I should think you can parse dBmV. However this is at 400-600MHz so your DMM is of no use. You want a calibrated RF receiver. Actually a cable TV box secret data pages.
This is my internet modem's status page. For several reasons the nominal power is higher for data-modem than for TV sets; I assume 0dBmV is a goal.
Maybe your cable-box or TV set can report cable levels. Otherwise you need a cable-guy meter, which must cost thousands. My cable company is tolerably easy about sending a guy out. My TV-side has always been "good" but I dunno the numbers.
This is my internet modem's status page. For several reasons the nominal power is higher for data-modem than for TV sets; I assume 0dBmV is a goal.
Code:
Freq Power SNR
9 543.00 MHz 1.10 dBmV 40.95 dB
1 453.00 MHz -0.10 dBmV 40.95 dB
2 459.00 MHz -0.10 dBmV 40.37 dB
3 465.00 MHz 0.00 dBmV 40.95 dB
4 471.00 MHz -0.10 dBmV 40.95 dB
5 477.00 MHz -0.10 dBmV 40.95 dB
6 483.00 MHz 0.10 dBmV 40.37 dB
7 489.00 MHz 0.40 dBmV 40.95 dB
8 495.00 MHz 0.70 dBmV 40.95 dB
.....Maybe your cable-box or TV set can report cable levels. Otherwise you need a cable-guy meter, which must cost thousands. My cable company is tolerably easy about sending a guy out. My TV-side has always been "good" but I dunno the numbers.
Apparently a passable cable-guy analog-cable meter is around a hundred bucks.
https://www.amazon.com/RY-S110-Handle-Digital-Signal-47-870MHz/dp/B00FCNUURI
For digital cable, $350:
https://www.amazon.com/dp/B00F2J0CHK
Signal reports in TV sets and in STBs:
How to measure and improve TV reception signal strength | Sony Estonia
How do I check a channel's signal strength? Comcast Cable TV FAQ | DSLReports, ISP Information
https://www.techwalla.com/articles/how-to-improve-cable-tv-signal-strength
https://www.amazon.com/RY-S110-Handle-Digital-Signal-47-870MHz/dp/B00FCNUURI
For digital cable, $350:
https://www.amazon.com/dp/B00F2J0CHK
Signal reports in TV sets and in STBs:
How to measure and improve TV reception signal strength | Sony Estonia
How do I check a channel's signal strength? Comcast Cable TV FAQ | DSLReports, ISP Information
https://www.techwalla.com/articles/how-to-improve-cable-tv-signal-strength
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I am smiling at your question and the WHY it might be. If you are running cable in the house yourself, you can use the built in diagnostics of a cable box as has been said. If a roofing crew sliced through a cable you probably need to call a tech or beg, borrow, or steal a fancy meter.
For example, I spent plenty of time years ago sitting on my garage roof staring down at a 13" TV screen on its back while aiming my satellite dishes.
For example, I spent plenty of time years ago sitting on my garage roof staring down at a 13" TV screen on its back while aiming my satellite dishes.
Thank you for the replies.
The new PVR box is pixelating and the regular fixes aren't working. I was hoping to check the strength to determine if it's the signal or the box, as in the past I've had no problem correcting it. The boxes are all being replaced by the cable company as they 'streamline' their equipment. Only one of the three TV's has a problem but it may be that it is because it is 3rd in line in the daisy chain configuration.
Cable guys will be here on Tuesday. They are familiar with our complex as they have been here quite a number of times.
The new PVR box is pixelating and the regular fixes aren't working. I was hoping to check the strength to determine if it's the signal or the box, as in the past I've had no problem correcting it. The boxes are all being replaced by the cable company as they 'streamline' their equipment. Only one of the three TV's has a problem but it may be that it is because it is 3rd in line in the daisy chain configuration.
Cable guys will be here on Tuesday. They are familiar with our complex as they have been here quite a number of times.
Ah, well he'll take care of it. BTW there is one common gotcha with cable, caught me a few times. The centre conductor has to stick out quite a bit from the F connector, at least 1/4". If it's less than this, it makes a bad connection, and this becomes all kinds of weird behaviour that you would never think related to a cable.
When you use splitters to get additional CATV drops you divide the signal in half. Normal CATV drops can run 10 dBmV. The cable loss to the first outlet does vary with frequency but is typically 3-6 dB. Thus a single outlet would run 4-7 dBmV. A splitter would cut this slightly more than in half or -3.5 dB. So the signal would run as low as .5 dBmV to as high as 6 dBmV for a very short entrance cable. Now if you insert a second splitter you could actually have a signal level of -3 dBmV! Run a bit of cable to a third outlet and it can be even lower!!
Now if you used a directional coupler instead of the first splitter the signal to the first outlet would be 8 dB lower than the line in, but the output to the next outlet would be 2 dB or do higher. Thus both the first and second outlet would have about the same signal.
Most TVs can work from 0dBmV to 10 dBmV.
Personally I have done distribution systems feeding hundreds of TVs and other stuff many times.
One time at a stadium where they were having problems I met with the local cable guys. They brought their meter and I brought my spectrum analyzer. They didn't much bother using their gear! The problem was easily solved. A bad feed signal.
