How does OTA Scanning works in new software?

[Sean Mota]

Frequently Asked Questions about OTA Scanning Fucntion​

1. How does OTA Scanning Works?
2. What happens if my local station does not provide PSIP (Channel Number, MPEG Service Number and Short Name) data?
3. The OTA Scanning Function added new channels but I have no PG information. What should I do?
4. How can I save my OTA channels that are found?
5. If you lose power or unplug the stb, would you lose your mapping?

OTA Scanning function in software 6.00 and later has two screens. One screen is identical to the Aim Satellite Dish screen (sorry I don't have an actual picture but I am working on it). It states (1) that local will be locked at 80 and (2) to allow for rain fade the strength must be at least at 85.

Aim Satellite Dish​

http://www.satelliteguys.us/attachment.php?attachmentid=1359

OTA Scan Screen​

http://www.satelliteguys.us/attachment.php?attachmentid=1361

1 - Some of you have asked why does the OTA scan has to lock at 80? How about OTA channels that exhibit signal strength lower than 80? does this means I am out of luck in receiving these?

Based on what I was able to find out. The 80 and 85 number on the Aim Satellite Dish (same for OTA) are based completely on a different scale than what the OTA signal quality or strength was based on software version 5.68.

This is how the process works (this comes from Motorola):

The way this works is that we take a sample of 8 lock status readings from the demod and then calculate a value based upon a combination of how many readings had "Signal Lock" status and the resulting SNR if a good quality lock was achieved.

1) A signal level reading of less than or equal to 80 indicates that the signal was not "locked" on any of the 8 sample readings we took. The actual value of the number in that case is based upon a scaled AGC value (i.e. it indicates how much power is present in that RF band). If this number is below 80 it is unlikely that you will get video unless something changed in between when you took the reading and when you attempt to look at video.

2) A signal level reading between 81 and 84 indicates that the signal was "locked" between 1 and 7 times when we took the readings. You can probably get a picture in the higher end of this range but it will likely have macroblock errors in the active video. It will take a fair amount of luck to decompress any video at all in the low 80's.

3) A signal level reading of 85 or greater means that it was "locked" all 8 times and the higher the number the better the SNR. Each tick on the scale after you are above 85 roughly cooresponds to a 1 dB increase in SNR.

Also - In order for a channel to get saved in the map, PSIP must be available in the stream with at least the following three fields present: Channel Number, MPEG Service Number and Short Name. You may sometimes see the scanning process pause when it hits a signal and then not actually save the channel. What is happening is that the scanning process is paused to allow a reasonable amount of time for PSIP data to come in even for low quality signal level. If no channel is saved after one of those pauses, it is likely because it failed to obtain the required data from the stream.

2 - What happens if my local station does not provide PSIP (Channel Number, MPEG Service Number and Short Name) data? You can try one of these three things.

a) - Speak to your station engineers and ask that the PSIP data (Channel Number, MPEG Service Number and Short Name) be passed to their stream.

or

b) - Request that your channels be mapped. If you haven't done so, send me an email to Sean_Mota@satelliteguys.us with your full address and which channels are not mapped in your PG. This process will only be able to map channels within your DMA.

or

c) - There is work in progress right now to create a super DMA map that will provide mapping (without OTA Scanning software) to more than one DMA. This is in the works and it will not be done till October/November. (this of course implies waiting for this mapping to be created)

3 - The OTA Scanning Function added new channels but I have no PG information. What should I do?

The PG information comes from the Satellite. The data itself needs to be entered by Tribune. Send an email to Sean_Mota@satelliteguys.us and I will make the request for you.

4 - How can I save my OTA channels that are found?

"found and added" OTA channel are cumulative. So this means that it will not delete your mapping. Now, here is the deal with version 6.0. There's a bug in it that does not allow it to keep the channels found. As I told you before this version 6.0 is beta. A solution has been found already.

