Threshold Device

Threshold Device


in automation and computer technology, a device, in this case a circuit, with several inputs and one output, designed to compare the values of the input signals against a given value, the threshold level. Output signal y can assume only one of two values, 0 or 1, and is related to input signals xi as follows:

where λi, is the amplification factor of signals xi (i = 1, 2, …, n) and λ0 is the threshold level.

Threshold devices are classified according to the static characteristic as two-position, three-position, reversible, and irreversible and according to the nature of the output signal as pulse, frequency, and amplitude devices. A threshold device that compares two signals fed to its input is called a zero element. The threshold device usually contains a nonlinear element, an amplifier, and a positive feedback loop. Their arrangement will determine the various characteristics of the threshold device: minimum threshold level (sensitivity); zero level drift, which describes the stability of the device; input impedance; range of input signals for which the element keeps the assigned static and dynamic characteristics; speed; noise stability; the presence of galvanic isolation between the input and output; and reliability.


References in periodicals archive ?
The ResQCPR System is a combination of two medical devices, the ResQPUMP ACD-CPR device and the ResQPOD Impedance Threshold Device.
0 Impedance Threshold Device, fits onto a rescue face mask or breathing tube.
The LUCAS also works with the ResQPod Impedance Threshold Device the rescue squad uses to help improve blood flow, Mr.
For the purposes of this review, a pressure threshold device was considered more reliable than a resistive expiratory muscle training device.
However, this study used ventilator manipulations rather than a threshold device and had several limitations.
In the second study, also by the ROC researchers, use of an impedance threshold device (ITD) to enhance venous return and cardiac output during CPR also produced the same rate of survival with satisfactory functional status as did standard CPR without an ITD.
The use of a threshold device to induce intraluminal airway pressure splinting has the potential advantage of generating an intraluminal pressure that is a function of the device, which means that intraluminal pressure is maintained at the set threshold pressure throughout the expiratory cycle, generating higher airway expiratory pressures, reducing airway collapse and DH, and thus possibly reducing dyspnea.
It's basically a threshold device,' Padora explains, 'made purposefully low so people bow their heads upon entry'.
Breathing Through an Inspiratory Threshold Device Improves Stroke Volume During Central Hypovolemia in Humans.