Don't bother messing with oscilloscopes. The quickest and easiest way to decode and validate IRIG-B signals is the Tekron IRIG-B Analyzer. With multilevel signal support, it gives accurate on-site fault diagnosis through a hand-held, rugged, portable and battery operated form factor. See our demonstration video here.
Tekron now takes this one step further when paired with the optional, free, ScopeApp™. ScopeApp™ is a revolutionary and easy to use IRIG-B oscilloscope app for Android devices that decodes and graphs IRIG-B signals when wirelessly connected to Tekron’s IRIG-B Analyzer. No internet connection is required once the app is installed, but if one is available you can email recorded captures to support personnel back at base for remote analysis and on the spot resolution.