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 non-
standard rate if so desired.
