Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jul Fri 10, 2020 5:33 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 18 posts ] 
Author Message
 Post subject: Detroit area test patterns being broadcast, pictures added
PostPosted: Mar Wed 11, 2020 5:01 am 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5282
Location: Ann Arbor, MI
For people who are getting their TV using an antenna, some of the stations changing RF channels in the Detroit area have their new transmitters on the air with a test pattern.
Tune to channel 32 to see WDIV's test pattern.
WWWJ does not leave the transmitter on all the time, but tune to channel 21 to see if it is on.
WTVS is taking over the RF channel used by WHNE and so is leaving the new transmitter off most of the time to allow WHNE to stay on the air as long as possible. Tune to channel 14. You will usually just see WHNE, but sometimes will see WTVS's new transmitter. WHNE will be getting a new transmitter and antenna, but will not be ready in time for the March 13 switch. I expect that they will be off the air for awhile.

_________________
Tom


Last edited by Tom Schulz on Mar Wed 11, 2020 7:43 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast pictures adde
PostPosted: Mar Wed 11, 2020 7:34 pm 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5282
Location: Ann Arbor, MI
Attachment:
IMG_0878.JPG
IMG_0878.JPG [ 809.4 KiB | Viewed 1644 times ]

WXYZ changed March 7. Recorded on a VCR, so some sharpness and contrast lost.

Attachment:
IMG_0881.JPG
IMG_0881.JPG [ 636.96 KiB | Viewed 1644 times ]

WDIV changing March 13.

It was interesting to watch WXYZ change. They started broadcasting programming on the new channel a few minutes after midnight but kept on broadcasting on the old channel until the end of the current program. The program on the new channel came on as a few pixels on top of the test pattern background and filled in over about a half of a second.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Wed 11, 2020 10:20 pm 
Member
User avatar

Joined: Nov Thu 11, 2010 6:03 pm
Posts: 1262
Location: Pewaukee, WI
This reminds me of a low power DTV station near me that for a few months a few years ago was broadcasting test patterns 24-7...I think they shut down at the end of it.


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Thu 12, 2020 1:02 am 
Member

Joined: May Sun 07, 2017 11:35 am
Posts: 925
Location: Belrose, NSW, Australia
On a related topic, there are many analog shut-downs on Youtube.

Here's a cute one from Sydney, Australia, which includes an edited version of their 1956 station close cartoon (it used to say "Good Night"):

https://www.youtube.com/watch?v=aWk5SvvCeA8

Remember the time when they actually shut down overnight?

_________________
Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Thu 12, 2020 4:20 pm 
Member
User avatar

Joined: Nov Thu 11, 2010 6:03 pm
Posts: 1262
Location: Pewaukee, WI
In Chicago some stations shut down in the wee hours of the night/ morning into the 90s (sign offs were really patriotic)...I was a kid then so I was rarely up that late, but I can remember being bugged that upon being woken up by BAD thunderstorms that a number of stations were off the air where I couldn't find weather info.


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Thu 12, 2020 6:16 pm 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5282
Location: Ann Arbor, MI
Attachment:
IMG_0885.JPG
IMG_0885.JPG [ 733.83 KiB | Viewed 1544 times ]

As of 10:00 A.M. March 12 the WDIV transmitter is on. That broken black bar at the bottom opens and closes.
I expect that sometime before midnight WTVS will have to turn their transmitter on. As of now WHNE is still on that channel.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Sun 15, 2020 4:15 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
Likely you are seeing the result of FCC Re-Pack.

The FCC auctioned off ALL the spectrum that was used for television broadcast that is above channel 36.

T-Mobile bought most of it.

Television can only broadcast on channels 2 through 36. Keep in mind the television could go to channel 83.

As part of Re-pack some stations will share a single channel between two or more competitors. We easily stuff two full HD and four SD channels on one 6 MHz wide TV channel.

This is stressing the transmitter manufacturers, and tower crews, as well as RF component manufacturers.

