Abstract: A system and method to detect ground faults in a multi-processor communication system that includes a communications link that extends between the processors. The processors isolate different sections of the link. Measurements made with different isolated sections establish the location of the fault. The processors can also make measurements of the link to establish the magnitude of a shunt impedance on the link. Where an abnormal value of shunt impedance is detected, the respective devices can activate or deactivate solid state isolation circuitry to disconnect a section of the link exhibiting the abnormal level of shunt impedance.

Abstract: A multi-processor communication system includes a plurality of processors in bidirectional communication with one another. One processor can transmit a message to an intended recipient. The message can be correctly received by other processors. In the event that the intended processor does not correctly receive the message and transmits a failure indicating message, the other processors, upon detection of the failure will retransmit the message. Ambient condition sensors can be coupled to some of the processors.

Abstract: An ambient condition detector includes at least a sensor for a first ambient condition and a second, sensor which is responsive to a second ambient condition not necessarily correlated to the first condition. Control circuitry, coupled to both sensors, processes an output from the first sensor to reduce transients and/or noise therein which are not correlated to the first ambient condition. Processing characteristics are altered in response to an output from the second sensor. The processing can take place at the detector or, in part, at the detector and, in part, at a displaced, common control element. The output from the first sensor can also be used to modify the processing of the output of the second sensor.

Abstract: A detector includes a sensor of an ambient condition. Outputs from the sensor are sampled at a predetermined rate when the outputs do not represent an alarm condition. The outputs are analyzed using pattern recognition techniques to determine if a predetermined profile, which precedes the presence of an alarm condition, is present. In the event that the profile is detected, the sample rate is increased along with associated sample value processing. The detector includes a programmable processor coupled to the sensor. The processor includes pattern recognition instructions for detecting the presence of the predetermined profile. The processor also includes instructions for altering the sampling rate in response to the detected presence of the profile. A second sensor can be incorporated to provide sample rate altering signals.

Abstract: A multi-processor system makes it possible to enhance information transmitted between processors. Any one of the processors can inject information into a data transmission between other processors. The injected information can identify or indicate the location of one processor with respect to another processor. Alternately, it can define which processor or processors should respond or specify an action to be taken. Where one processor is transmitting to another processor, a third processor, upon detecting the transmission, can insert additional information into the transmission sequence at an appropriate location. A fourth processor, also monitoring the communications sequence could insert additional information into the same sequence as well.

Abstract: A self-monitoring power supply can be incorporated into electrical devices which are part of a multi-device communication system. The power supply is energized by electrical energy received from a medium on an intermittent basis. The self-monitoring circuitry assures that the device has sufficient energy for carrying out its functions. Noise rejection and noise immunity can be enhanced in such devices by circuitry which upon detection of a transmission start signal or a clock pulse locks out data signals for a predetermined period of time and upon detection of a data signal locks out transmission start or clock pulses for a predetermined period of time.

Abstract: A method and an apparatus for automatically locating detectors in an ambient condition monitoring system incorporate a normally closed contact for open circuiting the associated communication link. A command can be issued to the detectors and which identifies a specific detector. In response to the command, at least some of the detectors open circuit the communication link. The specific detector transmits neighbor identification signals in each direction on the communications link. These neighbor identification signals are sensed and stored in each neighbor detector. Information identifying detectors which are neighbors to a selected detector can then be analyzed to establish locations of the various detectors relative to one another in the system.

Abstract: A dynamically adjustable communication system and method automatically adjust transmission rates of discontinuous waveforms from one signal level to another for the purpose of optimizing a quality parameter of a transmitted signal. Circuitry coupled to the transmission medium provides feedback to transmitter circuitry for the purpose of adjusting at least one of a rise time and a fall time parameter of a transmitted signal for the purpose of enhancing transmission quality. Transmission rate can also be automatically adjusted to maximize data rate and minimize errors.

Abstract: An ambient condition detector includes a sensor for a first ambient condition and a second, sensor which is responsive to a second ambient condition not necessarily correlated to the first condition. Control circuitry, coupled to both sensors, processes an output from the first sensor to reduce transients and/or noise therein which are not correlated to the first ambient condition. Processing characteristics are altered in response to an output from the second sensor. The processing can take place at the detector or, in part, at the detector and, in part, at a displaced, common control element.

