The SPNConference has a powerful new echo canceller that can handle echo cancellation for multiple incoming signals from the far side. You can have multiple codecs and a phone line coming in and bridge all of them together. You will need to assign a minimum of four signal buses (or mixes) for conferencing. We suggest the following protocol. Setting up the AEC signal routing. Conferencing requires a minimum of four mixes. Two are dedicated to the AEC itself. These are called the AEC Reference mix and the AEC Signal mix. You will need to assign two mix buses in the ASPEN units for these two mixes. We recommend you use mix bus 48 for the AEC Reference and Mix bus 47 for the AEC Signal. The third is the SEND Mix (AEC Out) – you will need to assign a bus for each outbound signal. For example – if you have just a telephone line, you will need one SEND mix for the Tel. If you have one phone and two Codecs, then you will need three Send mixes, one for the telephone and one for each of the codecs. We recommend you use the mix buses 46, 45, 44 etc for these signal mixes.

This will keep all your conferencing mixes close together and separate from your local amplification mixes. Finally, you will need your LOCAL mixes – these are the signals which will be sent to your local amplifiers and may be shared with microphones. How many of these you need is dependent on the number of amplifier channels you have in use. Reference Mix – should carry ONLY the incoming signals from the far side. That would be signals from the telephone, and codecs – the inbound part of any two way communications line. DO NOT put any microphones or local line level sources (such as multimedia inputs) on this mix. AEC Signal mix – should have ONLY the local microphones. No multi-media sources, no line level inputs – microphones only. AEC Out Mix(es) – Will SEND the output of the AEC (which is the echo cancelled microphones), plus any multi-media sources to the fars side. If you want to have a bridged conference system, you will have the codec incoming going to the telephone SEND mix and the telephone going to the codec SEND mix. BE CAREFUL HERE! Make certain that you do not accidentally route the incoming telephone signal BACK on the outgoing telephone SEND mix! Or Codec to codec, etc! Local Mixes – this brings the audio from the far sides and the microphones into the room – note that we are routing the incoming phone and codec signals to the same buses as the local microphones which then feed to the amplifiers.