Tektronix ASG100, ASG140 DATASHEET

Tektronix audio generators offer
potent solutions for audio testing.
The two-channel ASG 100 and
four-channel ASG 140 combine
compact size, ease-of-use and
programmability. Operated
manually or automatically, they
produce signals used for aligning,
servicing and testing of
audio facilities.

Test signal capability starts with
simple line up, polarity, and level
signals. Added to these are tone
sweeps for checking distortion,
frequency response and crosstalk.
Industry standard CCITT 0.33
signals and newly developed
Multitone signals support
advanced audio analysis capabil­ity found in the VM 700A. Digital
synthesis of signals ensures
signal stability and repeatability.

The ASG 100/140 are operated
by simple front-panel controls.
Alternately, users may operate
these generators via their rear­panel RS-232 remote control
port. Supporting a variety of baud

rates, this interface permits seam­less integration of audio signal
generators in ATE test schemes.
A wide variety of editing schemes
permits user-defined values to
be stored for later reuse.

ASG 100 Applications

The two-channel ASG 100 is for
situations where the generator is
inserted in-line with the audio
path of interest. When used in
this fashion, the ASG 100 can
insert a variety of test signals into
the audio program. The output
impedance is programmable,
allowing it to be used with either
power-matched or voltage-driven
signal distribution schemes.

ASG 140 Applications

The ASG 140 is designed for
situations requiring no in-line
connections. Its four audio outputs
are grouped in two stereo pairs
making it the ideal choice for
service and alignment of MII,
Betacam, D1, D2, D3,... VTRs.
Its audio output features 10fi
output impedance.

COMMON FEATURES
20 Hz to 20 kHz
24 dBu to -90 dBu
4 second Voice ID
Balanced XLR signal paths

CONTROLS
RS-232 remote control
Front panel lockout
Contact closure

SPECIAL MEASUREMENT SIGNALS
Multitone test signals
Audio/video delay signals
CCITT 0.33 signals
TEKTRONIX autosequences

ASG 140 FEATURES
Four balanced XLR signals
Fixed 10 Ohm output impedance

ASG 100 FEATURES
Balanced, loop-through operation
Programmable output impedance

Audio Signal Generators:
Two Channel ASG 100
Four Channel ASG 140

Copyright © 1997, Tektronix, Inc. All rights reserved.

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Output Signals

Several different types of audio
test signals, ranging from simple
to complex, are produced. The
most basic of these signals are
simple tones.

Tone, L Tone and R Tone consist
of sine waves that are program­mable in amplitude and frequency.
Many standard test procedures
specify tones for their purpose.
These requirements are satisfied
by the Tone set available in
Tektronix signal generators. One
combination of Tone amplitude
and frequency may be saved as a
default value. This might be used
as a test signal or can even be used
for an alert or warning signal.

active, the undriven channel is
grounded through its character­istic impedance. The amplitude
of the Sweep signal is controlled
by a programmable “Sweep Level”
control. Table 1 describes the
sweep frequencies and durations.

Sweep signals are commonly
used to measure particular audio
characteristics over a frequency
range. For example, Sweep
provides a constant amplitude
signal throughout the frequency
range. When this signal passes
through a system, the resulting
output signal indicates the
amplitude response of that
system. Other uses for Sweep
include the measurement of
distortion vs. frequency and
phase response vs. frequency.
L Sweep and R Sweep provide
signals that enable a user to
measure crosstalk or channel
isolation vs. frequency. The levels
of Sweep, L Sweep and R Sweep
are programmable. A particular
level may be defined as the user
default value.

Frequency Length Total Time

25 Hz 1 Sec 1.0 Sec
31 1 2.0
40 1 3.0
50 1 4.0
63 1 5.0

80 1 6.0
100 1 7.0
125 1 8.0
160 1 9.0
200 1 10.0
250 1 11.0
315 1 12.0
400 1 13.0
500 1 14.0
630 0.5 14.5
800 0.5 15.0

1000 0.5 15.5
1250 0.5 16.0
2500 0.5 16.5
3150 0.5 17.0
4000 0.5 17.5
5000 0.5 18.0
6300 0.5 18.5

8000 0.5 19.0
10000 0.5 19.5
12500 0.5 20.0
16000 0.5 20.5
20000 0.5 21.0

Table 1. ASG 100 & ASG 140 Sweep Signals.