Abstract: A system and a method for dynamically adjusting a level of filtering or smoothing applied to data received from fire detectors produces shortened response times for detection of a fire condition while at the same time minimizing the effects of uncorrelated noise in the absence of any fire condition. An increasing probability of a fire results in less filtering. Increasing values of the input signal from a respective detector, indicative of an increasing selected ambient condition such as combustion or temperature, provide a control input for reducing or bypassing the level of filtering of the respective input signal thereby reducing system response time. Where the unfiltered input data from a respective detector indicates a combustion or temperature profile moving toward clear air, the filtering or smoothing level can also be dynamically decreased thereby enabling the filtered signal values to return to their respective clear air values faster than would otherwise be the case.

Abstract: An apparatus and a method can be used to pre-process an output signal from an ambient condition sensor. The preprocessing removes noise pulses which are not correlated with an ambient condition being sensed. Preprocessing can be carried out by comparing the present output value to a prior output value and selecting a minimum value there between. The apparatus and method can incorporate storage for two prior values and the present output value can be compared to two prior values and a minimum or a maximum of the three values selected. Additional processing can be carried out by comparing the present output value to a nominal expected clear air output value. If the present value exceeds the nominal expected output value, a minimum is selected among the present output value and one or more prior values. If the present output value is less than the nominally expected value, a maximum is selected from among the present output value and one or more prior output values.

Abstract: Outputs from a smoke detector and non-fire sensors such as temperature and humidity can be combined to produce a delay in a signal from the smoke sensor indicative of a potential fire condition. The signals can be combined locally and all of the sensors can be carried in a single housing. Alternately, the sensors can be carried in separate housings and combined at a remote control panel. The value output from the humidity and temperature sensor can be used in determining whether or not to produce a delay. Alternately, the rate of change of either or both parameters can be used to determine whether a delay is necessary.

Abstract: A noise immune detection system includes a plurality of detectors that generate respective indicia representative of adjacent ambient conditions. A communications link extends between the detectors. A control element is coupled to the link to receive and process the indicia and to adjust an alarm threshold level in response to noise levels in the system. Respective indicia are filtered twice by the control element. In the presence of noise, as reflected in relative values of the filtered values of the indicia, the threshold value is automatically increased.

Abstract: A fire alarm system utilizes outputs from different types of fire sensors, such as photoelectric smoke sensors or ionization type smoke sensors and combines those outputs by subtraction so as to establish a delay interval during which one or both of the sensor output values must exceed a predetermined threshold value to cause the system to go into an alarm condition. Prior to subtracting the outputs from one another, each of the outputs can be raised to a predetermined exponential value so as to emphasize the effects of larger sensor output values. Where the two types of fire sensors each are generating outputs indicative of a fire condition, the calculated delays will be relatively short. In instances where only one of the two sensors is generating an output indicative of a fire condition, the calculated delay will be longer, so as to inhibit false alarms.

Abstract: A communication system includes a control element, a bidirectional communications link, and one or more devices coupled to the link. The control element, via driver circuits, reversibly applies a predetermined potential to the link for the purpose of energizing the one or more devices as well as communicating therewith. The devices can respond at appropriate time intervals. During the responding time intervals, the control element can continue to supply power to the devices.

Abstract: A compensated ionization-type sensor includes spaced apart active and reference electrodes. A center electrode is disposed between the active reference electrodes. A compensating electrode is disposed adjacent to the center electrode and, capacitively coupled thereto. The compensating electrode is electrically coupled to the active electrode. A compensating screen with a selected potential applied thereto surrounds the electrodes to compensate for velocity of the ambient atmosphere.

Abstract: An alarm system which incorporates a large number of ambient condition sensors makes a determination as to the existence of a predetermined alarm condition by detecting respective ambient conditions from each member of a group of sensors. The indicators from the plurality of sensors are each raised to a respective predetermined exponent and summed together. The resultant sum is compared to a predetermined threshold to determine whether or not the alarm condition is present. The detectors can be spaced apart from one another in a selected region and coupled to a central control unit by a bi-directional communications link. Running averages of sums can be formed to provide filtering or smoothing or trend analysis.

Abstract: A detector supervision system usable with detectors or sensors formed with a removable head and a surface mountable base includes an energy storage device which is carried on each base. The energy storage device is either a capacitor or an inductor, and is coupled to one or more of the terminals of the base. A conducting spring member is also carried on the base, attached to one of the terminals. The spring member is in a first position when the head is attached to the base. The spring member moves to the second position in response to the head being removed from the base. Detection circuitry can detect the presence of one or more energy storage devices which are switched into communication lines between detector bases in response to one or more of the heads being removed. The detection circuitry can signal a central control panel that one or more of the heads has been removed from a respective base.