Radio dynamic range

It is accepted to call the ratio (usually in decibels) of the maximum input signal to the minimum signal dynamic range.

The maximum signal level is limited by the permissible nonlinear distortions arising due to overload in the last stage of the amplifier with strong signals.

The minimum input level is determined by the sensitivity of the receiver

In modern broadcast receivers D = 40 ... 60 dB (100 ... 1000); for trunk D = 60 ... 80 dB (1000 ... 10000).

To expand the dynamic range using electronic devices with a large linear portion of the current-voltage characteristics and automatic gain control. Increasing the sensitivity of the switch module also increases the dynamic range.

Receiver Dynamic Range, on the one hand, determines the receiver's ability to detect a weak input signal, a greater noise level, and on the other hand, to process signals of a large level without distortion. The ratio of the maximum signal to the minimum signal at the receiver input determines the dynamic range of the receiver:

The following two parameters of the radio receiving device are of particular importance: dynamic range, free of interference SFDR (Spurious Free Dynamic Range), and dynamic range on blocking BDR (Blocking Dynamic Range).

The SFDR-free dynamic range is based on the ratio between the maximum input level for which third-order intermodulation products have a level lower than the noise level and the minimum distinguishable signal Smin .

Figure 1. Inter-modulation products of the third order receiver, limiting the dynamic range of the receiver

The upper limit of the dynamic range of the receiver by blocking the BDR is determined by the signal of a one-stop point, the lower - by Smin .

Figure 2. Illustration of determining the dynamic range of a BDR blocking receiver

The maximum gain of the functionally complete receiver path is determined based on the maximum possible in-band blocking P bl. This means that the maximum gain depends on the quality of the filter in front of the main gain cascades.