Good Read - Reply from local station regarding HD problem

Eric_C

SatelliteGuys Pro
Original poster
Apr 18, 2004
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I wrote UPN50 in Detroit regarding a problem I had with the VOOM OTA reciever and the picture swapping from SD to HD. I posted a while back about it and I thought I would post his reply.

First off, I was happy to get a personal response and not a canned email, second IMO he went through and explained things very well. I'll find out tonight how the problem is going but I thought everyone would be interested in reading the note

Thank you for the feedback regarding the changing SD/HD picture you're seeing at home.
WKBD carries primarily upconverted standard definition analog video that is mapped into the HD transmission (1080i) standard. The only programming that we broadcast as full high definition consists of 1) the Paramount "Enterprise" program on Wednesday evenings at 8 pm, 2) the UPN Friday night movie is usually, though not always, a high definition feature, and 3) one weekend movie a month from a special HiDef movie package that WKBD purchased some time ago. The Sunday rebroadcast of the "Enterprise" episode seen on Wednesday night is not done in HiDef, but is merely an upconverted analog version of it.
I'm not sure what leads you to believe that your receiver is randomly switching between HiDef and SD since I'm not familiar with the Motorola box or the Voom satellite package you speak of in your email. Is the Voom service provided by someone else? If so, who?
It's hard to provide you with good, hard answers on something like this because several players are involved. First, WKBD's HiDef channel on air ALWAYS runs a HiDef 1080i encoded video data stream. It cannot switch between the two modes. Secondly, while we provide a HiDef transport stream to our transmitter does not mean that the program is originating in a High Definition format. As I outlined above, any programs other than those specifically mentioned above are upconverted from a 525 line interlaced analog format known as NTSC, the same color system that's been in use in this country since the early 1950's. The upconverter first digitizes the analog video, then performs a lot of very complex operations to reduces noise and grain in the original analog signal, then provides remapping on the approximately 480 lines of active video into the 1080 lines of the HiDef picture space. This generally provides a fairly low data rate signal to be sent to the digital encoder which prepares the data for broadcast over the air. The data rate of this signal can occasionally exceed the allowed data rate for actual over the air broadcast, so the digital encoder just mentioned does some massaging of the video data to ensure a constant data rate for transmission. This encoder also adds digitized audio, closed captioning, and a bunch of other ancillary data needed so that the home receiver can reassemble the entire program for viewing. After all this, the signal gets launched into the air via our transmitter and antenna system.
At the satellite company's headend (receiver farm and transmission system), they receive and decode the program just as on off-air receiver at home would. But from here, the similarity ends. Since satellite time and bandwidth costs many tens of thousands of dollars per hour, most service providers cram as much data payload onto a satellite channel as they can. The equipment used to do this is also very complex and constantly evaluates the amount of bandwidth really needed to provide the picture with acceptable (though not optimal) performance. A still scene requires very little bandwidth whereas a scene filled with lots of action and detail requires much, much more. Since we, as broadcasters, have no way of controlling what the service providers do with the data once they get their hands on it, I can't begin to guess what's really going on with your picture. One of the ways digital reception can "fail gracefully" is to reduce the recovered data rate, and hence, reduce the resolution. This may be caused by non-optimal antenna alignment or atmospheric disturbances like heavy thunderstorms. Beyond these couple of things, I don't know what else I could reasonably blame for the problem.
If you'd like to continue this dialog, please feel free to write me describing exactly what you were seeing on the screen, what the weather conditions were at the time, etc. Another question comes to mind. Does your receiver allow off air reception from an antenna? If so, what kind of reception do you get with it? Is your viewing screen shifting between HiDef and Standard Def modes or is it really the receiver that's experiencing this behavior?
I look forward to hearing from you.
 
It seems the they didn't understand how the VOOM receiver works. They though that VOOM receives the signal at their "farm" (like they call it) and they broadcast it over the bird. The reality is that for the problem you're reporting, the VOOM STB is not different from any other OTA receiver.
 
Wow! I wish we could always expect such a detailed reply from a local station!
They obviously don't know what VOOM is, but other than that, I am really impressed!
 
WHy do they think Voom is providing you the signal? You need to clarify with them that you are recieving the signal OTA.
 
Eric,I get it without any problem on my Samsung 165 OTA receiver and my Dish 811(I am in Belleville)what city are you in because UPN-50 is broadcasting at very low power now but that would not cause it to switch,at what times(when)this happen?
 
He was not familar with Voom, I explained that my local comes OTA and not over the Voom service.

I never had this problem with my Samsung unit either and I haven't had it since I wrote them the email either.

Regardless of his unfamilarness with Voom I was very impressed with the quality of the answer, hell I was impressed I got one at all!

Bruce, I am in Green Oak Township, your probably saying WHERE?

Its just west of South Lyon, 1 block inside Livingston county. If you see where Livingston, Washtenaw, and Oakland all come together thats about where I am.
 
Most local stations in LA don't know much about transmitting local HD broadcasts. Here in LA NBC channel 4 signal frequently goes out. It's a low priority. The local HD OTA broadcast went down here in LA for the Oscars and channel 7 didn't even know it.
 
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