What is SINAD: radio receiver sensitivity specification

Signal to Noise ratio or SNR is one popular method of defining radio receiver sensitivity. But another measurements that's often seen, especially for VHF / UHF FM communications radios is called SINAD.
In this video Ian Poole of Electronics Notes takes a look at what SINAD is, and investigates what a typical measurement means. He also checks out the way SINAD is measured for radio receivers. Ian Poole also mentions that there are some standards associated with SINAD and finds out where they are used.
SINAD standards for Signal to Noise and Distortion, so this specification is more than just a signal to noise ratio because it includes the unwanted distortion products as well.
Whilst noise is traditionally the main limitation for sensitivity, any distortion and other unwanted products will also limit the ability of the receiver to discern the wanted signals.
As a result, SINAD is an important measurement because as we said, it looks at a variety of signal degradation issues in one measurement. And although it is most widely used for VHF or UHF FM two way radios, it can also be used for other analogue modes and frequencies as well.
SINAD can be defined as the ratio of the total received signal level, in other words, signal together with the noise and distortion to the noise and distortion level. This means that the higher the SINAD level, the better the quality of the audio signal.
In terms of the formula, SINAD is expressed in decibels and it is equal to the log to the base ten of the level of the combined signal, noise and distortion divided by the noise and distortion. It's worth noting that the signal levels are all measured as power levels and not as voltages.
More information about radio receiver sensitivity and SINAD: www.electronics-notes.com/art...
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[@ChiefMade]

Nice!

[@ElectronicsNotes]

Glad you liked it.

[@jeffsmith3350]

Thanks for the video. Unfortunately I still don't know how to interpret sensitivity specs on a UHF/VHF radio. If one radio has a rating of 0.25μV at 12dB SINAD, and the other has a rating of 0.35μV at 12dB SINAD, which is the better receiver? Thanks for any info.

[@ElectronicsNotes]

Sorry, I obviously did not explain this well enough - the lower the value in microvolts for the given signal to noise ratio or SINAD, the more sensitive is the receiver. If one receiver has a SINAD or 12dB at 1 microvolt and another one gives the 12dB SINAD for 0.1 microvolts, then the receiver with the 0.1microvolt figure can receive smaller signals for the same noise and distortion level and therefore t is the more sensitive. I hope this helps.

[@jeffsmith3350]

@@ElectronicsNotes Awesome! Thanks. Makes sense now.

[@acestudioscouk-Ace-G0ACE]

Well explained and useful. Are there levels of SINAD which are genereally regarded as a threshold or yardstick measurements of a sensitive FM receiver?

[@ElectronicsNotes]

I think the best way to look at that is to check out some specific radios in a group. Normally for VHF / UHF amateur radio handhelds, I would expect to see figures of better than 0.2 microvolts for 12 dB SINAD. But best to check a number of radios in the sector you are looking at and check the performance levels.

[@acestudioscouk-Ace-G0ACE]

@@ElectronicsNotes Thanks for taking the time to reply. It was most helpful and I appreciated it.

[@ElectronicsNotes]

@@acestudioscouk-Ace-G0ACE Pleassd to be able to help.

[@jeffsmith3350]

@@ElectronicsNotes Better, meaning higher than .2 microvolts, or lower?