Short spaced TV stations...

[Colly0410]

A quote from Wikipedia about WESH TV channel 2 Orlando... "The stations signal was short spaced to prevent interference with WTHS channel 2 in Miami."... I'm trying to work out what 'short spacing' means & how it prevents co-channel interference?

[old_tv_nut]

I think this article was poorly worded. If you look up the definition of "short-spaced" it means to reduce the power or increase directivity to protect another station on the same channel at less than normal distance.

The article says:
"On that day, the station activated a new 1,000-foot (305 m) transmitter tower in Orange City. The tower was located farther north than the other major Orlando stations' transmitters because of Federal Communications Commission (FCC) rules at the time that required a station's transmitter to be located within 15 miles (24 km) of its city of license. The station's signal was short-spaced to prevent interference with non-commercial educational station WTHS-TV (channel 2, now PBS member station WPBT) in Miami."

I think it should say:
"On that day, the station activated a new 1,000-foot (305 m) transmitter tower in Orange City. The tower was located farther north than the other major Orlando stations' transmitters to prevent interference with non-commercial educational station WTHS-TV (channel 2, now PBS member station WPBT) in Miami. The tower had previously been located closer to Orlando because Federal Communications Commission (FCC) rules at the time that required a station's transmitter to be located within 15 miles (24 km) of its city of license. The shorter distance to Miami had required the signal to be short-spaced."

see:
https://en.wikipedia.org/wiki/City_of_license

[old_tv_nut]

http://rogersimmons.com/wesh-channel-2/

this site says the first transmitter was furhther north, in Holly Hill (near Daytona Beach), so maybe it was short-spaced from the time it moved to Orange City, and the location in Orange City rather than even further south was part of the short-spacing.

[old_tv_nut]

"On that day, the station activated a new 1,000-foot (305 m) transmitter tower in Orange City. The tower was located farther north than the other major Orlando stations' transmitters because of Federal Communications Commission (FCC) rules at the time that required a station's transmitter to be located within 15 miles (24 km) of its city of license." Still doesn't make sense, because Orange City is 22 miles from Daytona Beach.

Also, any of the locations are more than 200 miles from Miami.

[Colly0410]

In UK when they reused a low band channel that was near'ish to a high power vertically polarised transmitter (all high power low band TX's were vertically polarised) they'd use horizontal polarisation to try & cut down co-channel interference, then the next co-channel TX would use vertical & so on. AFAIK all american TX's use/used horizontal polarisation...

[zeno]

In the good old NTSC days WESH was the most common DX station
to be picked up in New England. Always in there with the slightest
sporatic-E. No other did this, it would be random from certain areas.

73 Zeno
LFOD !

[Robert Grant]

Originally Posted by zeno

In the good old NTSC days WESH was the most common DX station
to be picked up in New England. Always in there with the slightest
sporatic-E. No other did this, it would be random from certain areas.

73 Zeno
LFOD !

I wonder if you lived in Hartford or Philly.

WEDU (Tampa, channel 3) was ultra-common, too, but WFSB or KYW have have drowned WEDU out.

Sporadic-E propagation in the VHF-Low TV band strongly favors paths of 1,000 miles (1,600 km), not much further, and not much shorter. If a TV DXer gets a station 350 miles distant, he/she will brag about it.

[old_tv_nut]

Originally Posted by Colly0410

In UK when they reused a low band channel that was near'ish to a high power vertically polarised transmitter (all high power low band TX's were vertically polarised) they'd use horizontal polarisation to try & cut down co-channel interference, then the next co-channel TX would use vertical & so on. AFAIK all american TX's use/used horizontal polarisation...

You are correct. Either pure horizontal or elliptical.

