STL-TR1-20-B
STL Link Transmitter-Receiver
Band 170-490MHz-20W

20W STL Link Transmitter & Receiver, Performant Audio Signal 170-490MH

GENERAL DESCRIPTION

This transmitter and its companion receiver are the core of a high quality, synthesised studio-to-transmitter link (stl), to be used for broadcast repeaters in conjunction with any standard FM or AM transmitter. They are an evolution of the previous extablished series stl whose main circuitry is still extensively used here with a new controller, user interface and software and more advanced oscillators in a compatible 2u 19" case. They allow the reception of mono or stereo signal and its retransmission without using any additional stereo-coder on the receiving end: in both cases the LF output signal from the receiver must be sent to the stereo input (linear or not pre-emphasised) of the local FM rebroadcast transmitter.

The stl is built for several different frequency slots from VHF to the SHF range. Two main models are built: one for the 200÷960 MHz and the other for the 1300÷2500 MHz range. While the exterior cabinet, the controls, the basic circuitry and the performances are the same, some internal components vary or are specifically tuned as required to cover this wide frequency band. Usually these components are the local oscillator, the power amplifier and the input/output filters The factory adjusted frequency slots are 10 to 50 MHz wide and must be specified in the order. In the preset sub-range, the frequency and power of the transmitter may be freely changed on the field. The receiver may require some more adjustment for wider frequency displacement: in fact the adoption of narrow, low loss input filters permitted to achieve the best possible rejection of interfering signals in the band at the expense of some frequency agility. So nearly 8-10MHz may be used without any retouching but wider variation up to 50-60MHz will require retuning of the input filter.

Being the apparatuses completely digitally controlled, they are extensively on field programmable by front panel or remotely in every respect. The alphanumeric display permits easy and accurate metering, adjustment and continuous monitoring of modulation levels, power, operation and internal parameters. All these information are externally available on the same RS232 I/O port that may be used to remotely control the transmitter. In addition to the serial I/O,some signals and controls are available on a parallel I/O socket for easy interfacing with others analog controllers or supervisory systems. A powerful 3-levels password management permits a very high degree of security and privacy as may be required in different situations.

The LF input and output levels are precisely adjustable over a broad range, by means of 0.5dB stepwise variable attenuators. The transmitter has also an auxiliary input, specifically designed for RDS and SCA encoders. A modulation monitor output permits to control other transmitters or STL's with the same internally processed high-quality mpx signal. Furthermore, the system is optimised to be compatible with external digital companding encoder/decoders and to provide RDS and SCA signals, with almost no attenuation.

Optional top-quality stereo encoder/decoder boards may be factory installed on the transmitter/ receiver or field retrofitted with minimum required technical skill. The powerful internal software and monitoring functions recognise their presence and enable the functions. A universal switch-mode power supply permits operation in the extended 95-250 V ac range with no intervention and a 24 V back-up battery input is provided too.

TECHNICAL FEATURES TRANSMITTER

The transmitter and receiver set are fitted in the same sized cabinet and are nearly identical on the front view. In fact they differ for the name on the front panel and the display and for the rear panel connector's accommodation.

Both the equipment are clean and easy to control from the front panel through a single knob. The wide alphanumeric display and a simple self-explanatory menu drives navigation through the various options. A single fast push on the jog knob acts as an "Enter" or confirmation while pushing for a longer time is interpreted as "Escape".

Some leds signal at a glance proper functioning and warning states. Two red led signal warning status, "Alarm"and"Limiter".Abi-stableyellow/greenledsignals"Ontheair" whileafourthonesignals"PLL Lock": both these two should be green in correct operation.

All equipment inputs and outputs but RF monitor are allocated on the rear panel. They are:

• The mains supply IEC320-type outlet, which incorporates the mains switch and the fuses. An additional earth screw for system earthing and a 24V= battery backup socket pair. In alternative the mains outlet with fuse-holder and the mains switch may be separate components
• The RF antenna connector, N-type
• The L & R stereo analog audio channels input on balanced XLR-type connectors (L input is used only with internal Stereo Encoder option).
• The AES/EBU stereo digital audio input on a balanced XLR-type connector which may be used as an alternative to the analog input (this is a special option and may be used only in conjunction with the internal Stereo Encoder option).
• The wide-band external processed stereo or composite signal input on a grounded unbalanced BNC connector
• A frequency limited (20k ÷ 100kHz) auxiliary channel input on a grounded, unbalanced BNC connector for a RDS or SCA signal.
• A LF modulation output for monitoring, RDS external synchronisation or re-broadcasting purpose, BNC-type
• A RS232 Dsub9 female remote serial control port, inverted wired.
• A parallel control port, Dsub9 male type

No internal or external preset is needed to correctly perform on 110 - 240V~ mains range

TECHNICAL FEATURES RECEIVER

Like the Transmitter, the Receiver front panel accommodates the single control knob, the display, four leds for immediate status control and a single output connector for IF monitoring.

Here too regular operation is signallized by green leds: "PLL Lock" and "Field". This latter is a bi- stable and lights in yellow when RF field is too low or absent. As in the Transmitter red leds signals improper operation. The first one, "Modulation", is activated by low or absent modulation; the last one is the general "Alarm" led.

The Receiver I/O connectors on the rear panel are:

• The mains supply IEC320-type outlet, which incorporates the mains switch and the fuses. An additional earth screw for system earthing and a 24V-battery backup socket pair. In alternative the mains outlet with fuse-holder and the mains switch may be separate components
• The RF antenna connector, N-type
• The main composite signal output (Mpx+, Mpx-) on two BNC-type connectors in antiphase, permitting direct drive of two separate transmitters or one in balanced mode.
• A buffered LF monitor, BNC-type connector that may be internally connected as an additional composite or wide-band or mono signal output.
• The filtered/de-emphasised mono signal on a balanced male XLR-type connector.
• The L & R audio channels output sockets on balanced XLR-type connectors (only with internal Stereo Decoder option).
• A RS232 Dsub9 female remote serial control port, inverted wired.
• A parallel control port, Dsub9 male type

RADIO LINK TRANSMITTER-RECEIVER TECHNICAL FEATURES

RADIO LINK TRANSMITTER TECHNICAL FEATURES

RADIO LINK RECEIVER TECHNICAL FEATURES