PHONEX CONNECTIONS
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PHONEX CONNECTIONS
15.1 TELEPHONE HYBRID CONCEPT
The hybrid phone is a device capable of interfacing with a telephone line of audio lines. In practice, the audio signals sent
toward the hybrid are received from the phone, and vice versa.
The telephone hybrid is widely used in radio and television, as it allows you to create simple audio connections with
remote locations in a very low cost. The signal coming from the telephone hybrid is run like a normal audio source.
The hybrids telephone operating in accordance with the principle of separation of the impedance, filtering also the power
supply to 60V normally present on telephone lines.
In its simplest form, the hybrid is conceptually an acoustic coupler, ie a device that picks up acoustically signals from the
handset. However a hybrid phone is in reality an apparatus more complex, capable of interfacing directly with the
telephone line and to carry out the separation necessary to avoid interference. Hybrid complex manage multiple phone
lines and can route the audio signals of a line to the other, thus creating a conference call, see how CONFERENCE of
Macrotel and Phonex.
15.2 TELCON, N-1 AND MIX-MINUS CONCEPT
Fundamental part of the use of a telephone hybrid, is the knowledge and the proper use of the system TELCO, also
called Clean Feed CF, or N-1 and / or mix minus.
All these terms identify the condition below:
The expression n-1 indicates, in professional audio, the audio return signal that is sent from the studio to one or more
remote sources, such as a telephone hybrid. This signal is also often called back audio, RX or, in English, mix-minus.
The expression n-1 refers to the notation of the principle of complete recurrence of Henri Poincaré, n +1, and showing
the mix of all the audio signals of the study less than that received from the remote unit. From the conceptual point of
view, then the remote unit receives back an audio signal that includes the entire product of the study unless itself.
Distancing a bit 'by theory, the n-1 is often a unique signal to all the remote units of a single program. A custom
widespread provides for the generation of two or three returns, assigned on the basis of which remote units need to
interact with each other: with the same n-1, in fact, two units are not able to hear each other. Sometimes, the return
audio is simply an auxiliary audio mixer to which are assigned to the signals to be sent to the remote unit, obtaining a
signal that is usable as a return but that is not technically a n-1 (see next capitol)