Telephone hybrid

A telephone hybrid (also Anschaltgerät ( ANG) ) is an electronic device with which audio signals of a telephone connection can be fed to a compatible audio output for further processing. At the same time to the interlocutor an external audio signal can be supplied on the other end of the telephone connection.

Dissemination and application areas

Telephone Hybrids are found primarily in radio studios and television control rooms. Areas of application are here telephone interviews, quizzes and surveys. Most of the procedure is as follows: The audio signal from the hybrid is fed to the transmitter console while sending sum is fed to the telephone hybrid. The caller can be heard on the air when needed and listening to everything that is sent, including the moderator, who wants to talk to him. The moderator may thus lead the conversation without needing a telephone handset. He speaks quite normal in the transmit microphone and hear the caller through his headphones or the sound.

Technical design

Technically, is required of a telephone hybrid, that it as good as possible decouples the outgoing and incoming telephone signals from each other to avoid feedback. Therefore, a conventional telephone and in general can not be modified for the tasks of a telephone hybrid.

Telephone Hybrids are available in different versions for analogue and ISDN connections. Some devices have their own keypad and the complete equipment of a traditional telephone, while others only work in the context of a telephone system for the purpose of injection of an incoming / outgoing call.

Telephone hybrid there is also the "active " electronic components, which have to be separately supplied with the operating voltage. The "passive" and thus cheaper devices are powered via the intercom circuit supplying power to the power supply with the required operating voltage. The function of passive devices can be significantly limited if they eg be operated on a PABX, whose speech circuit power supply only insufficient - eg is designed - only for the operation of simple telephones. Overall, the scope of services, superior quality and control of the audio signals in telephone hybrid active passive devices far. For passive devices is throughout an analog component and economical circuit design to find. Active devices are distinguished - regardless of mostly analog or digital signal processing - from higher quality components and more complex circuit structure, as well as by more adjustment at the individual electronic sub-circuits of the hybrid of.

Features

Different features are expanding the use of hybrids. Therefore, some devices have a call Detector to identify incoming calls with an optical signal. The signal produced this " Incoming Call" then allows other functions. To have professional equipment has a " Auto-Call " function that performs an automatic line seizure after a set number of calls. This is useful in a self -op studio, as the presenter can focus on the mission.

Furthermore, compressors and expander circuits are used in the signal paths to compensate for any clipping and volume variations of the transmit and receive paths. In order to ensure an optimal adaptation to the characteristics of the telephone line filter blocks are often used in both directions. These can only frequencies in the range of 300 to 3400 Hz happen. Therefore, a professional hybrid sounds generally better than adapter circuits with simple transformers.

The balance of the phone line either automatically using a sample and hold circuit - or manually by some trimmers. The transition of the hybrid circuit attenuation between the transmitting and receiving signal is optimized.

Professional broadcast systems use the special N-1 circuit ("N" minus 1), also commonly referred to as " clean feed " or " mix-minus ". Here, the two mixer output signals are available, which differ in the proportion of the telephone channel. For hybrids, the entire production transmitter signal is sent - only that here the phone signal is lost. (There are also applications in which only the signal of the speaker microphone is placed on the hybrid, however, then playbacks from the current program are -. Music / rate Quiz noise ... - not possible).

N-1 by the circuit, a feedback loop is avoided. Therefore, the professional telephone hybrids without " Internal N-1 " Education can not operate on simple mixing consoles ( semi-professional consoles without AUX -way ) without difficulty. This results in a loop, which leads to the telephone line at a resonance point. Now, the assigned channel for the telephone line ( the hybrid ) is pushed, is formed by the resulting feedback whistling. There are also external N-1 - boxes that generate the signal required by active subtraction. The circuits are often realized with differential amplifiers, operational amplifiers are used.

The connection to an analog phone line is done either in parallel or as an accessory in the N- female connector to a telephone socket. Terminal Connections may be used also when the hybrid is used in a fixed installation.

• Studio equipment
• Telephone network