FSK communication device for digital information
AssigneeOlivetti Telemedia S.p.A.
InventorsAndrew Bud, Luciano Campi, Franco Straullu
Life of this patent
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Abstract
A communication device (1) for computer local networks of the cordless type uses a modulator (MOD) able to perform FSK modulation on the data (DDI) to be transmitted, with optimum characteristics thanks to a digital switch (SW) controlled by the data (DDI) which commutes during transmission between two fixed frequencies received from a quartz oscillator, in association with a filter of the surface acoustic wave type (SAW). The device (1) permits a significant improvement in circuit integration and is simple and of low cost.
Claims23
A FSK communication device (1) for digital information adapted to be used in association with a computer apparatus which generates coded input signals (DDI), the said device comprising:
- modulator means (MOD) for receiving and modulating said coded input signals (DD1) at their input and generating first output signals derived from the said coded input signals (DD1);
- transmitter means (MIX1, F1, AMP, C, A) for receiving the said first output signals and generating transmission signals from the said first output signals, capable of being received by a further communication device compatible with the said communication device (1), characterized in that the said modulator means (MOD) comprise:
- oscillator means (OSC) for emitting a first synchronization signal having a fixed frequency;
- at least two divider means (DIV3, DIV4) receiving the said first synchronization signal at their input and emitting at least two output synchronization signals having each one a frequency equal to said fixed frequency divided by a predetermined numerical factor, the numerical factors of the said at least two divider means (DIV3, DIV4) being different from one another;
- commutation means (SW), connected to said at least two divider means (DIV3, DIV4), for receiving the said at least two output synchronization signals, and to said computer apparatus for receiving the said coded input signals (DD1) and emitting a first modulated output signal or a second modulated output signal, each of the said modulated output signals for a time period determined by the said coded input signals (DD1);
- mixer means (MIX) connected to the said commutation means (SW) and to a source of a first predetermined periodic signal (FO) for emitting at least a modulated digital signal at a predetermined frequency with a predetermined "FSK" deviation and said predetermined periodic signal (FO);
- and
- filter means (SAW) connected to said mixer means (MIX) for filtering said modulated digital signal, locking said predetermined periodic signal (FO), and emitting said first output signals from the said modulator means (MOD).
Dependencies are inferred from the claim text.