Tuner Board (Sband ) - Safran CORTEX RTR NeXt Series User Manual

4.2 Tuner Board (S band).
Overview: The Tuner board includes a double heterodyne RF to IF down conversion with 110dB gain
adjustment range to provide a 70 MHz pre-filtered and regulated signal.
Description: The RF input bandwidth 2185 to 2485MHz is delimited by 2 cascaded ceramic filters with
a Low Noise Amplifier to perform the input stage noise figure. The synthesizer and a first mixer perform
the RF input bandwidth frequency conversion down to IF-1 fixed frequency. A ceramic filter delimits the
bandwidth to 40 MHz and a Variable Voltage Attenuator achieves a part of the AGC gain (30dB).The
local oscillator and a second mixer performs the IF-1 frequency down conversion to 70MHz (IF-2). An
efficient IF pre-filtering is performed by a bank of SAW filters from 500 KHz to 36 MHz, software
selectable. Two Variable Voltage Attenuators achieve the last part of the AGC gain (80dB). Some High
Linearity gain blocks are properly located along the entire receiver chain, and warrant the compromises
between total gain, noise figure and linearity.
Two 70MHz IF outputs are available. The first one could be used as a test analog output or as an
output towards an IF recorder and the second one is used to be digitized by the ADP3 board. The
Variable Voltage Attenuators are digitally controlled by the tuner board across FPGA and DAC. The
attenuator linearity response is performed by a compensation table stored in flash memories.
Calibration is done at factory and cannot be modified by the user.
The synthesizer is designed around a typical low phase noise Integer-N PLL architecture with a
frequency step of 1MHz. The local oscillator follows the same design but with a frequency step of 100
kHz. Hence, the global frequency step of the RF board is 100 kHz. A smallest resolution can be
achieved digitally by the ADP3 board.
The FPGA is used as an interface to the PCI express bus and makes easier the control of the board in
the RTR system. The main functions are OL programming, reading and writing data in flash memory.
© Safran Data Systems – IMP000074 e14r1
Radio Telemetry Receiver
User's Manual
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Ref. D104004
Is.Rev 07
Previous Ref.: DTU000567
Date: 21/06/2021
Safran Data Systems
.
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