User's Manual

PTRL-LCD & RXRL-LCD
ELETTRONICA
33 / 36
User Manual
Rev. 2.3 - 26/06/19
8.3 Power supply interface
The interface card filters and stabilizes the voltages coming from the power supply,
to the 5 VDC and 18 VDC continuous voltages which are necessary for the supply
in the circuits of the unit, the 24V auxiliary continuous voltage inputs are connected
on the power supply interface, which is used automatically in order to collide with
possible AC supply absences.
8.4 Panel card
The panel card contains the microprocessor (PIC16F877Q) which implements
the monitoring software of the unit, the display and the other elements which are
necessary for the interface with the user.
This card is the interface with the other modules of the unit, both for the distribution
of the supply units and monitoring and for the measurements.
8.5 IF card
The IF card realizes the following functions:
• Processing of the audio and SCA outputs
• Amplification of the 10.7MHz signal
• Demodulation
This circuit receives the 70MHz signal, which is filtered, amplified and then passed
into a mixer which presents a signal coming from a 59.3MHz chrystal oscillator
to the other input. The signal (10.7MHz) obtained from the difference between
these two signals is filtered and amplified an once it is processed it is sent to the
front-end.
This card also processes the different audio MONO, MPX, SCA and RDS signals,
and sends them, together with the muting signal, to the Front-end card.
8.5.1 Audio output stage (mono version)
The audio input stage contains the circuits which realize the following functions:
• 15KHz filtering of the mono channel
• De-emphasis of the mono channel