When is DC coupling used?
DC coupling should be considered whenever there is information to be transmitted which has a frequency component lower than 100 Hz for telemetry transmitters, 6 Hz for video transmitters, or 1 MB/s for digital transmitters. There is a misconception that randomizing digital information removes the low frequency components. While the DC component is removed, the link should have a response down to 1/3000 of the randomized bit rate or the bit error rate (BER) will suffer. This phenomenon was discovered by Mr. Eugene Law of NAWC-Point Mugu and he subsequently authored a paper entitled (?) detailing his findings. See 2002 Proceedings of the ITC **********