Figure 4.6 Conventional Matrix vs. TDM Matrix
Today, nearly all matrix intercoms are based on TDM or similar technology. Telex manufactures the RTS™ Zeus™,
Modern Day Matrix Intercoms
As discussed in the last section, today’s matrix intercoms are TDM based. Let’s take a closer look at the architecture of such a system, as a prelude to understanding its exact capabilities
As shown in Figure 4.6, one major difference between conventional crosspoint matrices and TDM matrices is that a TDM matrix is comprised not simply of crosspoints, but is a
In the conventional crosspoint matrix shown in Figure 4.6, if the TD wants to listen to both the Director and the Producer, then crosspoints A3 and B3 are turned on (or closed). As these crosspoints are nothing more than switches, the relative levels of the signals are wholly dependent on the speaking level of the Director and Producer.
In the same example through the TDM matrix, the crosspoints are replaced by volume controls – the resulting matrix is referred to as having individual crosspoint level adjustments. In this case, the capability exists for the relative signals levels to be adjusted by volume controls for the Director and Producer as heard by the TD. Various means can be used to make that adjustment, but for now the salient point is that different listeners (or outputs) have the ability to selectively mix the signals from the sources they wish to listen to.
For the most part, this is the major difference between conventional crosspoint intercom matrices and modern TDM (or similar technology) matrix intercoms. There are other differences that are primarily a function of the addition of features and capability which are part of the normal product development process. These details will be discussed in the next chapter when we get into system design issues.
52 H a n d b o o k o f I n t e r c o m S y s t e m s E n g i n e e r i n g
