Voice Quality Testing Guidelines for Cordless CPE
Document Number SR-5024
Issue Number 01
Issue Date Nov 2001
ABSTRACT: SR-5024 was written to provide guidance in determining the quality of the voice path of cordless CPE. This document reflects the
current state of research for this topic and should be considered a living and dynamic area of investigation. With this consideration,
there are areas of this document that are not complete and require further investigation. Examples of such are the use of pure
sinusoidal tones as reference stimulus, the effects of electromagnetic coupling between phones and metal test fixtures, and the effects
of Radio Frequency (RF) interference.
Cordless CPE is defined as customer premises equipment that consists of a fixed base unit that acts as the tip and ring interface to
the voice network and a mobile, uncorded handset. The voice path is considered to have three separate parts, the transmit path, the
receive path, and the sidetone path. The transmit path is defined as the path containing the signal collected at the microphone (mouth
piece) of the handset and sent via the RF channel to the base unit. The receive path is defined as the path containing the signal
received at the tip and ring interface of the base unit and sent via the radio frequency (RF) channel to the speaker (ear piece) of the
handset. The sidetone path is the path containing the signals received at the microphone of the handset and sent to the speaker of the
handset. The impact of the local loop and its electrical and physical characteristics are not considered in this document.
The intent of this document is to identify and define objective testing methods that correlate to subjective voice quality. There
are several factors to be considered with this methodology. First, the determination of the impairments present in the path containing
the voice signals must be ascertained along with their associated impact on subjective voice quality. Second, physical parameters must
be identified that characterize the severity of those impairments. Third, typical environmental situations must be considered due to
their impact on the measured parameters. Environmental considerations include range from base unit to handset, physical obstructions
between the base unit and handset, and typical RF interference found in various usage environments such as households, apartment
buildings, or offices.