For over 20 years, i've been in communications maintenanceCommunications technologySpecialized students. The telephone is not visible, but it contains a system of analogue signals, digital coding and exchange controls. A lot of people think it's out of date, but if you read it on the second edition of "telephones and repairs", you'll find it's the bottom, it's not solid, it's the base station behind it, it's all the air。
Where's the phone
To be honest, it's not welding, but..Signal linkI don't know. An ordinary analog telephone machine, from the vibration of the amplitude in the microphone to the generation of dial-up pulses, is relayed back to the switch, with a mixed loop, a ringing circuit and a pick-up to detect the circuit. Any problem with the nodes could be "no sound" or "no noise" or "no machine". The students came up and tried to change their parts, but they couldn't locate the real failure point without breaking three or four, and there was a special chapter in the book about the failure tree, and i had the students walk through the object, much better than looking at it。
Digital telephones are more troublesome. Dtmf double audio, pcm code, time swap, with three full chapters in release 2, more than double the size of release 1. You have to really understand the numbers of each frequency combination to capture that millisecond abnormal waveform on the oscillator and to judge whether it's a coding or a decoding end. I've seen a lot of schoolbooks that are so full of shit that i can't even tell you what to do with my board。
How do you learn how to use a phone
Don't start with the theory. I've always been the first to ask students to unload an old magnetic phoneListeners, messengers, relays, branch boxes, each module is to be removed for separate testing and then returned for electron sound. When you touch every weld, every thread, and then you read the schematics, those boxes and arrows are no longer dead symbols. They're something you really touch. The wiring method of chapter 2 of the book, combined with physical reading, is really understood。
Release 2 contains more digital exchange and integrated operations digital network content than release 1 and this part is suggested in conjunction with the experiment. Take a dtmf decoded chip, put a 555 timer on the ringing circuit, turn those abstract frames from the book into a pile of electric resistance, capacitor, triode tubes. Specializing in communication technologyIt'll take ten times to do itI don't know. I was doing a little bit of work, and i had a phone set up, and then after six months, the whole thing worked out, and now i'm taking students。
Don't throw this book twice as a textbook. It's got one on the bed, it's been going around for two, three years, and the circuits and the cases of failure are going on. When you look at any communication device, you can see where the signal comes from, where it goes and where it breaks. In the field of communications technology, there is no fear of development in the background。
