THE USE AND ABUSE OF SINPO

THE USE AND ABUSE OF SINPO

(This post is an edited version of an article I wrote for "The World of Shortwave Listening" column of The Spectrum Monitor magazine - August 2017 issue. Further details on this excellent publication is available at www.thespectrummonitor.com)

The SINPO code is usually found included in a shortwave listener's reception report to a broadcaster. And the code is often quoted in listings of stations logged when contributed to DX club newsletters, Facebook groups and other shortwave listener forums. But often, we find a few misunderstandings in the way the numbers are compiled for the code.

Useful in describing the quality of radio transmissions, SINPO is an acronym for Signal Strength, Interference (from other radio stations and includes man-made interference), Noise (atmospheric), and Propagation (e.g. fading). Overall quality of reception is calculated after taking into account the previous four reception components (S, I, N and P). The five components are given a ranking from 1 (the worst) to 5 (the best).

You can also find variations on the standard SINPO code. SINPFEMO adds complexity by including F (Frequency of fading), E and M (relating to the quality and depth of modulation). SWLs will sometimes also see SINFO, replacing the easily misunderstood 'P' for Propagation with the more relatable 'F' for Fading. And in recent times, some shortwave broadcasters have encouraged the use of the much simpler SIO (Signal, Interference and Overall) code. Indeed, SIO is about all that is required for most situations, given that there are usually some types of atmospheric noise and propagation characteristics attached to the reception of radio signals on the shortwave bands. Broadcasters are most interested in the signal strength at the receiving location and, importantly, any interference suffered from other stations on the same or adjacent frequencies.

SINPO is occasionally referred to as one of the 'Brevity Codes’; a term used to collectively group together codes in a variety of radio communications for the purpose of delivering detailed information in short messages. Other brevity codes include the RST code used by ham radio operators and SWLs, the Ten Code developed for the CB band, the Q code originally developed for telegraphy communications back in the early 1900s, and a variety of military codes.

Interestingly, the SINPO code appears to have been one of the later additions to the brevity code category. It first appeared in the early 1950s under the CCIR (Consultative Committee on International Radio), a forerunner to the current ITU-R (the International Telecommunications Union - Radio Communications). In the most recent (2011) ITU-R Spectrum Management document on the code, it is described as an "....accurate description of the transmission quality and is easy to use." It can also be found in the eighth edition (2010) of the International Civil Aviation Organisation (ICAO) Abbreviations and Codes document. So, SINPO is still very much used today in a variety of applications.

However, there are three problems with SINPO: 
1) Obviously, it is open to the subjective interpretation of the listener. One listener's idea of a "good" signal is probably quite different from another SWL. 
2) As already mentioned, the interpretation of each component of the code, e.g. the I, N and P, can easily be confused by a non-technical listener, hence the reason for the simpler SIO code. 
3) Even the very definitions of the SINPO code can be unclear. 

An Example of the Third Problem with SINPO
In some references on the subject, Interference (I) has been described as both interferences from other stations and man-made noise (e.g. local electrically produced static). Yet other sources put man-made interference in with the Noise component. 

Personally, I have always considered the Interference component to refer to other transmitting stations impinging on the station you are listening to at the time. This is the concept behind the amateur radio Q-Code known as QRM. 

Man-made types of interference tend to be of a broad-banded nature (transmitting in an unintended manner across the frequency spectrum) and includes such noise or static interferences coming from a multitude of electrical appliances and gadgets, power poles and other local sources. I have always considered these types of interferences as a part of the component known as Noise, or QRN in the amateur Q-Code. In a recent face-to-face discussion with my long-time colleague Victor Goonetilleke on this very problem of interpreting SINPO, he concurred with my interpretation of these aspects of the code. 

Some references disagree with my (and others...) interpretation of the I and N in SINPO. International broadcasters are aware that atmospheric noise and local static will be always present to varying degrees, such is the nature of this medium known as shortwave propagation! There is nothing that an international broadcaster can do about man-made interferences at the listener's location nor propagational statics! But, as mentioned earlier, interference from other broadcasters on the same or adjacent frequencies is something that can be changed with better spectrum management, so feedback on that aspect of SINPO is of particular interest to stations. 

So what hope do non-technical listeners have if the proponents of SINPO can't agree on accurate definitions?

Although there is still widespread use of SINPO throughout the SWL hobby, it is clear that many listeners are still not comfortable with how to use the code. Correct practice would dictate that a ranking on the Overall component (the O in SINPO) would not be higher than any number given to one or more of the other components. If the lowest ranking of any of the other components was, say 3, then the Overall ranking should not be higher than a 3. Yet, we regularly see Overall rankings not relating to the other components. 

Examples of Confusing SINPO Ratings

SINPO = 42344 Even if Interference is rated as 2 (severe), then there is no way that Overall should be given a good ranking (4). Considering that it was combined with a Noise ranking of 3 (moderate), one would expect the overall reception to be, at best, probably a 2 (poor).

SINPO = 54323 Described here is a strong signal at the listener's location, some slight interference, but with moderate atmospheric noise and severe fading. Again, although the signal strength may have been very strong on this occasion, the combined presence of interference, noise and propagational disturbances would demand that this Overall ranking is marked down to probably a 2 (poor reception). Indeed, you would have to question the accuracy of this SINPO report of 54323 when the listener is claiming that the signal strength is excellent but the fading on the signal is severe!

