The kCBAdvDataTimestamp field is added to the advertisement by iOS. It is just the time stamp of when the advertisement was received and can be converted to a NSDate using:NSNumber *number = advertisementData["kCBAdvDataTimestamp"];NSTimeInterval absoluteTime = number.doubleValue;NSDate *date = [NSDate dateWithTimeIntervalSinceReferenceDate:absoluteTime];Apple also adds kCBAdvDataRxPrimaryPHY and kCBAdvDataRxSecondaryPHY to the advertisement data. Both are NSNumber values and are set to 0 in all the devices I have seen. Their purpose remains a mystery.