Figure 1. Polarity signal waveform.

LINE UP permits users to define
a tone to be used for alignment
purposes. In this case, a front­panel button affords easy access
to this signal.

VOICE plays back 4 seconds of
user-recorded signal intended for
voice ID purposes. This signal
is recorded by the front-panel
microphone incorporated in the
signal generator.

POLARITY is a troubleshooting
signal consisting of an asymmet­rical waveform (Figure 1). This
signal may be used to detect if
the plus and minus connectors
of an audio conductor have
been reversed.

SILENCE is an active mute
signal. Its suggested uses include
determining the noise floor of
a system as well as providing
a rapid way to silence an
output signal.

SWEEP generates frequency
sweep signals on Left, Right or
both channels simultaneously.
When a Left or Right Sweep is

0.58 V

–2.3 ms

2.3 ms

–0.31 V

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advanced audio analyzers, such
as the Tektronix VM 700A, auto­matically initiate an extensive
series of tests each time the
identifying preamble is detected.
Thus automatic, yet unattended
testing schemes are very
easily implemented.

Tektronix autosequences are
similar to those defined by the
CCITT specification. However,
TEK:90-95 sequences include
test signal level information
in the identifying preamble.
This further simplifies the
implementation of test schemes.

CCITT and TEK autosequences
are ideal for testing telecommu­nication and broadcast contribu­tion links. Since the identifying
preamble coordinates generator
and analyzer, split site tests,
whether performed over an STL,
satellite link, or coast-to-coast
copper or fiber connection are
simple to use.

In total, 6 CCITT and 6
Tektronix autosequences are
available. VOICE may be
appended to the beginning of
each of these signals to aid
source identification. Table 2
lists examples of both a CCITT
and a Tektronix autosequence.

CCITT 0.33:01 TEK:90

Seconds Freq. L Freq. R Level Seconds Freq. L Freq. R Level

1 1650/1850 1650/1850 12 dBm0 1.0 1650/1850 1650/1850 -12
1 1020 1020 0 1.0 400 400 0
1 1020 1020 -12 1.0 400 400 -8 dB
1 40 40 -12 .250 15000 15000 -8
1 80 80 -12 .250 13999 13999 -8
1 200 200 -12 .250 12503 12503 -8
1 500 500 -12 .250 11243 11243 -8
1 820 820 -12 .250 9001 9001 -8
1 1900 1900 -12 .250 7500 7500 -8
1 3000 3000 -12 .250 6203 6203 -8
1 5000 5000 -12 .250 3499 3499 -8
1 6300 6300 -12 .250 953 953 -8
1 9500 9500 -12 .250 400 400 -8
1 11500 11500 -12 .500 101 101 -8
1 13500 13500 -12 1.0 50 50 -8
1 15000 15000 -12 1.0 400 400 +10
1 1020 1020 +9 2.0 — — —
1 — — —
1 60 60 +9
1 2040 — -12
1 — 2040 -12
1 820 820 +6
1 820 820 -6
1 820 820 +6
8 — — —

Table 2. Examples of Autosequences produced by the ASG 100 and ASG 140.

Autosequences

Another class of output signals
is autosequences. Two general
categories are available. Industry
standard CCITT 0.33 sequences
consist of a 1 second identifying
FSK preamble followed by a
series of tones with specific
durations and levels. Six different
sequences are produced, each
with unique tones and levels.
Furthermore, certain sequences
are intended for monophonic
applications while others are
intended for stereo situations.
These autosequences are
powerful because certain

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Table 3. Multitone Test Signals.

MTone1 MTone2 MTone3 MTone4

59 Hz 23 Hz 47 Hz 23 Hz
117 94 141 117
187 141 281 234
246 223 656 750
293 270 1031 867
375 352 2016 1758
422 562 4031 3492
949 879 8109 6984

1184 1113 1500 13992
1512 1395 20016
1887 1758
2391 2227
3000 2789
3785 3516
4758 4430
6012 5590
7570 7043

9539 8871
12012 11180
15000 14074

17742
19992