5 - If you lose power or unplug the stb, would you lose your mapping? No.

 

[DarrellP]

Thanks for the explanation Sean. One thing I don't understand is:

It states (1) that local will be locked at 80 and (2) to allow for rain fade the strength must be at least at 85.

What does rain have to do with locking OTA? Rain has no effect on OTA, does the stb require a sat lock for OTA to function?

 

[Sean Mota]

Thanks for the explanation Sean. One thing I don't understand is: What does rain have to do with locking OTA? Rain has no effect on OTA, does the stb require a sat lock for OTA to function?

You are probably right. I have to check (when I get the photo) the screen that pertains to OTA to see if it has the same description as to the satellite screen. I was just going by what the screen has in the picture. Not sure yet if the screen happens to be the same.

I know that OTA functionswhether satellite locks or not. Once I get the correct picture I'll be able to see what's there.

 

[jgantert]

Question about OTA scanning... I'm in Columbia, MD and am currently mapped to Baltimore, but I can also recieve DC channels. With the new software, how does this work? If I do a scan, I will only be able to pick up the channels that the antenna is currently pointed to. So, can I scan Baltimore first, then DC and it will "remember" the Baltimore channels?

Also, will I get PG info for both areas (assuming channel info is available)?

Thanks,
-John

 

[Sean Mota]

Question about OTA scanning... I'm in Columbia, MD and am currently mapped to Baltimore, but I can also recieve DC channels. With the new software, how does this work? If I do a scan, I will only be able to pick up the channels that the antenna is currently pointed to. So, can I scan Baltimore first, then DC and it will "remember" the Baltimore channels?

Also, will I get PG info for both areas (assuming channel info is available)?

Thanks,
-John

John,

Yes, you will be able to ge multiple DMAs. The procedure that you just mentioned will work and the function will remember the channels that you picked up in one direction. Yes, to the PG information as well. If no channel information is available, we will need to do the same we did with the mapping (sending me an Email with the channel, city,) so that it we can request it.

 

[wasch_24]

Thanks for the explanation Sean. One thing I don't understand is: What does rain have to do with locking OTA? Rain has no effect on OTA, does the stb require a sat lock for OTA to function?

Darrell,
In my neck of the woods, Northern Virginia, thunderstorms and poor weather conditions can and do affect my reception on a few of my weaker stations (40-50 signal strength).

 

[fayrich]

Don't know about multiple scans in different directions---my Hughes and Samsung STB's lose prior finds each time you scan. Don't think the new scan feature will work how you would like. But, hopefully you can accomplish what you want by a manual entry???

 

[Sean Mota]

Don't know about multiple scans in different directions---my Hughes and Samsung STB's lose prior finds each time you scan. Don't think the new scan feature will work how you would like. But, hopefully you can accomplish what you want by a manual entry???

I know this the way a lot of stbs do it but the VOOM scan function saves all the channels it scans. Everytime you scan it does not delete it just saves. This is why it has another function to hide the ones that you do not care about.

 

[DarrellP]

The as of yet unanswered question: "Can a channel be entered manually?" With the Dish 6000 I can autoscan then do a manual entry if I want, if Voom left out this feature, it's a huge mistake, though the scan feature is a step in the right direction.

 

[fayrich]

That's good to hear Sean. It's rather a pain to have to scan multiple times to get all active stations because at any given time one or more of the locals may be too weak or not transmitting. Right on Voom!

 

[Sean Mota]

The as of yet unanswered question: "Can a channel be entered manually?" With the Dish 6000 I can autoscan then do a manual entry if I want, if Voom left out this feature, it's a huge mistake, though the scan feature is a step in the right direction.

This is not part of the scanning function. However, what would be the difference between this and having the scan function automatically scan for the channel?

1 - If the automatic scan function cannot pick up the channel based on the above rule, it won't be able to pick it up with the manual scan.

