The SDO Rating System

Reception quality or audibility is subjectively rated using the SDO system with numbers ranging from 1 to 5.

The best possible reception would be a 555 and the worst possible would be a 111 or 151.

[Examples below]

S is for signal strength, D is for degradation and O is for overall merit.

They are rated as follows:

Signal strength Degradation Overall merit Note: We add 'comments' to degradation to indicate that it is caused by interference, local noise, jamming, hetrodyne, propagation, RTTY, etc. We encourage our monitors to identify interferers whenever possible so that we may determine if we should change frequency or, based on coordination agreements and length of use, ask someone else to move.
5 - excellent 5 - none 5 - excellent
4 - good 4 - slight 4 - good
3 - fair 3 - moderate 3 - fair
2 - poor 2 - severe 2 - poor
1 - nil 1 - extreme 1 - nil

We use words to describe what the subjective levels of overall merit mean. Close attention to these usually forces a rating clearly into one catagory or another. 5 Excellent best possible shortwave reception, no more than slight degradation.
4 Good can be tuned in easily and listened to without difficulty despite slight to moderate degradation.
3 Fair can be listened to with difficulty.
2 Poor only portions of the program heard because of weak signal or annoying degadation.
1 Nil no IBB program heard.

Here are some examples of how SDO works.

We've pre-rated a few reception examples. You can look at how we rated the reception and listen to what it sounds like.

The first example is from our Remote Monitoring System (RMS) in Rangoon, Burma. It is a 20 second sample of our Iranawilla, Sri Lanka relay station on 9940 kHz in Burmese at 1702 UTC on April 29, 2016. 544 is one possible rating for this scary loud signal heavily processed as it leaves the transmitter.

The second example is from our Remote Monitoring System (RMS) in Addis Abeba, Ethiopia. It is a 20 second sample of our Djibouti mediumwave (1431 kHz) in Amharic at 1605 UTC on April 28, 2016. 544 is one possible rating for this distant medium wave signal heard barely after sunset.

The third example is from our Remote Monitoring System (RMS) in Hanoi, Vietnam. It is a 20 second sample of a RFA Vietnamese broadcast at 1432 UTC on April 28, 2016 from our Tinnian relay station. 322 is one possible rating for this fair signal spoiled by heavy Vietnamese 'fire engine' jamming.

The last example is from our Remote Monitoring System (RMS) in Beijing. It is a 20 second sample of a VOA Chinese broadcast on 11825 kHz at 1110 UTC on April 27, 2016 from our Philippines relay station. 322 is one possible rating for this fair signal [note the VOA jingle] spoiled by multiple, time-offset, co-channel CNR jammers.