Digital VLF-HF Receivers R&S® EK895/R&S® EK896
For all shortwave applications from 10 kHz to 30 MHz
Version
04.00
June
2003
◆ Compact DSP-based receivers for the
following applications:
– Radiomonitoring and radio
detection
– Radiocommunications
– Search operation, DF systems
– Frontend for HF intelligence tasks
◆ Digital signal processing (DSP) for
convenient and versatile operation
◆ Two models:
– Half-rack receiver R&S EK 895
– Search receiver R&S EK 896
◆ Realtime remote control or
master-slave mode
◆ Tried and tested system concept
◆ Excellent price/performance ratio
◆ Extremely reliable operation under
harsh environmental and EMC
conditions
Digital VLF-HF Receivers R&S® EK895/R&S® EK896
VLF-HF Receiver R&S EK895
with control panel
Special features
◆ Excellent large-signal behaviour, very
good intercept points
◆ High resolution of tuning frequency
down to 1 Hz
◆ Fast and low-noise synthesizer
◆ Demodulators for AM, CW, LSB, USB,
ISB, FM, FSK, AFSK and FAX included
in basic configuration
◆ 13 bandwidths from 150 Hz to 8 kHz
(quasi-continuous on request)
◆ RF preamplifier, switchable (noise
figure 8kT
)
0
◆ Double notch filter
◆ Noise blanker
◆ DATA LINK reception (option)
◆ Passband tuning
◆ Syllabic squelch
◆ Special RTTY (FSK/AFSK) mark and
space filters, matched to the selected
shift
◆ Digital data output
◆ Maximum input voltage protection up
to 100 V EMF
◆ Control interface fully complying with
international standards
◆ Low power consumption <25 VA
(basic model R&S EK895), therefore
little self-heating
◆ Powerful microprocessor for bus inter-
facing, menus and user programs
◆ Dual receiver as 19“ desktop or rack
models
◆ Free slots for retrofitting of options
◆ Integrated self-test down to module
level with plain-text result display
◆ Available with operator front panel or
remote-control-only front panel
◆ Highly compact; width
1
/219"
(R&S EK895) or 19" (R&S EK896)
Operational features
◆ Easy to operate via terminal,
computer or front panel
◆ High rejection of strong interfering
signals
◆ 1000 programmable channel memory
locations
◆ Scan mode for programmable
frequency ranges and any desired
channel sequences
◆ Remote control of all settings – over
any distance when using modems
◆ Ideal handoff receivers in stationary,
mobile and remote receiving systems
◆ High availability owing to long MTBF
and short MTTR
◆ Easy to adapt to special requirements
by means of optional plug-in modules
and standardized interfaces
2 Digital VLF-HF Receivers R&S
®
EK895/R&S® EK896
Overview
General characteristics of the
R&S EK895
With the R&S EK890 family, Rohde&
Schwarz is presenting a powerful generation of VLF-HF receivers which are topend products benefiting from many years
of experience in this field. All members of
this family are based on the R&S EK890
basic model. Due to the advantages of
digital signal processing, embedded in
the improved receiver versions R&S
EK895/R&SEK 896 a number of additional features and operational convenience have been added. Straightforward, menu-guided selection and programming of the receiving settings
ensure excellent processing and handling
of the received signal content. The compact design is due to the use of largescale-integration SMDs. Featuring full
system compatibility, the receivers provide the basis for extremely economical
customer-specific solutions.
With its excellent RF characteristics and
clearcut, full remote-control capability via
standardized data interfaces, the R&S
EK890 family is suitable for all civil,
administrative and military shortwave
applications. These receivers are an ideal
choice for receiving systems that have to
fulfill extremely high reliability requirements, in particular under harsh environmental and EMC conditions.
Operation is possible via an ASCII terminal, a computer (PC) or via the front panel.
Using line drivers, a master receiver can
control up to 99 remote receivers in master-slave operation. On the R&S EK895/
R&S EK 896, two wired and bus-integrated
slots for plug-in modules are provided for
extensions, e.g. BCD interface or input filters.
