Hc represents the number of employees, that is, the number of employees that the company HR (human resources) is expected to recruit.
Cit is California Institute of Technology, referred to as "Caltech", founded in 189 1, located in Pasadena, the northeastern suburb of Los Angeles, California, USA, and is a world-class private research university. ?
T/T (telegraphic transfer in advance), which is what we usually say, is a common payment method in trade. Advantages: high speed, the seller can get the money quickly, and the security is high. Disadvantages: high cost, generally the traffic between SWIFT.
Tp is twisted pair, which is the most commonly used transmission medium in integrated wiring engineering. It consists of two copper wires with insulating protective layer. Two insulated copper wires are twisted together according to a certain density, and the radio waves radiated by each wire will be offset by the radio waves emitted by the other wire, thus effectively reducing the degree of signal interference.
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Twisted pair is formed by twisting a pair of insulated metal wires. This can not only resist some external electromagnetic interference, but also reduce the mutual interference between twisted pairs.
When two insulated wires are twisted together, the interference signal acts on the two twisted wires in a consistent way (this interference signal is called * * * mode signal), which can eliminate the * * mode signal in the difference channel of the received signal, thus extracting the useful signal (differential mode signal).
The function of twisted pair is to make the noise produced by external interference on two wires the same (useless signal is called noise in the professional field), so as to extract useful signal in the subsequent difference channel. The difference channel is a subtraction circuit.
The in-phase signals (* * * mode signals) of the two inputs cancel each other (m-n), and the anti-phase signal is equivalent to x-(-y), which is enhanced. Theoretically, m=n and x=y in twisted pair and differential channel are equivalent to completely eliminating interference signals and doubling useful signals, but there are some differences in actual operation.