Please choose a topic:
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Operational
Range Questions
• What determines range?
• How can optimum range be achieved?
• What periodic system maintenance
would you recommend?
• Do colored lenses affect range?
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Trouble
Shooting Traffic Signal Preemption Systems Questions
• How do I determine whether the
problem is my transmitter or the traffic signal detector?
• How can a strobe head be tested
to determine whether or not it is faulty?
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Compatibility
Questions
• Will Priority Green work with
3M Opticom and Tomar Strobecom detectors?
• Will Priority Green work with
encoded detectors (receivers)?
• Are there any negatives to preemption-equipped
intersections that are programmed for
"Restricted Access" (meaning that only custom-encoded
transmitters can activate them)?
• Does Priority Green offer any
traffic signal detectors (receivers), phase selectors,
or
discriminators, at this time?
• Will the use of Priority Green
void other manufacturer’s warranties?
• Is Priority Green mechanically
and electrically compatible with my vehicle? With my
lightbar?
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General
Questions
• What is the difference between
"Low Priority" and "High Priority"
preemption?
• Why is it necessary to execute
a "Sale Agreement"?
• What are the state laws regarding
the use of preemption transmitters?
• What is that white flood lamp
on the traffic signal?
• Is optical traffic signal preemption
better than audio (siren-based) or radio-based
systems?
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Questions
about the MicroMount ExtremeRange (MMER)
• Mounts anywhere? Will it fit in
the lightbar, grill, engine compartment, glove box,
under the dash, under the seat, in the trunk, above
the visor?
• What is the ExtremeRange mode?
• If the ExtremeRange mode doubles
the power to the strobe head, is the range also doubled?
• Does the ExtremeRange mode reduce
the operational
life of the strobe emitter?
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Questions
about the Mobile Preemption Emitter (MPE)
• Can I use the MPE in a moving
vehicle?
• Must the MPE be pointed directly
at the detector?
• What battery life can be expected?
• Can I use rechargeable batteries?
• Is the MPE also a flashlight?
• How does the MPE work?
• Is the proprietary module replaceable?
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Operational Range
What determines
range?
Priority Green, 3M Opticom, and Tomar Strobecom
?traffic signal preemption are optically-based communications
systems. There are three major factors that determine
range in any optical system: the transmitter (power supply
and strobe head located in the vehicle), the detector
(also known as the “receiver” normally located
on or near the traffic signal), and the optical medium
between them (air). In a perfect world, the transmitter
is working perfectly and the lens covering the strobe
head is perfectly clean; the detectors sensitivity is
optimally set, the detector’s lens is perfectly
clean, and the traffic signal electronics are functioning
correctly; and there is no visible obstruction between
the transmitter and detector, no fog or bad weather.
It is reasonable to expect any working “system”
to function properly at a distance of 2500 feet between
the vehicle-mounted transmitter and the traffic signal
detector. The most common circumstances reducing range
are as follows:
Transmitter: Dirty lens, electronic
failure of the power supply, faulty strobe head, insufficient
power supply input voltage, and faulty cables and/or
wiring harnesses can decrease or prevent a system from
working properly.
Detector: Decreased range or system
failure can be caused by a dirty lens, electronic failure
of the preemption detector or traffic signal electronics
(damage due to lightning, circuit component failure,
etc.), power outage to the intersections, improper sensitivity
settings, improper aiming of the “telescopes”,
improper mounting locations, or detectors which have
been pre-programmed to only permit vehicles that can
transmit encrypted ID optical signals (Note: See “Will
Priority Green work with encoded detectors?” for
specific information related to encrypted ID optical
signals)
Medium: The line-of-sight between
the transmitter and detector can be compromised by fog,
smog, snow, rain, sleet, hail, dust, wind (detectors
mounted on suspended lines can sway and/or rock in the
wind, interrupting the line-of-sight), or any combination
of the aforementioned. The line-of-sight can also be
obstructed by other vehicles (notably large trucks),
large traffic signs, overpasses (normally due to improper
location of the detector, which can often be corrected
by either relocating the detector or adding another detector),
or any non-transparent physical obstruction.
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How can optimum
range be achieved?
System range optimization is a balance between
the user’s needs and the preemption equipment’s
capabilities. For instance, if the equipment used claims
a line-of-sight operation up to 2500 feet, yet your requirement
is 3000 feet, then no optimization on the part of the
user will overcome the product’s limitations. Physical
obstructions that cannot be resolved by relocating the
detector (receiver) or adding another detector can also
not be improved upon. It is assumed that the reader has
established that the system is, in fact, working, although
the range has been determined to be substantially less
than stated in the product specifications bulletins.
