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Author Topic: Signal Quality  (Read 2109 times)

jmone

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Signal Quality
« on: February 18, 2014, 11:40:28 pm »

1. Changed: In television signal OSD, "Strength" is renamed to "Quality" because that is what it actually is
I'm not sure what it is showing
Signal Strength
Signal Quality
Symbol Quality

I've always gone by this advice on the three different reportable variables (in DVB-T land anyway).
Quote
There are three percentages reported by the HDHomeRun -

Signal Strength (ss)
- raw power level as measured by the receiver

Signal Quality (snq)
- how clearly defined the digital data is

Symbol Quality (seq)
- Amount of correct or corrected data over the last second

The above definitions can be confusing, so a much simpler definition is to imagine listening to the radio:
- Signal Strength represents the volume
- Signal Quality represents how clearly you can hear the lyrics
- Symbol Quality indicates the percentage of the lyrics you could hear or guess correctly

As it turns out, Signal Strength is somewhat irrelevant; if your antenna isn't pointed properly, it doesn't matter how loud you turn up the volume, the static will prevent you from hearing the lyrics correctly. Similarly, amplifying a weak HDTV signal can result in a high signal strength but too much noise to decode the digital data correctly.

Use the Signal Strength for a rough idea of direction, but align the antenna for the highest Signal Quality, ignoring Signal Strength. When aimed correctly, Symbol Quality will show 100%, indicating no errors in the output. Splitters and amplifiers can introduce noise which will lower the Signal Quality, even if the Signal Strength increases.
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NickF

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Signal Quality
« Reply #1 on: February 19, 2014, 02:00:13 am »

Quote
1. Changed: In television signal OSD, "Strength" is renamed to "Quality" because that is what it actually is.
Can you clarify what is going on here?  Signal strength and signal quality are two separate parameters available from most tuner cards.  They aren't the same.  Which are you actually monitoring? I believe it is strength.  It would be good if you actually monitored quality too.

Edit: sorry, I hadn't seen jmone's post when I wrote mine. 

Nick.
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Yaobing

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Signal Quality
« Reply #2 on: February 19, 2014, 08:54:32 am »

Can you clarify what is going on here?  Signal strength and signal quality are two separate parameters available from most tuner cards.  They aren't the same.  Which are you actually monitoring? I believe it is strength.  It would be good if you actually monitored quality too.

Edit: sorry, I hadn't seen jmone's post when I wrote mine.  

Nick.

Short answer:

This change does not actually change the number we show OSD.  What we used to call "strength" is actually "quality".  I just corrected the name.

Detailed anwser:

We used to obtain a parameter called "signal strength" using ITuner interface.  According to Microsoft's documentation, it represents the Network Provider-specific signal strength metric.  I was not able to figure out exactly what metric it is.  And it seems to depend on individual devices.  That makes it hard to normalize it to a number that is easy to understand (a percentage).

Later we found another interface that gives four different parameters, lock status, present or not, quality, and strength.  The former two being booleans while quality is represented by a number 1 to 100, and strength indicates the strength of the signal in decibels.  I think it was for the fact that quality is on a percentage scale that we choose to display it.
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astromo

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Re: Signal Quality
« Reply #3 on: February 21, 2014, 03:02:48 pm »

Short answer:

This change does not actually change the number we show OSD.  What we used to call "strength" is actually "quality".  I just corrected the name.

I'm on MC19.0.118 and while the OSD shows "quality", the context menu still shows "strength". I take it that that inconsistency will be corrected at some stage?
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dean70

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Re: Signal Quality
« Reply #4 on: February 21, 2014, 04:28:28 pm »

why not show both (strength in db and quality as %)?
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Yaobing

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Re: Signal Quality
« Reply #5 on: February 21, 2014, 04:47:39 pm »

Yes and yes.
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