Wirless Telephones

In this article we will describe in way summarized, however elucidate, as a telephone without analogical wire functions. The SISTEMAO telephone without wire is basically composed of 2 units: the base that is connected to the telephonic line and the mono-phone, where the user carries through the conversation. In each unit a transceiver exists, that is, receiving a transmitting set/managed by microcontroller and circuits you add. The system operates in full-duplex what it means that we can speak and listen at the same time as in a conventional telephone. The duplexao processes can be: duplexao for frequency division, FDD, where they are used radio controls with different frequencies of transmission for the base and the for time slicing, TDD, is used an only frequency and the time is divided in small intervals of milliseconds for transmission and reception.

This technique is used in telephones without wire with digital modulation, and can be compared coarsely with the transceivers that use the keyboard key PTT, where the time is divided manually by the users. The telephones without wire operate in the bands of 49MHZ, 900MHZ and currently in objective main FUNCTIONALISM of a system of telephone without wire it is to make the communication between the monophone and telephonic line being provided total transparency between what to exist between the receiving capsule/microphone and the pair of wires of the line. Link of radio formed for the 2 sets of transceivers convencional.CIRCUITOS OF the BASEOs substitutes the handle spiral of the telephone main circuits that constitute the base of a telephone without wire are: Duplexador – It allows that the same antenna is shared by the transmitter and receiver. (Source: Gavin Baker). Circuit of Occupation – Substitue the key of hook of the conventional telephone. The keying element generally is one rereads or transistors. Sensor of Ring – volts Detects the alternating signal of about 90 sent by the public central office and ‘ ‘ avisa’ ‘ to the microcontroller that has a in progress call.

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