User`s manual

SIP User's Manual 15. Configuration Files
Version 5.0 331 December 2006
15.3 The Coefficient Configuration File
The Coeff_FXS.dat file is used to provide best termination and transmission quality
adaptation for different line types for FXS gateways. This adaptation is performed by
modifying the telephony interface characteristics (such as DC and AC impedance, feeding
current and ringing voltage).
The coeff.dat configuration file is produced specifically for each market after
comprehensive performance analysis and testing, and can be modified on request. The
current file supports US line type of 600 ohm AC impedance and40 V RMS ringing voltage
for REN = 2.
To load the coeff.dat file to the MediaPack use the Embedded Web Server (refer to Section
5.6.4 on page 166) or alternatively specify the FXS coeff.dat file name in the gateway’s ini
file (refer to Section 5.9.2.1 on page 203).
The Coeff.dat file consists of a set of parameters for the signal processor of the loop
interface devices. This parameter set provides control of the following AC and DC interface
parameters:
 DC (battery) feed characteristics
 AC impedance matching
 Transmit gain
 Receive gain
 Hybrid balance
 Frequency response in transmit and receive direction
 Hook thresholds
 Ringing generation and detection parameters
This means, for example, that changing impedance matching or hybrid balance doesn’t
require hardware modifications, so that a single device is able to meet requirements for
different markets. The digital design of the filters and gain stages also ensures high
reliability, no drifts (over temperature or time) and simple variations between different line
types.
In future software releases, it is to be expanded to consist of different sets of line
parameters, which can be selected in the ini file, for each port.
Note: Use the parameter ‘CountryCoefficients‘ (described in Table 5-35 on
page 132) to configure the FXO coefficients.