Atis, Dsc Encoding; Pll Circuit; Af Control Section; Af Selection - Raymarine RAY230E Owner's Handbook Manual

Technical Description

4.1.3.4 ATIS, DSC Encoding

4.1.3.4 ATIS, DSC Encoding
4.1.3.4 ATIS, DSC Encoding 4.1.3.4 ATIS, DSC Encoding 4.1.3.4 ATIS, DSC Encoding
The FSK modulating signal of 1200 bps is produced in the FSK Modem-1
(IC308). The modulation index is: 1.0 for ATIS and 2.0 for DSC.
4.1.4 Phase Lock Loop (PLL) Circuit 4.1.4 Phase Lock Loop (PLL) Circuit 4.1.4 Phase Lock Loop (PLL) Circuit
4.1.4 Phase Lock Loop (PLL) Circuit 4.1.4 Phase Lock Loop (PLL) Circuit
The standard PLL frequency of 12.8 MHz is divided by 512 to produce 25
KHz channel spacing by the PLL IC (IC4). The oscillation frequency of the
VCO, which has been divided down to 25 kHz just like the standard, is
applied to a phase comparator within IC4, producing a pulse output
corresponding to the deviation. The output pulse is converted into a DC
value through the external charge pump circuit (Q11 and Q12) and a loop
filter, which is supplied to the control terminal of the VCO as a frequency
control voltage. A part of the output from the VCO is fed back to the PLL IC
(f ) via the buffer amplifier (Q13). The loop filter is provided with a time-
in
constant changeover-switch using the IC3 to meet the requirement for
high-speed response by accelerating the rise characteristic at the time of
transmission/reception changeover and frequency changeover. The
detection circuit (IC5) enables the PLL unlocking signal to output without
fluttering.
4.1.5 Audio Frequency (AF) Control Section 4.1.5 Audio Frequency (AF) Control Section
4.1.5 Audio Frequency (AF) Control Section 4.1.5 Audio Frequency (AF) Control Section 4.1.5 Audio Frequency (AF) Control Section

4.1.5.1 AF Selection

4.1.5.1 AF Selection
4.1.5.1 AF Selection 4.1.5.1 AF Selection 4.1.5.1 AF Selection
AF signals (RxAF, Fog, Siren, and Hail) are selected by the AF selector
(IC310). RxAF and the received Hailer sound are transferred to the cross
point switch via the mute circuit (Q302, Q303). The Fog, Siren, and the
transmitted Hailer voice signals are transferred via the electronic volume
control circuit (IC312, IC313) to the AF amplifier, which develops across a
4 ohm speaker load.

4.1.5.2 Line Selection

4.1.5.2 Line Selection
4.1.5.2 Line Selection 4.1.5.2 Line Selection 4.1.5.2 Line Selection
The line selector (IC311) selects the microphone, the DSC signal, or the
IDC input (modulation input).

4.1.5.3 Speaker Selection

4.1.5.3 Speaker Selection
4.1.5.3 Speaker Selection 4.1.5.3 Speaker Selection 4.1.5.3 Speaker Selection
The relay circuit (RL301, Q306) switches over operation to the external
speaker.
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