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Question: We have a application for a Radio presenters IFB feed where the presenter doesn’t want a dis-concerting delayed feed of his own voice. Customer is using ST2110-30 audio streams from Eclipse Matrix fitted IPA card to a sound desk and is seeing high audio latency when running AES67 streams from our equipment and across their network.

Solution: Dated Oct 2020 these we are the figures we obtained .

Summary : to get the lowest latency values please use a PTP packet time of 125 μs on your AES67/ST2110-30 network . Reduce all RX frame buffers where possible on all devices to 128 samples or similar

Using a AP (audio precision) analyser we injected an analogue audio input signal into the matrix MVX input port. We then set up forced listens in local advanced forcing the audio from the MVX port to go out onto our IPA ST2110-30 TX stream.

 We connected the AP (audio precision) analyser to an analogue audio output from a matrix MVX port. We then set up forced listens in local advanced forcing the audio from the incoming IPA RX ST2110 stream to the MVX port. The AP (audio precision) analyser was set to measure the delay

We setup two test scenarios

 Test #1 : Using a Lawo A_line Mic8 unit and 1x IPA card. The Lawo box received our IPA ST2110-30 transmit stream and then via an analogue loopback on the Mic8 unit , it would then transmit a Rx stream back to the IPA. The AP (audio precision) analyser was used to measure the delay via analogue MVX ports

 Test # 2 : We had 2 x IPA cards in the frame. IPA# 1 was sending a TX stream only and IPA# 2 was only receiving 1 RX Stream. The AES67 side of the IPA cards (LAN 3 ports) were put into a separate VLAN on a Cisco SG350 switch

Results table: