Vehicle security system responsive to short and long range transmitters

A vehicle security system that includes a receiver/controller which may be installed on all vehicles on a dealer's lot and "taught" to respond to a low power short range "dealer" transmitter prior to sale and to a conventional relatively high power long range "customer" transmitter after sale. The short range transmitter permits a salesman to demonstrate the security system as a natural adjunct to the sale of any one of all the vehicle on a dealer's lot without affecting the state of security of other vehicles in the vicinity. The controller can be taught to respond to either a dealer or a customer transmitter but all dealer transmitter ID's are deleted when teaching a customer transmitter ID and vice versa. In addition only one dealer code can be stored at any one time. A removable valet switch is operative after sale of the vehicle to permit override of the system. Prior to sale the controller is programmed to inhibit operation to the valet switch. The removable valet switch and an LED indicator are housed in a single housing for convenience of installation and ease of use.

TECHNICAL FIELD 
This invention relates to remotely controlled vehicle security systems and 
more particularly to a system that can be selectively placed in one 
configuration prior to sale of the vehicle to the customer and a second 
configuration after sale. 
BACKGROUND ART 
Remotely controlled vehicle security systems are well known in the art. See 
for example Chen U.S. Pat. No. 5,285,186 assigned to the assignee of the 
present invention and hereby incorporated herein. Such systems generally 
include a vehicle mounted radio frequency receiver and a user carried 
transmitter. The receiver is tuned to receive and decode an encoded signal 
that identifies the user of the transmitter from which the signal emanate 
as one authorized to operate the vehicle. The receiver provides the 
identification (ID) code or signature word to a microprocessor based 
controller on the vehicle that compares the received code with a one or 
more valid ID's stored in the controller memory. If a valid code is 
received the microcontroller toggles between an ARMED and a DISARMED 
state. In the ARMED state, a starter solenoid interrupt relay is energized 
to interrupt the solenoid circuit and thereby prevent energization of the 
solenoid and starting of the engine. In the DISARMED state, the interrupt 
relay is deenergized to close its contacts in the starter solenoid circuit 
permitting the starter solenoid to be energized and thereby permit the 
vehicle to be started. The vehicle door locks may, at the same time, be 
toggled between a LOCKED and an UNLOCKED state. Some prior art security 
systems the microcontroller also receives inputs from triggers or sensors 
which monitor various vehicle conditions indicative of an intrusion or 
other compromise of vehicle security. If the vehicle security is 
compromised while the system is in the ARMED state, an alarm such as a 
siren or vehicle horn is activated. The status of the system is provided 
by a light emitting diode(LED) or other indicator, usually mounted on the 
dash to advise the owner of the state of the system and warn potential 
intruders of the existence of the security system. 
Usually, the security system includes a so-called valet switch located 
within the vehicle in a hidden but accessible location. Operation of the 
valet switch after turning the ignition switch ON, places the system in a 
VALET MODE that deactivates or overrides the security system and permits 
the owner to leave the vehicle with another user, such as a parking 
attendant, while avoiding potential inadvertent activation of the security 
system. 
Security systems have also been proposed that included a PROGRAM or LEARN 
MODE of operation, The controller can be placed in this mode only by an 
authorized user. While in this mode, a transmitter ID code word received 
from a new or replacement transmitter is stored in the controller memory 
and become a valid ID for operating the system. 
Although security system have been successful in reducing vehicle theft, a 
large percentage of vehicles delivered by manufacturers to franchised 
dealers do not include factory installed security systems. Indeed, 
security systems are not available as a factory installed option on many 
vehicles. Filling this gap are after-market security systems, the sale of 
which is to a large extent dependant on the desire of the vehicle 
salesperson at the dealership to promote the advantages of the security 
system. While the usual profit incentive exists, it is known that 
salespeople often disable the installed security system or if no system is 
installed do not aggressively promote the safety aspects of such systems. 
One reason, is that installation of a system is best accomplished during 
normal working hours by the dealer service department. However, vehicles 
are often sold after the service department is closed, and in any event, 
inclusion of the security system should not delay delivery of the vehicle 
to the customer. 
It would be advantageous if an after-market security system was installed 
on all vehicles on the dealer's lot. If the customer did not desire to 
purchase the system with the vehicle, it can be easily disconnected from 
the vehicle wiring harness by the salesperson. Moreover, if all vehicles 
include a system, demonstration of the security system is a necessary 
adjunct to demonstration of the vehicle by the salesperson. There is also 
the added advantageous of providing an additional measure of security to 
the vehicles on the dealer's lot. There are, however, several problems 
associated with such a proposal. For example, with existing systems the 
salesperson would need a universal transmitter (one that transmitted a 
code that was valid for all vehicles on the lot) in order to have access 
to each vehicle. The alternative would be to locate the valid transmitter 
for the vehicle to be demonstrated. While a universal transmitter would be 
convenient for the salesperson, multiple vehicles on the lot within the 
range of the transmitter would be ARMED or DISARMED as well as the vehicle 
being demonstrated. The aforementioned alternative is not only 
inconvenient but would normally make the valet switch available to the 
salesperson which is not desirable under normal circumstances. 
SUMMARY OF THE INVENTION 
In accordance with the present invention a security system is proposed 
which alleviates the aforementioned problems associated with prior art 
systems. The present system includes a receiver/controller which may be 
installed on all vehicles on a dealer's lot and "taught" to respond to a 
low power short range "dealer" transmitter prior to sale and to a 
conventional relatively high power long range "customer" transmitter after 
sale. Preferably, the transmitter identification code word size is used by 
the controller to distinguish the different transmitters. The security 
system can be demonstrated as a natural adjunct to the sale of the vehicle 
without affecting other vehicles in the vicinity. The controller cannot be 
taught to concurrently respond to both a dealer and a customer transmitter 
and all dealer transmitter ID's are deleted when teaching a customer 
transmitter ID and vice versa. In addition, only one dealer code can be 
learned at any one time. 
Override of the system is based on both hardware and software control. A 
removable valet switch is provided that can be operated in combination 
with the ignition switch to override system operation after sale to the 
customer. The removable aspect of the switch also provides the owner a 
further degree of protection against theft. System override by operation 
of the valet switch is available through the software only after teaching 
the controller a customer transmitter ID. When configured to respond to a 
dealer transmitter, a more involved override sequence is available that 
involves a sequence of operation of the ignition switch. This override 
sequence is only temporary and discourages system disablement during 
vehicle sale but does provides an emergency override should the occasion 
arise.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring now to FIG. 1 the remote controlled security system of the 
present invention includes a radio frequency receiver 10 mounted on the 
vehicle for receiving signals of a predetermined frequency from a 
relatively short range transmitter 12 or a relatively long range 
transmitter 14 both of which transmit at the predetermined frequency. 
Preferably, the signal from the short range transmitter cannot be received 
by the receiver 10 beyond a distance of approximately 4-6 feet, to avoid 
reception of the signal by receivers mounted on other vehicles located in 
a dealers lot. On the other hand, the transmitting power of the 
transmitter 14 is that of a conventional transmitter used in present day 
security systems and capable of generating a signal which can be received 
from a substantial distance of 50 feet or more. The transmitters 12 and 14 
are substantially the same with the following differences. First, the 
power output of the transmitter 12 is reduced in any conventional manner 
such as by resistor sizing in the gain control section of the transmitter. 
Second, the encoder that establishes the unique identification code word 
for the transmitter 12 outputs a code word containing a first fixed number 
of bits (M) while the code word produced by the transmitter 14 contains a 
second fixed number of bits (N). For example, the coded signal emitted by 
the transmitter 12 may include a 12 bit ID while that emitted by 
transmitter 14 may include a 24 bit ID. 
The receiver 10 is of conventional design and responds only to receipt of 
signals of a predetermined frequency such as those generated by 
transmitters 12 or 14. Upon receipt of such a signal the receiver 10 
inputs the 12 bit or 24 bit ID code to a controller 16. The controller 16 
is preferably microprocessor based and receives other inputs from an 
ignition switch 18, a learn switch 20, and a valet switch 22. The 
controller 16 controls energization of a LED generally indicated at 26 and 
a starter solenoid interrupt relay indicated at 28. Whenever the 
controller 16 is in the ARMED MODE, the relay 28 is energized to interrupt 
the circuit to the starter solenoid and prevent vehicle starting. 
As will be described more fully hereinafter, closure of the learn switch 20 
initiates a LEARN MODE of operation wherein the ID code from either one of 
the transmitters 12 or 14 may be entered into the memory of the 
microcontroller 16. However, the ID codes do not co-exist in memory, i.e. 