Assuming an unobstructed line-of-sight between the
transmitter and detector of 2500 feet, clean transmitter
and detectors lenses, and that both electronic systems
are fully operational, suggestions for improving the
range of any intersection are as follows:
Make certain that the detector is mounted and aimed
properly (refer to the manufacturer’s product manuals).
Make certain that the strobe head on the vehicle is
not optically occluded (obstructed or partially blocked),
and relocate if necessary.
Make certain that the supply voltage to the preemption
power supply in the vehicle complies with the manufacturer’s
specifications (refer to the manufacturer’s product
manuals).
Increase the sensitivity of the detector (refer to
the manufacturer’s product manuals).
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What periodic
system maintenance would you recommend?
Because the majority of the Priority Green customer base
belong to the emergency response sector, most readers
are primarily limited to vehicle maintenance and, at
best, requesting service for traffic signals that are
suspected to be faulty. Maintaining the transmitter is
generally limited to periodic cleaning of the strobe
head lens (routine car washes), replacing aging and/or
defective strobe heads, and ensuring that the transmitter
power supply is receiving the proper input voltage when
the vehicle is under heavy electrical load (i.e., engine
running, all emergency lights “on”, etc.).
The detector (receiver) lens should also be cleaned
on a regular basis. Road dust and dirt can and will collect
on the lens of even the best-designed product. Traffic
signal detectors should be tested frequently, particularly
during the warm weather months when thunderstorms are
more common. Nearby ground strikes can and will damage
even the best protected electrical apparatus.
Safety Alert! NEVER “assume”
that a preemption-equipped traffic signal is operating
properly! The Confirmation Light (high intensity flood
lamp that is often located near the detector on the traffic
signal to alert the emergency vehicle driver that he
has gained control of the intersection) may not be illuminating
because the detector isn’t working!!! ALWAYS PROCEED
WITH CAUTION!!! NEVER “ASSUME” THAT THE CONFIRMATION
LIGHT IS BURNT OUT!!!
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Do colored lenses
affect range?
Yes. Colored lenses do affect range, however the reduction
in range is often unnoticeable.
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Trouble Shooting
Traffic Signal Preemption Systems
(applicable to any system, any manufacturer)
How do I determine
whether the problem is my transmitter or the traffic
signal detector?
Priority Green offers a low-cost handheld transmitter/detector
analyzer, the MPE (Mobile Preemption Emitter ). The MPE
can be used to rapidly diagnose potential problems affecting
any preemption transmitter or detector.
Short of the Priority Green MPE, the simplest method
is to first test the vehicle-mounted unit at several
different preemption-equipped traffic signals. During
low volume traffic periods and with clear weather, approach
the various intersections at very slow speed (5 mph or
less) from a distance of one-half mile. Once the Confirmation
Lamp has illuminated, estimate or measure the distance
between the vehicle and the traffic signal under test.
If the transmitter fails to activate any preemption-equipped
traffic signal, or the range (distance between the transmitter
and detector) is extremely limited, the transmitter can
be assumed to be faulty. If, however, the transmitter
successfully activates preemption-equipped traffic signals,
but not others, then it can be reasonably assumed that
the traffic signals that failed to respond have defective
preemption detectors.
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How can a strobe
head be tested to determine
whether or not it is faulty?
Unless actual physical damage (i.e., cracked or broken
tube glass) has taken place, most strobe heads will not
just suddenly cease to flash. Strobe heads (strobe lights,
strobe tubes, strobe emitters, etc.) are generally rated
for a specific number of flashes at a specific power
level by their manufacturers. This “life expectancy”
is only an estimate, and can be decreased by high operating
temperatures, excessive power delivered to the head,
or any dissipation of the inert gas within the tube.
An intermittent or failing strobe head has a tendency
to flash erratically, often at a noticeably lower brilliance
than a new strobe head. Unfortunately, an erratic or
less brilliant flash will absolutely affect the range
and operation of any preemption system or product.
Always replace faulty or defective strobe heads as
soon as possible.
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Compatibility
Will Priority
Green work with 3M Opticom and
Tomar Strobecom detectors?
Yes. All Priority Green products are compatible with
3M Opticom and Tomar traffic signal preemption detectors.
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Will Priority
Green work with encoded detectors (receivers)?
