10
D:
AUDIO TESTS
(ITU standards only)
As the second audio line input could not be activated on either unit, it was not
possible to carry out tests 2 or 3.
Test 1 was carried out with test signals inserted into the
Headset Microphone
input
with the Echo Canceller set to OFF. The audio output level was then adjusted by the
system volume control.
Test 1:
Frequency response (-3dB)
(Insert a -30dB (Mic Level) signal at the local site, measure at remote site)
G.722 G.728 G.7111
5.6KHz 3.5KHz 3.3KHz
Test 2:
Headroom (measured on G722 connection)
(Insert increasing amplitude 1 KHz tone at local site, monitor for overload
distortion at remote site)
Overload occurs at:
Not Measured
Test 3:
Audio Level
(Insert -6dBm 1KHz tone at local site, monitor received level at remote site)
Remote site signal measures:
Not Measured
Test 4:
Echo Cancellation
Setup
The echo canceller is fully automatic in operation.
Lecture
Theatre Room
Audio levels adequate? (Y/N)
Not Tested
Y
Audio quality acceptable? (Y/N)
Not Tested
Y
Echo cancellation acceptable? (Y/N)
Not Tested
Y*
Quality of double talk
Not Tested
Poor
Comments: In tests with the JVCS Management Centre the received audio level
was measured as peaking between 0 and +4dBm. Tests were carried
out with AGC
Off
and the microphone level was adjusted to achieve
the correct received level at the management centre. With AGC
On,
when the user was not speaking there was a high background noise
level. AGC status
is selected from the Controls Menu.
*While the Echo Cancellation was acceptable there was a noticeable
residual echo at times.
