USER MANUAL
| LR-15: Radar-activated flashing beacons
2
2
NOW IT WORKS
2.1
THE RADAR AND SPEED MEASUREMENTS
LR-15 is a smart Doppler radar that constantly measures the speed of
approaching
“targets” (vehicles), separates
up to 10 simultaneous targets with different speeds and individually tracks them. The radar measures the speed of
each visible “target” approximately 10 times per second. The information about target includes the collection
of all
speed measurements during the period of time when a target is visible and the amount of reflected radar energy
called RSSI (Reflected Signal Strength Indicator). The RSSI depends on the distance to the target and its shape and
can be used to approximately estimate the size of the vehicle.
LR-15 can save traffic data on removable SD-Card in easy-to-process CSV files compatible with Microsoft Excel.
These data files include:
o
Individual real-time records with seconds resolution.
o
The Average, Minimal and Maximal speed of each vehicle.
o
Vehicles size / Radar cross section (maximal RSSI value).
o
Speed variation (acceleration/deceleration).
o
Speed Bins summary
(configurable periods and bin’s width)
.
o
Power supply voltage (configurable periods).
Typical speed measurements accuracy is +/- 0.8 km/h (0.5 mph). The accuracy of identification of individual
“target” may vary depending on traffic patterns and specifics of location. Under normal conditions
, the
identification error does not /- 8% of daily volume. For example, for 3,000 vehicles daily volume street,
the radar can count from 2,760 to 3,240 targets. The error can be bigger or smaller for a shorter period of time.
2.2
DETECTION RANGE AND COVERAGE
The detection range of the radar depends on the siz
e and shape of the “target”. A midsize sedan is typically
detected at the 100-120 meters range (330-400 ft). The range can be adjusted with configuration parameters such
as the
“Low RSSI” filter
.
The radar beam is 24° in horizontal 12° in the vertical plane. The width of the beam at the distance is calculated
using the following formula:
WIDTH = ANGLE * DISTANCE /57.26
The standard lane width in North America is 3.7m (12 ft). Therefore, the approximate coverage of the radar
depending on the distance:
Distance
Beam Width
Lanes
m
ft
m
ft
25
82
10
32
3
50
164
20
65
5
75
246
31
101
10
100
328
41
134
13
125
410
51
167
15
150
492
62
203
15
Table 1 Radar beam width vs distance.
