Digital Signal Processing Digital Signal Processing is the process of representing signals in a discrete mathematical sequence of numbers and analyzing, modifying, and extracting the information contained in the signal by carrying out algorithmic operations and processing on the signal. Digital signal processing (DSP) is the use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations. The digital signals processed in this manner are a sequence of numbers that represent samples of a continuous variable in a domain such as time, space, or frequency. In digital electronics, a digital signal is represented as a pulse train, which is typically generated by the switching of a transistor. Digital signal processing and analog signal processing are subfields of signal processing. DSP applications include audio and speech processing, sonar, radar and other sensor array processing, spectral density esti

  voltage regulator A voltage regulator is used to regulate voltage levels.  Voltage regulator, any electrical or electronic device that maintains the voltage of a power source within acceptable limits.  The voltage regulator is needed to keep voltages within the prescribed range that can be tolerated by the electrical equipment using that voltage. Types of voltage regulators  Linear voltage regulators Switching voltage regulators Linear voltage regulators Linear voltage regulators are the original type of regulators use to regulate the power supplies.  A linear voltage regulator works like a voltage divider. The resistance of the linear regulator varies with the connected load and input voltage. Therefore, it is able to supply a constant voltage signal. Types of Linear Voltage Regulators Shunt Series Shunt Regulators A shunt regulator is used for low-powered circuits. It works by directing the current away from the load and sending it into the ground. It provides a path from the input

  Grounding Grounding means to connect electrical equipment to a common reference ground or earth.  These three systems are Ungrounded Systems Resistance Grounded Systems Solidly Grounded Systems Types of grounding Solidly grounded system It is usually used in wye systems and this method is mostly used in the industrial, commercial and institutional power distribution system. in this method, the neutral is connected to the ground and thus it could ensure the neutral voltage is equal to the ground, by doing this method properly there won't be any phase to ground over-voltages. Reactance grounding In this method, a reactor is connected between the neutral point and the ground and the magnitude of the ground fault current can be reduced by changing the reactance. But this method is not used now because of the high transient voltage that appears during the ground fault condition Resonant grounding This method is also known as Peterson grounding because Peterson developed a coil which c

  Diaphragm Valves Diaphragm valves get their name from a flexible disc which comes into contact with a seat at the top of the valve body to form a seal. A diaphragm is a flexible, pressure responsive element that transmits force to open, close or control a valve. Diaphragm valves are related to pinch valves, but use an elastomeric diaphragm, instead of an elastomeric liner in the valve body, to separate the flow stream from the closure element. A diaphragm valve is a linear motion valve that is used to start, regulate, and stop fluid flow. The name is derived from its flexible disk, which mates with a seat located in the open area at the top of the valve body to form a seal. A diaphragm valve is illustrated in below Figure. Diaphragm valves are, in effect, simple “pinch clamp” valves. A resilient, flexible diaphragm is connected to a compressor by a stud molded into the diaphragm. The compressor is moved up and down by the valve stem. Hence, the diaphragm lifts when the compressor is

Hearing loss   What does hearing loss mean?   Majority of the human beings are able to hear sounds from a particular range. An individual is said to have hearing loss when he/she is unable to hear that commonly known range of sounds without any aid. common types of Hearing Loss   Conductive   When hearing loss is due to problems with the ear canal, ear drum, or middle ear and its little bones. Sensory Neural When hearing loss is due to problems of the inner ear, also known as nerve-related hearing loss. Mixed In this type of hearing loss, there may be damage in the outer or middle ear and in the inner ear (cochlea) or auditory nerve. Degrees of Hearing Loss Mild hearing loss With a mild hearing loss difficulty will occur for soft speech and listening in background noise. Moderate hearing loss With a moderate hearing loss one experiences difficulty hearing conversations, especially while in background noise. The TV or radio may be turned to higher levels also in order to be heard clearl

Blood pressure What is blood pressure ? Blood pressure is a measure of the force that your heart uses to pump blood around your body. Blood pressure is the force exerted by the blood against the wall of blood vessel Unit of blood pressure units are millimeters of mercury (mmHg) . What is Systolic blood pressure ? is force exerted by arterial walls during systole. It is the maximum pressure during ventricle contraction What is Diastolic blood pressure ?  is the force exerted by blood against arterial wall during diastole. It is the maximum pressure when the ventricles are relaxed Normal blood pressure is 120/80 mm of Hg Systolic pressure is 120 mmHg & diastolic pressure is 80 mmHg Pulse pressure Pulse pressure is the difference between systolic & diastolic pressure Normally, The pulse pressure is 40 mmHg Cardiac output It is the amount of blood ejected by heart in 1 minute Stroke volume It is the amount of blood ejected by heart in 1 cycle. Normally heart eject 70-80 ml blood in

  Biomedical Instrumentation Devices information Electrodes Many medical instruments are electronic devices and thus it should a electrical signal for an input. In the cases where biopotential may acquire, some form of electrodes used between patient and instrument. Medical Electrodes: There are few electrodes, ECG Electrodes: 1) Plate electrode 2) Suction Cup electrode 3) Needle electrode Plate Electrode It is use to connect patients extremities to ECG input amplifier. It consists of a binding attached to 3cm*5cm metallic plate. The plate is attached and held in placed against the patient’s skin by rubber strap surrounding the extremity. Suction Cup Electrode This is also use the same type of material as the electrode but us used in connecting the portion of body other than the extremities. Most frequently the suction cup electrode is connected to the patient’s chest electrode. A few advanced ECG machines also require a connection to the patient’s face or head and

