the form of pulses, the transmitter and the receiver

In digital communication systems, information is encoded in the form of pulses and then these light pulses are transmitted from the transmitter to the receiver.
I cann’t understand why "the"s are used in the sentence above.
the form of pulses, the transmitter and the receiver are not mentioned before.
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It is encoded in this particular way.
They are transmitted using this particular (type of) transmitter.
They are received by this particular (type of) receiver.

Thanks, Beeesneees!

When you read the sentence above, do you know what are “this particular way”, “this particular (type of) transmitter” and “this particular (type of) receiver”?
Does the use of “the” depend on writer? If the writer know about these particular things but the readers don’t have any ideal about those things, then “the” still can be used?

In speaking, the word “the” is often included when it is not needed, as buffering; it gives the speaker more time to think. Hems and haws are used for the same purpose, but do they actually think? Probably not.

In digital broadcasting, a single transmitter’s signal may reach many receivers. If you’re talking about the signal Bill gets, then there is “the” receiver. If you are talking about the signal broadcast by WOWO, then there are many receivers and speaking of “the” receiver is misleading.