the controller is programmed to respond to receipt of a ID code word from 
a customer transmitter during the LEARN MODE, to delete all dealer 
transmitter ID codes that exist in the controller memory. Likewise, 
receipt of a ID code word from a dealer transmitter during the LEARN MODE 
causes all customer transmitter ID codes to be deleted from memory. The 
subroutine in the program of the controller that controls the learning of 
ID codes, is shown in the flowchart of FIG. 2. The LEARN MODE is entered 
when the controller recognizes a predetermined sequence of inputs such as 
opening of the driver's door followed by closure of the ignition switch 18 
followed by closure of the learn switch 20. If a transmitter ID code is 
received while the controller is in the LEARN MODE, a determination of the 
origin of the code is made in the decision block 32. This determination is 
based on the number of bits, M for dealer and N for customer, in the ID 
code word received. If the code is from a dealer transmitter all existing 
codes ie. all dealer codes and all customer codes are deleted from memory 
at 36. After clearing the memory of any existing codes the received dealer 
code is stored in memory as indicated at 38. If on the other hand the 
signal received is not a dealer code but is rather a customer code as 
determined by the decision block 40, a decision is made at 42 regarding 
whether any dealer codes are stored in memory. If any dealer codes exist 
in memory they are deleted at 44 and the received customer code is stored 
as indicated at 46. After storage of the received code, or if the code 
received is neither a dealer nor a customer code, the program returns to 
the main loop. Though not shown in FIG. 2, a software counter may be 
started upon entry of the PROGRAM MODE to cause the program to return to 
the main loop if no signal is received within a predetermined time 
interval of for example 15 seconds. Accordingly, the system permits an 
authorized vehicle user to program the controller to respond to either one 
of two types of transmitters such as the short range dealer transmitter, 
while deleting any previously stored ID codes generated by the long range 
customer transmitter and vice versa. Further, only one dealer code can be 
stored in memory at any time. It is contemplated that each dealer will 
have a unique code assigned to the dealership and all dealer transmitters 
will be coded with this unique code. It is therefore desirable that the 
controller be inhibited from learning more than one dealer code at a time. 
On the other hand it is desirable that the controller be programmed to 
permit more than one customer code to be stored to accommodate several 
authorized users of the vehicle. For example the block 46 envisions a 
first-in-first-out memory arrangement that permits four customer codes to 
be stored at any one time. 
Once a valid ID code is stored in the memory of controller 16 and the 
system is no longer in the PROGRAM MODE, receipt of an ID code of the 
proper frequency causes a subroutine to be called to control arming of the 
system. With reference to FIG. 3 this subroutine includes decision blocks 
48 and 50 wherein a determination is made whether the received ID code was 
emitted by a dealer transmitter or a customer transmitter. This decision 
is made by counting the number of bits in the ID code using either a 
hardware or software bit counter. In either case, after detection, the bit 
counter is reset as indicated at 52. The received code is compared at 54 
with the codes in memory. If the received code is a valid code i.e. 
corresponds to one of the codes in memory, as determined in decision block 
56, then the system is toggled to the ARM MODE, if in the DISARM MODE, or 
vice versa as indicated at 58. If the code received is neither a dealer 
code nor a customer code or if the received code is not a valid code, the 
program returns to the main loop. 
Sequential closure of the ignition switch and the Valet/Override switch 22 
initiate a subroutine in the controller 16 which overrides the security 
system. Prior to delivery of the vehicle to the customer, override of the 
system is accomplished through a procedure involving actuation of the 
ignition switch between the on and off positions in a timed sequence which 
is prompted by the security indicator. This sequence of ignition switch 
operations is intended to prevent the casual overriding of the security 
system while providing a system override during a true emergency such as a 
lost or inoperative transmitter during demonstration of the vehicle. 
Referring to FIG. 4 the subroutine for overriding the security system 
includes a decision block 62 which determines which override procedure is 
in force. This subroutine may be called on a regular basis or upon 
predetermined system operating conditions. When the subroutine is called, 
and a dealer code is stored in memory as determined by the decision block 
62, the controller 16 determines at decision block 64 whether the ignition 
switch is in the ON position. If the ignition switch is not ON, the 
subroutine returns to the main loop. If the ignition switch is ON, a 2 
second timer is started and the LED 26 is flashed at a fixed rate as 
indicated at block 66. If the ignition switch is turned OFF before the 
expiration of the 2 second time interval a 5 minute timer is started. When 
the 5 minute timer is started, the flashing LED is extinguished. This 
action is depicted in the blocks 68, 70 and 72. If the ignition switch is 
maintained in the OFF position for the 5 minute interval as determined by 
the decision blocks 74 and 76, a 30 second timer is started and the LED is 
energized continuously as indicated at 78. If the ignition switch is 
turned ON before the LED is turned on at block 78, the program returns to 
the main loop. As indicated in blocks 80-90, the ignition switch must be 
turned ON then OFF and back ON again during the 30 second time interval in 
order to override the system at 92. 
After sale of the vehicle and storage of one or more customer codes in the 
controller memory, override of the system is accomplished by closing the 
valet switch 22 within a 20 second time interval following actuation of 
the ignition switch to the ON position. The after sale condition, i.e. 
customer codes are stored in memory, is detected by the decision block 62. 
If the valet switch is actuated to the ON position, before the ignition 
switch is closed, the program returns to the main loop as indicated in 
block 94. When the ignition switch is turned ON as detected by block 96, a 
20 second timer is started as indicated at 98. If the valet switch 22 is 
activated before the timer expires as determined by the blocks 100 and 
102, the security system is overridden. Otherwise, the program returns to 
the main loop. 
