questions with uncertain answers

[eyg2181]

ok i always wondered why stations are only on the odds (93.3 93.5 93.7) but no (93.4 or 93.6)

my guess would be, that all the stations would bleed through to the next even more than the do now if they are close by...like if there was a 93.2, you couldnt have a 93.3 b/c it would bleed through if it is a local station, and it would mess the dial up for certain areas...so i guess they have the FM dial set up like that for that reason...just to keep order...but i still am not 100% on that

also stations on the west start with "K" but stations on the east start with "W"...im guessing this is b/c there are so many stations and 4 letters to each call letter...that the amount of possible combinations would run out...like, there would be a WAAA and a WAAB, there would have to be a WZZY, And a WZZZ, and all those combinations would run out with all the stations that are out there...so they are separated by "K" and "W" depending on their location in the country...but im not 100% on that either

sorry if this makes no sense at all...but i said it the vest i could...im sure ya know what i mean.

 

[Len14043]

ok i always wondered why stations are only on the odds (93.3 93.5 93.7) but no (93.4 or 93.6)

also stations on the west start with "K" but stations on the east start with "W"...im guessing this is b/c there are so many stations and 4 letters to each call letter...that the amount of possible combinations would run out...like, there would be a WAAA and a WAAB, there would have to be a WZZY, And a WZZZ, and all those combinations would run out with all the stations that are out there...so they are separated by "K" and "W" depending on their location in the country...but im not 100% on that either

sorry if this makes no sense at all...but i said it the vest i could...im sure ya know what i mean.

While it is generally true that K's are west of the Mississippi River and W's are east of the Mississippi, it is not totally true. For instance, KYW and KDKA are in Pennsylvania and WOAI is in Texas. Saint Louis, west of the Mississippi, has K's and W's. Back in the mid 80's, an oldies station in Salt Lake City was WKRP. Although it's customary that a new station will begin with a K or W depending on where the station is located, I think a station anywhere can select any call letters available.

 

[jcolletta275]

ok i always wondered why stations are only on the odds (93.3 93.5 93.7) but no (93.4 or 93.6)

my guess would be, that all the stations would bleed through to the next even more than the do now if they are close by...like if there was a 93.2, you couldnt have a 93.3 b/c it would bleed through if it is a local station, and it would mess the dial up for certain areas...so i guess they have the FM dial set up like that for that reason...just to keep order...but i still am not 100% on that

You're correct. Here in North America, we set things up for FM so that there is a certain amount of separation between stations depending on several factors including signal strength and distance. That was indirectly intended to prevent interference between stations on different frequencies (as the primary goal was to prevent interference between two stations on the same frequency), but due to some poor engineering decisions on the FCC's part in recent years, we've kind of defeated that purpose here in the States. However, if you take a look at Great Britain and most other areas of the world, they do put stations on even-ending frequencies... they also have wider separation on the dial and keep more strict control over the technical details than we do.

also stations on the west start with "K" but stations on the east start with "W"...im guessing this is b/c there are so many stations and 4 letters to each call letter...that the amount of possible combinations would run out...like, there would be a WAAA and a WAAB, there would have to be a WZZY, And a WZZZ, and all those combinations would run out with all the stations that are out there...so they are separated by "K" and "W" depending on their location in the country...but im not 100% on that either

You're partially correct: when call letter prefixes (the first letter in the call sign) were assigned to the various nations of the world, we were given four prefixes: A, K, N and W. It was up to us how we used those prefixes, so we broke it down this way (for the most part): A is used for military purposes, N is used for transportation (aviation, shipping, etc.), W and K are used for broadcasting (and, previously, shipping as well). Most stations in the east received W calls and most in the west received K calls, but initially, we didn't make it a rule to divide K and W calls geographically (hence K exceptions such as KYW in Philadelphia, KDKA and KQV in Pittsburgh and KFIZ in Fond Du lac, Wisconsin).

Now this is where it gets interesting: the FCC's predecessor eventually decided to specifically assign W calls to the east and K calls to the west. The original dividing line was not the Mississippi River as it is today; it was to the west. It ran along state lines, from the Texas/New Mexico border to the east, up north through the Texas/Oklahoma panhandle region, east again along the Oklahoma/Colorado state line, north again along the eastern border of Colorado, back west between Colorado and Nebraska, then finally north along the state lines of Nebraska, Wyoming, the Dakotas and Montana.