2 - If you need to add a channel in another direction (assuming you have a highly directional antenna), you will have to rotate the antenna either way.

The only advantage in the Dish 6000 of adding digital channels manually is that the autoscan in the 6000 erases any mapping you have done previously. Voom circunvented this by not having the previously defined mapping deleted everytime you autoscan.

 

[wasch_24]

If you know the channel is there but it isn't always strong enough for a lock by the auto scan.

 

[Sean Mota]

If you know the channel is there but it isn't always strong enough for a lock by the auto scan.

How is it going to lock if the locking algorithm is based on the same rules as the autoscan. This happens to me with the Dish 6000. When I did not have ABC from my DMA, I used to get ABC from C.T. (65 miles away). I used the manual scan of the 6000 and was able to find it and it was added to the mapping but the signal was not strong enough to watch it. I got pixelated and dropouts all over the place. Now, is this locking up the channel? Nope because it was unwatchable. Is that an added benefit to have it? Yes, because you can see that is there but I could harldy watch anything on it.

 

[DarrellP]

Sean, someone with the new software posted that a station he picked up fine with the mapping would not pickup in the autoscan, so in his case it would benefit him to add it manually.

 

[Sean Mota]

Sean, someone with the new software posted that a station he picked up fine with the mapping would not pickup in the autoscan, so in his case it would benefit him to add it manually.

That's what he posted Yes. But that case needs investigation because according to what I posted above if you have a steady signal and the correct information is passed on, the autoscan will lock the signal. I remember the thread where he posted but I haven't heard anything else from him. I think he said he was getting 79 OTA signal quality but that does not translate to the 80 scale that it's need to lock the channel.

I am just going from the documentation. Maybe there's a need for this but we need more data to see if it will become a problem. I guess this is good to discuss but we need the scanning function available to everybody to see what kind of response we get and determine what's going on.

 

[wasch_24]

I guess it's specific to different areas. My FOX station fluctuates between 28-45 for the singal quality and I am still able to watch it on a clear day. I was under the impression that the scan won't pick this up because it is looking for 80-85 signal. If it didn't I could then manually tell it there is a station there and to not delete it from the PG. Or I could be way off base on this...

 

[Sean Mota]

I guess it's specific to different areas. My FOX station fluctuates between 28-45 for the singal quality and I am still able to watch it on a clear day. I was under the impression that the scan won't pick this up because it is looking for 80-85 signal. If it didn't I could then manually tell it there is a station there and to not delete it from the PG. Or I could be way off base on this...

The 80-85 signal lock scale is not based on the signal fluctuation. It is quite a different scale. As long as you have a steady signal (as I read above), you should be able to lock the signal.

 

[Sean Mota]

Here's more information about the Scanning function:

1 - "found and added" OTA channel are cumulative. So this means that it will not delete your mapping. Now, here is the deal with version 6.0. There's a bug in it that does not allow it to keep the channels found. As I told you before this version 6.0 is beta. A solution has been found already. The new version will not be released to the boxes that have 6.0 or 5.68 until is fully tested.

2 - If you lose power or unplug the stb, would you lose your mapping? No.

 

[Bob-o]

Hi, I have 5.68. Can't seem to find the right OTA antenna solution. I have many large tall trees 80+ft. Upgraded the Winngard II to a Terk TV32 attached to the chimney at cap height (about 20ft). Would going up another 5ft help or should I upgrade again to the Terk TV36? The towers are only about 6/7 miles away. Most of the channels are at 205 degrees, another important one is at 154 degrees. If I point it at about 180 degrees(half way in between) is there a good chance I won't need a rotor? I get occational pixalation in good weather and complete lose with rain fade. I would like to minimumize rain fade as much as possible. Do I just go out and buy the biggest monster antenna I can find?(G) Thanks for any input.

 

[Sean Mota]

Bob-o,

in your case with those trees you can certainly try a bigger antenna. You may even try a pre-amp but it won't be easy with those trees.