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Electronics work on DC and with a voltage range of ­48vDC to +48vDC. If the ELECTRONIC device is plugged into a standard wall outlet, there will be a transformer inside which will convert the AC voltage you are supplying to the required DC voltage NEEDED by the device.

Examples: Computer, radio, T.V, etc… 

Electric devices use LINE voltage (120vAC, 240vAC, etc…).Electric devices can also be designed to operate on DC sources, but will be at DC VOLTAGES above 48v.

Examples: incandescent lights, heaters, fridge, stove, etc…

Electronics work on DC and with a voltage range of ­48vDC to +48vDC. If the electronic device is plugged into a standard wall outlet, there will be a transformer inside which will convert the AC voltage you are supplying to the required DC voltage needed by the device.

Examples: Computer, radio, T.V, etc… 

Electric devices use line voltage (120vAC, 240vAC, etc…).Electric devices can also be designed to operate on DC sources, but will be at DC voltages above 48v.

Examples: incandescent lights, heaters, fridge, stove, etc…

It STATES that, while taking the samples of a CONTINUOUS SIGNAL, it has to be taken care that the sampling rate is equal to or greater than twice the CUT off frequency and the minimum sampling rate is known as the NYQUIST rate.

It states that, while taking the samples of a continuous signal, it has to be taken care that the sampling rate is equal to or greater than twice the cut off frequency and the minimum sampling rate is known as the Nyquist rate.

There is no DIFFERENCE, just language use, which differs from COUNTRY to country, so in Britain it is called a mobile, and in USA and South Africa and other places a cell phone. Even in Europe the name differs. The Germans call it a “handy”, which in English has completely another MEANING as an adjective, meaning useful. In ITALY it is called a telofonino or “little phone”.

 This difference in British and American English is also evident in many other things we use every day, like lifts and elevators, nappies and diapers, pickups and trucks. The list goes on and on, any student of English has to decide which he or she will use, as the default SETTING.

There is no difference, just language use, which differs from country to country, so in Britain it is called a mobile, and in USA and South Africa and other places a cell phone. Even in Europe the name differs. The Germans call it a “handy”, which in English has completely another meaning as an adjective, meaning useful. In Italy it is called a telofonino or “little phone”.

 This difference in British and American English is also evident in many other things we use every day, like lifts and elevators, nappies and diapers, pickups and trucks. The list goes on and on, any student of English has to decide which he or she will use, as the default setting.

For ANALOG modulation–AM, SSB, FM, PM and SM .
Digital modulation–OOK, FSK, ASK, Psk, QAM, MSK,CPM, PPM, TCM, OFDM.

For Analog modulation–AM, SSB, FM, PM and SM .
Digital modulation–OOK, FSK, ASK, Psk, QAM, MSK,CPM, PPM, TCM, OFDM.

AM­Amplitude MODULATION is a TYPE of modulation where the amplitude of the carrier signal is VARIED in accordance with the information bearing signal. FM­FREQUENCY modulation is a type of modulation where the frequency of the carrier signal is varied in accordance with the information bearing signal.

AM­Amplitude modulation is a type of modulation where the amplitude of the carrier signal is varied in accordance with the information bearing signal. FM­Frequency modulation is a type of modulation where the frequency of the carrier signal is varied in accordance with the information bearing signal.

When you talk into a mobile telephone it converts the sound of your voice to radiofrequency energy (radio waves). The radio waves are transmitted through the air to a NEARBY base station. The base station then sends the call through the telephone network until it reaches the person you are calling. When you receive a call on your mobile phone the message travels through the telephone network until it reaches a base station near to you. The base station sends out radio waves, which are detected by your telephone and converted BACK to speech. Depending on the equipment and the operator, the frequency that each operator utilises is 900MHz, 1800MHz or 2100MHz.

The mobile phone network operates on the basis of a series of cells. Each cell requires a radio base station to enable it to function.

There are three types of base station and each has a particular purpose:

1. The MACROCELL is the largest type and provides the main coverage for mobile phone networks.
2. The Microcell is used to improve capacity in areas where demand to make calls is high, such as shopping centres.
3. The Picocell only has a range of a few hundred metres and may be used to BOOST weak signals within large buildings.

Each base station can only cope with a CERTAIN number of calls at any one time. So if demand exceeds the capacity of a base station an additional base station is needed.

When you talk into a mobile telephone it converts the sound of your voice to radiofrequency energy (radio waves). The radio waves are transmitted through the air to a nearby base station. The base station then sends the call through the telephone network until it reaches the person you are calling. When you receive a call on your mobile phone the message travels through the telephone network until it reaches a base station near to you. The base station sends out radio waves, which are detected by your telephone and converted back to speech. Depending on the equipment and the operator, the frequency that each operator utilises is 900MHz, 1800MHz or 2100MHz.

The mobile phone network operates on the basis of a series of cells. Each cell requires a radio base station to enable it to function.

