Fig. 6-6 is a block diagram of a typical digital baseband signal transmission system. It is mainly composed of a transmission filter (channel signal generator), a channel, a reception filter, and a sampling decider. In order to ensure the reliable and orderly operation of the system, there should also be a synchronization system.
The functions of each block in the figure and the physical process of signal transmission are briefly described as follows:
(1) A channel signal former (transmission filter). Its function is to generate a baseband signal waveform suitable for channel transmission. Because its input is generally the transmission code generated by the code type encoder, the corresponding basic waveform is usually a rectangular pulse, and its spectrum is very wide, which is not conducive to transmission. The transmission filter is used to compress the input signal band and convert the transmission code into a baseband signal waveform suitable for channel transmission.
(2) Channel. It is a medium that allows baseband signals to pass through, usually a wired channel, such as a twisted pair, coaxial cable, etc. The transmission characteristics of the channel generally do not meet the distortion-free transmission conditions, so the transmission waveform will be distorted. In addition, noise n (T) is introduced into the channel, and it is assumed that it is Gaussian white noise with a mean value of zero.
(3) A reception filter It is used to receive signals, filter out channel noise and other interference as much as possible, equalize channel characteristics, and make the output baseband waveform conducive to sampling decisions.
(4) Sample selector. It is to sample and determine the output waveform of the receiving filter at a predetermined time (controlled by the bit timing pulse) in order to recover or reproduce the baseband signal under the background of unsatisfactory transmission characteristics and noise.
(5) Pulse timing and synchronous extraction bit timing pulse used for sampling are extracted from the received signal by the synchronous extraction circuit. The accuracy of the bit timing will directly affect the decision result.
This is the composition of the digital baseband signal transmission system brought by Shenzhen HDV Phoelectron Technology Co., Ltd. to you. I hope this article can help you to increase your knowledge. Besides this article if you’re looking for a good optical fiber communication equipment manufacturer company you may consider about us.
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