BUT in 1923, the boundary was changed to the Mississippi River, which meant that all new call letters assignments would be determined by that boundary. That meant that there would be many grandfathered W stations west of the new line, such as WOAI San Antonio, WBAP Fort Worth and WDAY Fargo.

Then, of course, you have the requested "vanity calls," which are assigned if it's proven by the station that the call letters have some heritage in the city they're to be assigned to (for example, WHO Des Moines or WWLS Moore, Oklahoma). And then there's the station I used to work for, KTGG in Spring Arbor, Michigan, who were assigned K calls in 1984 because someone at the FCC mistook "MI" as the postal abbreviation for Missouri (goes to show you the level of intelligence in the people who spend our tax dollars, doesn't it? ;D).

If you want more details about the history of the K/W separation, you can check out this page. It's where I learned a lot of things about the subject, much of which I never would have known (for example, the Detroit Police used to own a station with the calls KOP!).

 

[BRNout]

ok i always wondered why stations are only on the odds (93.3 93.5 93.7) but no (93.4 or 93.6)

also stations on the west start with "K" but stations on the east start with "W"...im guessing this is b/c there are so many stations and 4 letters to each call letter...that the amount of possible combinations would run out...like, there would be a WAAA and a WAAB, there would have to be a WZZY, And a WZZZ, and all those combinations would run out with all the stations that are out there...so they are separated by "K" and "W" depending on their location in the country...but im not 100% on that either

sorry if this makes no sense at all...but i said it the vest i could...im sure ya know what i mean.

While it is generally true that K's are west of the Mississippi River and W's are east of the Mississippi, it is not totally true. For instance, KYW and KDKA are in Pennsylvania and WOAI is in Texas. Saint Louis, west of the Mississippi, has K's and W's. Back in the mid 80's, an oldies station in Salt Lake City was WKRP. Although it's customary that a new station will begin with a K or W depending on where the station is located, I think a station anywhere can select any call letters available.

Len, you're right about the "K" stations in Pennsylvania, which received their calls before the Mississippi River was used as a K vs. W demarcation by the predecessor of the FCC. Other exceptions include WBAP Fort Worth, TX, WHO Des Moines, IA and WRR Dallas, TX. I believe there is a "K" station in Michigan that recently obtained those calls by accident because some nimrod at the FCC thought "MI" stood for Minnesota! The calls stuck - so there is an exception there too.

However, your mention of "WKRP in Salt Lake City" is incorrect. That station was actually KRPN Roy (107.9) with a translator (92.1 IIRC) that served the Salt Lake Valley. The official calls were never WKRP - it was just a catchy moniker that was used for a fairly unique oldies station. I used to listen to that station from time to time and, although it sometimes sounded amateurish, it was often entertaining with a great playlist!

 

[w9wi]

ok i always wondered why stations are only on the odds (93.3 93.5 93.7) but no (93.4 or 93.6)

my guess would be, that all the stations would bleed through to the next even more than the do now if they are close by...like if there was a 93.2, you couldnt have a 93.3 b/c it would bleed through if it is a local station, and it would mess the dial up for certain areas...so i guess they have the FM dial set up like that for that reason...just to keep order...but i still am not 100% on that

There certainly is a limit as to how close together on the dial you can put stations. At the same site, the FCC requires 0.8MHz separation - 93.3 94.1 94.9 95.7 96.5 etc.. But that doesn't explain why they used odd channels instead of evens; 93.4 94.2 95.0 95.8 96.6 would have worked just as well.

Allowing for a small guardband, an analog FM broadcast signal occupies 0.2MHz - 0.1MHz either side of the quoted frequency. A station that announces its frequency as 93.3 is occupying the space between 93.2 and 93.4. The FCC considers the FM broadcast band as starting at 88.0 and running to 108.0. Other services (TV channel 6 and aircraft navigation equipment, respectively) occupy the frequencies on either side.

So an FM station on 108.0 would "spill over" up to 108.1 and interfere with aircraft navigation. Similarly, one on 88.0 would spill over to 87.9 and interfere with TV.

Thus, the lowest valid FM frequency is 88.1, and they count up in 0.2MHz increments from there.

