More likely they have one of a couple of standard values as a reference frequency and then use a synthesizer to generate whatever other frequencies they need.Do all wireless devices have there own oscillating crystal at their own very specific frequency, each device being slightly different? If so, how is this level of accuracy when fabricating the crystals possible? Is it easier than I am assuming?
QPSK I believe. That's Quadrature Phase Shift Keying. Do you know what that is?Ok I see. Another slightly unrelated question. What is the most common digital modulation technique used in modern wireless systems like WiFi?
Check out page 6 of the following paper for a diagram of how a Barker code is used to encode data bitsYa I have heard of QPSK, its basically phase shifting using 90 degree angles to achieve 4 possible states.
So what are things like CCK (complementary code keying) and Barker code? That is what i got when looking up modern digital modulation methods, not QPSK.
I don't think "encrypt" captures what is going on. I think "encoding" and "decoding" are closer to the mark. When digital data is put onto a physical media there are certain desirable properties it needs to have. A known spectrum is one thing and a reliable decoding method is another. These topics are the subject of entire books, and a series of forum posts is not a great place to convey the required background information.So is all modulation just a form, or combination, of PSK, ASK, and FSK? Are all those other things (CCK, DSSS, Barker Code) just ways to "encrypt" the binary data being sent?
It seems modulation encoding would be as simple as "this phase represents 00, this phase represents 01..." Why does there have to be complicated encoding schemes for wireless digital transmission?yes........but encoding ASCII is not modulation.
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