Then there was the stadium I did all of the inhouse wiring. The local cable company put up ads saying "We wired this place!" Of course to make things worse they fed the building to the basement and connected via a single coax to my headend 6 floors and a quarter section away. They placed an amplifier just before my gear to get the signal back up to snuff. Of course all the images were of lower quality than it should have been. The next year the cable service changed to a different firm. Took them no time to move the amplifier to the building's service entrance. Of course this borough the quality up to first class. That is because you can push signal much better than letting it degrade and trying to pull it up.
No magic, once you lose signal quality, it is not coming back.
So Cal, you can sometimes add an amplifier before your first splitter if the signal quality is good enough, but properly distributing it works best. There are bidirectional amplifiers used for two way systems. CATV normal signals in and frequencies below that back out.
Now if you used a directional coupler instead of the first splitter the signal to the first outlet would be 8 dB lower than the line in, but the output to the next outlet would be 2 dB or do higher. Thus both the first and second outlet would have about the same signal.
Most TVs can work from 0dBmV to 10 dBmV.
Personally I have done distribution systems feeding hundreds of TVs and other stuff many times.
One time at a stadium where they were having problems I met with the local cable guys. They brought their meter and I brought my spectrum analyzer. They didn't much bother using their gear! The problem was easily solved. A bad feed signal.
Then there was the stadium I did all of the inhouse wiring. The local cable company put up ads saying "We wired this place!" Of course to make things worse they fed the building to the basement and connected via a single coax to my headend 6 floors and a quarter section away. They placed an amplifier just before my gear to get the signal back up to snuff. Of course all the images were of lower quality than it should have been. The next year the cable service changed to a different firm. Took them no time to move the amplifier to the building's service entrance. Of course this borough the quality up to first class. That is because you can push signal much better than letting it degrade and trying to pull it up.
No magic, once you lose signal quality, it is not coming back.
So Cal, you can sometimes add an amplifier before your first splitter if the signal quality is good enough, but properly distributing it works best. There are bidirectional amplifiers used for two way systems. CATV normal signals in and frequencies below that back out.
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Any splitter must be 3 dB per split if perfect, real ones are rated for 3.5 dB. So your loss from the line in to the last one is 21 dB. That is really a bit too wide a difference for most TV sets. Although some can handle 20 dB.
The 3 dB is basic. If you have a 75 ohm source and two 75 ohm loads with a passive transformer based splitter the power is split evenly. That is why there are directional couplers that only tap off part of the power. Normal amplifier output is 40-45 dBmV and the first tap is usually -32 dB. So the pass through signal loss is very low.
The 3 dB is basic. If you have a 75 ohm source and two 75 ohm loads with a passive transformer based splitter the power is split evenly. That is why there are directional couplers that only tap off part of the power. Normal amplifier output is 40-45 dBmV and the first tap is usually -32 dB. So the pass through signal loss is very low.
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All the cable techs I've had here have been good, but that's only 2 visits in 18 yrs
I've never had anything but internet by cable. 1st guy at my old house made me a cable because he called the premade ones crap. 2nd guy at my new house had a tougher time, I bought the house from original owner and he only had service from their competition. Tech had to go from house to junction box a few times to figure it out.Seriously, if you check for bad cables or a bad splitter that's about all you can do and maybe should do before a service call.
Service calls are free Big Tony. They charge so much monthly, they want to keep you as a customer.
We have telephone, internet and TV all from the same cable provider, Shaw.
Cable-Guy has just left after close to 2 hours here.
Apparently they no longer use mechanical meters. They use an app on their (phone?) to ping the equipment connected to the outlet in question to get their signal strength and other diagnostics.
He stands there, taps his phone (or is that a meter dressed up as a smart phone?), moves to each of the remaining stations and instantly has a graph of all he needs to know.
He then starts taking off all the wall plates to investigate further. He did find a 3 way splitter near the beginning of the chain, that had a low output on one line out. Weird because that splitter is only 3 or 4 years old. Still looked nice and shiny.
Anyway, he replaced that, went back to ping the affected station and said:
"Anything else I can help you with Mr. Weldon?"
I said ya, call me Cal.
We have telephone, internet and TV all from the same cable provider, Shaw.
Cable-Guy has just left after close to 2 hours here.
Apparently they no longer use mechanical meters. They use an app on their (phone?) to ping the equipment connected to the outlet in question to get their signal strength and other diagnostics.
He stands there, taps his phone (or is that a meter dressed up as a smart phone?), moves to each of the remaining stations and instantly has a graph of all he needs to know.
He then starts taking off all the wall plates to investigate further. He did find a 3 way splitter near the beginning of the chain, that had a low output on one line out. Weird because that splitter is only 3 or 4 years old. Still looked nice and shiny.
Anyway, he replaced that, went back to ping the affected station and said:
"Anything else I can help you with Mr. Weldon?"
I said ya, call me Cal.
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Just saw this. Ain't technology great? The cable box has a built in signal strength meter that can be accessed over the network. Don't even need to go into the service menu to see it!
It's the same with cable/DSL modems. All the diagnostics can be read remotely.
Kids these days are so spoiled. Glad you got it fixed.
It's the same with cable/DSL modems. All the diagnostics can be read remotely.
Kids these days are so spoiled. Glad you got it fixed.
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