1. TIA-1083-A and C63.19 Magnetic Interference Requirements Compared
A-Weighted Noise Measurement
Both use half-band integrator.
TIA-1083-A requires measuring in perpendicular and transverse orientations, whereas C63.19 also requires longitudinal.
TIA-1083-A has an absolute maximum -40 dB re 1 A/m limit. C63.19 has no requirement on absolute A-weighted noise level.

2. TIA-1083-A and C63.19 Magnetic Interference Requirements Compared
Signal-to-Noise Ratio (Signal Quality)
Both standards specify a requirement on the ratio of the desired signal level (measured at or near 1000 Hz) to the undesired A­weighted noise level.
TIA-1083-A has a single 45 dB minimum requirement that is approximately equivalent to the 30 dB requirement for a T4 rating in C63.19.

3. TIA-1083-A and C63.19 Magnetic Interference Requirements Compared
The difference in signal to noise ratio values for equivalent performance is due to the following:
A-weighted noise is measured the same way for both standards.
The signal level in C63.19 represents “nominal level speech input” (see Footnote 48 in 2007 version).
The signal level in TIA-1083 is the same as in Part 68 and is “approximately 15 dB above the average level” (see paragraph 2.4 in EIA RS-504 as reproduced in 47 CFR ).