The selection of 0.8MHz as the minimum separation between stations at the same site is of course done to ensure radios can separate adjacent stations. If you had stations on 93.3 and 93.5 on the same tower, most radios would receive a jumble of interference. The specific choice of 0.8 is rather arbitrary. Many radios can easily separate stations 0.4MHz apart. (indeed, in some cases the FCC now permits this) For really cheap radios, 0.8 isn't enough . It's basically a decision as to just how cheap of a radio we want to protect. We could have very easily chosen 0.7 or 0.9 instead, in which case we might have had both odd and even channels. (93.3 94.0 94.7 95.4 96.1)

Other countries have made other decisions. European FM radios tune in 0.05MHz steps, as not only are odd frequencies used, but so are some "half splits". 94.15, 96.35, etc.. South Africa reportedly implemented a completely off-the-wall step size - 0.072 or something like that. I'm sure that worked fine at a time when radios had analog tuning and it was no problem to dial up 97.344MHz. Today, one has to think they've made some adjustments! Another bizarre one: there is **ONE** even-frequency station in Australia. All the rest are odd.

also stations on the west start with "K" but stations on the east start with "W"...im guessing this is b/c there are so many stations and 4 letters to each call letter...that the amount of possible combinations would run out...like, there would be a WAAA and a WAAB, there would have to be a WZZY, And a WZZZ, and all those combinations would run out with all the stations that are out there...so they are separated by "K" and "W" depending on their location in the country...but im not 100% on that either

Actually, it was done to ensure radio operators could tell ships and shore stations apart. Three-letter W calls were issued to shore stations in East and Gulf Coast ports; K calls to shore stations on the West Coast. Four-letter K calls were issued to ships whose home ports were in the East; W calls to West Coast shipping. If someone sailing off Houston heard a station signing a callsign starting with "W", he could figure it was probably a shore station.

Because this was done for maritime purposes - and because ports on the Texas Gulf Coast are west of the Mississippi River - the dividing line has not always been the Mississippi. It started as the eastern borders of New Mexico, Colorado, Wyoming, and Montana. Once broadcasting got going, they did run out of callsigns pretty quickly. (only 676 3-letter calls are possible on each side of the dividing line, and they had to supply maritime shore stations out of that pool too) Moving the dividing line east was one of several steps taken to make more callsigns possible. Stations like WHO (Des Moines), WHB (Kansas City), and WKY (Oklahoma City) were "stuck" between the old and new lines, and got to keep their "non-conforming" calls.

There are 17,576 possible 3-letter calls on either side of the Mississippi. According to the FCC, as of the end of 2006 there are a total of 13,837 broadcast stations. (not counting low-power and translator operations that take calls from a different "pool") So there are a bit more than twice as many available calls as there are stations to use them. Of course, some calls are more desirable than others! - if you're running an active rock station, you'd much rather have WROK than WUSS... There was a proceeding at the FCC a few years ago to consider dropping the W/K distinction and allowing the use of A and N for broadcast calls. The FCC seemed willing to do it but the broadcasters weren't interested.

 

[KeithE4]

Also, the United States didn't get the full K-block until 1929. KA-KC were originally assigned to Germany, with KD-KZ assigned to the U.S. That's why early stations were assigned the KD block first - callsigns starting with KA-KC weren't American calls in 1920-21!

The AA-AL block came later as well, but I don't know the year.

AFAIK, N and AA-AL blocks are strictly for military use, with hams being the only exception to that rule unless the FCC gets an OK from the Dept. of Defense. There was a shortwave station assigned the call letters NDXE back in the '80s, but it never made it on-air. I think the FCC had to get the DOD's permission to give out that callsign, however.

 

[vchimpanzee]

If you had stations on 93.3 and 93.5 on the same tower, most radios would receive a jumble of interference.

It's on these boards somewhere, and if I had enough time I could probably find it, but for three or four days two stations in the same market were both broadcasting at 96.5 because of a fight over who the FCC had the right to grant the license to.

Serious interference problems, as you might imagine.

 

[vchimpanzee]

About the K and W situation, I guess if an FM or TV station was co-owned with one of the stations with the wrong first letter, they could keep it even if the AM did something else. There was also no rule saying there had to be four letters rather than three, but apparently there is now, so the older stations have been grandfathered in too.

WIS-AM in Columbia, S.C., for example, is now WVOC but the TV station is still WIS. WRC in Washington, D.C.--same.

 

[vchimpanzee]

I don't know why they did this, but a station at 98.3 back in the 1980s said it was at 98.2. The DJ may have made a mistake, but it made sense because the station was allowed to be too close to a station at 98.7. More recently, a station at 98.1 was allowed to increase its signal, which should never have been done. I have serious problems with the 98.3 station just 15 or 20 miles away, going toward the 98.1 station.

