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. You'll need the RealAudio Player or plug-in to hear these. It's free! The first example is from our Remote Monitoring System (RMS) in Luanda. It is a 20 second sample of our Sao Tome mediumwave (1530 kHz) in English at 0314 UTC on July 1, 2001. 544 is one possible rating for this long-distance, over-salt-water, near-the-coast mediumwave reception. The second example is from our Remote Monitoring System (RMS) in Tel Aviv. It is a 20 second sample of our Rhodes mediumwave (1260 kHz) in English at 0616 UTC on July 1, 2001. 444 is one possible rating for another long-distance, DAYLIGHT, over-salt-water, near-the-coast mediumwave reception. The third example is from our Remote Monitoring System (RMS) in Quito. It is a 20 second sample of a VOA Spanish broadcast at 1210 UTC on July 1, 2001. 232 is one possible rating for this poor reception of a broadcast actually meant for Central America. The last example is from our Remote Monitoring System (RMS) in Phnom Penh. It is a 20 second sample of a RFA Vietnamese broadcast at 2339 UTC on July 1, 2001. 422 is one possible rating for this poor reception of a good signal due to jamming.