In telecommunication, a measuring receiver or measurement receiver is a calibrated laboratory-grade radio receiver designed to measure the characteristics of radio signals. The parameters of such receivers (tuning frequency, receiving bandwidth, gain) can usually be adjusted over a much wider range of values than is the case with other radio receivers. Their circuitry is optimized for stability and to enable calibration and reproducible results. Some measurement receivers also have especially robust input circuits that can survive brief impulses of more than 1000 V, as they can occur during measurements of radio signals on power lines and other conductors.
Measuring receivers are used with calibrated antennas to
- determine the signal-strength and standards-compliance of broadcast signals,
- investigate and quantify radio-frequency interference,
- determine compliance of a device with electromagnetic interference and TEMPEST standards and regulations.
Measuring receivers are also used without antennas to
Measuring receivers are widely used in metrology and calibration lab environments, spectrum monitoring and electromagnetic-compatibility facilities.
Depending on the intended application area, several types of measuring receivers can be distinguished:
- Spectrum analyzers are intended to graphically display the amplitude spectrum of a radio signal on a logarithmic scale.
- Modulation analyzers are intended to accurately measure not only the signal power level, but also the degree of modulation (such as AM depth, FM/PM deviations), and modulation distortions.
- EMI receivers are designed to comply with the detailed equipment requirements of measurement standards for radio interference, such as the civilian specification CISPR 16-1-1 or the military specification MIL-STD-461. The EMI receiver has defined IF-Bandwidths (typically 200 Hz, 9 kHz, 120 kHz, 1 MHz) and standardized detector modes (peak, quasipeak, average, rms, CISPR-AV and CISPR-RMS, RMS-Average). They use a preselection for an improved dynamic range. Rohde & Schwarz holds the patent for RMS-Average Detector which is important to be compliant to CISPR 16-1-1.
- Time-domain EMI Measurement systems are systems that perform a baseband sampling and simulate all the IF-Bandwidths and detectors digitally. Typically this is done via Short Time Fast Fourier Transform (STFFT). Such measurement systems emulate several thousand EMI receivers digitally in parallel. The most advanced instruments allow to speed up the measurement by a factor of 4000. Measurements can be performed according to the standards CISPR 16-1-1, MIL461 and DO160. The benefit are extremely fast measurements.
- TEMPEST receivers are designed to comply with the requirements of measurement standards for compromising-emanations such as SDIP-27 or NSTISSAM TEMPEST/1-92. For example, their frequency range extends down to acoustic frequencies (typically 100 Hz), their bandwidth can be adjusted in 1-2-5 steps from a few hertz to more than 100 MHz, and their sensitivity and noise figure aims to be close to what is technically feasible.
Some measuring receivers (such as Rohde & Schwarz's FSMR, ESU or Agilent’s N5531S) also include a signal analyzer, power meter, and a sensor module to allow the instruments to be used together or individually for general-purpose measurement tasks.
The time-domain EMI measurement systems TDEMI of GAUSS INSTRUMENTS show additional features like weighted spectrogram mode, oscilloscope mode as well as measurement of discontinuous disturbance according to CISPR 14-1.
Manufacturers and products
- CRFS Limited
- Dynamic Sciences International, Inc. [www.dynamicsciences.com]
- DSI-450 and DSI-600 EMI test receivers
- R-110B Survellance Receiver and R-1550-A TEMPEST test receivers
- GAUSS INSTRUMENTS GmbH, www.gauss-instruments.com
- TDEMI 30M, TDEMI 1G, TDEMI 3G, TDEMI 18G, TDEMI 26G for measurements according to CISPR and MIL/DO
- Narda Safety Test Solutions
- PMM 9010-9060 EMC/EMI test receivers.
- Rohde & Schwarz
- FSG and FMx series signal and modulation analyzers
- ESU, ESIB, and ESCI measuring receivers for EMC and field-strength measurements
- FSET series TEMPEST preselectors, spectrum analyzers and measuring receivers
- SMR, SCR measureing receiver series for EMC measurements
|40x40px||Wikimedia Commons has media related to Spectrum analyzers.|
- Multi-page spectrum analyzer tutorial covering superheterodyne or swept frequency and FFT analyzers.
- Spectrum Analyzer / Measuring Receiver Tutorial and Basics
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