It won't block portable receivers that are used to feed flight tracking companies. Your N number is easily determined from what your ADS_B transponder broadcasts, so even when you don't file a flight plan, you can be tracked and your N number is available. The FAA has a program called Privacy ICAO Address(PIA) program. What they do is provide you with an ICAO address that does not relate to your real N number and on the FAA registry don't include any personal information for that record. You need to obtain a third party call sign, for example FFL from ForeFlight and you file with the PIA ICAO address in the transponder (a maintenance configuration setting) and set the call sign into the aircraft ID before each flight in your transponder. That way if someone hears you on the radio with ATC, you are not using your real N number, but rather the third party call sign and your transponder ADS-B Out is broadcasting the ICAO address associated with an unassigned N number in the FAA registry. Your transponder also broadcasts the call sign. The FAA can figure out who you are, but not the tracking companies. If someone is recording ADS-B data near an airport and video tapes the aircraft that are broadcasting the PIA, they could figure out the association with your N number. You can periodically request a new PIA and third party call sign if you or someone compromises your aircraft identity.