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[CountryBumkin]

I have a couple of OTA TV channels that don't have strong reception. I was looking at the on-screen signal strength and the numbers are confusing. For example:

1) I have a "weak" channel that shows video but it is choppy and cuts in and out (unwatchable).  It has a Quality rating = 6, and a Strength of 80. Sometimes a different signal meter display shows (same channel) displaying this info "Resolution 720p, Quality 70, Strength 80".  So the same channel shows Quality 6 or a Quality 70 depending on which meter display is on the screen.
I have another channel that says "no signal" but the Quality = 5 and the Strength = 80. There is no picture or audio (just blank screen) as expected.

2) On a channel that works well, the meter display shows "Resolution 480i, Quality 100, Strength -20".
The measurement "-20" is surprising. I would have though "Strength =100" would be maximum, but -20. What does this mean?

So it appears that a strength of "-20" is Good, and "80" is bad.

[Yaobing]

A while back, someone on this forum suggested that Quality was a better measure.  That was why I added quality value on the OSD.  If I understand this correctly, signal strength represents the strength of signal coming into the tuner, while quality represents how much error correction that is done inside the tuner.  So if Quality is low, the tuner has to do a lot of correction in order to reconstruct the original picture, and may end up not being able to reconstruct the original picture because too much correction is needed.

I have not seen a negative number on the strength myself.  It is a bit puzzling.  Maybe different tuners have different ways of gauging it?

[mojave]

Here is what HDHomerun says about strength vs quality:

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.

The free HDHomerun Signal Meter app shows that the JRiver numbers and the HDHomerun numbers coincide on my system. It is a cool little app and lets you adjust your antenna for the best signal quality.

[CountryBumkin]

I reopened this old thread because there have been several questions lately related to bad TV pictures/reception and that got me thinking again about the built in signal meter and how it works.

Question 1) Is the JRiver signal strength/quality numbers given the same "numbers" for everyone regardless of tuner manufacture?

Meaning, is the scale used for Strength and  Quality the same regardless of the brand tuner card installed (or does the number come from the Tuner card itself - and if so, what if for example Hauppauge uses 0-100 strength scale and Silicon Dust uses 1-5 scale)?
Question 1b) so where do the signal numbers come from? How are they calculated?

Question 2) Why are some of the numbers given negative? It would seem to make more sense if they were 1 - 100 (not -100 to 100). Question 2b) What is the actual/full range of this scale used?

Perhaps this is something that JRiver can think about and improve on in the future.
_______________________________________________________________________________ ____________________________
BTW - I found this nice explanation of Signal Strength versus Signal Quality (for anyone interested).

Signal Strength is simply a measure of the power of a signal. If the measurement is expressed in watts or some variant thereof, the measurement implies the the amount of heat that would be dissipated if all of the energy was terminated in a purely resistive load. Signal Strength does not measure the integrity of information that may or may not have been encoded or modulated into a radio wave. In the case of OTA DTV, power in units of dBm is common.

Signal Quality generally refers to some sort of measurement that describes how well the measured signal resembles the original signal transmitted, or, how likely the original information may be decoded or demodulated without error. A signal can be altered, distorted or interfered with in many ways, therefor, the quality of a signal can be measured in many ways. Signal to noise ratio is a measure of how much noise and/or interfering signal has been added to the desired signal. In the case of digital signals, error rate is often used as a measure of quality.

[JimH]

Thanks for all the help you've been with TV lately.  The EPG change caused a lot of problems and you were a big help.

[CountryBumkin]

Thanks Jim. This is an area I'm interested in - and use a lot. But I'm still learning too.

[RoderickGI]

Interesting. I have a DigitalNow Quad DVB-T tuner card (sadly no longer available) and MC has always shown Signal Strength and Signal Quality in the 0 - 100 range.

Since installing a better digital TV antenna, I get 100 for both on all channels. I've never seen any "strange" numbers.

So I suspect that the numbers you are seeing are coming from the hardware itself, and are raw logarithmic numbers using the dBm scale.
https://en.wikipedia.org/wiki/Decibel
"For example, dBm indicates a reference power of one milliwatt."

When a logarithmic scale is used with reference to a predefined value, a negative number means the measurement is less than the reference value. i.e. For dBm, less than one milliwatt.

It is likely that my card has chosen some arbitrary range to assign to 0 to 100, such as 0 <= -20 dBm, 100 >= 0 dBm. I can't find information to confirm that is what it is doing though.

[jmone]

I've just been through this with Silicon Dust on my new HDHomeRun Ver 4 (DVB-T).  It reports Signal Strength / Signal Quality / Symbol Quality.  I don't know which "Quality" MC reports but Symbol Quality is the only one of the three that matters at the end of the day.  This is the measure of how well your pic will look, but keep in mind that poor Symbol Quality can come from issues with Signal Stength / Quality (either too low or high if you are using a RF amplifier). 

In my case the issue was a poorly configured switch/nic combo dropping packets (not setup correctly for 802.3ad Dynamic Link Aggregation).

[kstuart]

It would be nice if that Android App was also a Windows program (for tuners that are not networked).

[DocLotus]

I'm seeing weird numbers too such as...
-1000
-5000
-9500
etc. They also have a minus sign in front of them as shown above.

Sometimes I see normal numbers such as 60, 80, 90, etc but only on a very few channels and only sometimes. The same channel will later report one of the minus numbers such as -6500.