Signal Strength Jumping

Station issues typically result in signal loss for intervals lasting much longer than a few seconds at a time. Meter behavior like this indicates that the tuner has lost its lock on the digital station. There are two possible culprits.

The biggest cause is multipath interference -- signal reflections arriving at the tuner at slightly different times, "confusing" it as to which one is the true signal. A more-directional antenna usually solves this issue.

Pre-amplifier and/or tuner overload can also cause this to happen. Overload distorts the digital signal such that the tuner can't decode it properly. Reducing amplifier gain, or removing the amp, resolves this problem.

What were the weather conditions? I am thinking wind and trees. It doesn't take much to knock down a digital signal, at least in my experiences.

I'm not sure if this is what's happening to you, but sometimes the signal drops off for me if a large truck drives through the path from tower to antenna.

You might want to try an inline amp. 20-40 miles is out a bit. I have trouble at 15 miles locking in a digital signal in my rural area with out an amp. See if it persists over the next few days. It may just go away, some temp interference perhaps.

Mike

I have seen a similar problem over the summer with a local PBS station, check your local forum to see if others are noticing drop-outs where it was once solid.

Otherwise call the station they might be aware of a problem.

I see this when there are helicopters flying around. Normally there are none but if there is a wreck, fire, etc, there will be a few. They can cause multipath at a pretty good distance where you might not hear them. If it becomes a daily issue then something else has changed. Amps can go bad and do weird stuff like that on digital. Back in the analog days it was easy to see an amp go bad.