The model development of residual BER focuses primarily on the source's phase noise and the power amplifier AM/PM distortion, These key components usually represent the greater part of the residual error budget and are often responsible for the vast majority of the cost of the radio, There are other secondary contributors to the error floor, including group delay distortion or inter symbol interference (ISI).
In most cases group delay distortion is not a significant factor largely because of the tremendous power of modern digital equalizers.
The Japan ADSL splitter has a POTS impedance of 600 ohms with voice band delay distortion
of 250 microseconds.
The series include low-pass, high-pass, band-reject and bandpass filters, and can also be used as delay lines, with desirable control of group delay distortion
Group delay distortion
also may be introduced into the FFA system because the varactors resonate to change their phase.
A non-linear phase response will cause group delay distortion
, introducing data-dependent jitter or intersymbol interference into the data stream.
The problem with this approach is the introduction of group delay distortion
The effect of group delay distortion
on a quadrature phase-shift keying (QPSK) digital transceiver is considered.
Also incorporated into the design are multisection group delay equalizers that minimize the effects of group delay distortion
The IF filter for both systems is required to have 200 kHz of band-width, low insertion loss and low group delay distortion
This test translator is said to deliver reliable translations with a minimum of amplitude and delay distortions
The digital adaptive equalizers can compensate for any type of linear distortions in the channel including magnitude and group delay distortions
in the cable, impedance mismatches in terminations and reflections from unterminated stubs and cable splices.