Communications: electrical – External condition vehicle-mounted indicator or alarm – Transmitter in another vehicle
Reexamination Certificate
2002-05-27
2003-10-07
La, Anh (Department: 2632)
Communications: electrical
External condition vehicle-mounted indicator or alarm
Transmitter in another vehicle
C340S901000, C340S903000
Reexamination Certificate
active
06630891
ABSTRACT:
BACKGROUND
Emergency vehicle (EV) operators needing to move expeditiously through congested urban traffic may nevertheless be unable to do so. Drivers of other vehicles, unaware of an EV's approach because of limited visibility, air conditioning, sound insulation and/or loud music systems, delay or halt the EV's progress by blocking its path. Historically, horns, sirens and/or lights have been used to signal an EV's approach, but such warnings are increasingly inadequate and dangerous. See, for example, the background discussions in U.S. Pat. Nos. 5,235, 329 and 5,495,243, both incorporated herein by reference.
The invention of the '243 patent relates to improving the efficacy of warning lights on emergency vehicles but requires a line-of-sight to any vehicle intended to receive the warning. The line-of-sight requirement means that warnings can be selectively applied, but the effective warning range is relatively short, particularly in urban environments. On the other hand, while the warning system described in the '329 patent does not require line-of-sight to a warned vehicle, it is relatively non-selective.
The augmented warnings described in the '329 patent are intended to assist the relatively few drivers who actually need warnings to react reasonably (as by stopping or turning away from the EV's path). But many other drivers would, in general, also receive the warnings. These other drivers, who are not in or near the EV's path, would ideally not react to these false warnings (as by moving to the right lane and stopping) because in doing so they would be likely to needlessly aggravate traffic congestion. In part because it compounds the problem of false warnings, the invention of the '329 patent tends to increase traffic congestion rather than reducing it. This drawback substantially limits the net benefits of the warnings provided by the '329 invention.
To significantly improve on the '329 invention, warning methods and apparatus would preferably be more precisely focused on the vehicles and drivers actually in or near an EV's path. Since this path is generally unpredictable, warning systems should provide critical information in (nearly) real time to selected vehicles in the vicinity of the EV. Relatively long range predictions of appropriate avoidance maneuvers would confer little benefit, since even the EV driver may be uncertain about an EV's exact intended path and speed. There may be, for example, a choice of EV destinations (e.g., one of several hospitals for emergency medical treatment), a choice of routes (e.g., alternatives to avoid congestion or road construction), or a moving objective (e.g., a suspect fleeing a police stop or an accident scene). In summary, EV avoidance maneuvers preferably rely on information concerning likely encounters with relatively nearby EV's, and that information may change abruptly.
Several systems have been proposed to address one or more of the above needs. For example, U.S. Pat. No. 6,160,493 (incorporated herein by reference) describes a radio warning system that reliably transmits warning information, possibly including global positioning system (GPS) coordinates of the transmitter's location, to any system receiver within the range of a spread-spectrum signal. Extrapolating from successive sets of these transmitter coordinates might reveal an EV's intended path relative to other drivers.
The use of GPS coordinates to specify a transmitter's location could improve the value of a warning and reduce the incidence of false warnings, but the coordinates would only be available to the minority of drivers having the equipment to interpret GPS signals. The relatively high cost of needed GPS-related equipment in both transmitting and receiving vehicles would thus tend to discourage widespread adoption of the system. And without widespread adoption, any such system would be only marginally useful. Unfortunately, this situation would not be significantly improved by eliminating the GPS features of the system (i.e., the coordinates). Most drivers receiving a warning signal without at least some information on the transmitter location would experience the false warning problems described above.
Another recently-proposed system described in U.S. Pat. No. 6,326,903 (incorporated herein by reference) includes provision for electromagnetic transmission of information on direction-of-travel from one EV to another EV and/or from an EV to (controllable) traffic signals in its path. Again, the preferred source of direction-of-travel information is a GPS, although other, less accurate systems using a common direction reference (such as a compass) are also described.
A major drawback of all similar systems is that use of a common direction reference, whether based on GPS or another external coordinate system, requires each vehicle in the system to have equipment to access the common external reference. This equipment might reduce the incidence of accidents between EV's, but its unnecessary cost and complexity would also discourage widespread adoption of the system. And drivers not having access to the common direction reference, being unable to use the system, would be likely to cause about the same degree of congestion and delay as they do now.
Another communication system providing information useful in controlling traffic congestion is described in U.S. Pat. No. 5,448,599 (incorporated herein by reference). The system of the '599 patent provides reliable spread-spectrum communication between two vehicles, with the option of including speed and distance information for one vehicle relative to another vehicle. Relative speed (proportional to Doppler shift derived from the spread-spectrum signal) could be combined with distance information to inform a driver of his distance from an EV and the speed of the EV's approach, but not the direction of approach.
The system of the '599 patent provides valuable information to a driver receiving a warning signal, but the patent describes use of either a retransmitter-receiver pair or a passive reflector-receiver pair to obtain the distance separating two vehicles. Once again, cost and complexity are increased to obtain desired warning information. Further, if passive reflectors were used instead of retransmitters, the reflected signals would be useful only for relatively short distances (about 200 meters in the example provided in the patent).
Thus, as shown by the examples above, the warning systems proposed to date are relatively complex, costly, intrusive and/or ineffective. Lower cost versions of these systems suffer some of the same disadvantages as the old sirens, lights and horns, providing late, false, distracting and/or misleading warnings to too many drivers, while offering insufficient benefits in reducing EV delays and avoiding accidents.
A better warning system is needed to provide timely alerts to drivers who are either within or approaching the likely path of an EV. Such a system should provide relatively selective warnings in nearly real-time, and it should be reliable, secure, relatively inexpensive, flexible and user-friendly enough to be widely adopted. It should also make effective use of each driver's judgment and knowledge of local traffic patterns, providing supplemental information in a plurality of compatible formats usable by drivers to avoid an EV's path.
SUMMARY OF INVENTION
The present invention comprises improved vehicle warning systems that combine certain beneficial features of earlier warning systems with novel elements that confer important advantages in cost, effectiveness and/or operational flexibility. The invention relates in part to encoder-transmitter subsystems for transmitting encoded warning signals and corresponding receiver-decoder-alert subsystems. Each encoded warning signal comprises an ID code which is a unique identifier (e.g., the vehicle identification number) for the vehicle carrying its corresponding encoder-transmitter subsystem. Encoder-trans
Gilstad Dennis W.
La Anh
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