BSV Forum - Writing - Resources

SINPO, 5x5, and Faith

Aug 13 2014 07:55 am   #1Saggit
Back in the day, the Navy created the SINPO code to explain a number of factors affecting signal transmission. It vanished, but by the 60s was in use for shortwave stations. You sent SINPO reports to distant stations--usually foreign ones--to acquire QSL cards, often very fancy postcards acknowledging your receipt of their signal. I have a bunch of these of these; mainly from the 60s, abandoned in the 70s, and resumed briefly in the 80s when my father lay dying of cancer, and I lacked the funds to go visit him more than a couple of times.

But enough of that.

So what is SINPO?

S = Signal strength.
I = Interference from other stations.
N = Noise. Jammers, or unintentional electronic interference that may come from a variety of sources.
P = Propogational disturbance. Come summer (hah), local AM stations may fade in favor of very distant ones. This is less likely on FM, but relatively likely on shortwave. It has to do with disruptions in the ionisphere, and stuff like that there.
O = Overall.

So...

35151 = Average signal strength and good in general, except for noise, which renders the signal just about inaudible.

52554 = Great signal, but there's a lot of interference from other stations. Still, it's not enough to prevent the staiton from being strongly heard and understood.

55555 = Perfect signal, no problems, excellent result. You gotta message to send? Hey, I heard ya, five by five.

The Navy long ago stopped using SINPO, but it's enshrined in shortwave listeners' use. Faith may have known a sailor, but probably knew a shortwave listener at some point. And whomever the writer was that put those words in her mouth, they open upon a lost world of broadcasting.
Aug 13 2014 09:41 pm   #2slaymesoftly
That's fascinating! Thanks so much for sharing that explanation.


Back in the day, the Navy created the SINPO code to explain a number of factors affecting signal transmission. It vanished, but by the 60s was in use for shortwave stations. You sent SINPO reports to distant stations--usually foreign ones--to acquire QSL cards, often very fancy postcards acknowledging your receipt of their signal. I have a bunch of these of these; mainly from the 60s, abandoned in the 70s, and resumed briefly in the 80s when my father lay dying of cancer, and I lacked the funds to go visit him more than a couple of times.

But enough of that.

So what is SINPO?

S = Signal strength.
I = Interference from other stations.
N = Noise. Jammers, or unintentional electronic interference that may come from a variety of sources.
P = Propogational disturbance. Come summer (hah), local AM stations may fade in favor of very distant ones. This is less likely on FM, but relatively likely on shortwave. It has to do with disruptions in the ionisphere, and stuff like that there.
O = Overall.

So...

35151 = Average signal strength and good in general, except for noise, which renders the signal just about inaudible.

52554 = Great signal, but there's a lot of interference from other stations. Still, it's not enough to prevent the staiton from being strongly heard and understood.

55555 = Perfect signal, no problems, excellent result. You gotta message to send? Hey, I heard ya, five by five.

The Navy long ago stopped using SINPO, but it's enshrined in shortwave listeners' use. Faith may have known a sailor, but probably knew a shortwave listener at some point. And whomever the writer was that put those words in her mouth, they open upon a lost world of broadcasting.
I am not a minion of Evil...
I am upper management.
Aug 13 2014 11:25 pm   #3Saggit
My pleasure. I've been meaning to put that up for years! Just never got around to it. Given the detail with which Faith Lehane was built, it's a shame the show featuring her never became a reality. On the other hand, we do have some truly fantastic fanfiction, usually with Xander or Wesley and her.