HDHomeRun QAM Audio/Video hickups on certain channels at certain times

[mkanet]

I am getting this very annoying hickups in QAM audio/video.

When I check HDHomeRun Config GUI, I notice that sometimes the Signal Quality will go up and down constantly. It will never go down to zero, but the signal quality will drop down from about 80% to 60% for a split second. Signal strength is stable at 80% and Symbol quality always at 100%. The audio/video will not necessarily hickup when when the signal quality goes up and down. Is it normal for the signal quality to jump up and down like that?

I have tried this even with a 2 way amplifier for HD signals (Radio Shack) and it boosts the Signal strength up to 100%, but the signal quality reacts the same way. Symbol quality is at 100% as well.

PLEASE NOTE: I do NOT have this problem at all with my 2 STB cableboxes which are connected to the same splitter. My 2 STB and HDHomerun are all connected to the same splitter with 6 feet cables; receiving the same exact signal.

The signal quality doesnt always jump up and down. In fact, its stable as I'm typing this message.

[jdamore]

Does it hickup on both tuners of the HDHR (hardware issue)?

I dont know what 60% signal translates in DB but that sounds a little low. I would think 100% signal would be -0db of attenuation.

Did you put the amp right at the HDHR or at the entry of the house? I think you would want it at the entry of the house as amplifying the signal right before the HDHR would only amplify the noise.

[mkanet]

Amp near the entry of the house.

Signal quality as opposed to signal strength. The HDHomerun utility distinguishes those two separately. Signal strength is very high already.

Originally Posted by jdamore

Does it hickup on both tuners of the HDHR (hardware issue)?

I dont know what 60% signal translates in DB but that sounds a little low. I would think 100% signal would be -0db of attenuation.

Did you put the amp right at the HDHR or at the entry of the house? I think you would want it at the entry of the house as amplifying the signal right before the HDHR would only amplify the noise.

[mikesm]

QAM is a complicated beast. Could you give me a more complete run down of how things are connected once it enters the house, including location of splitters, distance of cable etc? Do you modulate any channels?

Also, do you know how far away you are from the optical node? How many amps between you and the fiber basically...

Cable QAM modulated video is sent with FEC (forward error correction). This means that you could be having issues but the system is able to repair the problems without hitting errors. I am not sure but I think signal quality could be this metric (good frames). Bad quality could mean FEC is kicking in. A properly designed system doesn't depend on FEC for link margins.

The hdhomerun is not nearly as good as a Moto STB in terms of diagnostics. I don't know why - their parts can give you a lot more info. If the STB can be hooked up to the same jack the HDhomerun is, you can jump into the diagnostics menu after tuning to a channel that the HDhomerun is having issues with. There you can look at signal levels, FEC corrections, etc... If you can do that and report back what it is saying, that would be great.

Look at this http://en.wikibooks.org/wiki/How_to_.../Configuration
for hints about getting diagnostics info. There is a lot of good stuff there, but we are focusing on inband diagnostics for this.

Also, if you could do that for a few channels (analog too) across the spectrum, that would be helpful. Cable, particularly cable as found in some homes, has different losses at different frequencies. The higher frequencies (close to 700) lose a lot more db/ft that down at VHF (200 MHz or so). This is called "tilt" in the business. Professional amps have tilt controls so they can amplify the higher frequencies more than the lower frequencies to compensate for this.

Also you need to worry about too much signal. If you feed an amp with a signal that is too strong, the amp may clip, causing momentary distortion across all channels. If the STB's are behind the same amp, I don't think this is your problem, but I wanted to make sure things you knew about this issue if it might be helpful.

PS what firmware are you using? Some users are reporting scattered issues with breakups with the current firmware version. See if you can't back out to the 0423 version if you are running current and see what that does.

Don't worry, we'll track this down. :-)

thanks,
mike

[mkanet]

Man Mike, youre like a rocket scientist when it comes to TV cable. Youre definitely the right person to post on this thread. Now I know what FEC is

Before you had posted on this thread, I decided to run a cheap 100ft cable directly from the side of the house (where cable from the street tie in) directly into the splitter to my 2 cableboxes and HDHomeRun. When I did that, all my channels tuned in rock solid with no dropouts/pixelization, etc. I spoke to the person who ran the cable through my attic and he needs to basically do that again The cable he used through the attic was actually shorter than the one I used; but was screwed up somehow (most probably one of the connectors). Anyway, that was a simple enough test.

Again thanks for posting!

-MKA

Originally Posted by mikesm

QAM is a complicated beast. Could you give me a more complete run down of how things are connected once it enters the house, including location of splitters, distance of cable etc? Do you modulate any channels?

Also, do you know how far away you are from the optical node? How many amps between you and the fiber basically...

Cable QAM modulated video is sent with FEC (forward error correction). This means that you could be having issues but the system is able to repair the problems without hitting errors. I am not sure but I think signal quality could be this metric (good frames). Bad quality could mean FEC is kicking in. A properly designed system doesn't depend on FEC for link margins.

The hdhomerun is not nearly as good as a Moto STB in terms of diagnostics. I don't know why - their parts can give you a lot more info. If the STB can be hooked up to the same jack the HDhomerun is, you can jump into the diagnostics menu after tuning to a channel that the HDhomerun is having issues with. There you can look at signal levels, FEC corrections, etc... If you can do that and report back what it is saying, that would be great.

Look at this http://en.wikibooks.org/wiki/How_to_.../Configuration
for hints about getting diagnostics info. There is a lot of good stuff there, but we are focusing on inband diagnostics for this.

Also, if you could do that for a few channels (analog too) across the spectrum, that would be helpful. Cable, particularly cable as found in some homes, has different losses at different frequencies. The higher frequencies (close to 700) lose a lot more db/ft that down at VHF (200 MHz or so). This is called "tilt" in the business. Professional amps have tilt controls so they can amplify the higher frequencies more than the lower frequencies to compensate for this.

Also you need to worry about too much signal. If you feed an amp with a signal that is too strong, the amp may clip, causing momentary distortion across all channels. If the STB's are behind the same amp, I don't think this is your problem, but I wanted to make sure things you knew about this issue if it might be helpful.

PS what firmware are you using? Some users are reporting scattered issues with breakups with the current firmware version. See if you can't back out to the 0423 version if you are running current and see what that does.

Don't worry, we'll track this down. :-)

thanks,
mike