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  • jcoman commented on ravin108's instructable How to set up a coax (MoCA) network5 months ago
    How to set up a coax (MoCA) network

    There are a few reasons that you won't see MoCA interference from a MoCA adapter on a modem in your network.First, MoCA devices are always installed forward of modems, with short jumper cables. Second and third harmonics will not manifest in that short of a distance. At 800mhz, you'd need a jumper around 14.7" before that harmonic could manifest itself. At 1.5ghz you'd need 8.5" or so. These measurements are roughly the full wave distance at those frequencies. Most MoCA are installed, in CATV applications, with jumpers around 6" long.Second, there is a band pass filter in the MoCA, so the frequencies MoCA runs at are knocked out before hitting the modem, because that MoCA adapter sits in front of the modem.The second reason I give is why cable companies separate telephone...see more »There are a few reasons that you won't see MoCA interference from a MoCA adapter on a modem in your network.First, MoCA devices are always installed forward of modems, with short jumper cables. Second and third harmonics will not manifest in that short of a distance. At 800mhz, you'd need a jumper around 14.7" before that harmonic could manifest itself. At 1.5ghz you'd need 8.5" or so. These measurements are roughly the full wave distance at those frequencies. Most MoCA are installed, in CATV applications, with jumpers around 6" long.Second, there is a band pass filter in the MoCA, so the frequencies MoCA runs at are knocked out before hitting the modem, because that MoCA adapter sits in front of the modem.The second reason I give is why cable companies separate telephone MTA's (modems) from a MoCA network either by isolating them with MoCA splitters (with built in POE filters) or by using a splitter feeding a separate splitter isolated with a POE filter. A MoCA device will sometimes cause some problems with telephony modems -- not all the time, but some of the time. Telephony modems are more robust because of the way they are provisioned and their upstream/downstream requirements. So its rare that MoCA will cause problems, making it harder for techs to diagnose.Many CATV boxes are starting to build in MoCA filters. It's been found that MoCA will cause random/Intermittent issues with television adapters/boxes. Pace (Arris), to name one company, is building in filters in the newer equipment - and they work pretty well. Prior to the build in of POE filters, some of us techs found that using a POE filter on the CATV box in reverse would eliminate interference issues that was causing tiling on the TV. Arris recently came out with a white sheet that describes just this method as one of the alternative fixes - if a MoCA splitter or system isolation is not possible. Honestly, there are some great white papers on MoCA on the Arris website. I'm actually more impressed by your knowledge. Most consumers don't take the time to actually understand the equipment and its limitations. It's the toughest part of the job. I've had thousands more discussions with people about why wifi will not go 500' through four or five concrete walls than I have had intelligent conversations about MoCA.

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  • jcoman commented on ravin108's instructable How to set up a coax (MoCA) network5 months ago
    How to set up a coax (MoCA) network

    As a cable tech, yes, a MoCA filter is a requirement. I'm surprised a Charter tech would remove your filter - it can cause serious problems in their system.There is the security issue - which I'm not even addressing because it's just best to put a filter in line. And, at least in the company I work for, it's mandatory that any MoCA network have a POE/MoCA filter installed.I have been on many, many trouble calls where failure to install POE/MoCA have caused issues with downstream SNR/MER on DOCSIS channels. While CATV systems may run at different frequencies than MoCA, it's the second and third order harmonics that cause the problems I have personally seen. I work in a 750mhz system and while MoCA operates between 800-1500mhz - it's those second order harmonics that land square in my sys...see more »As a cable tech, yes, a MoCA filter is a requirement. I'm surprised a Charter tech would remove your filter - it can cause serious problems in their system.There is the security issue - which I'm not even addressing because it's just best to put a filter in line. And, at least in the company I work for, it's mandatory that any MoCA network have a POE/MoCA filter installed.I have been on many, many trouble calls where failure to install POE/MoCA have caused issues with downstream SNR/MER on DOCSIS channels. While CATV systems may run at different frequencies than MoCA, it's the second and third order harmonics that cause the problems I have personally seen. I work in a 750mhz system and while MoCA operates between 800-1500mhz - it's those second order harmonics that land square in my system's DOCSIS frequencies causing intermittent internet issues between actives. So basically all your neighbors within 200-300 feet of your device.MoCA won't pass through active amps/line extenders because the upstream frequencies are much lower than a MoCA's operating frequency, thankfully. Upstream gets knocked out because the amps/LE's only work in a specific frequency range on the return - usually 0-45mhz, 0-75mhz, or something like that depending on the number of upstream carriers.And the hard part about it all is, if one guy installs a MoCA device without a POE/MoCA filter without the cable company knowing; finding that interfering device is very, very difficult. You literally have to go door-to-door to find the offending device.You can find a lot of this information on the Arris website. They have great information on MoCA.

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  • jcoman commented on jcoman's instructable The Tape Measure Antenna7 months ago
    The Tape Measure Antenna

    You sand off a section on the driven element, flux it and tin it with solder. You seperate the conductor and outer stranded shielding, making them into a Y shape ( being careful to not let them touch eachother) and solder them to the areas you just cleaned and soldered.

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