ET91

Four instruments in one for PLC, FDM and communication line testing

Four instruments in one

ET91 is a hand-held, battery-operated instrument that combines a level generator, a selective and wideband level meter from 100 Hz to 2400 kHz, a measuring bridge and a high-resolution spectrum analyzer. It is designed for testing power line carrier (PLC), frequency division multiplexing (FDM), audio tone and FSK communication systems, and for characterizing cables and voice channels.

No frequency calculation

FDM test instructions often specify the test frequency as carrier ± tone. ET91 sets the carrier and the audio frequency separately, in carrier + tone and carrier - tone formats, so there is no need to calculate the receive frequency. In the tracking modes, the generator controls the selective level meter: only the transmit frequency is set, and the receiver tunes to the carrier ± the transmitted frequency.

Applications

• Commissioning and maintenance of power line carrier (PLC) links and FDM systems.
• Measurement of level, noise, carrier leak, crosstalk and non-linear distortion in voice channels.
• Cable characterization: loss, longitudinal balance, impedance, return loss and crosstalk.
• Interference location and power spectral density analysis.

Generator and level meter

Selective level meter

It receives a single frequency or a multi-tone test signal (MTTS) between 100 Hz and 2400 kHz, with 2 ppm ± 1 Hz accuracy and 1 Hz setting steps. Five bandwidths -20 Hz, 200 Hz, 1.74, 1.95 and 3.1 kHzcover noise, carrier leak, crosstalk and non-linear distortion measurements, with a range of -120 to +10 dB and results in dB, dBm, dBr or mV. Maximum and minimum limits give an immediate PASS/FAIL indication.

Wideband receiver

Six selectable band filters, from 100 Hz-4 kHz to 24-2400 kHz, with auto ranging. The balanced and coaxial inputs accept 75, 135 (125) and 150 Ω or high impedance between 10 and 2400 kHz, and 600 Ω or high impedance below 10 kHz.

Generator

It generates a quartz-accurate test signal with 1 Hz resolution, as a single frequency, a multi-tone signal (MTTS) or a sweep. The balanced output delivers +10 to -60 dBm (up to +20 dBm below 10 kHz) and the coaxial output +10 to -60 dBm, with 0.1 dB resolution and ±0.3 dB accuracy.

Tracking modes

In synchronous tuning, the receiver follows the transmitter frequency. In the FDM channel mode, the instrument transmits at the audio input of the channel and measures in the carrier band, with a receive frequency equal to the carrier ± the transmitted frequency.

Measuring bridge, noise and spectrum

Built-in measuring bridge

It measures longitudinal balance (LCL) from 0 to 70 dB under ITU-T Rec. O.9, return loss from 0 to 40 dB and impedance from 50 to 1600 Ω, all versus frequency. The crosstalk and loss measurement (NEXT/LOSS) reaches 80 dB across the whole 100 Hz to 2400 kHz band.

Wideband and impulse noise

The psophometer measures voice-channel noise under ITU-T Rec. O.41, and the wideband measurement adds eight filters from 3.1 to 2400 kHz. Measurements last from 1 s to 72 h: up to 1 min they are shown quasi-analogue and from 5 min as a 60-slot histogram. The impulse noise counter detects pulses longer than 500 ns, with a 1 to 500 mV threshold and up to 65,000 counts.

High-resolution spectrum analyzer

It analyzes from 100 Hz to 2400 kHz in six spans, from 2.4 MHz with 500 Hz to 8 kHz resolution down to 4 kHz with 10 to 20 Hz resolution, and plots 300 frequencies with sensitivity down to -140 dBm/Hz. The trace is evaluated in NORM, PEAK, AVG and SAVG modes, in dBm or dBm/Hz, to check output power spectral density, crosstalk and other interfering signals.

End-to-end measurements and options

Master-slave mode

Two instruments, one at each end, automatically measure carrier cables and voice channels. The master initiates the measurements and collects the results; the slave performs them on the master's commands and sends back the values, and both communicate over the line under test. The automatic program covers loss, noise at both ends, return loss, impedance, balance (LCL), near-end crosstalk (NEXT) and far-end crosstalk (FEXT).

Software options

• Group delay distortion with a 37-tone signal, from 0 to 10 ms with 1 µs resolution, under ITU-T O.81.
• Phase jitter (ITU-T O.91) from 0.2 to 30° p-p and frequency error of ±30 Hz.
• Micro interruptions from 0.6 ms to over 1 min, in five categories, over 4 min to 72 h.
• Spectrogram and spectral trace as reference.

Hardware options

External 40 dB attenuators, coaxial and balanced, for levels up to +40 dB between 10 and 2400 kHz with ±0.5 dB accuracy, and a 12 V car power adapter.

Memory, software and power

Test setup and result memory

To speed up routine tests, the instrument stores 100 user-defined test setups -with generator and level meter parameters and PASS/FAIL limitsand 100 results.

Two USB ports

The USB A port takes a USB stick (FAT16 or FAT32) to exchange results and setups with a PC without installing any driver, which helps users who have no administrator rights. The USB B port connects the instrument directly to the PC.

PC software

The PC software transfers results and displays them numerically and graphically, produces test protocols in selectable size and file format, and prints them. Its editor creates test setups and sends them to the instrument memory; it also shows the hardware and software versions and the calibration date, and remote-controls the spectrogram with continuous result transfer during the measurement.

Battery life and display

The internal NiMH battery gives about 8 hours of operation and is recharged in place in less than 3 hours with the mains or car adapter. The 320 × 240 dot graphic TFT display is backlit, and menus are available in English, German or Russian.

ET91 — SPECIFICATIONS · GENERATOR AND RECEIVERS

ET91 — SPECIFICATIONS · BRIDGE, NOISE AND SPECTRUM

ET91 — OPTIONS AND GENERAL DATA