Receiver sensitivity

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The term receiver sensitivity characterizes the sensitivity of a receiver . The expression of the receiver sensitivity is a signal that the receiver can "just about" receive. Numerical values ​​can be specified as linear or logarithmic received power or, more rarely, if the input impedance is known, as a voltage in the microvolt range. In order to avoid subjective falsifications when measuring receiver sensitivities, fixed framework conditions are defined for the signal description (“just about to be received”).

MDS echo

Signal size for measuring the MDS

This abbreviation MDS denotes the lowest possible reception power for receivers in radar devices . The English-language long form of this abbreviation is ambiguous, however.

Minimum detectable signal (MDS)

The term minimum detectable signal is used to determine the minimum possible reception power for automatic target recognition . This value is usually measured at the IF amplifier output and indicates the power at the receiver input when the measured signal is 3  dB above the mean level of the background noise. It is usually given in dBm and, with good radar receivers, is in the order of −100 dBm… −110 dBm.

example

A number from practice: with an input impedance of 50 Ω, a receiver sensitivity of 4 µV was specified for the P-12 , which was measured with a signal / noise ratio of 4 to 1. Values ​​of around 2.2 µV were not infrequently achieved.

Minimum discernable signal (MDS)

The term Minimum Discernable Signal is used when the signal is still to be recognized by an operator from the noise. This value is usually determined on a display device and is the specification of the power at the receiver input when the signal is just barely recognizable on the display device. The signal must then even be smaller than the mean noise level, because the different pulse duration of the noise peaks in relation to the measurement signal enables detection at a smaller amplitude than the noise peaks. The value is usually given in dBm and reaches values ​​of −110 dBm… −120 dBm with good radar receivers. However, it is precisely this value that is subjectively falsified during the measurement.

example

A number from practice: the receiver sensitivity of the ASR-910 must be at least −110 dBm.

Minimum Visible Signal (MVS)

An operator-dependent interpretation is also available for the less frequently used terms Minimum Visible Signal (MVS) and tangential sensitivity . Here, the useful signal received is not only mixed with the noise, but also with other interfering signals such as B. compared fixed target echoes , which often vary in strength and therefore do not result in a constant reference.

literature

  • Volkmar Brückner: Elements of optical networks . Basics and practice of optical data transmission, 2nd edition. Vieweg + Teubner, 2011, ISBN 3-8348-1034-7 .
  • Martin Werner: communications engineering. An introduction to all courses, 7th edition, Vieweg + Teubner Verlag, Wiesbaden 2010, ISBN 978-3-8348-0905-6 .
  • Friedrich Benz: Measurement technology for radio engineers. Springer Verlag, Vienna 1952.
  • Volker Jung, Hans-Jürgen Warnecke (Hrsg.): Handbook for telecommunications. Springer Verlag, Berlin / Heidelberg 1998, ISBN 978-3-642-97703-9 .

See also

Web links