Titus 3-DRX Installation And Operating Manual

3-DRX3-DRX

AUTOMATIC THREE CHANNEL DIGITAL AES/EBU

REPEATER and ANALOG AUDIO SWITCHER

INSTALLATION AND OPERATING MANUAL

3-DRX SECTION 1

INTRODUCTION

The TITUS TECHNOLOGICAL LABORATORIES 3-DRX AUTOMATIC THREE
CHANNEL DIGITAL REPEATER / ADC SWITCHER was designed to overcome many

of the problems associated with stereo broadcasting and production. Automatic insertion
of a secondary or tertiary stereo digital or analog audio source upon silence digital error
as well as manual control of these and other conditions are just some of the features of
the 3-DRX.

In the Automatic mode the microprocessor based 3-DRX operates to correct the loss of
digital audio by bringing up a secondary digital source. It does this by sampling the
primary digital source for errors in either frequency or digital format or loss of signal. At
this point the unit can bring up the secondary digital audio source if so programmed and
it is without errors or bring up a tertiary analog source. There are four possible
sequences that the 3-DRX can follow that are programmed by the user (explained later
in this manual). There is also an audio silence sensor associated with each digital input.
This sensor can be programmed into the source changing sequence so that when a
source looses audio for an extended period of time but the digital clock exists the 3-DRX
will switch to an alternate source (based on the sequence selected).

In the Manual mode the user can control the 3-DRX by the front panel pushbuttons or
via the rear panel remote connector. The 3-DRX can also be controlled by a serial link.
Programming of the 3-DRX is via an RS-232 serial data link on the rear panel.

Relay outputs are available to indicate which source is active. An open collector output
indicates whether the unit is in Automatic or Manual mode. Inputs are TTL level for
manual control.

The 3-DRX conforms to the AES-3 and AES-3ID standards for digital formats. In the
digital mode (digital 1 or 2 source with digital output) the unit is “transparent”, adding
approximately 20 frame delay to the signal (well within AES standards). The 3-DRX acts
as a repeater in this mode, leaving the stereo digital signal in the digital domain. As a
repeater the 3-DRX can be also used to extend the length of a digital cable to double
that of a “single hop”. In the “transparent” mode the 3-DRX will repeat the same data
rate (sampling rate) as the source.

The analog input is converted to digital format. The format is 24 bit, “Professional” with a
rear panel selectable sampling rate of 32 kHz, 44.1 kHz, or 48 kHz.

An external “SYNC” connector is provided to offer the user an external input from a
digital signal to synchronize the 3-DRX A/D converter to a station source or a non­standard rate if so desired.

The 3-DRX operates from 90 to 264 VAC at 47 Hz to 63 Hz input making the unit quite
versatile. Connectors on the rear panel conform to AES-3 XLR type connectors and
AES-3ID type BNC connectors. The 3-DRX can be selected to be bridging input, 110
Ohm or 75 Ohm terminating inputs. If power is lost to the unit a bypass relay will bring up
the Digital source 1 input directly to the AES outputs bypassing the unit. The indication
on the remote relay output will be that of Source 1 and the Auto/Manual indicator output
will be “Manual”.

NOTE: Automatic detection of a serial link on the remote connector will override
any manual rear panel remote control inputs to the unit. (See installation for
details).

3-DRX SECTION 2

INSTALLATION

After unpacking the 3-DRX check for physical damage to the unit due to shipping. If
there is any problem with the unit please contact the factory immediately and notify the
carrier of the damage.

The inputs for the 3-DRX are XLR or BNC type with selectable terminations. The
selections are 75 Ohm, 110 Ohm, or bridging. Appropriate cable for digital audio should
be used. Shielded pair wire should be used to connect to the AES-3 inputs or coax
connected to the BNC inputs.

The outputs for the 3-DRX are AES-3 OR AES-3ID. Only one output should be used at a
time. Select the appropriate output by switching SW-3 #4 ON for AES-3ID (the BNC) or
OFF for the AES-3 (XLR) output you are planning to use. SW-3 #3 provides a switchable
110 Ohm termination for the “SYNC” input.

The 3-DRX analog inputs are high impedance, balance bridging inputs with pin 2 as
“hot”. Levels up to +24 dBu can be accommodated. The 3-DRX operates at a fixed bit
depth of 24 bits however the sampling rate is rear panel selectable via the first two
switches on SW-3. Select the desired sampling rate from the following table:

SW-3 #1 SW-3 #2

32 kHz ON ON

44.1 kHz OFF ON
48 kHz ON OFF
EXT SYNC OFF OFF

The “SYNC” can be from another serial digital source or paralleled with either the Source
1 or Source 2 inputs. This allows the A/D converter to be synchronized with an external
source.

The remote I/O connector is multi-functional (see remote I/O connector diagram). This
connector provides relay closure output indicating which source is active. It also
provides an open collector output indication of operating mode (Automatic or Manual).
This port also is used for connection to an RS-232 terminal such as a PC running
“Hyperterm” or other such “dumb terminal” mode. The connection is at 9600 baud, 8 bits,
no parity, one stop bit, no handshaking. If an RS-232 is attached to the 3-DRX then no
other inputs or outputs (other than the relay outputs) should be connected to the unit.
The 3-DRX can also be accessed via a modem attached to this port as well.

NOTE: The 3-DRX determines if there is an RS-232 serial terminal attached to the
remote control I/O port on power-up. A terminal should not be attached after
power-up as doing so will interfere with normal operation of the 3-DRX.