Functioning Of E.g. Receiver / Exciter - R&S M3SR 4100 Series Operating Manual

M3SR Series 4100

1.5 Functioning of e.g. Receiver / Exciter

The modules are controlled and monitored by the control logic, part of the module Mother-
board. In addition, the control logic contains a memory for configuration data and module
parameters.
The Radio Controller (= RC) as a central module controls the entire radio and handles all
user voice and data services. The RC consists of a microcontroller with external memory,
and digital signal processors (= DSP) and control logic. The control interface to the modules
is the parallel radio control bus (RCB). The control interface to the power amplifier is the se-
rial radio control bus. The enhanced serial synchronous interface (= ESSI) is the digital in-
terface between digital IF processing on the radio controller and IF sampling/IQ modulation
in the frontend.
When the radio operates in receive mode, the radio frequency signal is taken from antenna
connector X2112 to the module Frontend. In the frontend, the radio frequency signal is
transmitted along the HF path to the mixer stages. The mixer stages get the LO signals (LO1:
40.058 MHz to 70.048 MHz, LO2: 80 MHz) from the module synthesizer. The AGC-con-
trolled 2
frontend.
In transmit operation, the signal generation of the modulated carrier at 48 kHz is achieved by
a direct digital synthesizer (= DDS) with a digital quadrature modulator. Afterwards the IF is
upconverted to the final RF frequency. This is done by mixer stages. The mixed signal is am-
plified for low noise generation. Unwanted products of the mixed signal are suppressed with
a pre-selector and a low-pass filter, respectively.
The module Synthesizer generates two RF signals (LO1, LO2) for the module frontend and
two reference signals (100 kHz, 10 kHz) for other modules. All generated frequencies are
synchronized by an internal 10 MHz oven-controlled crystal oscillator (= OCXO) or by an ex-
ternal 1 MHz, 5 MHz or 10 MHz reference frequency.
The module Power Supply uses the +28 VDC input voltage to generate all voltages required
in the radio.
The Interface Module connects the RCB and discrete signals between the motherboard and
up to three further rear modules.
The audio Front Panel accommodates control and display elements.
The optional module Control Unit plus the FSW0 software form the man-machine interface
(= MMI) of the radio. The MMI guides the operator through menu-based operating proce-
dures and selectively visualizes all status types on the display. Commands are entered by
making use of the control elements and the keypad. Operation and indication of the radio's
operating status are both menu-oriented, operator interaction is performed via the display
and keyboard.
1.8
nd
IF signal with a frequency of 48 kHz is demodulated in the digital section of the
User Information
Operating Manual 6175.4760.02 – 01