Wednesday, February 19, 2014


SINPO is an acronym. Here's what it stands for:
  • S - Signal Stregnth
  • I - Interference
  • N - Noise
  • P - Propagation
  • O - Overall Rating
In shortwave radio, a SINPO response indicates to the transmitting station the quality of the received signal. The SINPO code in consists of  five rating numbers with each digit describing the signal, interference, noise, propagation and overall reception quality. A perfect SINPO score would be 55555. However, because of the nature of terrestrial reception two near receivers with different terrain or equipment would rate a message with different SINPO scores. XRS actually has an app for that here.

I have also seen references the same code as "SINFO." In that case, the 'F' stands for Fading, instead of 'P' for Propagation. They are otherwise identical. There are also scant references to an SIO code. Both are referred to in Andrew Yoder's book Pirate Radio. This just compares signal to interference for an overall measure. Of course not all shortwave listeners area aware of SINPO and just use common adjectives. In it's original form there were quantifiable observations for each digit. This has diminished over time and the SINPO scores have become less formal. This may have led to the creation of SINPFEMO.

S - Signal Stregnth
I - Interference
N - Noise
P - Propagation
F - Fading of Frequency
E - Modulation Quality (Excellent)
M - Modulation Depth (Maximum)
O  - Overall Rating

It is highly likely that both systems originate in a much older code created by BBC engineers called RAISO.In true British spirit this was actually shortened for utility. The full acronym was RAFISBEMVO. In true engineer spirit, many of the letters stood for nothing at all making it difficult to memorize or use. The book Early Shortwave Stations by Jerome Berg has a little more information on this.SINPO and SINPFEMO were formally recommended by the Comité consultatif international pour la radio in 1961. Why they've been supplanted by the ITU, their recommendations stand.

R - Carrier Strength
A - Fading (Depth)
F - Fading (Frequency)
I - Interference
S - Static
B - Background Noise
E - Transmitted Noise
M - Modulation (Degree)
V - Modulation (Duality)
O - Overall Rating

If any British readers can direct me to more research material on this I'd appreciate it.