SINPO = 45444 Along with the SINPO rating, this SWL wrote in his report that the reception was good with no atmospheric noise. So why did he give a rating of 4 for the Noise component?

SINPO = 55555 or 11111 There may be a few opportunities to give a station "all fives". For example, China Radio International seems to have a booming, laser-like, mile-wide signal on many occasions. But in most other instances, there is usually some form of degradation to the signal, such as in the form of slight pulsating fades. And if you are telling the station that it is "all ones", then I don't know how you even heard it if the signal was barely audible, while interference, noise and propagation disturbances were extreme!

So, is it any wonder that over the years a few broadcasters have expressed frustration and confusion at the accuracy of some reception reports. It has even been suggested by a few listeners that some broadcasters look more kindly on higher SINPO ratings, and hence are more likely to reward the listener with a QSL card! Wrong!

While many international stations are familiar with the SINPO code, not all broadcasters prefer its use. And for stations offering only a relay of their domestic service on shortwave, such as South American or smaller Asian stations, the fully written out description of reception is much more easily understood and possibly more reliable. These days, many experienced DXers have taken to providing both SINPO and a written description of the quality of reception.

An additional word of advice here: 
As indicated earlier, providing information on any observed interference from other broadcasters operating on or adjacent to the desired station's frequency is of particular interest to broadcasters. It can be most helpful if the listener can identify the interfering station that he is hearing at his location, so close attention should be paid to this component of the code.

The Changing Relevance of the Reception Report
Back in the day, shortwave broadcasters ran large international services to many target areas around the globe. All operations were done "in-house" with the listeners' letters department sending on feedback about reception quality to the engineering or technical division. A station relied on listener feedback and reports to ensure that their signal was reaching the target zone with good strength and no interference on the once over-crowded shortwave bands. In those days, there was a feeling that the reception report held some importance and provided valuable information on reception conditions.

In the last twenty years, there has been a distinct change in the way that shortwave radio stations operate their services and deliver their content. Many broadcasters use commercial transmission brokers to make decisions about frequency management in the shortwave spectrum. Independent organisations such as WRMI, Babcock Communications, TDF (Télédiffusion de France), Broadcast Belgium, SpaceLine Ltd. and others provide services that allow the station to focus mainly on content and leave the worry of transmission to separate frequency management organisations and brokers who either own or rent airtime from transmitter sites and relay stations.

This has enabled broadcasters such as Radio Japan to offer a better service using a variety of "tailor-made" transmitter sites scattered around the globe beaming strong signals into target zones, instead of relying solely on their own Yamata site in Japan to deliver the signal. In addition, stations can now assess the successful transmission of their broadcasts through the use of their own remote receivers or the many independent remote online SDR receivers scattered around the world.

What this means for the faithful shortwave listener is that their reception report could perhaps be viewed by some stations as being less about a way of communicating technical information on reception conditions and more about the station maintaining a connection with their "customer" - the listener. As transmissions are now commonly being outsourced, the station is more focused on gaining feedback on the programs they air. And the information on reception conditions is not always being passed onto the engineering department (....if indeed a technical division still exists within the broadcasting organization!).

Some reception reports are VERY basic!!

Yet, some listeners provide scant, if any, comments on programs in their reports. Recently, I've seen some pretty horrible examples of what are euphemistically called reception reports! Their details consist of "man talking", "woman talking", "music", and then the demand for a QSL card. A colleague of mine calls this approach the "Gimme QSL" syndrome! The very things that stations want these days - comments and feedback on programs - are not being supplied by many listeners. Could this be the reason why some broadcasters don't issue QSLs anymore, or at best offer only an "acknowledgement" card, letter or email without details of date, time or frequency of the reception? This opens up a whole new discussion for a future post here at MEDXR!



Final Thoughts
Returning to the SINPO code then, we can see its use, along with the declining value of the traditional reception report format, are becoming less important these days. So, when writing a report for an international broadcaster, I suggest that
1) You use the SINPO code, ensuring that the Overall rating relates correctly to the other four components that make up the code. 
2) You may prefer instead to use the somewhat easier SIO in place of SINPO, as it is the components of Signal Strength, Interference and Overall Quality that are the most important here. 
3) I also recommend that a written description of the reception quality be included, in case the person reading your report is not familiar with SINPO. 
4) Above all, try to provide feedback on the programs heard during your listening session. The station will thank you for it! 

In wrapping up this discussion, I came across a monograph from the BBC Engineering Division back in September 1962 entitled “Propagational Factors in Short-Wave Broadcasting” by L. J. Prechner, B.Sc. Published about 10 years after the initial introduction of the SINPO code, the article discusses fading, ionospheric disturbances, maximum and minimum useable frequencies, and the problems of accuracy in short and long-term predictions. It also mentions statistical analysis of SINPO. Although our understanding of the ionosphere is far more enhanced these days, this monograph is still worth reading for enquiring minds wishing to delve deeper into the subject. You can download it at: http://downloads.bbc.co.uk/rd/pubs/archive/pdffiles/monographs/bbc_monograph_43.pdf

73 and good DX to you all,

Rob Wagner VK3BVW

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