The basic difference between fdm and fdma is that fdm is used in wired system where as fdma is used in wireless communication.
A PLL is different than a VCO. Each has its own use. Actually a PLL (Phase Locked Loop) contains a VCO (Voltage controlled oscillator). A VCO is an oscillator whose frequency is related to an input voltage. You can use it when you need a varying frequency that is controlled by a varying voltage. But it is not great at outputting a consistant exact voltage because it is very sensitive to its environment (e.g. temperature). A PLL will "lock" its output frequency to some input frequency. So it can oscillate at a frequency that is controlled by an input oscillator. Not too useful if the output frequency is the same as the input. But the output frequency can be divided before it is compared to the input. This allows the output frequency to be higher (some multiple of) the input frequency. Once a PLL is "locked on" to an input frequency it can be very stable.
Optical data transmission is the name of the method of sending data through fiber optic cables. One optic cable can contain hundreds if not thousands of optic fibers. Simplex and half duplex systems use only one fiber to communicate. Simplex transmits only in one specific direction, while half duplex can send in both directions but not at the same time. If likened to a walkie-talkie radio, when the talk button is pressed it is transmitting out but will not be able to receive incoming transmission until the talk button is released. In a full duplex system, two fibers are used to communicate. One fiber is transmitting from point A to point B and the other fiber is transmitting back from point B to point A.
When applied to electrical waveforms, a 'harmonic' is a multiple of the fundamental frequency.
If an inline capacitor is inserted in the feedback from the output to the input of an op-amp it will act as a frequency filter and only boost audio frequencies within the resonant frequency range of the capacitor. If you gang multiple op-amps in a wein bridge arrangement you get an analogue audio filter capable of shelf boost or cut.
SUB STATION An intermediate electricity-distributing location from which electrical energy is transformed and transmitted to users within a given geographical area. GRID STATION It is a station where multiple inputs/outputs comes and goes , where the voltage is transformed as it is required.
Multiplexing is the process of combining multiple signals over one media line. There are several types of multiplexing: frequency division, time division, and wavelength division.
AM radio broadcasting uses frequency division multiplexing to allocate different frequencies to different radio stations. Cable television systems use frequency division multiplexing to transmit multiple channels simultaneously over a single cable. Cell phone networks use frequency division multiplexing to separate different users' calls on the same frequency band.
Currently the mobiles use GSM(Geo Synchronous Mobiles ) and CDMA(Code Division Multiple Accesss) techniques. GSM inturn uses TDMA(Time Division Multiplexing) or FDMA(Frequency Division Multiplexing) or sometimes both to fit in the required criteria.
Time Division Multiplexing and Frequency Division Multiplexing. Allows multiple data channels across a single medium by separating the data streams onto different frequencies (FDM), or by sending one stream, waiting, then sending the other stream (TDM).
WDM (wavelength division multiplexing)
multiplexing refeers to the transmission of different signals in the same channel simultaneously. There are many forms of multiplexing that can be used, including frequency division multiplexing(FDM) where individual signals are transmitted over adjacent , non overlapping frequency bands. they are transmitted in parallel and simultaneously in time. In time division multiplexing(TDM) each signal is allowd to use the whole bandwidth for a certain period of time. Multiplexing is needed so that the available channel can be used efficiently and also to save costs. There is too much to know about multiplexing, here is just a short overview. One thing that one has to know is multiple access.
Faouzi Bader has written: 'Advances on processing for multiple carrier schemes' -- subject(s): Orthogonal frequency division multiplexing, Multiple access protocols (Computer network protocols)
Multiplexing and multiple accessModern telephone networks allow bandwidths in their channels that are much larger than those is needed for a digitalized telephone channel. Basically, a number of channels share a common transmission medium with the aim of reducing costs and complexity in the network. Multiplexing is defined as the process by which several signals from different channels share a channel with greater capacity. When the sharing is carried out with respect to a remote resource, such as a satellite, this is referred to as multiple access rather than multiplexing. There are various ways of performing this sharing:# FDM/FDMA (Frequency Division Multiplexing/Frequency Division Multiple Access): Assigns a portion of the total bandwidth to each of the channels. # TDM/TDMA (Time Division Multiplexing/Time Division Multiple Access): Assigns all of the transport capacity sequentially to each of the channels. # CDMA (Code Division Multiplexing Access): In certain circumstances it is possible to transmit multiple signals in the same frequency and at the same time, with the receiver being responsible for separating them. This technique has been used for years in military technology, and is based on extending the spectrum of the signal and reducing the transmission power. # PDMA (Polarization Division Multiple Access): Given that polarization can be maintained, the polarization direction can be used as a multiple access technique, although when there are many obstacles noise can make it unsuitable, which is why it is not usually used in indoor installations. Outside, however, it is widely used to increase transmission rates in installations that use microwaves. # SDMA (Space Division Multiple Access): With directional aerials, the same frequency can be re-used provided the alignment of the aerials is correctly adjusted. There is a great deal of interference but this system lets frequencies obtain a high degree of reusability.
Multiple subcarrier frequency refers to a method of dividing a single carrier frequency into multiple smaller subcarriers. This technique is commonly used in communication systems like Orthogonal Frequency Division Multiplexing (OFDM) to efficiently transmit data by dividing the available frequency bandwidth into multiple subchannels. Each subcarrier carries its own data stream, allowing for parallel transmission and improving spectral efficiency.
Broadband refers to telecommunication that provides multiple channels of data over a single communications medium, typically using some form of frequency or wave division multiplexing.
A single communications channel can carry simultaneous data transmissions from multiple sources through techniques like multiplexing. Multiplexing divides the channel's bandwidth into multiple segments, allowing different signals to be sent concurrently without interference. Common methods include Time Division Multiplexing (TDM), where time slots are allocated to each source, and Frequency Division Multiplexing (FDM), which assigns different frequency bands to each signal. This efficient use of the channel's capacity maximizes data transmission while minimizing the risk of collisions.
Andrea Borella has written: 'Wavelength division multiple access optical networks' -- subject(s): Multiplexing, Wave length, Congresses, Wavelength division multiplexing, Light, Optical communications