Self-controlling vehicles are acting increasingly autonomous, such that runtime verifi- cation, i.e. error reports to the system, by monitors is becoming an essential part of the self-navigation of the machinery. A sensor can deliver a constant stream of data to a monitor, which is generated by a specification. Until now, most models assumed that the data has to be precise and accurate. However, a drone has to fly in a natural environment, with unexpected factors such as a storm or a blizzard, which can cause wrong measurements and result in inaccurate data provided to the monitor. Intervals are proven to solve this issue, thus enabling the possibility to define error mar- gins for a given data stream. The monitor can therefore check and process inaccurate data. Currently, intervals are not present in most specification languages. This thesis introduces intervals for the stream-based specification language RTLola. We present the addition of new arithmetic operators and show the advantages of using intervals.