- Neighbor having ISP speed problems. - 4 Updates
- what's a quick way to verify UVC from germicidal lamp? - 1 Update
| Jeff Liebermann <jeffl@cruzio.com>: Jan 22 10:40AM -0800 > If that is so, where would a 300MHz signal originate in the house? 2nd harmonic of the ingress test function in his tester. Some CATV testers can generate test carriers to help check for cable leakage. It can also be generated at the CMTS (cable modem termination system). Helicopters are used to fly over the cable looking for leaks. The pilot frequency is usually about 140 MHz Another possible is the 3rd harmonic of a local FM broadcast transmitter. The harmonic need not be generated in the FM transmitter, but could simply be caused by a non-linear device in the cable system generating the harmonic. It also doesn't need to be generated in the house and could enter the cable (ingress) anywhere along the cable line. Look for loose or rotten connectors and read about ingress in CATV systems. The tech should have unplugged the house cable system from the network to see if the 300MHz signal was still there. If it goes away, it's being generated in the cable system. If it's still there, it's either in his unspecified model tester, a local radio/TV station, or being generated by something in the house. Try turning off electronics and see what happens. >The coax was connected to the Modem/router on one end and the spectrum >analyzer? on the other end. Could the Modem/router generate a 300MHz signal? Yes. The reverse (upstream) channel is usually 5-50MHz. You could be looking at harmonics from that. However, that's unlikely. Some cable modems use channels at the high end of the spectrum (>1000MHz) for upstream, but those probably won't produce 300MHz. > The last test was testing the speed at the end of the cable where it >would go into the router, Good. Ok, so you have a "leak" in the cable somewhere in the house. Tear apart the system and try to isolate the bad segment. The most likely culprits are the F connectors. Pull on the F connector. If it falls apart or disconnects from the coax, it's defective. Make sure that your cables are all RG-6/u and not RG-59/u which tends to be old and awful. Use push-on connectors (that require a push on tool to install properly), and not the ring crimp type. <http://www.learnbydestroying.com/jeffl/antennas/Misc/slides/CATV-tools.html> >the input of the modem and cause it to be slow. He just kinda shrugged >and said he wasn't sure. >Would overloading the input of a modem cause it be slow? Yes. The front end of the cable modem has an AGC (automagic gain control) that has signal level limits that should be observed. Too much signal will result in signal distortion. It's easy enough to build or buy a F-connector type attenuator, and add it in line at the modem. Start with 3dB or maybe 6dB. I've never had anything improve with less signal, but it's worth a try. >Cable guy did suggest he try a new modem. Thanks for reminding me about my favorite rant for this newsgroup. Is there some reason you conveniently left out most numbers that could be of use in diagnosing the problem? Is it because you've been reading Cuisitor Doom's posting and using them as a template? Perhaps you prefer vague and general answers instead of specifics? I think you get the idea. Kindly disclose: 1. Type of coax cable used in the house. If it's RG-59/u, your neighbor will not like my recommendation. 2. Model number of the cable modem. 3. Maker and model number of the tester used. 4. CATV company name. 5. DOCSIS 2.0, 3.0, or 3.1? From your stated speeds, my guess(tm) is DOCSIS 3.0 While your at it, are you doing the speed tests with a wired ethernet connection, or are you trying to do it via wireless? Wireless is often slower than your cable speed and is subject to interference from other wi-fi systems. Use a CAT5 cable (and a fast computah). >I'm going to try a few things before he spends his money. > Mikek Cable modems are fairly cheap. Cable gateways, which include a router, wi-fi, switch, etc, are more expensive and difficult to find legally. This is what I like and which might work if approved by the cable ISP: <https://www.newegg.com/arris-sb6190-cable-modem/p/N82E16825694017> However, since he's your neighbor, you could probably remove his modem, and temporarily replace it with yours and see if it makes a difference. If nothing changes, then replacing the modem will probably not do anything useful. Check the power supply on the modem. I've seen those deterioriate over the years and produce some really bizarre symptoms. For signal levels, if the modem is by Arris/Motorola, point your web browser to 192.168.100.1 and you'll get some signal level diagnostics. