The result of decommutation is the reconstruction of sensor measurements, packed bus data, or computer words. To be more meaningful and easily comprehended, measurements are viewed in user-friendly formats like engineering units (miles per hour, degrees centigrade, or psi), not as raw counts from a transducer. Real-time processing requires that data be converted/manipulated in real time to satisfy the immediate need to evaluate data and make decisions regarding safety, test continuation, controlling a satellite’s movement, etc.

To L-3 Telemetry-West, real-time processing means producing all the results from an algorithm before the next set of measurands arrive. The alternative is non-determinism and loss of data until processing resources are available. While buffering data for a very short period may be acceptable, loss of data is not. Adding more or faster resources may not produce desired results. In cases like this, you need a high-performance deterministic system that supports linear processing growth, where doubling the number of processors doubles processing resources.

In addition to EU conversion, real-time processors serve other functions, including the following:

• Alarm Checking — Real-time processors continuously check values against norms to ensure out-of-limits and caution boundaries are not exceeded or to predict problems due to trending over time.
• Bit Manipulation — Telemetry frames are not always orderly with one measurand per word. When resources are at a premium, instrumentation engineers will combine unused bits from several word locations to form an additional measurand. It is up to the real-time processor to assemble the new measurand and inject the result into the stream for further processing.
• Derived Parameters — A single meaningful attribute (e.g., air speed as a mach number) may be the result or derivation of multiple measurands (temperature, altitude, velocity) inhabiting multiple data streams.
• Data Compression — Often, data is sampled too frequently, producing too much data. This data is "compressed" using sampling or averaging algorithms.

Off-the-shelf ground systems, like those from L-3, typically include an extensive algorithm library appropriate for a variety of telemetry applications (see the table below for a general military flight test algorithm library).

A GUI eases the creation of the ground system setup database for real-time processing. L-3 products incorporate GUIs that range from simple fill-in-the-blank displays to elegant drag-and-drop techniques, where you can build a logic tree from a palette of functions, easily enter data, and select parameters with a point and click.

With L-3 systems, you can create your own application-unique real-time algorithms in traditional computer languages such as C, C++, and Java.