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100% Digital Detection:
Completely software-driven, true 100% digital motion detection completely converts, amplifies and processes the sensor’s low-level signal in the digital domain without any analog circuitry. The sensor’s entire signal is processed without any saturation or noise, which provides increased accuracy, reliability and superior false alarm immunity.
Conventional “Digital” Motion Detection:
Conventional “digital” motion detectors have an analog stage that is used to amplify the sensor’s signal. The analog circuitry causes most of the signal to be lost due to the saturation of the amplifier. Therefore, there is no real benefit in adding a processor to an analog motion detector since most of the signal is lost in the amplifier stage and there is no data to process over a conventional analog decision-making circuit.
Shield is a software algorithm that is comprised of three major parts:
Real Time DSP (Digital Signal Processing):
The DSP portion of the software digitally amplifies and filters the sensor signal in real time. Unlike analog filtering, digital filters are accurate, unaffected by temperature levels, have no phase distortion and do not add cost or hardware components. The result is a clean and accurate digital signal with maximum S/N ratio.
Movement Analysis:
Movement generates a unique sequence of signals. For each signal, Shield measures and calculates the signal’s parameters (amplitude, duration, peak level, polarity, rise time and shape) in real time and then stores them in memory. Each signal is compared with a reference bank of movement and non-movement signals. If the signal does not meet movement criteria, it is immediately rejected.
RFI/EMI Protection:
The high dynamic range of the digital samples and high sampling rate allow high level RF signals to be recorded without clipping or any other distortion. Shield recognizes RFI/EMI conditions and effectively distinguishes interference signals from movement signals without compromising the detection of movement., reliability and superior false alarm immunity.
Auto Pulse Signal Processing (APSP) measures energy from each detected signal and stores it in memory. To generate an alarm, the memory must reach a required minimum level. Thus, in the presence of high-level signals (very low risk of false alarms) the detector immediately generates an alarm, functioning as a “non-pulse count” detector, while low level signals (presenting a high risk of false alarms) will cause the detector to automatically switch to a very high pulse count mode – resulting in excellent protection against false alarms. Pulse counting rate depends on signal energy levels and can go much higher for RFI signals.
Auto Pulse Signal Processing (APSP) measures energy from each detected signal and stores it in memory. To generate an alarm, the memory must reach a required minimum level. Thus, in the presence of high-level signals (very low risk of false alarms) the detector immediately generates an alarm, functioning as a “non-pulse count” detector, while low level signals (presenting a high risk of false alarms) will cause the detector to automatically switch to a very high pulse count mode – resulting in excellent protection against false alarms. Pulse counting rate depends on signal energy levels and can go much higher for RFI signals.
Dual edge processing separates the entry and exit signals so each signal must reach the required level. If the entry and exit signals do not reach required energy levels, an alarm is not generated thus dramatically increasing false alarm immunity. Single edge processing (found in most PIRs) adds the entry and exit signals until the required energy levels are reached before an alarm is generated.
Compares the entry and exit signals’ polarity. Only movement signals will generate opposed polarity signals, which will be processed by the software. Any interference signals will generate the same polarity signals, which will be rejected by the software providing unmatched RFI and EMI immunity.
