Point me in the right direction, looking for how to use my BTPDA-4 meter - AVS Forum
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post #1 of 7 Old 01-09-2014, 05:36 PM - Thread Starter
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I picked up a Blonder Tongue BTPDA-4 meter.  I'm looking for some basic pointers in using the meter to check cable service at the demark.  For consideration/diagnoses of internet service quality issues and general tv service quality.  Several of my friends have had significant trouble with the drop line so I'm excited to have this meter to rule out the service and better know where to look for line troubles.

The meter battery was bad so I replaced it with a transmitter battery from one of my Futaba radios (8 1.2v NiCd).  Powering up now so we have a working unit!

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post #2 of 7 Old 01-09-2014, 06:39 PM
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Here's a couple hundred pages to get you started: http://www.blondertongue.com/UserFiles/file/Marketing%20Literature/2014_BRG_lo-res.pdf
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post #3 of 7 Old 01-09-2014, 06:45 PM - Thread Starter
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Quote:
Originally Posted by olyteddy View Post

Here's a couple hundred pages to get you started: http://www.blondertongue.com/UserFiles/file/Marketing%20Literature/2014_BRG_lo-res.pdf

I'm not trying to design a cable plant.  I just was curious about how to use the meter to check for good signal at a cable demarc using this meter.  Is there one channel/freq that will represent the middle of the band for my data business?  I have good knowledge of rf/cable/antenna.  Just not DOCCIS.

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post #4 of 7 Old 01-09-2014, 09:48 PM
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Actually, you sample a few at the low end of the channel band and a few at the high end. I have a couple of BTPDA-4s and will try to find one today when I rummage through my truck. You need to have it set for cable STD and probably for QPSK and for digital, but I have several similar looking Blonder Tongue and Sencore meters that set up differently, so I won't even try to remember which set-up regimen the BTPDA-4 uses before I get one back in my hands.

I've lost track of the recommended demark levels over the years. i remember that in the late 1990s, a lot of cable companies determined that it was better for them to come in a little weaker than they had been and to use drop amps because doing so reduced their system's "cumulative ;leakage" that they were responsible for minimizing.

Have you figured out how to get readings yet? Does your system have any analog channels at all? I remember when cable companies used to keep one clear analog channel up in the neighborhood of 115 to 120 just so it could be "eyeball" tested for graininess. I think that techs were supposed to try to maintain a wallplate level of -10dBmV for 64QAM and -6dBmV for the more common 256QAM and 0dBmV for analog NTSC, so I'd figure that the demark levels might normally run maybe 10 dB above that, but I'm sure anyone working as a cable tech can give you more reliable estimates.
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post #5 of 7 Old 01-09-2014, 09:51 PM
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I don't know how you have YOUR system configured, but typically DOCSIS 2.0 (and earlier) systems employed a single Carrier for 2-Way Cable Modems (may be different modulation types), where users in a local neighborhood SHARE the single 2-Way Data Carrier.....and MULTIPLE Carriers MAY be used across the network to provide sufficient capacity for ALL users, incl Digital Phone Modems. Recent DOCSIS 3.0 Cable Modems can use Channel Bonding, where FOUR (or EIGHT) QAM Carriers (need NOT be consecutive channels) are logically combined into a much higher Shared Capacity.
http://en.wikipedia.org/wiki/DOCSIS
http://www.cablelabs.com/specifications

So you need to ACCESS EACH CABLE MODEM to see which Frequency or Frequencies are used and which of the several modulation types are being employed to determine the requisite SNR, etc.
http://www.dslreports.com/faq/16085
http://forums.smallnetbuilder.com/showthread.php?t=2097 [Cited IP Addresses work for most (all?) Cable Modems & Routers.]
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post #6 of 7 Old 07-08-2014, 01:01 PM
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Hello squirrels,

Were you able to find a user manual for your BTPDA meter I'm in the same boat I cannot find a manual for the meter.
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post #7 of 7 Old 07-08-2014, 02:07 PM
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I just emailed information@blondertongue.com and they responded back with the manual I wanted to attach it to this thread but even after it's zipped it's too big.
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