The LA100 Audio Analyser is a complete audio test system in
daily use world-wide by broadcasters, manufacturers, telecom and studio engineers. The
flexibility of the system means that testing a broadcast satellite link or FM transmitter is as easy as testing a mixing console or studio intercom.
The LA100 comprises the LA101 Audio Oscillator and the
LA102 Audio Measuring Set, which can be supplied separately or together in a single
19" rack mount case (referred to as the LA100R).
The Lindos Analyser LA100
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The units have rechargeable Lithium Ion
batteries which trickle-charge when mains power is connected, making them as portable as a
multi-meter - ideal for both field and bench applications.
The LA100 can be used for manual or automatic testing, with
the results displayed in numerical and graphical form on the back-lit LCD, or uploaded to a computer using the software support package Lin4win (included with the LA100). Lin4Win provides the ultimate in computer controlled audio analysis, and there is a rich built in instruction set for those who wish to write customised control software.
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- Measures Level, Frequency, Phase, Noise, Crosstalk,
Distortion, Rumble, W&F
- Used by engineering professionals world-wide-in both routine
and mission-critical applications
- Lindos standard test sequences for fast automatic
testing
- Fast auto-ranging with manual override
- Low distortion synthesised oscillator
- Fully floating 10, 75 & 600 Ω outputs
- Graphical frequency response display
- Pass/fail tolerance limits
- Built in mains/rechargeable battery operation
- Prints directly to Epson and HP compatible printers
- Serial computer interface for remote control
- Lin4win Windows support software for optional PC control
- Back-lit LCD with high contrast & wide viewing angle
- Optional carry cases for field use
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LA101 Front Panel
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LA102 Front Panel
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LA101 Back Panel
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LA102 Back Panel
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Digital Waveform Generation 
Digital waveform synthesis guarantees quartz-accurate
frequencies and stable levels corrected to a few hundredths of a dB by calibration factors
embedded in the main software EPROM. This design offers fast level changing, frequency
sweeps and glitch-free tone bursts.
The up-down buttons control the frequency from 5Hz to 38kHz
in third-octave steps and the level from 100dBu to +26dBu in precise 1dB steps. The *
key gives fine control, with 32 steps per octave and 100 steps per dB. User programmable
presets give instant access to five commonly used frequencies and levels.
The LA102 is a precision millivoltmeter with an array of
filters and rectifiers which, under microprocessor control, provide most world standards
in audio measurement. For ease of use there are five basic measurement functions (level,
noise, distortion, etc), and each offers a range of options. For example, tapping the
NOISE key will quickly give a reading using the ITU-R 468 weighting filter and rectifier,
but pressing the OPTION key produces a menu listing various other noise measurement
options (ITU-R 468 unweighted, A weighting, ARM-2K, rumble etc). The displayed bar graph
exhibits the correct dynamic characteristics for each standard, so the level options
include a true rms, VU and PPM rectifier characteristics with a choice of bandwidths
(2Hz-100kHz, 22Hz-22kHz or 400Hz-22kHz).
Range changing is automatic with manual override and the
bar graph can be zoomed (5:1) when dealing with small signal variations. There are also
facilities for setting relative levels and peak hold, and for changing the displayed units
(dBu, dBV, W or V). When the LEVEL function is selected, the frequency and phase
difference (between channels) is also displayed. Left and right input levels can be
displayed on a dual bar graph together with a mean phase and phase jitter display.
Distortion is measured at 6 spot frequencies using a novel
band-stop plus high pass filter. No nulling or tuning is required. Apply the signal -
press 'DIST' - read the result - in less than a second. The design guarantees immunity
from errors caused by frequency drift.
Crosstalk is measured at the same 6 frequencies, with
selective filtering to reduce the contribution from out of band noise. Wow and flutter is
measured weighted or unweighted, and various other measurements include quantising
distortion, difference frequency intermodulation distortion, rumble and frequency
intermodulation distortion. Other features include balanced inputs via PO jacks (front) or
XLRs (rear) with switchable 600 Ω loading, channel
selection and a speaker and 'scope
output that let you monitor the measurement (after the filtering and gain stages).
LA100 front panels.
