So after the other posts I put up about measuring and decoding DCS.... a lot of folks emailed me (we're talking more than 10) and asked me what the frequency of the DCS track signal is?
(I guess they were interested in troubleshooting potential interference or something).
Anyways the "frequency" is a complicated question because the DCS PN-code is a broadband signal. One of the side effects of this is that even though the digital spread-chip rate is only 3.75 MHz, the actual signal is wider by more than a factor of 2 (like 7-8 MHz). I know this seems very not-intuitive and I don't want anyone just taking my word for it... Therefore instead of a hand-wavy answer ... I did a quick analysis from the very basic principles and showed all the steps so everyone can see how it's done.
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DISCLAIMER: I know it's a bit math intensive but feel free to skip to the end if you just want the spectrum... I just put the rest in case someone wants to know how the calculation is done.... even for other projects besides DCS signals...
Who knows? Maybe someone will read it and get a A+ instead of a B in their signals and systems class...
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Anyways it's attached as a PPT and PDF. Feel free to ask questions!
P.S. Just so you know there's a pile of paper on my desk with equation scribbles because I had to work out the algebra and make sure it was clean before I transcribed it into power point.
