That's an excellent question. I do know that I am occasionally showing a ghost of myself that I just found out and I think I am also getting a reflection from the UAT towers as well. I do have my ID input into IFLYGps. I did talk to FreeFlight Support, and I was told to set my encoder to 10 foot increments.
Below, quoted from FreeFlight Support Engineers -
"We've seen a few types of Ghost:
- Transponder and ADS-B outputting different altitudes in the same aircraft. Both systems should be fed altitude data by the same encoder. This one is resolved by setting the encoder to transmit to the RANGR 10 ft increments. If there are two different altitude sources for the RANGR and transponder, this ghost will persist.
- When you fly into radar coverage, it takes 2-3 radar sweeps to coorelate your radar position to your ADS-B position. In that time period a TIS-B target is generated by the Radar system and fed to the ADS-B network at your exact location and altitude. The FAA is working on this.
Hope this explains it. "
So, I am waiting for another response to a question I just sent in today before I reprogram the encoder (FreeFlight TC978) to the 10 foot increments which feeds a garmin GTX 327 that is set (factory) at 100 foot increments for Mode C (haven't taken time to study schematics transponder inputs for a 10 foot setup yet on Xpndr). Trying to find out if there will be conflicts between Encoder, Transponder, and ADS-B 978 UAT box (in/out). All of this has nothing to do with IflyGPS software as all moving map software (ForeFlight and others) are showing ghosts. Its in the ADS-B system.