I'm currently sending high speed serial over a coax cable. I've got an oscilloscope hooked up (on the load end) trying to watch the clock pulse signal. I've got a 10 ft coax cable with a 12.5 Mhz clock signal. I'm unsure of the coax impedance and the load impedance.
The clock signal appears to be deformed. I'm curious if this deformation is due to the cable acting like a transmission line and specifically due to transmission line reflection.. However, I'm unsure on some of the properties of the reflection.
Is the reflection of a signal frequency dependent? Thus the superposition of all of the frequencies in the square wave would be phase adjusted and report a bad clock signal?
Best Answer
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If \$Zc=\sqrt{\dfrac{L}{C}}=Z_{source}=Z_{load}\$, then there is no frequency dependance, the signal is just delayed but not distorted. If any part of above equation isn't equal, then you get standing waves.