NXR-810
31
■
Modulation circuit (Analog/Digital signal processing)
In the case of the Analog Signal Processing mode, the
transmitting audio signal is amplifi ed by IC405 (C/4), input to
the MICADCO terminal of the MCU (IC20), and audio pro-
cessed by DSP (IC6). The processed audio signal from the
MODDAC terminal of IC20 is passed through an anti-aliasing
fi lter at IC404 (A/2), and is then amplifi ed to a suffi cient level
by IC404 (B/2), and amplifi ed by the summing (TD) amplifi er.
The Digital Signal Processing mode is the same as the Ana-
log Signal Processing mode.
4-9. Other circuit
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Real-time clock
The clock function is based on a real-time clock IC (IC17).
When the power supply is off, it is backed up by an internal
secondary lithium battery.
5. Display unit
The Display unit (X54-3730-20) is different from X54-
3580-20 which is used in the TKR-750/850/751/851.
The Display unit (X54-3730-20) consists of the following
circuits:
(1) LED circuit
(2) Key switch circuit
(3) Power supply voltage detector
5-1. LED circuit
The display circuit consists of various types of LEDs:
7-segment type D506 and D507 (red), D503 (red: transmis-
sion), D504 (green: busy), D505 (green: power on).
IC502 to IC505 are shift registers that convert MCU serial
data to parallel data and turn on the LEDs.
5-2. Key switch circuit
There are PF key 1 to PF key 6 on the Display unit. Using
these key switches, mode settings are available.
The logic signals pushing these key switches are entered
directly into the MCU (IC20).
5-3. Power supply voltage detector
The Display unit has a power supply voltage detector cir-
cuit.
The power supply voltage (SB) is divided through two re-
sistors (R545 and R546).
The divided voltage is input to the MCU via the IC508.
CIRCUIT DESCRIPTION /
电路说明
■解调电路 ( 模拟 / 数字信号处理 )
在模拟信号处理模式下，发射音频信号由 IC405(C/4) 放大，
输入到 MCU(IC20) 的 MICADCO 端子，由 DSP(IC6) 处理音频。
IC20 的 MODDAC 端子的经过处理的音频信号通过 IC404(A/2)
的抗混叠滤波器，然后由 IC404(B/2) 放大到足够的电平，并
由加法 (TD) 放大器放大。数字信号处理模式与模拟信号处理
模式相同。
4-9. 其他电路
■实时时钟
时钟功能以实时时钟 IC(IC17) 为基础。当电源关闭时，则
以内部二次锂电池作为后备电源。
5. 显示单元
显示单元 ( X54-3730-20) 不同于 T K R -750/850/751/851 中
使用的 X54-3580-20。
显示单元 (X54-3730-20) 由以下电路组成 ：
(1) LED 电路
(2) 键开关电路
(3) 电源电压检测器
5-1. LED 电路
显示电路包含多种类型的 LED:
7 段式 D506 和 D507( 红色 )、
D503( 红色 : 发射 )、
D504( 绿色 :
繁忙 )、D505( 绿色 : 打开电源 )。
I C502 到 I C505 是将 M C U 串行信号转换为并行数据并打开
LED 的移位寄存器。
5-2. 键开关电路
显示单元上有 P F 键 1 到 P F 键 6。使用这些键开关，可以
进行模式设定。
按这些键开关的逻辑信号被直接输入 MCU(IC20)。
5-3. 电源电压检测器
显示单元具有电源电压检测电路。
电源电压 (SB) 通过两个电阻器 (R545 和 R546) 进行划分。
划分的电压经由 IC508 输入到 MCU。