Lindos sequence testing has become the de-facto standard
for telecomms, broadcasting and production testing around the world. Its simplicity and
speed allows a system to be evaluated using measurements which conform to world standards
with no chance of error.
Sequence testing can be used to evaluate fully any audio
circuit automatically in about a minute. Microphone circuits or P.A. systems; intercoms or
intercontinental satellite links - Lindos sequence testing can cope. The test sequence is
built from test segments and each test segment consists of the audio test signal preceded
by an FSK (frequency shift keyed header). The header acts as a synchronising trigger for
the LA102, as well as identifying the segment code and the LA102 responds automatically
and makes and stores the necessary measurements. Since the FSK is sent over the audio
path, no other communication is necessary between the LA101 and the LA102, so the test
sequence may be received automatically at a remote site, or at a different time if the
sequence is recorded and played back later. Speed errors on tape replay, which can put
other systems out of synchronism, are well tolerated by the LA100 because each segment is
retimed from its own FSK header.
Over 60 test sequences are built in. Additionally, up to 10
user-defined sequences can be held in non-volatile memory. These are editable either from
the LA101 front panel, or on a PC running our Windows software. This flexible approach
lets you specify the precise tests and levels to suit the equipment under test. The system
is fully backwards compatible, and any LA102 of any vintage will respond to any Lindos
sequence.
The test results can be displayed on the LCD (including
frequency response graphs) or printed directly to a standard printer via the RS232 serial
port. User
headings can be added and pass/fail tolerances edited and applied, all from the front
panel.
Pass/Fail Tolerance Testing
For routine production line testing, quality control, or
acceptance testing, the automatic test sequences allow fast and simple measurements. To
make routine testing even easier, the LA102 can compare the test results against tolerance
limits and give an immediate "PASS" or "FAIL" display. Measurements which fail the
tolerance test are highlighted with an asterisk (*) on both the display and the printout.
Ten tolerances are built in to the LA102 and these include
British Telecom lines specification (EPS81, EPS84 and EPS98), various lines and studio
specifications and an
LA100 self test. In addition to these pre-defined tolerances, up to 5 user tolerances can
easily be entered from the front panel aided by the LA102's helpful prompts.
Computer Control
Lin4Win is a software package providing unrivalled PC
support for the LA100 Audio Analyser. Running under all versions of Windows it offers powerful
results management tools, sequence & tolerance editors, and easy software and hardware
configuration. Close liaison with LA100 users has ensured that this package has all the
features necessary to make audio testing even easier.
Key features include:
- Control Panel - operate the LA100 entirely from the PC
keyboard
- Sequence Editing & tolerance editing - quick and easy, no need to cycle through lists of characters everything can be entered through the keyboard
- Export of high resolution sweep data to any spreadsheet for
in-depth analysis.
- Developed by Lindos - guaranteed compatible with future
LA100 firmware.
- Lifetime support including free updates as they become
available.
The Control panel
The 'Control Panel' allows control of the LA100 in manual mode
from the PC keyboard. The LA101's output level, frequency and the LA102's measurement options are all only a mouse click away. Quick preset buttons can be setup with any level or frequency.
Custom Editors
When writing Lin4win's sequence and tolerance editors, our
primary aim was to make them easy to use. Although the editors built in to the LA100 are
very powerful, they rely on the front panel keypad for all input. With Lin4Win you can type a segment list or tolerance definition and upload it to the LA100. Because you can save definitions the user can have as many as they like.
Results Management
Lin4win offers the ultimate flexibility in results
management. Once downloaded from the LA100, results can be displayed, saved to disc,
printed or exported to other applications using normal cut and paste techniques. In
addition, frequency response plots can be overlaid and
analysed on screen. A live cursor continually updates numeric information about each
trace.
The default print-out format has the popular Lindos format,
but this can be customised and user comments added as required.
Future Proof
Lin4win was developed in-house. This means that as the
firmware of the LA100 evolves, Lin4win will be developed to keep pace, and our policy of
providing our users with free updates applies. Technical support is freely available by
'phone, fax or e-mail.
The LA100 has no potentiometers, no
edge connectors and no ordinary switches - 30 years experience has taught us that
they are best avoided. Rugged construction around only two PCBs with quality IDC and IC
sockets allows superb access for servicing,- and plastic panels are cheap and easy to
replace if damaged.
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