Uses
The comprehensive sequence control can
be used for all demanding shortwave
reception tasks. Due to flexible programming of the processor, the following operating modes are possible:
◆ Manual operation
◆ Remote control or master-slave
operation
◆ Channel scanning, sequential and
programmable
◆ Frequency scan
◆ Channel reception
◆ Password-protected channel
reception
The R&S EK890 family thus fulfills the
requirements for versatile use in voice
receiving and any kind of data communication system as well as for all radiomonitoring, radio detection and radio
intelligence (COMINT) applications. For
application in DF systems, an R&S EK895
is used as the master (controlling synthesizer), its LOs being brought out for external amplification, distribution and phaselocked application to all other receivers.
The built-in memory has capacity for nonvolatile storage of 1000 complete channel
settings so that channel management
and control by an external computer are
not required but are nevertheless additionally possible. Due to their excellent
characteristics regarding dynamic range,
low synthesizer noise and gain control
range, the receivers are ideal high-performance frontends for subsequent signal
processing.
Two independent Receivers R&S EK895 with remote-control panel in a 19“ rackmount adapter
Digital VLF-HF Receivers R&S® EK895/R&S® EK896 3
Search Receiver R&S EK896
The R&S EK896 has especially been
designed for complex tasks of radio
detection and search reception, its operating principle and configuration perfectly matching the relevant requirements. Basically it is fitted with panel
controls and LCD displays for local and
remote-control operation.
High-speed and reliable radiomonitoring
is supported by temporary storage of a
complete receiver setup and its transfer
to or readout from the connected slave.
The R&S EK896 is the optimal operator’s
position in modern radiomonitoring systems. In the usual master-slave mode, a
master receiver can control up to 99 slave
receivers via additional line drivers to
handle simultaneous radiomonitoring or
specific radio detection tasks. Due to its
outstanding characteristics, the R&S
EK896 is ideal for use as a standalone
receiver. All R&S EK895 options can be
fitted.
Design
RF unit
The antenna signal is routed via a lowpass filter, which is provided for rejecting
image frequencies and suppressing oscillator reradiation, and applied to the input
mixer where it is converted to the first IF
of 41.44 MHz by means of an oscillator
variable in 1 Hz steps. The crystal filter
that follows determines the maximum
receiving bandwidth of 10 kHz and rejects
the second image frequency. A fixed frequency of 40 MHz is used for conversion
to the second IF of 1.44 MHz.
The high-performance mixer at the
receiver input ensures excellent largesignal behaviour. The intercept points are
typically +70 dBm (IP
(IP
); the crossmodulation transfer is 10%
3
for an interfering signal of +21 dBm. In
most cases, additional filters such as suboctave filters are therefore not required.
) and +35 dBm
2
IF/AF processor (DSP)
The second IF is converted to the third IF
of 25 kHz using a 5.66 MHz fixed frequency. After digitization of the third IF in
a 16-bit A/D converter, the processor
assumes all signal generation and processing tasks (DSP) including the following:
◆ Automatic, remote or manual control
(AGC, DGC, MGC)
◆ Measurement of received levels
◆ Filtering with 13 fixed or quasi-contin-
uously adjustable bandwidths
◆ Demodulation, passband tuning,
double notch filter
◆ Noise blanker, syllabic squelch
◆ Generation of BFO frequency as
analog IF from 0 to 40 kHz, digital IF
as serial data and I/Q data stream
Synthesizer
The synthesizer supplies all the conversion frequencies required for the RF and
the IF demodulator units. Due to direct
digital frequency synthesis, the first conversion oscillator can be varied in 1 Hz
steps. The settling time of the oscillator is
5 ms for any frequency variation. Two
phase-locked loops (PLLs) produce the
40 MHz and 5.66 MHz fixed frequencies.
The operation of the total of four PLLs in
the synthesizer is continuously monitored.
Search Receiver R&S EK896 with front panel for local/remote control
4 Digital VLF-HF Receivers R&S
®
EK895/R&S® EK896
In the basic version, all the frequencies
are derived from a temperature-compensated crystal oscillator. Higher accuracy
requirements can be fulfilled by including
a heated crystal oscillator (optional
OCXO) or using an external frequency
standard (1 MHz, 5 MHz or 10 MHz).
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