There are three types of base station and each has a particular purpose:

Each base station can only cope with a certain number of calls at any one time. So if demand exceeds the capacity of a base station an additional base station is needed.

1. Attenuation is the reduction in amplitude and intensity of a signal. Signals may ATTENUATE exponentially by transmission through a medium, or by increments calculated in electronic CIRCUITRY or set by variable controls.
2. Attenuation is an IMPORTANT property in telecommunications and ultrasound applications because of its IMPORTANCE in determining signal strength as a function of distance. 
3. Attenuation is usually measured in UNITS of decibels per unit length of medium (dB/cm, dB/km, etc) and is represented by the attenuation coefficient of the medium in question.

Multiplexing (known as muxing) is a term used to refer to a processwhere multiple analog MESSAGE signals or digital data streams are combined into one signal over a shared medium. The aim is to SHARE an expensive resource. For example, in TELECOMMUNICATIONS, several phone CALLS MAY be transferred using one wire.

Multiplexing (known as muxing) is a term used to refer to a processwhere multiple analog message signals or digital data streams are combined into one signal over a shared medium. The aim is to share an expensive resource. For example, in telecommunications, several phone calls may be transferred using one wire.

These are the two different means of mobile communication being presently used worldwide. The basic difference lies in the Multiplexing method used in the aerial communication i.e. from Mobile Tower to your mobile and vice versa. CDMA USES Code Division Multiple Access as the name itself indicates, for example you are in a hall occupied with number of people speaking different language.

You will find that the one language you know will be heard by you and the others will be treated LIKE noise. In the same manner each CDMA mobile communication takes PLACE with a “code” communicating between them and the other end if one is knowing that code then only it can listen to the data being transmitted i.e. the communication is in the coded FORM.

On the other hand GSM (Global System for Mobile Communications)uses narrowband TDMA, which allows eight SIMULTANEOUS calls on the same radio frequency. TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels.

These are the two different means of mobile communication being presently used worldwide. The basic difference lies in the Multiplexing method used in the aerial communication i.e. from Mobile Tower to your mobile and vice versa. CDMA uses Code Division Multiple Access as the name itself indicates, for example you are in a hall occupied with number of people speaking different language.

You will find that the one language you know will be heard by you and the others will be treated like noise. In the same manner each CDMA mobile communication takes place with a “code” communicating between them and the other end if one is knowing that code then only it can listen to the data being transmitted i.e. the communication is in the coded form.

On the other hand GSM (Global System for Mobile Communications)uses narrowband TDMA, which allows eight simultaneous calls on the same radio frequency. TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels.

Full duplex refers to the transmission of data in two directions SIMULTANEOUSLY. For EXAMPLE, a telephone is a full­duplex devicebecause both parties can talk at once. In contrast, a walkie­talkie is ahalf­duplex device because only one party can TRANSMIT at a time. Most MODEMS have a switch that lets you choose between full­duplex and half­duplex modes. The choice depends on whichcommunications program you are running.

In full­duplex mode, data you transmit does not appear on yourscreen until it has been received and sent back by the other party. This enables you to validate that the data has been accurately transmitted. If your display screen shows two of each character, it PROBABLY means that your modem is set to half­duplex mode when it should be in full­duplex mode.

Full duplex refers to the transmission of data in two directions simultaneously. For example, a telephone is a full­duplex devicebecause both parties can talk at once. In contrast, a walkie­talkie is ahalf­duplex device because only one party can transmit at a time. Most modems have a switch that lets you choose between full­duplex and half­duplex modes. The choice depends on whichcommunications program you are running.

In full­duplex mode, data you transmit does not appear on yourscreen until it has been received and sent back by the other party. This enables you to validate that the data has been accurately transmitted. If your display screen shows two of each character, it probably means that your modem is set to half­duplex mode when it should be in full­duplex mode.

Feedback is a process whereby some proportion of the output SIGNAL of a system is PASSED (FED back) to the input. This is often used to control the dynamic behaviour of the system.

Types of feedback:

Negative feedback: This tends to reduce output (but in amplifiers, stabilizes and linearizes operation). Negative feedback feeds part of a system’s output, inverted, into the system’s input; generally with the result that fluctuations are attenuated.

Positive feedback: This tends to increase output. Positive feedback, sometimes referred to as “cumulative causation”, is a feedback loop system in which the system responds to perturbation (Aperturbation means a system, is an alteration of function, induced by external or internal mechanisms) in the same direction as the perturbation. In contrast, a system that responds to the perturbation in the opposite direction is CALLED a negative feedback system. 

Bipolar feedback: which can either increase or DECREASE output.

Feedback is a process whereby some proportion of the output signal of a system is passed (fed back) to the input. This is often used to control the dynamic behaviour of the system.

Types of feedback:

Negative feedback: This tends to reduce output (but in amplifiers, stabilizes and linearizes operation). Negative feedback feeds part of a system’s output, inverted, into the system’s input; generally with the result that fluctuations are attenuated.