[zeno]

In the Boston area we had 2 OTA pay TV stations in the late 70's
Ch 27 in Worcester ( Wistah in NE speak) used the Zenith system &
Ch 68 from Boston ( B-T system ??). IIRC Ch 68 used circular polarization. On
the biggest UHF antennas it was always very snowy even at +- 30 miles.
Both installed cut to freq antenna & the signal from CH 68 was rock solid.
Just before OTA pay died "someone" sold off boxes for a few hundred $$ each.
It lasted about a year then back to unscrambled NTSC. Gee I wonder who
was selling them

73 Zeno
LFOD !

[Colly0410]

I've actually experienced 'short spacing.' When Channel Five (Channel Five is the station name, it doesn't actually transmit on channel 5) started in 1997 in UK the only spare channel in the UHF (the VHF band was de facto not used since the 1970's) in most parts of the country was 37, so most high power stations used 37. I lived about half way between two Channel Five channel 37 TX's (Lichfield near Birmingham & Emely Moor near Leeds) when I lived in Kirkby-in-Ashfield near Mansfield, my antenna was pointed at Lichfield but was wiped out by interference from Emley Moor with severe patterning & beating effects making it unwatchable. I moved to Hucknall near Nottingham & received a good picture when the local'ish Waltham TX started TXing Channel Five on channel 35. I now get perfect Channel Five pictures from Waltham via over the air Freeview & Virgin free cable. (If you use Virgin media for broadband & landline phone you get free cable TV.)

[NowhereMan 1966]

I know back in 1948/49, WDTV of the Dumont TV network went on the air on channel 3. They were later shunted down to channel 2 in the early 1950's because Cleveland, OH had WEWS in channel 3 and there was concern that in the middle of the two cities, you would have co-channel interference. Later on, WDTV became KDKA-TV when Dumont went under and Westinghouse bought the station. There was a channel 6 in Beckley, WV that ran at halff maximum power because there was WJAC in Johnstown, PA on channel 6 also. Maybe not exactly co-channel interference, but when WTAE-TV, channel 4 in Pittsburgh signed off at night, there were times WRC-TV from Washington DC came in.

[KentTeffeteller]

And to add to this, co channel interference in that era was a very real problem, especially for viewers in between the two affected station signal. Those viewers had more interference issues than people living closer to either station. Short spacing is not good band planning, the recent years FM band debacle is a major reason why. Stations on a frequency need 50-100 miles or even a bit more depending on ERP, and also there needs to be reasonable interference protection. I think directional antennas are going to be a reality in practical terms for the FM broadcast band to have a chance at being usable. Especially for listeners who live between the two signals equally apart.

[NowhereMan 1966]

Originally Posted by KentTeffeteller

And to add to this, co channel interference in that era was a very real problem, especially for viewers in between the two affected station signal. Those viewers had more interference issues than people living closer to either station. Short spacing is not good band planning, the recent years FM band debacle is a major reason why. Stations on a frequency need 50-100 miles or even a bit more depending on ERP, and also there needs to be reasonable interference protection. I think directional antennas are going to be a reality in practical terms for the FM broadcast band to have a chance at being usable. Especially for listeners who live between the two signals equally apart.

I know, I live 8 miles north of Wheeling, WV on the Ohio side of the Ohio River and one station that plays a lot of 70's and 80's music, I love the 80's, is on 105.5 Mc, WUKL Bethlehem, WV, but when I drive to work in the Pittsburgh area, I get about 4 or 5 miles into PA and the translator they have on 105.5 Mc in Pittsburgh takes over and it is from 104.3 Mc, a Froggy country music station.

When Mom and I went to California in 1987 and drove from Frisco to LA on I-5 in the San Jouquin Valley, there were many FM stations going back and forth on the capture effect, the FM band was a pain in the butt to listen to.

[Alex KL-1]

Originally Posted by NowhereMan 1966

I know, I live 8 miles north of Wheeling, WV on the Ohio side of the Ohio River and one station that plays a lot of 70's and 80's music, I love the 80's, is on 105.5 Mc, WUKL Bethlehem, WV, but when I drive to work in the Pittsburgh area, I get about 4 or 5 miles into PA and the translator they have on 105.5 Mc in Pittsburgh takes over and it is from 104.3 Mc, a Froggy country music station.

When Mom and I went to California in 1987 and drove from Frisco to LA on I-5 in the San Jouquin Valley, there were many FM stations going back and forth on the capture effect, the FM band was a pain in the butt to listen to.

