
scanning). To aid in mitigating inductive coupling, each DSP-22-2 unit comes with two frequency switches for each
channel. They are binary coded allowing up to four different operating frequencies.