Digital VLF-HF Receivers R&S® EK895/R&S® EK 896
Version
04.00
June
2003
For all shortwave applications from 10 kHz to 30 MHz
Compact DSP-based receivers for the |
Digital signal processing (DSP) for |
Tried and tested system concept |
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following applications: |
convenient and versatile operation |
Excellent price/performance ratio |
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Radiomonitoring and radio |
Two models: |
Extremely reliable operation under |
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detection |
– Half-rack receiver R&S EK895 |
harsh environmental and EMC |
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Radiocommunications |
– Search receiver R&S EK896 |
conditions |
– Search operation, DF systems |
Realtime remote control or |
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– Frontend for HF intelligence tasks |
master-slave mode |
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VLF-HF Receiver R&S EK895 with control panel
Digital VLF-HF Receivers R&S® EK895/R&S® EK 896
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 8kT0)
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 interfacing, 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
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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 large- scale-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 mas- ter-slave operation. On the R&S EK895/ R&S EK896, 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-perfor- mance 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 |
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Search Receiver R&S EK 896
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 (IP2) and +35 dBm (IP3); the crossmodulation transfer is 10% for an interfering signal of +21 dBm. In most cases, additional filters such as suboctave filters are therefore not required.
Search Receiver R&S EK896 with front panel for local/remote control
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.
In the basic version, all the frequencies are derived from a temperature-compen- sated 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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Digital VLF-HF Receivers R&S® EK895/R&S® EK896 |
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