The test procedures that reference this document are intended to allow a competent technician or engineer to perform the tasks of determining, to a reasonable degree of certainty, the level of performance for the various parameters detailed. The procedures are general in nature and with sufficient forethought and preparation, can be adapted to individual devices, cascades or complete systems. The primary focus for these procedures is for bench or laboratory testing, but the principles discussed are equally applicable to field testing. When the suggestions made in this document conflict with the detailed steps of a specific procedure, the specific test procedure will take precedence.
In order to maintain the simplicity and reduce the overall size of the individual procedures, most theoretical and practical discussions regarding test equipment, methodology and variations in techniques, as well as information which is generic or repetitive in nature is discussed in this document. This will also allow alterations and/or updates to be handled more easily by reducing the total number of documents (or sections) which will be affected. Specific information or data required for a single test, or a limited number of tests, will be found in those procedures as needed.
Measurements can normally be separated into two types, absolute and relative. Absolute measurements are used for determining such items as signal levels, modulation deviation, etc. Relative measurements are made with respect to a reference level or parameter and some examples are distortion, frequency flatness, depth of modulation, etc. Absolute measurements are typically more difficult to make within the same tolerance limits as relative measurements since more measurement tolerances within the test equipment and test configuration must be considered. Relative measurements are often quite accurate since many of theses tolerances are cancelled in the final calculations, especially when measurement conditions are carefully maintained. Relative measurements are often used as the basis for comparison