
DSP-22-2 User Manual
Page 9 of 25
DSP-22-2_MAN_E
Channel 1
–
Normal Sensitivity / Sensitivity Boost (DIP Switch 3)
Each channel of the detector has a user selectable feature that increases the sensitivity of the detector after initial
detection. This feature is most often used to allow a detector to have a lower starting sensitivity and then increase
it after a vehicle has been detected. This is useful in situations where high-bed tractor-trailer vehicles will be
passing over the loop. With this feature the detector may be able to detect the high-bed portion of the vehicle
without having to be overly sensitive and susceptible to false detections. NOTE: If detection of high-bed tractor-
trailers is required, correctly sized loops must be used.
DIP
Switch 3
Function
OFF
Channel 1 Normal Sensitivity
ON
Channel 1 Sensitivity Boost
Channel 1
–
Frequency (S3 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. 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.
If there are suspicions that loops are interacting, change one of the detector’s frequency settings for the suspect
channel 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 channel to high and the other channel to low will provide the maximum
frequency separation.
DIP Switch
Frequency
1
2
OFF
OFF
Channel 1 High
OFF
ON
Channel 1 Medium High
ON
OFF
Channel 1 Medium Low
ON
ON
Channel 1 Low
Channel 2
–
Enable / Disable (DIP Switch 10)
Channel 2 has a DIP switch to enable or disable the channel. For those situations where channel 2 is not needed,
the channel can be disabled by setting DIP switch 10 to the OFF position which will turn off the channel 2 LED and
turn off the channel 2 output. The factory default is enabled (DIP switch 10 ON).
Channel 2
–
Sensitivity (DIP Switches 4 and 5)
Channel 1 has four possible sensitivity levels. In most situations the sensitivity setting medium high (DIP switch 1
OFF and DIP switch 2 ON) will work effectively. For those situations where this setting is not sensitive enough,