Reciprocal Mixing Dynamic Range
Reciprocal Mixing Dynamic Range (RMDR) ( German as: dynamic range for "mutual mixing" ) is an English technical term , of an important property of RF - receivers describes.
definition
The RMDR describes quantitatively the reduction of the signal-to-noise ratio (SNR) of a receiver in the presence of a relatively large interfering signal (in addition to the mostly relatively small useful signal, although undesirable but often unavoidable) . It is defined as:
"The degradation of the receiver output signal-to-noise ratio due to the mixing of strong interfering signals with the noise skirts of the synthesizer."
"The reduction of the signal-to-noise ratio of the receiver output signal due to the mixture of strong interfering signals with the noise sidebands of the synthesizer."
The definition dates back to 1986, when synthesizers (more precisely: synthesis generators) as local oscillators (LO) were just as current in reception technology as heterodyne detection using analog mixers embodied the state of the art (at that time). However, even today, in the times of RF direct sampling , direct digital synthesis (DDS), and software defined radio (SDR), it is still valid.
The decisive factor is the reduction of the dynamic range of the receiver in the presence of a strong interfering signal at a certain frequency separation. As the useful signal is converted by mixing the frequency with the aid of the LO signal, an (undesired) interference signal that is present can also be mixed to the same frequency by noise sidebands ( English noise skirts ) of the LO signal. Although the sidebands are significantly smaller than the LO signal amplitude, since the interference signal can be significantly larger than the useful signal, relatively large interference in the output signal can nevertheless result.
This signal-to-noise ratio is a characteristic quality feature for good receivers and is specified in decibels . A value of around 100 dB or more is regarded as “good”.
Web links
- Measurement of Reciprocal Mixing in HF Communication Receivers in the Fixed Service. Recommendation ITU-R F.612, 1986 DOC; 72 kB
- What is Reciprocal Mixing - Measurement & Specification. Article at Electronics-Notes.com , accessed September 3, 2019.
Individual evidence
- ↑ Robust wireless communication in Markt & Technik from November 8, 2016 at elektroniknet.de , accessed on September 3, 2019.
- ↑ Measurement of Reciprocal Mixing in HF Communication Receivers in the Fixed Service. Recommendation ITU-R F.612, ( DOC; 72 kB ) 1986, accessed on September 3, 2019.
- ↑ Icom - The Transceiver IC-7851 (RMDR) (PDF; 1.5 MB) at icomeurope.com, accessed on September 3, 2019.