Polycom VSXTM 6000 E AUDIO TESTS ITU standards only, Test 1 Frequency response -3dB, 14kHz, Room

E:AUDIO TESTS (ITU standards only)

Tests 1-3 were carried out with test signals inserted into the AUX (Auxiliary) input.

Test 1: Frequency response (-3dB)

(Insert a -6dB signal at the local site, measure the frequency corresponding to an audio level reduction of 3dB at the remote site from the level received when a 1kHz tone is transmitted).

Siren™ 14, 24kbit /s	Siren™ 14, 48kbit /s
14kHz	14kHz

Test 2: Headroom (measured on a Siren™ 14, 48kbit/s connection)

(Insert increasing amplitude 1kHz tone at local site, monitor for overload distortion at remote site)

Overload occurs at: +10dBm

Test 3: Audio Level

(Insert -6dBm 1KHz tone at local site, monitor received level at remote site) Measure the level on the VCR output with the local volume at mid range.

Remote site signal measures: -18dBm measured on audio output

Test 4: Echo Cancellation

Setup The echo canceller is fully automatic in operation.

	Lecture Theatre	Room
Audio levels adequate? (Y/N)	Not tested	Yes
Audio quality acceptable? (Y/N)	Not tested	Yes
Echo cancellation acceptable? (Y/N)	Not tested	Yes
Quality of double talk	Not tested	Very Good

Subjectively the quality of the Siren™ 14 audio and echo cancellation was excellent. The provision of: audio level meters for the microphone and VCR inputs; level adjustment on the VCR inputs and an internal tone generator, are all very useful operational features.

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