SINPO code

For the North Korean city, see Sinpo.

SINPO, acronym for signal, interference, noise, propagation, and overall, is a code used to describe the quality of radio transmissions, especially in reception reports written by shortwave listeners. Each letter of the code stands for a specific factor of the signal, and each item is graded on a 1 to 5 scale (where 1 stands for very bad and 5 for very good).

The use of the SINPO code is subjective and varies from person to person. Not all shortwave listeners are conversant with the SINPO code and prefer using plain language instead.

Code explained

S (Signal strength)

Simply the strength of the transmission.

I (Interference)

Interference from other stations.

N (Noise)

The amount of noise.

P (Propagation)

Whether the signal is steady or fades from time to time.

O (Overall merit)

An overall score for the listening experience under these conditions.

Examples of SINPO code applied

In responding to a shortwave reception, the SINPO indicates to the transmitting station the overall quality of the reception.

The SINPO code in normal use would simply consist of the 5 rating numbers listed without the letters, as in the examples below:

54555 - This indicates a relatively clear reception, with only slight interference; however, nothing that would significantly degrade the listening experience.

33434 - This indicates a signal which is moderately strong, but has more interference, and therefore deterioration of the received signal.

Generally, a SINPO with a code number starting with a 2 or lower would not be worth reporting, unless you had no noise, interference or loss of propagation, since it would be likely the reception would be unintelligible.

Somebody may rate a signal as 33232 whilst someone else might rate it as 44333. Likewise, although the original SINPO code did lay down technical specifications for each number (i.e. a number 3 in the P column meant a fixed number of fades per minute) these are hardly ever adhered to by reporters. Nor is it advisable to use the so called 'Signal Strength' meter to judge signal strength. No 'S' meter on a communications receiver under US $600 in price is anything more than a tuning indicator. The 'S' meter reading is usually dependent on the setting of the RF gain control, so use your ears, not the needle, to judge signal strength. You may also find references to the "SINFO" code in some literature. In this case the 'F' stands for Fading, instead of 'P' for Propagation, but the two codes are essentially the same.

It is also clear that many listeners cannot distinguish between the 'I' which stands for man-made interference, the 'N' which stands for natural atmospheric noise, and the rating for 'Propagation' is not often understood. There are some books and periodicals that maintain the SINPO code as being the only one for DX reporters. However, from a station's point of view some stations suggest the SIO code - a simpler code which is used by most professional monitoring stations around the world.

See also

• RST code