Juice for the rig was supplied by the small 12V sealed lead acid battery in the background. Although lithium ion batteries are great for supplying power while being light, and I'll use one if I ever take my rig backpacking, SLA batteries are nice because they are cheap and use more common chargers.
The primary advantage of using a laptop rather than the iPad is that I can run pretty much any digital mode, not just PSK-31. The downside is that the laptop is a lot bulkier and the iPad and uses more power.
We have a chance of some thunderstorms today but I decided to give it a try out back, using my portable vertical antenna.
As you can see, I used my 15", mid-2009 MacBook Pro, which is running OS 10.9.5 and Fldigi. I did a separate post on configuring it.
I first tried calling CQ on 20M PSK31. Nobody came back but checking pskreporter.info showed that my signal was getting out as far as Montana.
I then posted to the AR15.com ham forum and switched frequencies to our forum's digital mode channel, and had a nice, extended rag chew with a member in Missouri, using Olivia 16/500. I was running 5 watts, while he ran 10 watts into a G5RV at about 35'. We both had 100% copy over a QSO that lasted a good 15 minutes.
This was a great proof of concept. I'll be bringing it with me camping in Tioga County, PA, next weekend.