FM stations have also this issue here I live (Brazilian triple border with Argentina and Paraguay; Foz do Iguaçu). Besides some pirate station playing havoc with my 70's-80's-90's preferred station, some legal stations are crowded one adjacent or almost to each other (bad planning and communications between countries). Well, for poor stations, it's favorite sport is to change frequency from time to time. And, the radio comms cannot use VHF band due to harmonic interference from poor stations; where I work, the private radio comm network needed to be UHF.
Also from TV analogue era, was common to have some TV channels adjacent being used (4-5, 8-9, 12-13 for example). For this, the solution of rotating the antenna applies, due to different country station location.

[NowhereMan 1966]

Originally Posted by Alex KL-1

FM stations have also this issue here I live (Brazilian triple border with Argentina and Paraguay; Foz do Iguaçu). Besides some pirate station playing havoc with my 70's-80's-90's preferred station, some legal stations are crowded one adjacent or almost to each other (bad planning and communications between countries). Well, for poor stations, it's favorite sport is to change frequency from time to time. And, the radio comms cannot use VHF band due to harmonic interference from poor stations; where I work, the private radio comm network needed to be UHF.
Also from TV analogue era, was common to have some TV channels adjacent being used (4-5, 8-9, 12-13 for example). For this, the solution of rotating the antenna applies, due to different country station location.

True, that is a big problem in border area, radio signal travel across the border no problem and sometimes there can be interference with both or all nations if they do not share the same or similar band plans. I know if I past Mercer County, PA ( Mercer County, on Mom's side, my ancestors was among the first settlers there after fighting the American Revolution) and north, as an amateur I can to be careful since I would be above "Line A" and prohibited from transmitting on 420 - 430 Mc because in Canada that is used for different purposes than amateur radio. I was also above Line A when I was eclipse chasing in April and ended in Ashtabula County, Ohio.

BTW, WTAE-TV, channel 4 in the analogue days was one of those Class B (IIRC) low power VHF stations in Pittsburgh. VHF-Lo TV stations from channels 2 to 6 can transmit up to 100 kW but WTAE-TV was restricted to 50 kW because there was a Channel 4 in Washington DC (When WTAE-TV went off the air, many a night, I could get the Washington, DC station, WRC) O the other side, there was a channel 4 in Columbus, Ohio so Pittsburgh was in between. I lived in the West Hills of Pittsburgh and WTAE-TV had their transmitter East of Pittsburgh so there were times it was hard to get over the air, it was a true challenge plus I also lived near the airport, a busy flight pattern. There was an adjacent Channel 5 too, WDTV to the south in Bridgeport, West Virginia.

WTAE-TV went on the air in 1958, until then, except for a brief time with a weak UHF station, Pittsburgh only had KDKA-TV which was WDTV (until the West Virginian TV station took those call letter later on, but Pittsburgh was on the Dumont Network and was said to be the belt buckle. There were people who tried to pull in TV stations from adjacent TV markets such as Steubenville, Ohio, Wheeling, West Virginia and Johnstown, PA too.

One of WTAE-TV first shows, a huge part of Pittsburgh history, was called Top Banana, Second Banana and the Musician that was al ocal variety show. The musician was named Joe Negri who was also the first musical director on WTAE-TV. He is a jazz guitarist and a local legend, he played the Handyman in Mr. Roger's neighborhood. He turns 98 in two days, he got his first start in radio at the age of 3 (been performing on radio since 1929), still performs, still teaches music. Married to the same wife for 70 years too.

Another Pittsburgh TV oddity was we had two NET/PBS stations, WQED on channel 13 and WQEX of channel 16. Joe Negri performed on them too. Pittsburgh was the last US city to still have an all black and white TV station and WQEX was it. It was low budget, using al old 1953 vintage UHF TV transmitter up till it died in 1986. A lot of them ore far our programs ended up there plus a lot of British TV shows too. I was like Brit Box before Brit Box, albeit in black and white. I remember watching Dr. Who and Black Adder on it.In 1986 when they got s new transmitter, they went to color.

Sorry I went long but I love history and Pittsburgh does have a vivid TV/radio history like most places in the world. I also like to go to Youtube to see what TV is like in other nations too, it is fascinating.