Sennheiser EM 203 User manual

INSTRUCTION FOR USE EM 203

CONTENTS
1 TECHNICAL OVERVIEW
1.1 Computer Control
1.2 Diversity
1.3 HIDYN plus®noise reduction system
1.4 Block diagrams
2 POSSIBLE TRANSMITTER/RECEIVER COMBINATIONS
2.1 EM 203 receiver/SK 2012 TV(HiDyn plus®) and SKM 4031 HiDyn plus®
2.2 EM 203 receiver/SK 50/250 UHF and SKM 5000 (HiDyn plus®)
2.3 EM 203 receiver/SER 20 transceivers
3 PUTTING THE EM 203 TO WORK
3.1 Mains connection
3.2 Antenna connection
3.3 AF connection
3.4 Start-up procedure/operating indicators
4 AVAILABLE MODULES
4.1 EM 1046 RX RECEIVER MODULE
4.1.1 Adjustment
4.1.2 Receiver frequencies
4.1.3 Squelch
4.1.4 Selection RF signal/deviation/battery condition
4.1.5 Display-text/frequency/battery condition
4.1.6 Entry of brief text
4.1.7 System configurations and specifications
4.1.8 Remote monitoring of transmitter battery
4.1.9 Monitoring of audio signals
4.1.10 Stand-by
4.2 MONITOR
4.2.1 LED indicators
4.2.2 Monitor headphones
5TECHNICAL DATA

Introduction
The wireless Mikroport multi-channel sound transmission system EM
1046 is a transmitter/receiver system in a modular design. It offers
comfortable handling and can be relied on for dependable service.
• 3-channel diversity receiver EM 203 with microprocessor-controlled
receiver modules
• Ultimate flexibility in the selection of transmitter and receiver
frequencies thanks to easy-to-replace PROMs and EEPROMs.
The present manual shall help you to get acquainted with the EM 203
receiver.
• The chapter "START-UP PROCEDURE" helps you to connect the
unit to the mains and to put it to work.
• The chapter "AVAILABLE MODULES" provides you with
information on every single module. It explains how to adjust them
to satisfy your individual transmission requirements.
The necessary modules for this receiver system are incorporated into a
"Mainframe". For programming and servicing, the EM 1046 RX
receiver modules can be removed to the front. Output module, input
module and mains power supply module, however, are integral parts of
the system.
IMPORTANT INFORMATION
Each HF input is supplied with a wideband power distributor 1:3,
which intendedly does not affect the adjustment possibilities of the
EM 1046 RX receiver modules. In order to achieve sufficient sensitivity
and protection against subscriber's extention stations, an antenna with
booster and pre-selection is required. In general, Sennheiser's
AB 1036 TV antenna booster is used.
Refer programming of the EEPROMs in the receiver modules to
qualified service personnel or Sennheiser's Service Department,
30900 Wedemark, Germany.

Technical overview 1
Computer control 1.1
Diversity 1.2
HiDyn plus®noise reduction 1.3
Block diagrams 1.4

Every single EM 1046 RX receiver module has an in-built micro-
processor for the RF section, the operating elements and all indicators.
It serves to control the following components or parameters:
• phase locked loop (PLL) synthesizer
• function of keys
• 8 digit LED display
• two LED bargraph displays
• true diversity
• monitoring
• squelch threshold
• description fields
• stand-by
• storage of all receiver parameters (e. g. receiver frequencies) in a
permanent memory
During diversity operations, the microprocessor controls every one of the
two receiver chains that are combined on one module.
The receiver parameters and the selectable frequencies can easily be
changed with the help of a conventional computer system as every
receiver module incorporates an additional service interface. Changes
are only possible within the admissible RF bandwidth.
The software can easily be adapted to your individual requirements and
updated at any time by Sennheiser’s Service Department. Our
servicemen simply replace the PROM in the receiver modules.
Computer control 1.1

