When you tap on a traffic target while using a Stratus ADS-B receiver, you will get an information pop-up. In the description, you may see the frequency band used (978 or 1090ES) followed by "ADS-B", "ADS-R", or "TIS-B".
When "ADS-B" is shown in the description it indicates that the information was obtained via Air-to-Air broadcast, which is a direct broadcast from an ADS-B Out-equipped aircraft.
When “ADS-R” is shown in the description, it indicates that the ground station re-broadcast the ADS-B message it received on the other ADS-B frequency. This is a service provided to client aircraft that indicate they do not have a dual frequency receiver.
When "TIS-B" is shown in the description it indicates that the information was obtained via broadcast from a ground station. Ground stations provide the TISB service for ADS-B Out-equipped client aircraft. The TISB target is not ADS-B Out-equipped and is detected by a secondary radar system. All TISB targets must have an operating mode C transponder.