  Air-operated valves Air-operated valves is Opening and shutting take place with the power of air pressure An air-operated valve is a type of power operated valve that uses air pressure against a piston or diaphragm to produce linear or circular movement to operate a valve. Types are 2-way, 3-way and 4-way. The 2 way air-operated valves can be either normally closed or normally opened. Modulating control valves each with 4-20mA I to P converter linked to pneumatic a valve positioner controlling a diaphragm actuator What is an air operated valve? An air operated valve, also known as an angle seat valve is a vital component for any pneumatic circuit. The valve works to direct or block airflow, controlling the speed or sequence of operations, promoting the effective functionality of a component or piece of machinery. Air operated valves are available as either a normally open or normally closed valve, the components work to control the process of media through a valve. An air operated va

  Control Valve Fail Safe Action Loss of instrument air supply pressure Loss of electrical power There are four choices as to control valve “response” to the emergency condition  Fully Close Fully Open In Last Position Continue Throttling For either fail-safe loss of Instrument Air Supply or loss of electrical power, it is the actuator’s benchset range spring that “drives” the control valve’s plug to its fail-safe open or closed position. Loss of Instrument Air Supply Pressure Fully Close The actuator’s benchset range spring “drives” the valve plug “closed” when loading air pressure goes towards or near 0 psig. (Air to Open Fail Close “Reverse”) Because Instrument Air Supply piping systems can be extensive (big), the Instrument Air Supply can decay too slowly causing operational problems. In such cases it may be desirable to use a 3-way pilot switching valve to “anticipate” the eventual loss of Instrument Air Supply and quickly stroke the control valve to its fail-safe position, elimin

  Comment on fail safe action i.e Air to Open (ATO) and Air to Closed (ATC) of control valve. Air to Open (ATO) of Control Valve (Failure Close (FC) - Air to Open) The actuator's benchset range spring "opens" the valve plug when the loading air pressure drops to or near 0 psig. (Air to Closed Fail Open “Direct”) Same scheme as I.a. A back to air to closed fail open arrangement can be applied to a fail open control valve to eliminate transient effects. Fail close means the valve will close when the signal is interrupted or lost. This is the opposite of the above scenario. Since air pressure is required to keep the valve open, it will automatically close when the power goes out because there is no longer a working air source. Actuated or automatic valves that return to a pre-set position after removal of actuating force are called "fail-safe" valves. The most common type is "fail-safe normally-closed." On the other hand, "fail-safe normally-open&quo

  Double Seated and Single Seated What is the difference between a double seated and single seated globe valves. Single seated globe valves Large amount of force required to drive the stem Double seated globe valves Stem can be driven with small amount of force Single seated globe valves Tight shut off  Double seated globe valves Can not achieve perfect closure resulting in leakage  Single seated globe valves Used in small diameter applications Double seated globe valves Used in larger diameter applications  Single seated globe valves Used for controlling large range of process parameters hence used in oil and gas production, power generation Double seated globe valves Used for high flow and high pressure services Single seated globe valves Single seated valves are used in case of higher shut-off and the pressure range is low compared to a double-seated valve. Double seated globe valves Double seated valves are pressure balanced and can be used for high-pressure applications. Single se

  Elements of process control loop 1. Identify which of the following is an example of a “primary sensing element”: A) I/P transducer B) Instrument signal cable C) Control valve D) Diaphragm E) Digital controller Answer : Diaphragm 2. In order for a control loop to work well under a wide range of conditions, it must possess: A) Calibration drift B) Hysteresis C) A very expensive transmitter D) Proper documentation E) Negative feedback Answer : Negative feedback 3. Which of the following is not a “final control element”? A) A pressure transmitter B) An electric motor C) A heating element D) A control valve E) A servo Answer : A pressure transmitter 4. The purpose of a “shield” wire on an instrument signal cable is to: A) Hold a steadier setpoint value B) Ensure technician safety C) Minimize the possibility of sparking D) Protect the cable from corrosion E) Minimize electrical noise Answer : Minimize electrical noise 5. The most common analog signal standard for industrial process instru

  PNP & NPN Transistor PNP Transistor The transistor in which one n-type material is doped with two p-type materials such type of transistor is known as PNP transistor. It is a current controlled device. The small amount of base current controlled both the emitter and collector current. The PNP transistor has two crystal diodes connected back to back. The left side of the diode in known as the emitter-base diode and the right side of the diode is known as the collector-base diode. The hole is the majority carriers of the PNP transistors which constitute the current in it. The current inside the transistor is constituted because of the changing position of holes and in the leads of the transistor it is because of the flow of the electrons. The PNP transistor turns on when a small current flows through the base. The direction of current in PNP transistor is from the emitter to collector. The letter of the PNP transistor indicates the voltage requires by the emitter, collector and the

 Basic elements of Digital Signal Processing (DSP) Classification of Signals 1. Which of the following is the odd component of the signal x(t)=e(jt)? a) cost b) j*sint c) j*cost d) sint Answer: j*sint 2. The deflection voltage of an oscilloscope is a ‘deterministic’ signal. a) True b) False Answer: True 3. The even part of a signal x(t) is? a) x(t)+x(-t) b) x(t)-x(-t) c) (1/2)*(x(t)+x(-t)) d) (1/2)*(x(t)-x(-t)) Answer: (1/2)*(x(t)+x(-t)) 4. Which of the following is done to convert a continuous time signal into discrete time signal? a) Modulating b) Sampling c) Differentiating d) Integrating Answer: Sampling 5. For a continuous time signal x(t) to be periodic with a period T, then x(t+mT) should be equal to ___________ a) x(-t) b) x(mT) c) x(mt) d) x(t) Answer: x(t) 6. Let x1(t) and x2(t) be periodic signals with fundamental periods T1 and T2 respectively. Which of the following must be a rational number for x(t)=x1(t)+x2(t) to be periodic? a) T1+T2 b) T1-T2 c) T