The problem with EMP is that its been used as a plot device in Hollywood for decades now and everyone thinks it takes out all electronics. It doesn't. Your caar and cell phone and ipad are going to be just fine. The power grid and stuff hooked up to it are susceptible just like a lightening strike. And sensitive front ends like dish and HF antennas could be wiped. There will be a lot of car alarms triggered.

In Starfish Prime which was a one megaton high altitude burst it set off some burglar alarms in Hawaii and took down some of the power grid and thats it.

It fries satelllites beause it ionizes the upper atmosphere and pumps up the Van Allen belts with protons and electrons. Thats probably the most dangerous effect. he Iridiums would probably crap within a couple of weeks along with all spysats. Most of the GPS constellation would make it through. Don't know how the commercial comsats would fare but one analysis said they would all be wiped if not shielded by the earth.