Appendix 3 - Cisco SX20 - Detailed Audio Tests
The SX20 Plus CODECs do not permit the audio protocols to be forced, hence we were only able to carry out detailed tests on G.722.1 and AAC-LD audio coding.
Test 1: Frequency response (-3 dB)
(Insert -6 dB signal at local site, measure at remote site)
G.722.1 |
AAC-LD, 64K |
AAC-LD, 128K |
7.00 KHz |
20.0 KHz |
20.0 KHz |
Test 2: Headroom (measured on AAC-LD signal coding)
Insert increasing amplitude 1 KHz tone at local site, monitor for overload distortion at remote site
Overload occurs at: +12dBm
Test 3: Audio level
(Insert -6dBm 1KHz tone at local site, monitor received level at remote site.)
As the audio output level is affected by the volume control this test was not carried out.
Test 4: Echo Cancellation
Setup The echo canceller is fully automatic in operation. The quality of echo cancellation and doubletalk from the system was excellent.
Lecture Theatre |
Room |
|
Audio levels adequate? (Yes/no) |
Not tested |
Yes |
Audio quality acceptable? (Yes/no) |
Not tested |
Yes |
Echo cancellation acceptable? (Yes/no) |
Not tested |
Yes |
Quality of double talk |
Not tested |
Excellent |