Receiver dynamics
In the transmission curve of a receiver, the receiver dynamic is the range between the limit sensitivity (maximum sensitivity) and the range of the limit of the output signal.
To measure a receiver transmission curve, a signal of a defined size is connected to the receiver input using a signal generator and the amplitude of the receiver output signal is measured. Two values are of particular importance here. These are
- the limit sensitivity and
- the range of limitation of the output signal .
The limit sensitivity is the level at which no amplitude of an output signal can be measured (in the graphic this is the level −118 dBm). With a steady increase in the level of the input signal, ideally a linear increase in the output signal can be measured. From a certain level (here from −96 dBm) the amplitude can no longer be increased, the output signal has reached its maximum possible value. The receiver is in the limit. The difference between these two absolute levels is defined as the receiver dynamics, which is then given in a relative level (here 22 dB).
This measurement is of practical importance in the construction of receiver circuits. The recipient should only be as sensitive as necessary. Too great a sensitivity only causes additional interference signals to be received. If the receiver is driven to the limit by too strong input signals, then non-linear distortions ( distortion factor ) occur and the quality of the received signal deteriorates.
In the case of receivers used in radar devices , however, the greatest possible sensitivity is required. In order to avoid operation in the area of the limitation, the receiver dynamics must be greater here than with receivers of communication technology , which is achieved through the use of logarithmic amplifiers .
literature
- Ralf Rudersdorfer: radio receiver compendium . 1st edition. Elektor International Media BV, Aachen 2010, ISBN 978-3-89576-224-6 .