 

[Grrrradio]

I don't know for sure, but it may also be the case that British stations broadcast with lower audio fidelity and/or lower modulation levels. (I do know that they apply less pre-emphasis to high audio frequencies.) This would cause the FM carriers to "deviate" less. (In case you're not familiar with the technical side of things, FM stations continually change their frequency by very small amounts, which are themselves determined by the audio that's being fed into the transmitter. Broadly speaking, your receiver detects those variations and converts them back into audio.) The less audio you're feeding in, the smaller the variations, and hence the less "space" the signal takes up on an analog dial.

(Incidentally, does anyone know if the British allocation and spacing criteria are similar to the American ones? In other words, does our 4-channel, 0.8 MHz same-site limitation translate down to a 4-channel, 0.4 MHz limitation for them? And if a decent home stereo pulls in a certain fringe station from 90mi away on 96.7 with a local on 96.3... does this mean you could do the same in England with the fringe station on 96.5?)

As for the call-letter thing, I thought I once heard that stations in states bordering the Mississippi were free to use either a K or a W call. Then again, I'd also heard that Minnesota was the only place this was allowed, since it's the only state that the Mississippi actually runs through. Can anyone confirm or deny either of these?

 

[jcolletta275]

As for the call-letter thing, I thought I once heard that stations in states bordering the Mississippi were free to use either a K or a W call. Then again, I'd also heard that Minnesota was the only place this was allowed, since it's the only state that the Mississippi actually runs through. Can anyone confirm or deny either of these?

Actually, the river runs through Louisiana as well. But you're partially correct: they can't choose their prefix, they still go by the rule, but those are the only two states where non-grandfathered stations can have either a K or W prefix (again, depending on whether they're east or west of the river).

 

[BRNout]

I don't know for sure, but it may also be the case that British stations broadcast with lower audio fidelity and/or lower modulation levels. (I do know that they apply less pre-emphasis to high audio frequencies.) This would cause the FM carriers to "deviate" less. (In case you're not familiar with the technical side of things, FM stations continually change their frequency by very small amounts, which are themselves determined by the audio that's being fed into the transmitter. Broadly speaking, your receiver detects those variations and converts them back into audio.) The less audio you're feeding in, the smaller the variations, and hence the less "space" the signal takes up on an analog dial.

Honestly, I do not know whether there are technical differences in the feed - but the audio coming out of most UK FM stations sounds just as good in my radio as US stations do.

(Incidentally, does anyone know if the British allocation and spacing criteria are similar to the American ones? In other words, does our 4-channel, 0.8 MHz same-site limitation translate down to a 4-channel, 0.4 MHz limitation for them? And if a decent home stereo pulls in a certain fringe station from 90mi away on 96.7 with a local on 96.3... does this mean you could do the same in England with the fringe station on 96.5?)

It seems that local stations in crowded areas (like London) are spaced as close as 0.4 MHz apart (Choice FM is at 96.9, LBC is at 97.3; Magic Fm is 105.4, Virgin Radio is 105.8 and Heart FM is at 106.2). I know for a fact that all of the stations I've listed except for Virgin broadcast from the same site (Croydon). When you get into the BBC frequencies, things can get even more cramped - for example Radio One broadcasts to London with 4 kw from Crystal Palace on 98.5 and is broadcast from nearby Wrotham with 250 kw on 98.8. Strangely enough, it seems to work out. The biggest problem in the London area is the preponderance of pirates - some of which set up shop as close as 0.1 MHz away from one of the weaker local commercial stations. Now THAT causes interference. The FM dial in London is just full of pirates. There's something on almost every 0.2 MHz.

Also, when traveling, the 0.1 MHz step puts an end to reception for dxing purposes as you have a station like Capital at 95.8 and Invicta in Thanet, Kent at 95.9 (only 250 w) - which will wipe out Capital in the Thanet area. That's less than 50 miles from London. So, the dial is more crowded over there. Tougher to do long-haul dxing because there are too many stations with the same frequencies or with frequencies that are 0.1 MHz apart. It cuts down on the range. Not to mention that most commercial stations in the UK run with far less power (usually 4 kw or less). The big powerhouse tx sites tend to belong to the BBC.

 

[jcolletta275]

The only technical difference I know of (and, yes, in this case, that means "that I know of"... there may very well be others) between GB and US stations is that British stations process with 50uS pre-emphasis instead of our standard 75uS.

 

[Tom Wells]

Italy uses .1 spacing on FM and eliminated their radio-TV regulatory body.
There are more stations than you can imagine, and they all interfere with each other to the point that no signals were clear enough to listen
to in the area between Milan and Torino.
What a mess it was! This was in 1993, I suppose it's just as bad now....