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| dplatt@coop.radagast.org (Dave Platt): Jan 22 10:48AM -0800 > If that is so, where would a 300MHz signal originate in the house? >The coax was connected to the Modem/router on one end and the spectrum >analyzer? on the other end. Could the Modem/router generate a 300MHz signal? Sure... if one of its onboard clock/oscillator chips is running at that frequency (or a subharmonic of it like 100 or 150 MHz). Some years ago I helped chase down an "over the air" interference problem, where a strange signal was getting into the inputs of a bunch of repeaters in the 2-meter band (144-148 MHz). We tracked down the source to an apartment building in San Jose. One apartment dweller had an Ethernet switch which was radiating a harmonic of its oscillator frequency, whenever it was passing Ethernet traffic, and this signal wandered around between 144 and 145 MHz. The signal was apparently leaking out via both the Ethernet cables and through the router's power wiring and wall-wart... strong enough to be picked up miles away! I traded the owner one of my spare Ethernet switches for his noisy one, and the problem went away. Never did learn what was actually wrong with the noisy one (it was a well-known brand with a good reputation for quality). >Would overloading the input of a modem cause it be slow? It's not impossible. If a signal is too strong it can push the RF circuitry into saturation, which causes several sorts of Badness... distortion of the strong signals, suppression of weaker ones, and the creation of intermodulation "images" between strong signals. You could try adding a 75-ohm coaxial "pad" (a bidirectional attenuator of the correct impedance) to see if it helps... try a 6 dB or 12 dB pad. Another thing to check for, is to make sure that the home's coaxial wiring is a "straight run" from the service entrance to wherever you have the modem... no dividers or side branches. If you do have a signal splitter (so e.g. you can run both the modem and a TV or DVR) make sure that all unused ports on the splitter have 75-ohm terminators screwed into them. If there are any branches coming off of the splitter that go to other rooms, make sure they're either in use (with e.g. a TV) or have a terminator. Unterminated branches on a coax network can cause signal reflections, and admit outside noise... both can hurt reception. >Cable guy did suggest he try a new modem. Well worth trying. Maybe see if you can get a loaner from someone to try, before spending $$. |
| amdx <nojunk@knology.net>: Jan 22 04:11PM -0600 On 1/22/2020 12:40 PM, Jeff Liebermann wrote: > can also be generated at the CMTS (cable modem termination system). > Helicopters are used to fly over the cable looking for leaks. The > pilot frequency is usually about 140 MHz Quite a few years ago, they drove by my house and said it was singing. It must have been pretty bad, because the, it was a mojor road near me. They replaced a bunch of connectors and said it was quiet now. Then maybe 4 years ago, two guys were outside my house asking if I had a cable running in the ground right here, nope. They suggested I needed my house rewired, but they added, if I sign up for a maintenance contract at $4 a month, they will rewire the house for free. I signed up, a month later no one had showed up, I called and complained. They sent someone out and he even ran me a fifth wire for future expansion as I requested. All five wires running outside the house, no splitters in the attic. They raised the maintenance fee to $5 the next month, I paid that and cancelled. Now, I have cut the cord and have nice system for my antenna, and a separate coax to my modem. > upstream, but those probably won't produce 300MHz. >> The last test was testing the speed at the end of the cable where it >> would go into the router, Good. I'm sorry this line was wrong, where I said speed, I should have said signal strength. > awful. Use push-on connectors (that require a push on tool to install > properly), and not the ring crimp type. > <http://www.learnbydestroying.com/jeffl/antennas/Misc/slides/CATV-tools.html> Ya, I have one similar in style to the Apica, If we install new cable, we can use it. I even have a 500 ft spool of the orange cable the company uses for direct burial. I bought it the local metal scrapyard. I suspect someone stole it and then sold it for the copper to the scrapyard, I hope they didn't discard it because it was defective. > build or buy a F-connector type attenuator, and add it in line at the > modem. Start with 3dB or maybe 6dB. I've never had anything improve > with less signal, but it's worth a try. I got a couple of splitters from him before he left, one two way, -3db, and another with -4.5db tap and the rest -7db. I wanted to insert just to drop the signal level a little. The cable guy tried to hard wire the computer, I wasn't there then, I was told they think there is a bad connection in the modem, they had to keep wiggling it