Referring now to FIG. 5 the low power dealer transmitter 12 is a single 
button transmitter of conventional design which has been modified to 
reduce output power. The transmitter 12 includes an RF oscillator 
generally designated 104 and an encoder 106. Power is supplied by a 
battery 108 through an operator control switch 110. An indicator in the 
form of LED is provided for indicating when power is applied. The 
transmitter ID code word for the dealer transmitter is set by the state of 
the switches S2-S12 and is transmitted whenever the switch 110 is closed. 
The switch S1 is connected across a resistor 116 in the base circuit of 
transistor 118. The switch S1 is normally set to the open position so that 
the output power is substantially reduced by the inclusion of the resistor 
116 in the base circuit. Under certain circumstances, such as high RF 
noise conditions, it may be necessary to utilize the full power of the 
dealer transmitter. In that case the switch S1 may be closed to shunt the 
resistor 116 so that the transmitter can radiate full power. Closure of 
the switch 110 controls the ARM/DISARM function of the security system. 
The code format for the dealer transmitter 14 is shown in FIGS. 6a-6c. A 
pulse width modulated code is employed where a binary "1" bit is 
represented by a high voltage level for 2/3T and a low voltage level for 
1/3T where T is the bit time interval of for example 1 microsecond. A word 
consists of N bits transmitted over a 12 microsecond period followed by a 
12 microsecond quiet period. The power of the dealer transmitter is 
relatively low so that the receiver does not respond to a dealer 
transmitter unless the transmitter is in close proximity to the vehicle. 
Thus, in a dealers lot, where a large number of vehicles are configured to 
respond to a dealer code, only the vehicle to be demonstrated to the 
potential customer will be affected by operation of the dealer 
transmitter. 
Referring now to FIG. 7 the customer transmitter 14 is of conventional 
design and includes an RF oscillator generally designated 120 and an 
encoder 122. Power is supplied by a battery 124 through a pair of operator 
control switches S11 and S12 that also supply inputs to the encoder 122. 
An indicator in the form of an LED is provided for indicating when power 
is applied by closure of either of the switches S11 or S12. The 
transmitter ID code word for the customer transmitter is set by the state 
of the switches S1-S10. It will be understood that the code may be 
established by other well known means such as by selectively cutting 
electrical tracings etched on a printed circuit board or by programming an 
EEPROM. Closure of the switch S11 controls the ARM/DISARM function while 
closure of the switch S12 may control an axillary function such as 
operating the vehicle trunk. The code format for the customer transmitter 
14 is shown in FIGS. 8a-8c. A pulse width modulated code is employed where 
a binary "1" bit is represented by a high voltage level for 3/4T and a low 
voltage level for 1/4T where T is the bit time interval of for example 1 
microsecond. A word consist of N bits transmitted over a 24 microsecond 
period followed by an 8 microsecond quiet period. During the 24 
microsecond interval the customer ID is transmitted twice to form a 24 bit 
word. As previously indicated the controller 16 counts the incoming bits 
from the receiver 10 to determine whether the identification code words 
are being received from the transmitter 12 or 14. 
Referring now to FIG. 9, a housing 130 for supporting both a removable 
valet switch and the LED 26 is shown. Mounting the LED and valet switch in 
a single housing provides convenience of installation and ease of use. One 
end 132 of the housing includes a generally rectangular shaped opening 134 
for receiving a valet switch holder 136. The valet switch structure is not 
shown but is of conventional design and suitably operated by a push button 
138. Preferably the button is pushed in to place the switch in a latched 
position and subsequently pushed in to release the switch from the latched 
position. Male terminals 139 extend from the holder 136 for insertion into 
mating receptacles (not shown) in the end 132 to establish an electrical 
path through wiring 140 and connector 142. The connector 142 is intended 
to be inserted in a suitable input port of the controller 16. The housing 
130 includes an end 144 containing an opening 146 for receiving an LED 
holder 148 that houses the LED 26. The LED 26 is electrically connected to 
an output port of the controller 16 through wiring 150 and connector 152. 
The housing 130 includes integrally formed mounting extensions 154 and 156 
containing slots 158 and 160 that are adapted to receive suitable 
fasteners for mounting the housing 130 to the underside of the vehicle 
dash. The housing 130 is provided with suitable recesses 162, 164 and 168 
for accommodating the wiring 140 and 150 to permit the housing to be 
mounted flush with the dash. 
While the best mode for carrying out the invention has been described in 
detail, those familiar with the art to which this invention relates will 
recognize various alternative designs and embodiments for practicing the 
invention as defined by the following claims.