ANSI EIA-364-108:2000 pdf download.Impedance, Reflection Coefficient, Return I OSS, and VSWR Measured in the Time and Frequency Domain Test Procedure for Electrical Connectors, Cable Assemblies or Interconnection Systems.
This procedure applies to interconnect assemblies, such as electrical connectors, and caNe assembiLes.
1.2 Object
This Linclard describes test methods to measure impedance, Tef1CCUOfl coefficient, return toss, and voltage standing wave ratio (VSWR) in the time and frequency domains.
NOTE — These test methods are written for test professionals who are knowledgeable in the electronics field and arc trained to use the referenced equipment. Because the in.surement values are heavily influenced by the fixturing and equipment this method cannot describe all of the possible combinations. The major equipmcnt manufacturers provide Application Notes for more in’depth technical description of how to optimize the use of thcir equipment. It is imperutive that the referencing document include the necessary description and sketches for the test professional to understand how to seLup and perfomi the requested measurements.
13 Definitions
1.3.1 Measurement system rise time
Rise time measured with the fixture in place, withou( the cpecimcn, and with filtering (or normalization). Rise timc is typically measured fron 10% Ic 90% levek.
1.3.2 Specimen environment impedance
The impelance presented to the signal conductors by the fixture. This impedance is a resuft of transmission lircs, termintioa resistors, attached reccivers or signal sources, and fixture parasitics.
The reflection coefficient at the input port of the device under test, defined as ibc ratio of the reflected voltage to the incident voltage
1.3.8 Termination (eLectronics usage)
An impedance connected to the end of a transmission line, typically to minimize relkctcd energy on the line.
1.3.9 Step amplitude
The voltage difference betwccn the 0% and 1O0% levels, ignoring ovcrthoot and undershoot.
2 Test resources
Care shouid be taken when esablisLiing the eqiiivalence between time and frequency domain measurements. The relationship bctween the two is complex and the applicaticrn of bandwidth=(035/rise time) should not c used without further computations and unc1erstandin.
2.1 Equipment
2.1.1 Tirnedomnin
2.1.1.1 A Time Domain Ref)ectometer (TDR) is preferred, although an oscilloscope and pulse generator may be used. A network analyzer may be used with FFT (Fast Pourier’Transform) software.
NOTE — The test pmfessicnal should be aware of limitations of any math operation performed by an instrument (e.g., FFT).
2.1.1.2 Variable rise Lime
A means should he pnwidcd frr varying the signal rise time if required. This may bc included within the test equipment itself, or possibly through additional filtering or software.
NOTE — l’he test professional should be aware of limitations of any math operation pcrformed by an instrument or software; e.g, normalizatioii or filtering.ANSI EIA-364-108 pdf download.