Diversity 1.2
Every EM 1046 RX receiver module operates on true diversity.
An antenna splitter, integrated into the chassis, serves to route the
antenna signals from both antennas to the three receiver modules.
The receiving antenna not only receives direct electromagnetic waves,
but also reflections from walls, windows, ceilings and other installations,
which results in the cancellation of these waves, so-called „field strength
gaps“. Repositioning the receiving antenna is a possible remedy,
provided the transmitter remains in its original position. However,
as most transmitters are used for portable applications, the
„field strength gaps“ then occur in other positions. The effects of
field strength variations can only be eliminated through the use
of true diversity techniques.
Sennheiser’s specially developed diversity system is based on two
receivers operating on the same frequency and two separate antennas.
A comparator ensures that the receiver with the strongest RF signal is
automatically and noiselessly switched to the AF output. Diversity
operations can compensate for considerable variations in field strength,
thus providing an enormous gain in transmission reliability.
Nota bene: Every single EM 1046 RX receiver module incorporates two
receivers for diversity operation.
Automatic electronic switching
of audible frequency signal Receiver 2
Receiver 1
Control signal
Steuersignal
Control signal

HiDyn plus®1.3
»HIDYN plus®« NOISE REDUCTION SYSTEM
The »HIDYN plus®« noise reduction system serves to reduce the effects
of RF interference fields. It increases the signal-to-noise ratio and gets
close to about 110 dB for peak modulation.
»HIDYN plus®« is a wideband compander system. It is a combination of
a compressor at the transmitter (ratio 2:1) and an expander at the
receiver, the compressor reducing the volume of the signal and the
expander restoring it. The optimized dynamic range and the control
amplifier in the transmitter effectively reduce modulation problems.
»HIDYN plus®« has been expecially developed by Sennheiser for studio
and stage applications.
Its features:
• extemely low degree of noise modulation
• level compensation
• excellent dynamic range due to the control amplifier
DYNAMICS OF THE AF OUTPUT SIGNAL
DYNAMICS OF THE AF INPUT SIGNAL
EXPANSION AT THE
RECEIVER
COMPRESSION AT
THE TRANSMITTER
DYNAMICS OF THE AUDIO SIGNAL
IN THE RF-SIGNAL (MAX 60 DB)
SYSTEM NOISE PLUS MODULATION/DEMODULATION
NOISE IN THE TRANSMITTER PATH
HIDYN plus
®
HIDYN plus
®

Block diagram EM 203 1.4

Possible transmitter/ 2
receiver combinations
EM 203 receiver/ 2.1
SK 2012 TV (HiDyn plus®)
and SKM 4031 TV-HiDyn plus®
Transmitters
EM 203 receiver/ 2.2
SK 50/250 UHF
and SKM 5000 (HiDyn plus®)
Transmitters
EM 203 RECEIVER/ 2.3
SER 20 TRANSCEIVER

2.1
EM 203 receiver/
SK 2012 TV (HiDyn plus®)
and SKM 4031 TV-HiDyn plus®
AB 1036 TV
2 GZA 1036 TV
450 - 800 MHz
or
2 GZA 1036-9
140 -960 MHz
SKM 4031 TV-HiDyn plus®
SK 2012 TV (HiDyn plus®)
MKE 10-2 R MKE 102-2 R
MKE 2-2 R
EM 203 receiver
NOTA BENE
NOTA BENE
SK 2012 body-pack transmitters can be
retrofitted (change from HIDYN®to HIDYN
plus®) to make them suitable for use with EM
1046 receivers.
To this purpose please send the transmitters to
be retrofitted to Sennheiser's Service Depart-
ment, 30900 Wedemark.
Attention: After the transmitters have been
retrofitted, they are no longer compatible with
HIDYN®.
SKM 4031 TV transmitter microphones can be
used in conjunction with EM 203 systems if
they incorporate a HIDYN plus®compander.
This is the case with SKM 4031 HIDYN plus®
condenser microphones.
Models incorporating a compander can be
retrofitted. To this purpose please send the
microphones to Sennheiser's Service Depart-
ment, 30900 Wedemark, Germany.
Attention: After the transmitters have been
retrofitted, they are no longer compatible
with HIDYN®.