Preemption-equipped traffic signals that are programmed
to only respond to custom-encoded preemption transmitters
will not work with any Priority Green product at this
time. However, the actual percentage of preemption-equipped
intersections that only respond to custom-encoded transmitters
is very small.
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Are there any negatives
to preemption-equipped intersections that are programmed
for “Restricted Access” (meaning that only
custom-encoded transmitters can activate them)?
Yes. Priority Green does not offer transmitter ID encryption
of its devices at this time due to the logistical problems
and liability often created where such systems are deployed.
If a preemption-equipped traffic signal is programmed
so that it permits access only to predetermined vehicles,
every single traffic signal within the territorial boundary
of the equipped emergency vehicle must be similarly equipped.
The programming of traffic signal preemption detector
electronics is almost never performed by the departments
who must make use of them, making the logistics of maintaining
such a system cumbersome, impractical, and very expensive
- particularly when new vehicles are equipped with transmitters
and every traffic signal must then be programmed to accept
the new vehicles - logistical responsibilities that responding
departments cannot directly control. Liabilities arise
when bordering departments, which may have vehicles equipped
with preemption transmitters, cannot gain access to encrypted
intersections or, worse, when it is “assumed”
that access can be gained, creating a potentially high
risk situation because the responding emergency vehicle
driver believes that he/she has control and right-of-way
through the intersection.
Priority Green promotes the spirit of cooperation between
neighboring communities, and does not support any product,
system, or legislation that mandates traffic signal preemption
encryption for any other purpose than “Low Priority”
mass transit applications. The concept of “restricted
access” does not meet the general public’s
needs if it fails to allow control of emergency response
personnel through preemption-equipped traffic signals,
or puts those same emergency response personnel at risk
because they may be unaware that a given intersection
is programmed for “restricted access” only.
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Does Priority
Green offer any traffic signal detectors (receivers),
phase selectors, or discriminators, at this time?
Priority Green does not offer detectors (receivers),
phase selectors, or discriminators at this time. All
Priority Green products are compatible with 3M Opticom
and Tomar traffic signal preemption detectors.
Priority Green strongly recommends the use of 3M Opticom
detectors, phase selectors, and discriminators, as the
Company believes the history, quality, and success of
this product line speaks for itself.
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Will the use of
Priority Green void other manufacturer’s warranties?
No. Legal precedents have actually been established that
prevent marketplace competitors from even threatening
to void warranties when competing or interactive devices
can not be proven to “harm” the product under
warranty.
All Priority Green products are compatible with 3M
Opticom and Tomar traffic signal preemption detectors.
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Is Priority Green
mechanically and electrically compatible with my vehicle?
With my lightbar?
The Priority Green MicroMount ExtremeRange product is
the most compact and versatile traffic signal preemption
power supply in the world, which means that it can be
installed in virtually any location within any known
vehicle or lightbar. All products will operate on any
9 to 15 VDC electrical system (select option –28
to increase the product range to 28 VDC), with by far
the simplest and least time consuming installation process
in the industry.
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General
What is the difference
between “Low Priority” and “High Priority”
preemption?
“Low Priority” is generally used by mass
transit authorities to increase the time duration of
green lights or and/or decrease the time duration of
cross-traffic red lights. “High Priority”
takes precedence over “Low Priority”, and
the purpose is to secure control of the intersection
by maintaining a single direction of traffic flow by
holding the traffic signal green until the emergency
vehicle has passed through that intersection. “Low
Priority” is generally considered to be 10 hertz
(10 flashes-per-second) while “High Priority”
is 14 hertz.
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Why is it necessary
to execute a “Sale Agreement”?
Priority Green will not sell traffic control products
to individuals, companies, or organizations that are
not legally authorized to use the devices. The “
Sale Agreement” is a tool used by Priority Green
to determine the authenticity of the buyer, and to prevent
unauthorized individuals from illegally obtaining the
product.
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What are the state
laws regarding the use of preemption transmitters?
Laws vary from state to state. To determine your states
laws consult your state’s Department of Transportation.
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What is that white
flood lamp on the traffic signal?
The “Confirmation Light” is primarily used
to “confirm” that the intersection has been
accessed by an approaching emergency vehicle. Individual
state Departments of Transportation determine when the
light actually illuminates, and if it flashes or not.
In most instances, the Confirmation Light will remain
illuminated (or flash) until it no longer detects the
preemption transmitter, which is usually because the
emergency vehicle has passed through the intersection.
