How does dialup work? Answered
Hello. I am currently working on making my own dialup BBS, but seem to have run into a problem. See, I understand how the raw data is sent over the phone line (FSK, and how 56k basically uses an ADC with a DAC together, and outputs according to the PSTN sample rate). However, there are some things which I have specific questions about.
First, when data is communicated between a BBS host and a BBS user, how is the text sent? If I recall correctly it just uses ASCII characters. Is this correct? How does it handle the login input and similar functions?
Second, could someone please explain how the modem handshake process works? I have seen a photo explaining the various parts, but I don't completely understand it. See this photo to see the photo I am referencing: https://i.imgur.com/Q3lKIr1.jpg
Lastly, could someone please explain trellis modulation (TCM) for dummies?
I was lead to believe that a BBS does use ASCII characters to transmit data, due to a video where someone used a text terminal, along with a mode, to connect to his BBS.