EMX D - Tek PD -182 Vehicle Single Loop Detectors With Loop Frequency Display
PD182 Single Channel Vehicle Loop Detector allows for detection of metalic objects entering into the
field formed around the detection loop. We have designed PD-182 with the following objectives in mind:
1. Fully compatible with most popular 11 pin loop detector of market.
2. Diagnostic capabilities using LED, without external accessories.
3. Frequency display using LED to show real frequency working between 50Khz to 200Khz
4. Level Meter using LED to show in real time any detection from loop field.
5. More options like four frequency, eight sensitivity level, four signal filtering.
6. Loop isolation protection for lightning and transient damage.
7. Selectable permanent presence (to eliminate premature barrier/gate closure)
8. High quality components from Germany and Japan for high stability of detection
9. DETECT STOP function allows detection only when a vehicle has come to a complete stop on the loop.
10.All parameter can be adjust by software, and have more range to select such as the sensitivity and
frequency.
Specifications
Tuning: Automatic
Detection type: Presence/Pulse
Presence time: Adjustable in 4 steps (default: 11 min, 33 min, 55 min, infinity)
Pulse duration: 100 ms / 500 ms
Signal filtering: Adjustable in 4 steps (LOW, MED-LOW, MED-HI, HI)
Loop inductance: 20 uH – 1000 uH
Frequency range: 40 kHz – 140 kHz
Frequency selection: 4 combinations (LOW, MED-LOW, MED-HI, HI)
Sensitivity: 0.001 % - 0.5% digital in 8 steps
Detection speed: <10 ms (at LOW filtering stage and at loop frequency of 40 kHz)
Startup time: ~ 1 sec
Power supply: 220 VAC
Current consumption: ~ 0.035 A
Temperature range: -35°C – 120°C
Sensor protection: Galvanic isolation + gas discharge tube for lightning protection
Frequency Selection
Frequency of loop oscillator is primarily defined by the wire loop geometry and the number of windings. In order to slightly change the frequency of the loop oscillator there are two DIP switches DIP 1 and DIP 2. Loop oscillator frequency is displayed on yellow status LED after the device is reset. LED will blink in steps of 10 kHz. Example: if LED blinks 7 times it means that the frequency of loop is from 70 kHz to 79 kHz. Sensor should be reset after making any frequency adjustments!
Sensitivity Levels
When metallic object approaches the loop it changes its inductance which in turn changes the oscillator frequency. Oscillator frequency is internally represented by number that has range of 1 to 255. Smaller metallic objects (for example bicycles) make smaller changes to this number while larger objects (such as cars) make bigger changes. Sensitivity has two thresholds: detect threshold which represents the number that the object must change inside the MCU in order to declare detection, and Undetect threshold which represents the number that is required in order for it to remain in "detect" state. Undetect threshold is always smaller than the detection threshold and is usually 1/2 or 1/3 of the detection threshold.
Filtering Levels
Filtering is very important part of sensors internal operation. There are 4 filtering levels that can be selected and fine-tuned using this PC configurator app. Parameters that define filtering levels are:
1 - Mean value (average) calculation defines how many consequent measurements of loop frequency oscillator are required in order to produce one clean measurement.
This option directly influences the speed of detection: larger number = slower detection speed but higher stability; lower number = faster detection but smaller
stability.
2 - Detection filter defines how many successive detections are required in order to declare a real detection. This option prevents false detections (glitches).
3 - Speed of positive drift compensation is an important filtering parameter which defines the rate at which the sensor will adjust baseline frequency to the new frequency that changes in the opposite direction of change that occurs when metallic object approach the loop. This parameter defines the time required to recalibrate the baseline value when metallic object moves away from the loop. Value entered here is multiplied by 17 and expressed in milliseconds.
4 - Speed of negative drift compensation is the most important filtering parameter which defines the rate at which the sensor will adjust baseline frequency to the new frequency that changes in the same direction of change that occurs when metallic object approach the loop. Lower number for this parameter means that the sensor will faster compensate for the frequency drift but it also means that vehicles must arrive over the loop faster than the sensor compensates for that change. Value entered here is multiplied by 17 and expressed in milliseconds.
Note: Number used for negative drift compensation can also be used for positive drift compensation. Parameter used for positive drift compensation should be equal to or smaller than the number used for negative drift compensation.
There are 4 levels of filtering that can be programmed into the sensor and later selected by the appropriate DIP switches.
Hold Time
If this option (DIP 9) is selected to infinity, the "detect" state will remain as long as there is a vehicle above the loop. One possible problem of using this option is that in "detect" state sensor electronics do not track and compensate for frequency drift. In extreme situations this can either cause false detect when vehicle finally leaves the loop (in this case device must be reset manually), or somewhat slower response time of further detections until device completes positive frequency drift compensation.
Drift compensation during detection
The drift compensation during detection is used when you expect a vehicle to be parked over the loop entire night, so that natural changes can be compensated when morning comes and vehicle leaves the loop. This option is useful if the oscillator is not stable ( change temperature or have electric noise near from wires ).
Detect Stop
Feature will allow detection only when a vehicle has come to a complete stop on the loop. This is a worldwide unique feature to PD-182 detector. Major advantage if you want to ignore cross traffic in tight spaces. In order to detect if smaller objects stopped moving, Minimum vehicle idle time over loop and Maximum allowed change for idling of the Detect Stop should be adjusted.
ASD - Automatic Sensitivity Damping
When power on PD-182, all components inside are cold, and need time to stabilize voltage. If the sensitivity is maximum, the small change of temperature during first seconds until components are heating can make false detection. Only decreasing the sensitivity solve this question completly. This function is a good way to startup with safe.
ASB – Automatic Sensitivity Booster
DIP 6 – This option increases sensor sensitivity to maximum upon detection. This is usually used to detect trucks and vehicles with trailers if sensor is not already configured to maximum sensitivity. If sensor is already configured to maximum sensitivity, this option is ignored.
Relay Pulse Mode
DIP 11 – In case Relay Pulse Mode is selected; this option defines whether the pulse will occur when vehicle approaches the loop or leaves the loop. When DIP switch is at “on” position then the pulse will occur when vehicle leaves the loop, otherwise the pulse occurs when vehicle arrives on the loop.
