Method of selecting impedance setting for loop start trunk line
AssigneeMitel Networks Corporation
InventorsYonghua Fang, Mirjana Popovic, Dieter Schulz
Life of this patent
Estimating the term…
Abstract
A method of selecting an optimum impedance for a loop start trunk line, comprising successively applying respective ones of a plurality of impedance settings to the loop start trunk line, for each impedance setting measuring the impulse response of the trans-hybrid echo path by applying audio test signals to obtain a time-domain trans-hybrid transfer function and deriving a frequency-domain spectrum representative of trans-hybrid loss, and then calculating figure of merit of the transfer function based on the power spectrum. Once all impedance settings have been tested, the optimum impedance is selected as the impedance setting associated with the highest calculated figure of merit.
Claims4
The method of selecting optimum impedance for the trans-hybrid echo path of a loop start trunk line, comprising:
- successively applying respective ones of a plurality of impedance settings to said loop start trunk line;
- for each of said impedance settings measuring the impulse response of said trans-hybrid echo path to obtain a time-domain trans-hybrid transfer function and deriving a frequency-domain spectrum representative of trans-hybrid loss, and then calculating figure of merit of the transfer function based on the power spectrum, said calculating of the figure of merit including determining a maximum peak B in the power spectrum, averaging the trans-hybrid loss to obtain an average value A, calculating the flatness of the frequency-domain power spectrum as a variance V from the average value A, and generating said figure of merit
- merit
- =
- {
- -
- 10000
- ,
- if
-
-
- (
- B
- >
- 0
- )
- A
- 2
- -
- (
- w3
- ×
- B
- )
- -
- (
- w4
- ×
- V
- )
- ,
- else
- ,
- where w3 and w4 are weight values equal to one;
- and
- selecting as said optimum impedance one of said plurality of impedance settings associated with the highest calculated figure of merit.
Dependencies are inferred from the claim text.