Each multi-path would have a certain weight factor attributed to it to account for the reflection and transmission losses. It has been observed that at higher frequencies the channel attenuation increases. Hence the channel might be described as random and time varying with a frequency dependent signal-to-noise ratio SNR over the transmission bandwidth. Noise in Power lines is a significant problem for data transmission.
Typical sources of noise are brush motors, fluorescent and halogen lamps, switching power supplies and dimmer switches. The noise in power lines can be impulsive or frequency selective in nature. The noise in power lines can be classified into four categories:.
For low cost, low data rate applications, such as power line protection and telemetering, FS is seen as a good solution. Frequency selective fading as experienced by the power line channel severely impairs the capacity of FSK for data rates beyond a few kilobytes e second. A high degree of error control coding would be needed. Combined with the low spectral efficiency of FSK, it would limit the data rate achieved. The signal of each user is spread using a spreading code at the transmitter.
The receiver de-spreads the message using the same code. CDMA provides robustness against narrowband noise and other forms of interference. However, the processing gain must be high to effectively counter interference from other users. While transmitting over power lines at high data rates, the symbol duration is so small that delayed versions of one symbol gets smeared over a large number of other symbols.
This makes the detection process complicated since it requires complex equalization techniques to counter the inter—symbol interference. Serial data is passed through a serial-to-parallel converter. It splits data into a number of parallel channels with individual modulators. Each modulator has a different carrier frequency and carries a small portion of the original data rate. This increases the symbol length so that it becomes longer than the longest delay path.
This solves the inter-symbol interference problem to a large extent. OFDM also avoids transmitting at frequencies in deep fade. All parallel Modulators are required to attain a minimum threshold of signal-to-noise ratio, otherwise, they are shut off.
Modulators with a high signal-to-noise ratio are made to carry more bits using adaptive bit loading technique. For the Medium access control of multiple users to the network transmission capacity, a resource sharing strategy is used.
Contention based protocols may cause collisions hence they are not suitable. The PLC Market is expanding dynamically. Advanced energy services include applications such as automatic meter reading, programmable controllers and demand supply management. Homeplug standard uses OFDM in a burst mode as a physical layer modulation. Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up.
Download Free PDF. Conducted immunity requirements tests for power line communication coupling interface circuit International Conference on Electrical Engineering and Software Applications, Adel Ghazel. A short summary of this paper. Conducted immunity requirements tests for power line communication coupling interface circuit. An important research activity has been focused on applied to coupling circuits designed, by authors, for the characterization and modelling of the broadband power line narrowband Power Line Communication channel measurement.
The use of a transients tests specifications. An characterization, coupling circuit, immunity requirements tests appropriate design for narrowband PLC coupling circuits is presented in [12].
It is based on band pass filtering and I. The possibility of ensuring data transmission over the widespread electric power In this paper, authors present the specifications and the supply network makes the PLC technology a very attractive results of immunity tests applied to the designed coupling solution for deploying fast and reliable communication interface circuit in order to use it for characterizing the services [1].
However, the power line channel is a hostile narrowband PLC channel. Section II describes the environment for data transmission since the electric experimental setups used for making measurements on the infrastructure has been first dedicated for power delivery.
Section III outlines the specifications of immunity suffers from the presence of several types of disturbances such requirements tests, especially for surge tests and fast transient as the background noise and the impulsive noise [2].
The use bursts tests. In section IV, the tests results are presented and of sophisticated communication techniques allow to overcome commented. Experimental Measurement Setup access [3,4]. The vector network industry and the market interest. These low frequency PLC analyser HPE is able to measure the S- parameters of the systems can deliver up to kbps based on multicarrier channel by emitting a signal at an electrical outlet and receiving solutions for Smart Grid applications such as advanced it at another one.
The complex transfer function of the PLC metering infrastructure AMI , demand response and in-home channel is given through the transmission coefficient S21, and environment [1]. Two similar coupling circuits narrowband PLC channel is then of paramount importance to are used to connect the network analyser to the power line, and develop reliable PLC systems and improve transmission the measurement setup is calibrated by a direct connection chains performance.
The set-up of a suitable model for the between these two coupling interfaces. Government work not protected by U. Figure 2. Proposed coupling interface circuit design in the receiver side The transmitter coupling circuit, with protective circuitry, is obviously symmetric to the receiver one as shown in Fig. Experimental setup used for a transfer function and impedance measuremens b noise measurements B.
Coupling Circuit Design In order to make measurements on the power line, appropriate coupling circuits have been designed then realized and used [12].
The coupling interface performs several Figure 3. In addition to its filtering function, the coupling circuit transient overstress during power-up and surges on the power guarantees impedance matching with the measurement device line. In following sections, hazards when making measurements. Also, it provides authors will present the description and the results of equipment protection against many risks of damage, mainly experimental measurements to verify the conformity to due to the direct connection to the mains.
As shown in Fig. We have used a high voltage series capacitor of 0. In particular, the EN part [13], which protection devices on the mains coupling path, to prevent high includes the basic standards EN [14] electric fast energy disturbances coming from the mains from damaging the transients and EN [15] surges , defines the test internal circuitry of the measurement instrument. Protection methods and immunity limits ensuring the electromagnetic components have been well selected to be added to the compatibility on the grid.
Surges Tests Specifications clamping device that turns on in the case of an overvoltage Surge tests are specified as both common and differential condition. The surge waveform, which is defined in EN, exceeding the supply rails and provide additional protection by is shown in Fig. The front time T1 of a surge voltage is defined as 1.
The time to half-value T2 further enhances surge protection by limiting overvoltage represents the time interval between the virtual origin O1 and spikes which could damage the high voltage series capacitor. Immunity Tests Setup The setup used for testing the coupling interface immunity is schematically shown in Fig. The conducted EMC test system Schaffner System is able to generate surges and fast transient bursts conforming to immunity requirements tests specifications.
0コメント