Positive feedback: This tends to increase output. Positive feedback, sometimes referred to as “cumulative causation”, is a feedback loop system in which the system responds to perturbation (Aperturbation means a system, is an alteration of function, induced by external or internal mechanisms) in the same direction as the perturbation. In contrast, a system that responds to the perturbation in the opposite direction is called a negative feedback system. 

Bipolar feedback: which can either increase or decrease output.

MUCH attention has been given by researchers to negative FEEDBACK processes, because negative feedback processes lead systems towards equilibrium STATES. Positive feedback reinforces a given tendency of a system and can lead a system away from equilibrium states, possibly CAUSING quite unexpected RESULTS.

Much attention has been given by researchers to negative feedback processes, because negative feedback processes lead systems towards equilibrium states. Positive feedback reinforces a given tendency of a system and can lead a system away from equilibrium states, possibly causing quite unexpected results.

EXAMPLES :

• –ve FEEDBACK is —Amplifiers.
• +ve feedback is – OSCILLATORS.

Examples :

A transducer is a device, USUALLY electrical, electronic, electro­mechanical, electromagnetic, PHOTONIC, or photovoltaic that converts one type of energy or physical attribute to another for various purposes including measurement or information transfer.

In telecommunication, the TERM transponder (shortforTransmitter­responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) has the following meanings:

1. An automatic device that receives, amplifies, andretransmits a signal on a different frequency (see alsobroadcast TRANSLATOR).
2. An automatic device that transmits a predetermined messagein response to a predefined received signal.
3. A receiver­transmitter that will generate a reply signal upon proper electronic interrogation.
4. A communications satellite’s channels are called transponders, because each is a separate transceiver or repeater.

A transducer is a device, usually electrical, electronic, electro­mechanical, electromagnetic, photonic, or photovoltaic that converts one type of energy or physical attribute to another for various purposes including measurement or information transfer.

In telecommunication, the term transponder (shortforTransmitter­responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) has the following meanings:

A rectifier changes alternating current into direct current. This process is CALLED rectification. The three main types of rectifier are the half­wave, full­wave, and bridge. A rectifier is the opposite of an inverter, which changes direct current into alternating current. HWR­ The simplest type is the half­wave rectifier, which can be made with just one diode. When the voltage of the alternating current is positive, the diode becomes forwardbiased and current flows through it. When the voltage is negative, the diode is reverse­biased and the current stops.

The result is a CLIPPED copy of the alternating current waveform with only positive voltage, and an AVERAGE voltage that is one third of the peak input voltage. This pulsating direct current is ADEQUATE for some components, but others require a more steady current. This requires a full­wave rectifier that can convert both parts of the cycle to positive voltage.

FWR­ The full­wave rectifier is essentially two half­wave rectifiers, and can be made with two diodes and an earthed centre tap on the transformer. The positive voltage half of the cycle flows through one diode, and the negative half flows through the other. The centre tap allows the CIRCUIT to be completed because current cannot flow through the other diode. The result is still a pulsating direct current but with just over half the input peak voltage, and double the frequency.

A rectifier changes alternating current into direct current. This process is called rectification. The three main types of rectifier are the half­wave, full­wave, and bridge. A rectifier is the opposite of an inverter, which changes direct current into alternating current. HWR­ The simplest type is the half­wave rectifier, which can be made with just one diode. When the voltage of the alternating current is positive, the diode becomes forwardbiased and current flows through it. When the voltage is negative, the diode is reverse­biased and the current stops.

The result is a clipped copy of the alternating current waveform with only positive voltage, and an average voltage that is one third of the peak input voltage. This pulsating direct current is adequate for some components, but others require a more steady current. This requires a full­wave rectifier that can convert both parts of the cycle to positive voltage.

FWR­ The full­wave rectifier is essentially two half­wave rectifiers, and can be made with two diodes and an earthed centre tap on the transformer. The positive voltage half of the cycle flows through one diode, and the negative half flows through the other. The centre tap allows the circuit to be completed because current cannot flow through the other diode. The result is still a pulsating direct current but with just over half the input peak voltage, and double the frequency.

An operational amplifier, often called an op­-amp , is a DCcoupled high ­gain electronic voltage amplifier with differential inputs and, usually, a SINGLE output. Typically the output of the op­amp is CONTROLLED either by NEGATIVE feedback, which LARGELY DETERMINES the magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative gain and oscillation.

An operational amplifier, often called an op­-amp , is a DCcoupled high ­gain electronic voltage amplifier with differential inputs and, usually, a single output. Typically the output of the op­amp is controlled either by negative feedback, which largely determines the magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative gain and oscillation.

The FREQUENCY at which the RESPONSE is ­-3dB with RESPECT to the MAXIMUM response.

The frequency at which the response is ­-3dB with respect to the maximum response.