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Is optical traffic
signal preemption better than audio (siren-based) or
radio-based systems?
All traffic signal preemption systems have trade-offs,
so comparisons should be made based upon cost, operational
requirements (range, ease of installation, etc.), and
future expectations. However, it should be pointed out
that by far the most prevalent traffic signal preemption
technology is optical.
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MicroMount ExtremeRange
Mounts anywhere?
Will it fit in the lightbar, grill, engine compartment,
glove box, under the dash, under the seat,
in the trunk, above the visor?
Yes, it will mount in all of these locations. The compact
design of the MicroMount has been engineered to fit in
tight locations that have previously not been capable
of housing a preemption power supply. The MicroMount
is also a rugged waterproof product, easily withstanding
the hostile environment of an engine compartment or the
greenhouse-type heat of a lightbar on a hot summer day.
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What is the ExtremeRange
mode?
When the ExtremeRange mode is enabled, the MicroMount
will double the amount of power delivered to the strobe
head.
The ExtremeRange mode is especially attractive to the
law enforcement community. A police cruiser traveling
at an extremely high rate of speed needs all of the distance
it can get when it comes to preempting traffic signals
- the greater the speed of the vehicle, the less time
it takes to cover a fixed distance. A vehicle traveling
at 100 mph will cover approximately 150 feet per second.
Therefore, the 12 seconds (or less) that it would take
to descend upon an intersection that can normally be
accessed from 1800 feet out might not be enough time
for the traffic signal to cycle into the preemption mode,
clear the traffic, and safely pass through the intersection.
The ExtremeRange mode preempts the light at distances
up to 2500 feet.
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If the ExtremeRange
mode doubles the power to the strobe head, is the range
also doubled?
No, but depending upon the type of strobe head being
driven, the increase in range can be significant - it
could be the difference between sitting in traffic at
a red light or preempting the traffic signal to your
advantage. At a minimum, several hundred feet of additional
range can typically be expected.
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Does the ExtremeRange
mode reduce the operational
life of the strobe emitter?
Here’s a better question: does a user-controllable
feature that enables a traffic signal to be accessed
from a greater distance, and therefore possibly saving
time and lives, make the possibility of limiting the
life of the strobe emitter worthwhile? Yes!
The more power delivered to a strobe emitter, the shorter
its operational life (with respect to the number of times
that it can be “flashed”). This holds true
for any strobe emitter. The ExtremeRange mode does deliver
more power to the strobe emitter, although in most cases
the reduction in operational life will be negligible.
The ExtremeRange mode does not have to be used. But
the knowledge that you have the option of additional
range, if and when you need it, might one day save a
life.
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MPE (Mobile Preemption
Emitter)
Safety Alert! This product is
not to be used in a moving vehicle under any circumstances!!!
Can I use the
MPE in a moving vehicle?
The MPE will not work effectively from a moving vehicle.
The product has been intentionally designed to be range-limited,
and holding the device steady in one’s hand while
driving is virtually impossible.
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Must the MPE be
pointed directly at the detector?
The MPE need only be pointed in the general direction
of the detector on the traffic signal.
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What battery life
can be expected?
While any standard “D” cell batteries will
work, Priority Green recommends the use of industrial
alkaline “D” cell batteries. Assuming the
product is used several times each week for approximately
15 minutes per use, the batteries can be expected to
last many months.
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Can I use rechargeable
batteries?
The use of rechargeable batteries is not recommended.
The voltage-per-cell of most rechargeable “D”
batteries is only 1.2, compared to the 1.5 volts of alkalines.
The lower voltage of the combined rechargeable batteries
(4.8 volts verses 6.0 volts) results in reduced light
output and range.
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Is the MPE also
a flashlight?
The MPE should not be used in place of a flashlight,
nor does it function as a flashlight.
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How does the
MPE work?
The MPE contains a proprietary circuit that is epoxy
encapsulated. This circuit first takes the 6.0 volts
supplied by the four “D” alkaline batteries
and coverts it to two separate higher voltages: 400 and
6,000 volts. The 400 volts is developed and stored in
a capacitor, and 14 times each second a microcontroller
sends a signal that triggers the flashtube (with the
6,000 volts), and this discharges the storage capacitor
into the tube, creating the stroboscopic white light.
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Is the proprietary
module replaceable?
Yes. Return your MPE to our factory for replacement or
repair. The flashtube itself is also factory-replaceable.
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