Jim


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Sun 15, 2020 8:09 pm 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5282
Location: Ann Arbor, MI
Yes, it is due to the re-pack.

As I expected, WHNE had to go off the air to give their pre repack channel to WTVS. They shut down at 11:55 P.M. and WTVS came on at 12:02 A.M.
Things were a mess Friday morning. Two stations switched shortly after midnight. WPXD was broadcasting on both their new and old channels in the morning. Another station had a test pattern on their new channel and programming on their old channel. So If anyone re-scanned in the morning they got somewhat of a mess. Everything was straightened out by noon. I had expected better coordination between the stations than that.

I got some information from WHNE about their plans. They have their new transmitter but they don't have their new antenna. The antenna manufacturer needed a special part which they ordered from a company in Italy. The part is ready but right now nothing can be shipped from Italy. Ouch!
Those poor people. They have been assigned RF channel 3.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Mon 16, 2020 5:10 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
TV stations broadcast PSIP data (Program System Information Protocol) within their digital stream.

If PSIP quits working or if there are multiple copies being transmitted the station is essentially off the air. Most TV sets can't find the signal if it can't read the PSIP.

Jim


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Mon 16, 2020 7:59 pm 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5282
Location: Ann Arbor, MI
jimmc wrote:
TV stations broadcast PSIP data (Program System Information Protocol) within their digital stream.

If PSIP quits working or if there are multiple copies being transmitted the station is essentially off the air. Most TV sets can't find the signal if it can't read the PSIP.

Jim

What I found when WPXD had both transmitters broadcasting the same programming with the same PSIP was that my TV and recorder had two 31-1s, two 31-2s, two 31-3s. etc.
In one case they were interleaved and in the other case one complete block was followed by an identical complete block. This was with using the channel up and down buttons.

My Zenith digital converter box can tune by RF channel and everything I have will tune by RF channel if a channel number has not been learned as something.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Tue 17, 2020 12:31 am 
Member
User avatar

Joined: Sep Thu 14, 2006 3:27 pm
Posts: 12626
Location: Carmel, Indiana
Aren't test patterns a mute point now, a throwback from the past, since TVs screens use digital displays? Maybe there's some use in the adjusting the color.

_________________
Michael Feldt
www.indianaradios.com


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Tue 17, 2020 12:50 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
Color Bars are alive and well. They have a moving object as digital things will trap a still frame if the signal stops.

We still use NTSC Color Black for internal GenLock. The new internal GenLock is PTP (precision Time Protocal) It is distributed by a Cisco type switch.

Jim


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Mar Tue 17, 2020 1:22 am 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5282
Location: Ann Arbor, MI
In addition to the above:

The test patterns have black, gray and white sections. Some also have a bar that varies from black to white. Those can be used to set the brightness (black level) and contrast.

The test patterns also give the broadcast engineers something run through equipment under test and something to broadcast while setting up and testing a transmitter.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Apr Sun 05, 2020 10:47 pm 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5282
Location: Ann Arbor, MI
Since I mentioned WHNE in this thread I thought that I should post that it is now back on the air on RF channel 3. They decided to call themselves virtual 3 also rather than calling themselves 14 as they used to do. I think that they want to be known a 3 to emphasize the need for an antenna that can receive the low VHF band. According to their facebook page there are a lot of former viewers that have been unable to get them on channel 3.

Also, theoretically there is a WUDT that has RF channel 8 on virtual channel 23. I am in Ann Arbor and can find no evidence that they are on the air.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Apr Mon 06, 2020 5:36 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
As we move to ATSC3.0 many broadcasters are planning Same Frequency Repeaters. Works kinda like cellular.

There will be a main, full power transmitter somewhere and then fill in with the repeaters.

In the Phoenix AZ market, the UHF stations run about 1 Megawatt ERP and the three VHF stations are around 40 kW ERP. This market has to respect the Mexican border.

The low end of the UHF band seems to end up with lower power limits. Channel 14 sits next door to the 450 MHz two way radio band.

In my experience the VHF band propagates poorly compared to UHF band. The low end of VHF 2 -6 seems less desirable.

