MT-MR PLATINUM. POINT TO POINT AURAL RADIO RELAY SYSTEM
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MT-MR PLATINUM
POINT TO POINT AURAL RADIO RELAY SYSTEM
chapter IV
THE MR PLATINUM RADIO LINK RECEIVER
4.1.- Description.
MR Platinum Radio Link Receiver is a wideband, high quality equipment, conceived to integrate a STL (Studio-
Transmitter Link), together with MT Platinum Link Transmitter. Designed in first instance for 400 MHz band, MR
Platinum Receiver is being now developed to receive multiple frequency-modulated audio signals over the whole
sector of frequency spectrum assigned to Radio Relay and STL service, mainly at 200,300, 470 and 900 MHz
frequency bands, covering both VHF & UHF frequency ranges. As happens with MT Platinum transmitter, the MR
Platinum receiver is designed to operate in 20 MHz sub-bands. Not only it can operate within a one-hop STL, but it
also can integrate more complex Relay systems, working in baseband-repeater stations with or without dropout &
insertion at each repeater.
MR Platinum receiver is a completely solid-state device who can operate 24 hours daily along many years without
any service interruption or loss of service quality. It can receive a wideband monaural program , or a multiplexed
stereophonic audio plus three SCA or RDS channels, containing audio analogic information, or digital low speed
data. Its baseband distortion level, sensitivity, image rejection and noise level can be compared with many higher-
priced equipments characteristics. However, this receiver is one of the cheapest available at professional Broadcast
market in our present days.
Essentially speaking, MR Platinum receiver is an specialized FM reception equipment, double-conversion super-
heterodyne type, tuned by a Voltage-Controlled local oscillator (VCO) who in turn is stabilized and tuned by a
Phase-Locked Loop (PLL) . Selection of received frequency by PLL is obtained through a Microcontroller device
(specialized Microprocessor) who is previously programmed with all the frequencies that Equipment can receive
within its operational sub-band. This Microcontroller selects the operating frequency by sending digital orders to the
programmable frequency divider circuits at PLL unit , who sets this frequency and keeps it constant, thanks to the
high-stability reference oscillator (TCXO) employed in the Automatic Frequency Control loop.
Operational parameters of this receiver can be easily checked while it is normally functioning, also through
Microcontroller unit, since this unit is fitted with a Interactive Digital Display, this allowing to perform both the
received frequency setting and the main parameters readings. This receiver includes a double-section active
filtering pre-selector system at its front end that highly improves its selectivity, overall noise figure and image-
rejection characteristics. Both pre-selector filter sections has low-noise transistor amplifier stages integrally built
within the same filter unit.
Both active amplifier stages cancels filter insertion losses and increases the net gain of received signal to the
proper level to drive the mixer stage at optimal conversion efficiency. Mixer stage is also a low-noise, double-
balanced device that mixes this received RF signal with another incoming from the VCO local oscillator in non-
linear heterodyning process, in order to produce a third signal, the Intermediate Frequency (IF) signal, this
