IEEE 1027-1996 pdf download IEEE Standard Method for Measurement of the Magnetic Field in the Vicinity of a Telephone Receiver
1.Overview
This standard describes the methodology for measuring the magnetic field strength in the vicinity of a telephone receiver.
Recommended test equipment,including probe coils and test circuits, are described in clause 4. Magneticfield probe calibration is outlined in clause 5. Test procedures are described in clause 6. Annex A describes asuitable integrator circuit for linearizing the probe coil output voltage. Annex B gives the derivation of therelationship between the electrical output of the probe coil and the magnetic field strength. Annex C illus-trates a method of generating a known magnetic field using Helmholtz coils.
1.1 Scope
Magnetic fields of analog and digital telephone receivers, as well as non-traditional telephone receivers, suchas wireless devices, may be objectively measured using this standard. Receivers not connected to a telephonemay be evaluated as well. Measurement of static fields, such as those created by permanent magnets, is notcovered.
The methodology described in this standard is suitable for measurements in the range of 100 Hz to10 000 Hz.
1.2 Purpose
The impetus for this work was derived from a need to specify the alternating magnetic field at selected locations around a telephone receiver required for satisfactory inductive coupling to hearing aids. It is also usefulfor other applications where knowledge of the magnetic field strength is required.
The results, thus obtained, may be used to evaluate or specify the magnetic field strength produced by areceiver on a standardized basis.
The accuracy and reproducibility of measurements made in accordance with this standard will depend primarily upon the accuracy of the test equipment used, the care with which the measurements are conducted.and the inherent stability of the telephone or transducers, or both, under test.
Where a given set of measurements is repeated in the same laboratory and by the same operator, a relativelyhigh degree of reproducibility should be obtained.When comparing measurements made by different laboratories, however, allowances should be made for the influencing factors mentioned above
2.References
This standard should be used in conjunction with the following publications. When the following standardsare superseded by an approved revision, the revision shall apply, but the impact on results should be deter-mined.
IEEE Std 100-1992, The New IEEE Standard Dictionary of Electrical and Electronics Terms (ANSI).
EEE Std 269-1992,1EEE Standard Methods for Measuring Transmission Performance of Analog and Digital Telephone Sets (ANSI)
EEE Std 1206-1994.1EEE Standard Methods for Measuring Transmission Performance of TelephoneHandsets and Headsets (ANSI).
ITU-T Recommendation P.37-1993, Magnetic Field Strength around the Earcap of Telephone Handsetswhich Provide for Coupling to Hearing Aids.2
ITU-T Recommendation P57-1993,Artificial Ears
3. Definitions
3.1 ear reference point (ERP): The intersection of the receiver ear-cap axis with the external ear-cap plane(planar area containing points of the receiver-end of the handset which, in normal handset use. rest againstthe ear) as shown in figure 1
3.2 frequency response: The ratio of the magnitude of the system output to the magnitude of the stimulusover a specified frequency range.
3.3 Helmholtz coils: A pair of coils so proportioned as to provide a known uniform magnetic field that maybe used to calibrate a probe coil.
3.4 integrator: A device having an output proportional to the time integral of the input signal
3.5 magnetic field strength: The magnitude of a time-varying magnetic field, that, when coupled to a coil,induces a voltage. The unit of magnetic field strength is amperes per meter (A/m).
3.6 probe coil: A coil (air or magnetic material core) used to sense an alternating magnetic field
IEEE 1027-1996 pdf download
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