The viewer doesn't understand that the virtual channel 3 is actually on a high power UHF and the virtual and RF channel 5 is transmitting on a low power VHF . They buy an ALL DIGITAL flat panel indoor antenna and put it inside their stucco house (wire mesh keeps the stucco in place), and can't get a watchable signal.

Then through the magic of flakey computers, the PSIP data quits which essentially takes the station and its 5 sub-channels off the air.

Jim

Jim


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Apr Mon 06, 2020 10:53 pm 
Member
User avatar

Joined: Aug Thu 12, 2010 6:25 pm
Posts: 365
Location: Durham, NC
Low-VHF channels propagate just fine, with better than line-of-sight reception (at least in analog days) out to 50 miles or more, depending on terrain of course. This was understood in the late '40s when the FCC set up the channel allocations, with spacing to prevent (they hoped) co-channel (and adjacent-channel) interference. It quickly turned out to be too short a spacing in practice, even with transmitters rarely exceeding 30KW ERP. Then of course the ionosphere once again made itself known, as it does on a more-or-less regular basis, which caused TV reception at very long distances. So, I'd say that the low-V channels propagate fine, but with some occasional surprises.

Low-V does tend to suffer from multipath reception -- airplanes used to cause all sorts of amusing video effects, back in the early days anyway. Transmitter powers and antenna gain & patterns eventually minimized those problems. Digital TV doesn't suffer much from multipath if signal levels are adequate.

When UHF started up in the early '50s, reception was initially pretty consistent, but with WAY less coverage. The FCC allowed UHF stations to have about 10 times the radiated power (when it could be obtained) to compensate.

That was my experience, anyway. Cable TV pretty much makes it all moot anyway, though I recognize that a lot of folks prefer OTA, and some have rediscovered its joys.

_________________
Mark Nelson
A collector of TV signal boosters and UHF converters -- God help me!
tv-boxes.com


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Apr Tue 07, 2020 5:17 am 
Member

Joined: May Sun 07, 2017 11:35 am
Posts: 925
Location: Belrose, NSW, Australia
As a kid I grew up in Cabramatta, a suburb of Sydney. That was in the 1960s.
We didn't live on a hill or anything and the antenna (a 215, nothing special) was pointed about 20 degrees east of optimum. Despite this we'd get Ch3 Newcastle mostly out of the noise. That's 133km, or 83 miles.
Other parts of the state would pick up this transmitter over twice this distance, usually using a phased array - like this one except with a couple of Band 1 reflectors.
Attachment:
PhasedArray.png
PhasedArray.png [ 75.35 KiB | Viewed 969 times ]

Complaints of poor reception of band 1 are usually receiving antenna or power line noise related.
The original transmitter was by RCA, installed in 1961. Transmitting mast is 142 metres, the mountain it's on is 412 metres above sea level. So it's not especially high.
I don't know the transmitter power or the EIRP.

_________________
Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


Top
 Profile  
 
 Post subject: Re: Detroit area test patterns being broadcast, pictures add
PostPosted: Apr Wed 22, 2020 4:42 pm 
Member
User avatar

Joined: Mar Sun 22, 2020 5:56 am
Posts: 417
Location: Arvada, CO
Indiana Radios wrote:
Aren't test patterns a mute point now, a throwback from the past, since TVs screens use digital displays? Maybe there's some use in the adjusting the color.


The Color bars are alive and well as jimmc said. However the Indian Head test patterns are not used much anymore, as well the convergence lines and dots. These are all for calibrating Picture tube television sets. Digital televisions do not need to have their convergence, vertical height/linearity and horizontal width corrected every one and a while.

_________________
Electronics are filled with smoke. It’s my job to put the smoke back in when they fail.


Top
 Profile  
 
Post New Topic Post Reply  [ 18 posts ]  Moderators: 7jp4-guy, Mr. Detrola

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 10 guests



Search for:
Jump to:  


































-->


Privacy Policy :: Powered by phpBB