EK895

The Rohde & Schwarz EK895 is a compact DSP-based receiver for radiomonitoring and professional radio detection. Straight forward, menu-guided selection and programming of the receiving settings ensure excellent processing and handling of the received signal content. With its excellent RF characteristics and clearcut, full remote-control capability, the EK895 is suitable for all civil, administrative and military shortwave applications. The built-in memory has capacity for non volatile storage of 1000 complete channel settings so that channel management and control by an external PC are not required but are nevertheless additionally possible. Due to his excellent characteristics regarding dynamic range, low synthesizer noise and gain control range, the receiver are ideal high-performance frontends for subsequent signal processing.

In the standard version, the Rohde & Schwarz EK895 is available with an operator front panel. This front panel also permits manual control and display of all functions while full remote-control capability is maintained. This version is particularly suitable for use as a master receiver in receiving systems or as a standalone unit. The operator interface allows for a combination of hardkey and softkey entries. Parameters that are frequently handled, i.e. receive frequency, channel, BFO frequency and passband tuning (PBT), can be entered directly. All current receiver settings are continuously displayed in large high contrast characters on a backlit LCD. An additional bargraph indicator allows display of either the receive level (0 dBuV to 120 dBuV, in 5 dB steps), the DGC (remote gain) or MGC (manual gain) settings or the frequency offset, as a tuning aid and deviation indication.

Quasi-continuous IF bandwidth control is available as an option (EK895S7) with 128 steps from 100 Hz to 9 kHz. As standard the EK895 features 13 bandwidths from 150 Hz to 8 kHz with excellent 60/3 dB ratio :

EK895 features :

• Excellent large-signal behavior, very good intercept points.

• Fast and low-noise synthesizer.

• Demodulators for ISB, FSK, AFSK and FAX included in basic configuration.

• Double notch filter.

• Passband tuning.

• Syllabic squelch.

• Special RTTY (FSK/AFSK) mark and space filters, matched to the selected shift.

• Maximum input voltage protection up to 100V EMF.

• Free slots for retrofitting of options.

• Integrated self-test down to module.

• Available with operator front panel or remote-control only front panel.

Block diagram of the R&S EK895 receiver

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 behavior. The intercept points are typ +70 dBm (IP2) and +35 dBm (IP3), the crossmodulation transfer is 10% for an interfering signal of +21 dBm.

The second IF is converted to the third IF of 25 kHz using a 5.66/4 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 fixed or quasi-continuously adjustable bandwidths. Demodulation, passband tuning, double notch filter. Noise blanker. Syllabic squelch. Generation of analog IF output from 0 Hz to 40 kHz or digital IF output as serial data and I/Q data stream.