Appendix 3 - Cisco SX20 - Detailed Audio Tests

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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