
Studer D19
The Echo Canceller
The Studer Echo Canceller is a reliable and easy-to-use system for a
problem in digital live broadcasting: monitoring signals return to
the commentator with a noticeable delay. The resulting irritating
echo effect is suppressed with the Echo Canceller.
■ Echo suppression for live broadcast monitoring
■ Compensates satellite and MPEG Codec processing delays
■ Automatically adapts to delays of up to 1 second
■ Easy operation with automatic or manual delay setting
■ Compact Studer D19 design
– The Echo Canceller is operated locally with a few frontpanel elements.
– A 3-digit delay indicates the currently selected pre-delay in the range of 0...999 msec.
– With the mode switch one of the following modes can be selected:
CONT
In continuous mode the predelay circuit is adapting automatically to the current situation.
The delay line is set after having
detected a reliable correlation
between local and return signal.
This mode is selected for environments with changing configurations. ■
Operation

Digital transmission in outside broadcast has a number of
obvious advantages but also some unwanted side effects. In
complex live broadcasts the signal can sometimes be connect-
ed via cable and sometimes via satellite; in some cases the
data is transmitted in bit reduced form. Delays of up to sever-
al hundred milliseconds are the result. This becomes parti-
cularly noticeable if the broadcast signal returns to the
source as a monitoring signal.
A typical example is sport
broadcasting. The program is
switching from one location
to another, the reporter is
listening and waits. When
instructed by the control
room, he will start to
speak ... and will be con-
fronted with his own
delayed voice in his
headset. ■
MAN
If the installed configuration has
a known delay, the manual mode
will be the preferred one. It allows to set the pre-delay with
the up and down key, to increment or decrement the current
delay. ■
ONCE
The one-shot mode is to set the
delay line once, it then remains
constant. It combines the advantages of continuous and manual
mode - automatic adaption and
reliable operation with low quality return signals. ■
The problem
Location 1
Location 2
Location 3
Location 4
Trans-
mission
Line
Return Signal
On Air Signal
Central
Control Room
(Monitor)

The solution
For suppressing line reflections and feedback in telephone applications
a solution in the form of a echo compensating circuit was already
developed in telephone hybrid applications. Corresponding algorithms for the digital realisation are available, but their working range
is not wide enough.
The Studer Echo Canceller is looped locally (in the OB van) into the
return line. By using an additional delay line (0...1 sec) the standard
algorithm now works in its optimal range of 5...20 msec. ■
Location 1
Monitor
Local Signal
+
+
–
Delay
delayed return signal
The algorithms will suppress the delayed commentator signal from the incoming on-air signal. The reporter hears all
sound sources except his own delayed voice.
In place of the suppressed signal, the local comment can
be added directly, allowing the reporter to hear his own
voice undelayed.
The delay line can be set automatically through a correlation measurement from the local and delayed signal, or have a fixed setting if the data are known. ■
Trans–
mission
Line
With the direct volume potentiometer the volume of the directly added
local signal is adjusted from mute to full level.
The return signal may be bypassed to the local output by means of the
bypass key.
The display field provides further information about selected modes
and the status of the pre-delay adjustment. ■

Specifications
■ Input / Output
– LOCAL IN Analog line input of local source signal
XLR, balanced, transformer coupled
Sensitivity -6 ... +24 dBu
– FAR IN Analog line input of return signal
XLR, balanced, transformer coupled
Sensitivity -6 ... +24 dBu
– LOCAL OUT Analog line output of processed return signal
XLR, electronically balanced
Sensitivity -6 ... +24 dBu
■ General
Sampling Rate 16 kHz
Bandwidth 140...7300 Hz
Compensation Range 1 sec maximum
Echo Suppression typ. 15...35 dB, depending on quality of return signal
Measuring Rate typ. 20...30/min.
Power Supply 90...260 V AC, 50...60Hz
Mechanical Size 19" rack mount size, 1 HU
Ordering Number 60.662.001.00
Local out
Local in
Far in
to control room
level &
correlation
detector
signal
return
Acoustic
Echo
Canceller
+
+
A
D
–
A
D
A
D
direct
volume
delay
line