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communications channel
Wiki User
∙ 11y ago
Wiki User
∙ 12y agoA communications channel
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What is the function of coupling capacitor in substation?
A coupling capacitor in substation is used for power line communication purposes. It used after the wave trap. The capacitance ranges from 2200pf to 10,000pf. It offers very low impedance to high frequency carrier signal and allows them to enter the line matching unit and offers a very high impedance path to low frequency signal or wave and blocks it for reaching the line matching unit. In short, it allows only those frequencies needed for communication purposes.
What is the use of capacitor before input of power supply AC?
They are used to offer a low impedence path to high frequency interference from switching sources such as fridges and thermostats. Also to curb radio frequency breakthrough.
What is a reverberating circuit?
a closed circuit, in which the signal continually travels around a circular path over and over until one of the components (usually neurons) stops functioning and the signal is not transmitted to the next component; proposed by Hebb as the mechanism for short-term memory
What is the difference between a resonant and a non-resonant circuit?
When a circuit is said to be resonate it means a signal or wave that is being generated has some relationship with a reflected or feedback signal such that the generated signal is reinforced with the reflected or feedback signal. This reinforcing of the signal may cause a standing wave of constructive interference and required the generation of the signal and the reflection or feed back to be in phase or Coherent. if there is no phase coherency then it can be harder to achieve the standing wave of constructive interference. However is the Phase is detected and delay is compensated it can be achieved like in a laser ring gyro, which uses two resonate cavities that have there path length adapted to cope with heat expiation.
Is Sparking between contacts can be reduced by inserting a Resistance in the line?
not it will be more effective to use a capacitor in parallel...1/WC->0 as high frequency switching waves w-> inf.C provides a shrt circuit path.
Define and describe FDM?
FDM: Frequency-division multiplexing. A multiplex system for transmitting two or more signals over a common path by using a different frequency band for each signal.
Guided versus unguided network?
Guided Media : Guided Transmission Media uses a "cabling" system that guides the data signals along a specific path. The data signals are bound by the "cabling" system. Guided Media is also known as Bound Media Unguided Transmission Media consists of a means for the data signals to travel but nothing to guide them along a specific path. In a guided medium signal passes through a physical pathway(s),while in an unguided medium signal passes through a vacuum, it is independent of a physical pathway.
In GSM which frequency uplink or downlink is greater?
The main reason of selecting a lower frequency for up-link channel in GSM is because of free space path loss. The more is the frequency the more is the loss. As mobile phones, being a battery driven device, have limitation in terms of power we should always look for lower path loss. Whereas BTS antennas can transmit the signal (in down-link channel) with a comparatively high power, which will compensate the path loss. And that is why it is chosen to have lower frequency for up-link and higher frequency for down-link in GSM standards. The same theory applies in almost all type of radio communication. NOTE: Frequency and power are independent of each other. For example you can control the transmission power of BTS antenna, which still transmits in the same frequency.
What is communication bus in IT?
If by IT you mean computer architecture, then the communication bus would be a physical path on the circuit board, that connects various components which passes electrical signals between each other.The nature of the signal is either "on" or "off" and the path is either serial or parallel in nature. The timing of each signal is regulated by a controller to avoid more than one component from sending a signal.
Explain if transmit baseband signal directly in a wireless system and why?
An antenna must be the order of magnitude of the, wavelength signal in size to be effective. Using only baseband transmission, FDM could not be applied and (Path loss, penetration of obstacles, reflection, scattering and diffraction. All the effects depend onthe wavelength of a signal.
What is the signal path for HDMI connections?
The signal path for HDMI connections can either be single link or double link. The single link is called type A/C.
What can you use a signal generator to find?
To trace a problem in an amplifier. Send in a signal and trace its' path.
How come low frequency current needs a return path but high frequency current does not?
The higher the frequency the lower the impedance is in air, vacuum or other insulation. High frequency usually finds its return path via stray capacitance. Some part of the energy is radiated by the conductors, as they form an antenna, even if not intended to do so. In this case the antenna impedance provides the return path.
What are the problems due to which transmission line suffers mainly?
Transmission lines suffers from three major problemsa. Attenuation distortionb. Delay distortionc. Noisea. Attenuation distortion: it is the loss of energy as the signal propagates outward. The amount of energy depends on the frequency. If the attenuation is too much, the receiver may not be able to detect the signal at all, or the signal mat fall below the noise level. For reliable communication, the attenuation and delay over the range of frequencies of transmission should be constant.b. Delay distortion: the second transmission impairment is delay distortion. Communication lines have distributed inductance and capacitance, which distort the amplitude of signals and also delay the signals at different frequencies by different amounts. It is caused by the fact that different Fourier components travel at different speed. It is due to velocity of propagation that varies with frequency. Thus, various frequency components of a signal arrive at the receiver at different times.c. Noise: Noise is a third impairment. It can be define as unwanted energy from sources other than the transmitter. Thermal noise is caused by the random motion of the electrons in a wire and is unavoidable.Source of Noise:Thermal:Agitates the electrons in conductors, and is a function of the temperature. It is often referred to as white noise, because it affects uniformly the different frequencies.Intermediation:Results from interference of different frequencies sharing the same medium. It is caused by a component malfunction or a signal with excessive strength is used.Cross talk:Similarly cross talk is a noise where foreign signal enters the path of the transmitted signal. That is, cross talk is caused due to the inductive coupling between two wires that are close to each other.Impulse:These are noise owing to irregular disturbances, such as lightning, flawed communication elements. It is a primary source of error in digital data.
What you called a fiber optical cable in which the light signal follow a single path?
Baseband systems use digital signaling over a single channel. Signals flow in the form of discrete pulses of electricity or light. Figure 2.19 shows a baseband transmission with a bidirectional digital wave. With baseband transmission, the entire communication channel capacity is used to transmit a single data signal. The digital signal uses the complete bandwidth of the cable, which constitutes a single channel. The termbandwidthrefers to the data transfer capacity, or speed of transmission, of a digital communications system as measured in bits per second (bps).
What are guided unguided media?
guided media is the transmission medium in which data/signal is guided by the cable or wire so used to a specific path. there are 4 types of guided media --> open wire -->twisted pair --> co-axial cable -->optical fibre for more details open the link ----- http://www.techbooksforfree.com/intro_to_data_com/page37.html#37
What wave has a shorter wavelength AM or FM?
Generally, the wavelength of an FM signal is shorter than an AM signal. A typical FM broadcast band is 88-108 MHz, while a typical AM broadcast band is 540-1660 KHz, making the FM signal wavelength 100 times shorter.
