Home | Back to Wavescan Index

"Wavescan" is a weekly program for long distance radio hobbyists produced by Dr. Adrian M. Peterson, Coordinator of International Relations for Adventist World Radio. AWR carries the program over many of its stations (including shortwave). Adrian Peterson is a highly regarded DXer and radio historian, and often includes features on radio history in his program. We are reproducing those features below, with Dr. Peterson's permission and assistance.

Wavescan 345, August 5, 2001

The Story of the SINPO Code

Back in the era of early transmissions by Morse Code, the reception quality of a particular wireless signal was simply described in words, indicating, for example, strong signal with moderate interference. However, as time went by, there was a need to express more specifically the quality of a received wireless signal.

In the later Morse Code era, the "Q" Code was developed, and this provided a more specific method for describing reception quality. Generally there were five criteria listed and these were described as follows, though no specific numbers were mentioned at this time. These "Q" Codes were:

In the early 1920's, radio broadcasting stations began to proliferate in the United States. Reception reports were encouraged, and two different types of blank reception report cards were available. One was a non-specific card, usually described as the "Applause Card". The listener simply wrote in to the stations on this card, stating that he enjoyed a particular program. The quality of reception was not necessarily indicated on this "Applause Card".

Another type of reception report card actually listed several of the "Q" Code signals, including all five of the previously mentioned items. A scale of figures could be used with these designations, usually running 1 through 5, or 1 through 9.

Many of the concepts and practices of the early amateur radio world spilled over into the radio monitoring world, and this included some of the terminology used for describing signal quality. Quite popular in the era immediately before World War II was the "S-QSA" Code, which was a mixture of two different amateur codes.

In the "S-QSA" Code, "S" stood for "Strength" and "QSA" for "Readability". The "S" figures ran 1 through 9, and the "QSA" figures ran 1 through 5.

However, there was no uniformity throughout the radio world, and this led to a certain amount of confusion. Thus it was that the BBC in London devised a new reporting code in 1942, consisting of simply three elements with values running 1 through 5. In this new SFL Code

In this SFL Code, a perfect radio signal would be described as SFL 505.

Subsequently, Gustav-Georg Thiele at Deutsche Welle modified the new BBC code and devised the now well-known SINPO Code. This new code was launched in 1961, and officially adopted by CCIR-ITU, the international radio advisory in Berne, Switzerland, around 1970. In the SINPO Code, the number values run 1 through 5 and the letters are:

In the SINPO Code, a perfect radio signal would be described as SINPO 55555.

Subsequently there have come variations to the SINPO Code. For example, several international shortwave stations like to use an abbreviation of SINPO using only three elements, SIO. Then another variation is SINPFEMO, giving greater detail about the modulation of the received radio signal. However, the original SINPO Code stands firmly as the world's most reliable and most popular reporting standard.

This Week in Radio History - Radio Yemen, August 1, 1954

The Yemen is a small country made up of two different sections with two major cities, Aden and Sana'a. The territory covers 200,000 square kilometres and the population is around 6 million.

Initially, radio broadcasting in Aden was a spasmodic event, with Cable & Wireless providing a communication transmitter for broadcasting purposes when needed.

The first broadcasting transmitter in the Yemen was installed in Sana'a in 1954, and test broadcasts were commenced on shortwave on August 1, 1954. The frequency was 7365 kHz and the power was 1 kW.

These days, Aden and Sana'a operate a multitude of radio transmitters on FM, mediumwave and shortwave. Sometimes it is possible to receive a QSL letter or QSL card from Radio Yemen, though they are really quite rare. Radio Yemen is today remembering 47 years of radio broadcasting history.