TinyGPS++ Question about gps.encode(ss.read())
From http://arduiniana.org/libraries/tinygpsplus/
Validity, Update status, and Age
You can examine an object’s value at any time, but unless TinyGPS++ has recently been fed from the GPS, it should not be considered valid and up-to-date. The isValid() method will tell you whether the object contains any valid data and is safe to query.
Similarly, isUpdated() indicates whether the object’s value has been updated (not necessarily changed) since the last time you queried it.
Lastly, if you want to know how stale an object’s data is, call its age() method, which returns the number of milliseconds since its last update. If this returns a value greater than 1500 or so, it may be a sign of a problem like a lost fix.