I was attenpting to fly at a fairly large public event yesterday and I kept getting a No Signal message and a Strong Interfernce in the area message. I was trying to fly my P3A using DJI GO and an LG 8.3 tablet. I've flown from this spot several times before. I drove a few miles to a closed airfield that is now used to store FEMA trailers. I get a message that it's a no fly zone and couldn't get the motors to start. There hasn't been an airplane land there in probably 20 years and I've flown from that location before with my P2V. Getting frustrated I went back to the origional location. I noticed a drone in the air but it seemed to be on a crash decent into a bridge or the river. It was coming down at what appeared to be a 45 degree angle at a very fast speed. I lost sight of it. The local police department recently bought four P3Ps and I figured it was one of theirs. They might have lost a bird yesterday. Anyway I tried again to fly and had no problem. I did about a 7 minute flight around the event and landed. When I tried to take off again I got the same No Signal and Strong Interference message. Is it possible that officials were jamming the signal at some point and I just lucky and hit a time when the jamming was off? If so what would happen if you're flying and they start the jamming or you fly into the affected area. I'm thinking I could have lost my P3A yesterday and it's a scary thought.