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User Manual
Rev. 1.0 - 29/11/05
PTRL NV/3 & RXRL NV/3
The incoming signal is broadband amplified in the LNA amplifier IC1. Module output
is converted by diode mixer IC2 and the local oscillator signal at P3 input.
The local oscillator is normally synthesised at reception frequency less mean
frequency, i.e. 70 MHz. In some cases, depending on operating range, the local
oscillator may be synthesised to incoming frequency value summed up with FI value.
Right after the first mixer, a duplexer sends the signal through a variable pin diode
attenuator (D1, D2) controlled by AGC via TR1. The signal is then amplified by IC3
and filtered by the first FI filter at 70MHz (L5, L6, L7 and associated components).
RT1 enables accurate setting of IF gain and sends the signal to the second (active)
filter IC4. Here, the signal is converted at 10.7MHz and processed through the TR2-
TR6 chain that includes amplifiers with local AGC and band-pass filters. The output
signal from this chain is applied to the third mixer IC8 and to the FI monitor output
buffer TR7.
The signal converted by IC8 at 460 kHz is squared by IC9 and demodulated using a
very-high linearity "pulse count" circuit with very low added noise and distortion. The
two monostable devices accommodated in IC11 are energised by the individual
half-waves of the modulated signal and provide output pulses with strictly constant
duration that are summed up and buffered by TR8, TR9, IC12. At IC12 output, the
signal is integrated by the filter comprising L18-L20 and amplified by IC13a.
IC13b allows for amplitude compensation of the demodulated signal after FI filtering
according to varying frequency. Likewise, IC13c provides for phase compensation
on the same signal. IC13d provides an output voltage proportional to incoming signal
tuning with respect to frequency centre.
8.2.2 Mainboard, Interface, Control and BF Output Board
The mainboard provides the main interface between control circuits, the other receiver
board and the BF signal. It distributes the control signals from the CPU to the other
boards and the power supplies; its also processes and buffers the BF signal for the
outputs
The signal coming from and broadband-filtered by the FM demodulator is pre-
processed in the circuit made up of IC1 and IC2; the latter two components form a
mild phase-compensated low-pass multiplex filter that provides mild attenuation of
the BF signal at frequencies above 75kHz to reduce the noise caused by the signal
on the adjacent channel in stereo demodulation.
From the IC1b output, the signal is made to pass through the programmable attenuator
comprising IC3 and IC4 that operate on a 1/2 dB step to provide output dynamics in
a -1.5 to +12 dBm range. IC7b and IC8 make up the buffer for the output multiplex
signal. Please note that IC8b uses an inverted signal with respect to IC8a so as to
obtain two identical push-pull outputs or a single differential output.
Summary of Contents for PTRL NV/3
Page 1: ...PTRL NV 3 RXRL NV 3 User Manual Volume 1 Manufactured by Italy...
Page 4: ...PTRL NV 3 RXRL NV 3 ii User Manual Rev 1 0 29 11 05 This page was intentionally left blank...
Page 8: ...4 52 User Manual Rev 1 0 29 11 05 PTRL NV 3 RXRL NV 3 This page was intentionally left blank...
Page 55: ...51 52 User Manual Rev 1 0 29 11 05 PTRL NV 3 RXRL NV 3 10 Ensemble View 10 1 PTRL NV 3...
Page 56: ...52 52 User Manual Rev 1 0 29 11 05 PTRL NV 3 RXRL NV 3 10 2 RXRL NV 3...