SINPO Rating

Your chance to give 'marks-out-of-five' on how badly degraded the signal is by interference, noise and propagation effects respectively. The definitions for the degradation effect are shown as Extreme (1), Severe (2), Moderate (3), Slight (4) and Nil (5). It might be helpful to consider that in the RS(T) reporting system we use R5 to report a perfectly readable signal, and R1 for a signal that is unusable. With SINPO all we are doing is splitting the "R" report into its individual components I, N and P:

	S	I	N	P	O
Rating	Signal	Degrading effect of:			Overall
Scale	Strength	Interference	Noise	Propagation disturbance	Rating
5	Excellent	Nil	Nil	Nil	Excellent
4	Good	Slight	Slight	Slight	Good
3	Fair	Moderate	Moderate	Moderate	Fair
2	Poor	Severe	Severe	Severe	Poor
1	Barely audible	Extreme	Extreme	Extreme	Unusable

• "I" stands for interference, or QRM. Think about this as a reading for the degrading effect of interference on the QSO, i.e. 5 for none, 1 for a lot. When giving the report you can think the same way as you do with the "R" report for RS(T) - for a signal with very heavy QRM you give it a report of 1, and a signal with little or no QRM gets a report of 5.
• "N" is for the degrading effects of noise, i.e. QRN. Again we can think about the report as 5 for none, 1 for a lot. Note that interference from a broad-band data transmission might sound like noise, so if you can do some checks to ensure that you gave correctly determined whether the apparent noise is indeed noise rather than QRM.
• "P" is a measure of propagation-related distortion such as fading, flutter or perhaps an auroral rasp on the signal. Again, it is seen as a measure of the degrading effect on the desired signal, also scoring 5 for none, 1 for a lot. This is perhaps the more difficult one on which to report, as on a strong signal the effects of QSB may be less noticeable with the good AGC systems in our rigs these days. Conversely it could be that you hear more pronounced fading from QRP stations and therefore give a different report for P between QRO and QRP stations.

Finally, the O report is a measure of the extent to which all these factors contributed to the overall rating; 5 for excellent and 1 for unusable. O=1 is also used for “not heard”; when it is known that the station is transmitting on channel. SM.1135 has a useful set of tables to help the assessment of O. Table 3 below shows the assessment suggested for telephony transmissions:

Overall rating	Operating Condition	Quality
5. Excellent 4. Good	Signal quality unaffected Signal quality slightly affected	Commercial
3. Fair	Signal quality seriously affected; channel usable by operators or by experienced subscribers	Marginally commercial
2. Poor 1. Unusable	Channel just usable by operators Channel unusable by operators	Not commercial

ITU SM.1135 SINPO Reporting Code for “overall” assessment of a telephony transmission.

Source: ITU and RSGB