55 OBAMA NELSON INFORMATION & COMMUNICATION CO. LTD. TEL : 822-851-2780 ~ S(EXT210) FAX; 82-2-857-5583 THEORY OF OPERATION (MODELING) I. FREQUENCY GENERATION ov The frequency generation circuit ie composed of the synthesizer U401 and the VCO, The block diagram illustrates the interconnect and support circuitry used in the design. Refer to the schematic for reference designation. The supplied voltage for the synthesizer is the regulated 4.0 'V which also serves the rest of the radio.
56 « OBAMA NELSON INFORMATION & COMMUNICATION CO., LTD. TEL : 82-2-851-2780 ~ S(EXT210) FAX: 82-2-857-0583 mode. The VCO consists of the Cockpits oscillator of the Q402. A sample of the RF signal 4 from the enabled oscillator is routed from Q403, C424, through to the per-scaler input. i After frequency comparison in the synthesizer, a resultant control voltage is supplied into the VCO. This voltage is a DC voltage between 1.0 and 3.5 volts when the PLL is locked on specified frequency.
57 OBAMA NELSON INFORMATION & COMMUNICATION TEL : 82-2-851-2780 ~~ S(EXT210} FAX : 82-2-857-9383 FIRST IF The first IF consists of a 21. MHz crystal filter and amplifier. The crystal filter provides second image protection and inter modulation protection with approximately 3.75kHz bandwidths) for 12.5kHz models. The IF Amplifier, 3104, provides approximately 104B of gain at 21.7MHz. SECOND DEFIBRILLATOR IC The Second Demonstrator COLORBLIND-V, U201) accepts the 21.
-58OBAPAUL NELSON INFORMATION & COMMUNICATION CO. LTD. TEL : 82-2-851-2780 ~ S(EXT210) FAX « 82-2-857-9583 transmission line and transforms the low impedance of the shunt diode to a high impedance at the input of the harmonic filter. In the receive mode, The diodes are both oft, hence, there exists a low attenuation path between the antenna and receiver ports.