Please throw out your random thoughts on this please. Help me get my brain spinning. Some technologies out there use AC riding on DC for digital communications. One example is in the 4-20mA space where HART is a communications protocol that uses two frequencies for 1s and 0s coupled to the DC 4-20mA. There is also techs coupling high frequencies on AC power. If I wanted to couple high frequency content onto 100V DC what issues would I run into, granted I have the components that can do the coupling. How strong a AC would have to be and what would happen if it were even higher DC voltage. Thanks.