Why is distance important?
Trained officers know that radars can detect vehicle a long way away, based on size. A semi can be picked up at
a distance that is much farther than a motorcycle, for example.
Without distance information, SafetyZone would be in danger of alerting the officer to far-away large vehicles
rather than those that are close and pose a real danger. A far-away semi may slow down long before it nears the
patrol vehicle and not be a real threat. Distance (range) information minimizes the number of false alerts
generated by Ranger.
When setting the distance for the SafetyZone alert, the officer is advised to choose a distance that will give
sufficient warning for him to take evasive action in the presence of dangerous vehicles but will not trigger the
alert for vehicles a long distance away. The following chart will assist in the selection of the alert distance:
Vehicle distance in yards
Speed
50 yds
100 yds
150 yds
200 yds
250 yds
300 yds
350 yds
400 yds
35 mph
2.9 sec
5.8 sec
8.8 sec
11.7 sec
14.6 sec
17.5 sec
20.5 sec
23.4 sec
40 mph
2.6 sec
5.1 sec
7.7 sec
10.2 sec
12.8 sec
15.3 sec
17.9 sec
20.5 sec
45 mph
2.3 sec
4.5 sec
6.8 sec
9.1 sec
11.4 sec
13.6 sec
15.9 sec
18.2 sec
50 mph
2.0 sec
4.1 sec
6.1 sec
8.2 sec
10.2 sec
12.3 sec
14.3 sec
16.4 sec
55 mph
1.9 sec
3.7 sec
5.6 sec
7.4 sec
9.3 sec
11.2 sec
13.0 sec
14.9 sec
60 mph
1.7 sec
3.4 sec
5.1 sec
6.8 sec
8.5 sec
10.2 sec
11.9 sec
13.6 sec
65 mph
1.6 sec
3.1 sec
4.7 sec
6.3 sec
7.9 sec
9.4 sec
11.0 sec
12.6 sec
70 mph
1.5 sec
2.9 sec
4.4 sec
5.8 sec
7.3 sec
8.8 sec
10.2 sec
11.7 sec
75 mph
1.4 sec
2.7 sec
4.1 sec
5.5 sec
6.8 sec
8.2 sec
9.5 sec
10.9 sec
80 mph
1.3 sec
2.6 sec
3.8 sec
5.1 sec
6.4 sec
7.7 sec
8.9 sec
10.2 sec
85 mph
1.2 sec
2.4 sec
3.6 sec
4.8 sec
6.0 sec
7.2 sec
8.4 sec
9.6 sec
90 mph
1.1 sec
2.3 sec
3.4 sec
4.5 sec
5.7 sec
6.8 sec
8.0 sec
9.1 sec
Table 1: Alert time vs. detection distance and vehicle speed
Difference between SafetyZone and IACP-prohibited “Speed Monitor Alerts”
When SafetyZone is started, any locked speed information that is contained on the face of the radar is preserved,
but in SafetyZone mode, the radar ceases to display new target speeds. This is done so that SafetyZone cannot be
used as a “speed monitor alert” as defined by the International Association of Chiefs of Police.
To quote their definition of speed monitor alert, it is “a function that alerts the operator when a target speed signal
is received that is equal to or above a pre-selected threshold speed” so that an officer can take enforcement on that
vehicle without developing a proper tracking history. The IACP’s Enforcement Technology Advisory Technical
Subcommittee (ETATS) allows speed measurement devices to contain safety alerts like SafetyZone as long as the
alert does not report the vehicle’s speed to the officer when it is triggered. Also, to comply with the IACP
guidelines, if the officer chooses to exit SafetyZone mode while it is displaying an active threat alert, the
transition to normal speed measurement mode will be inhibited until the threat has passed, further inhibiting
SafetyZone from being used as a “speed monitor alert”.
When the Ranger reports a “THREAT” condition, the horn or an auxiliary sounding device will start beeping. Once the
officer has acknowledged the threat, pressing any of the buttons on the keypad will set the unit in Rear-Alert Stop mode. This
is indicated by “RAL StP” (Rear Alert Stop) message on the display. This message will stay on as long as there is a threat. To
set the Ranger in the normal operating mode, any of the transmit keys (Front Antenna, Rear Antenna or Stand-by) have to
pressed. If any other key has been pressed, the Ranger stays in Rear Alert Stop mode with “RAL StP” displayed.
A simple way to state this is that speed alerts which only alert the officer to a dangerous condition are allowed,
but speed alerts show the officer the speeds of speeding vehicles for enforcement reasons are not allowed.
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