Crosstalk
Current
Current Sources
those systems, the crosspoints are the actual switches that close or open to connect or disconnect talk and listen paths. RTS™ ADAM™, ADAM™ CS, and Zeus™ Intercom Systems do not actually use crosspoint switches, but use a technique called time division multiplexing (TDM), in which communications are routed as digital packets. However, use of the term “crosspoint” persists since packet routing basically accomplishes the same thing as conventional crosspoints: namely, connecting distinct talkers and listeners. In this sense, a crosspoint can be thought of simply as a communication link between any two points in the intercom system.
Interference caused by audio energy from one line coupling (“leaking”) into adjacent or nearby lines.
A current is a flow of electrons past a point in a circuit and is measured in amperes (coulombs per second). Practical currents in electronics are measured in: amperes, milliamperes
RTS™ Systems uses “Current Source” technology in many of its communications products. This technology allows the summing of signals on a single pair of conductors across a single system bus termination. This allows a distributed conference line system. Stations can be added arbitrarily anyplace in the system. The system allows two to 75 stations to be put on the system with only a maximum level difference of six decibels. The current source allows a signal to be put on the bus without shorting out the other signals.
D
Daisy Chain
dB dBm
dBu
DC decibel (dB)
Dedicated Line
Destination
Dielectric
Dim
Some TW user stations allow the stringing together (or daisy chaining) of user stations. These stations have a “loop through” or “extension” connector as well as a ‘line” or “line input” connector. Connecting up a TW system by connecting one user station to another via the line and loop through or “ext” connectors. This is as opposed to “home running,” which is running a cable from each user station to a central point (“home”).
Decibel, see definition for decibel.
A reference level where 0 dBm equals 1 milliwatt. In a 600 ohm system 1 milliwatt corresponds to a voltage of 0.775 volts.
A reference level where 0 dBu equals the voltage as a dBm (0.775 volts) but without the 600 ohms in the circuit.
Direct Current. Example: current as from a battery.
1.
1.A term used by some to indicate a single path in a
A destination is anything that a talk key talks to or a listen key listens to. A destination can therefore be any port,
An insulating (nonconducting) medium or material.
“Dim” occurs in two contexts in RTS™ Digital Matrix Intercom Systems.First, there is the Dim Table feature. Dim tables are used to correct a feedback problem that can occur between two keypanels operating in close proximity that have keys assigned to talk/listen to a common destination. Dim tables are set up in AZ™EDIT (search for keyword “dim” in AZ™EDIT help. Once a dim table is set up, it can be assigned as a level 2 talk assignment for those keys that are causing the feedback problem. For information about how to make this assignment from a programmable keypanel, search for “Dim Table” in the keypanel manual index.There is also an adjustable speaker dim feature available on the
134 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