to get a connection, but then they would lose it. I said "all 4 ethernet connectors?" No answer for that. So, I also want to take my laptop over and my cable and hard wire it. If it measures slow, I'll suggest we connect the modem outside where the cable comes up out of the ground and see if it has proper speed. If yes, then replace the cable in house. > 4. CATV company name. > 5. DOCSIS 2.0, 3.0, or 3.1? From your stated speeds, my guess(tm) is > DOCSIS 3.0 Cursitor had no effect in my lack of important data. I did it all myself. First it was about 36*F outside and I took the garbage out and saw the cable truck, so I wondered over to neighbors to supervise. ;-) I didn't inspect the cable guys meter, it was two parts the measuring device and a separate display. they were both in there bag or holder and I didn't get a good look. By the time we got to a 300MHz bump it was getting dark. If this goes any further, I'll answer 3 or 4 of your 5 questions. > connection, or are you trying to do it via wireless? Wireless is > often slower than your cable speed and is subject to interference from > other wi-fi systems. Use a CAT5 cable (and a fast computah). Yes we have that awareness of product speed , and the cable guy got 70 MBPs on his phone. That's still not what he is paying for. As I said he had 200 MBPs, I talked him down to 100 MBPs, saying, "I can stream all 3 firesticks and use my computer without buffering. He only has one TV and his wife's cellphone to deal with. I'll add, I have an old slower laptop, but when I speed test with wifi on that at my home, I get the full 60 MPBs that I pay for. > Cable modems are fairly cheap. Cable gateways, which include a > router, wi-fi, switch, etc, are more expensive and difficult to find > legally. He has the combo unit now a Netgear. This is what I like and which might work if approved by the > cable ISP: > <https://www.newegg.com/arris-sb6190-cable-modem/p/N82E16825694017> Cable guy a gave a little push to Arris. > modem, and temporarily replace it with yours and see if it makes a > difference. If nothing changes, then replacing the modem will > probably not do anything useful. Usually have to call the cable company and have them ping some info to the modem when first installing. Then I'd have to re ping it back at my house. I have a different cable company, not positive mine is compatible with his Comcast service. But I could check. > over the years and produce some really bizarre symptoms. > For signal levels, if the modem is by Arris/Motorola, point your web > browser to 192.168.100.1 and you'll get some signal level diagnostics. NetGear, 192.168. 1.1 or 192.168. 0.1 Thanks Jeff, Mikek |
| Jeff Liebermann <jeffl@cruzio.com>: Jan 22 06:15PM -0800 >On 1/22/2020 12:40 PM, Jeff Liebermann wrote: >> On Wed, 22 Jan 2020 07:35:55 -0600, amdx <nojunk@knology.net> wrote: >Quite a few years ago, they drove by my house and said it was singing. Ummm... we were trying to fix your neighbors mess, not yours. Please try not to confuse things (and me) by adding your mess to the soup. >All five wires running outside the house, no splitters in the attic. >They raised the maintenance fee to $5 the next month, $1 per wire for a service contract. I gotta try that on my next wiring bid to see if it works. >Now, I have cut the cord and have nice system for my antenna, and a >separate coax to my modem. Modem as in cable modem? Just curious. >>> would go into the router, Good. >I'm sorry this line was wrong, where I said speed, I should have said >signal strength. Just ignore what I scribbled about having found the problem in the neighbors wiring. However, this gives me a chance to try out my new service "Remote Viewing and Diagnosis" where I sit in a contorted yoga position, and try to visualize the problem. In my minds eye, I see your neighbors cable wiring to be a tangle of rotting cables and badly installed F connectors. Viewing the scene with my crystal ball results in the same image, thus confirming my diagnosis. In order to fix it, simply replace everything. >> <http://www.learnbydestroying.com/jeffl/antennas/Misc/slides/CATV-tools.html> >Ya, I have one similar in style to the Apica, If we install new cable, >we can use it. The Aprica compression connector tool is a problem. It's designed to fit exactly one size of F-Connector. Each manufacturer has a different size so as to lock in their larger customers into only using their connectors and tools. I suggest you use Belden SNS1P6U (red) connectors: <https://www.ebay.com/itm/Thomas-Betts-RG6-Ultimate-Snap-N-Seal-Connectors-SNS1P6U-Pack-of-50/174156136846> You should be paying about $0.50 per connector. I prefer the orange handle tool, which fits literally everything (including BNC and RCA phono connectors) but does require some fiddling with the adjustments to work correctly. Hmmm... I can't find it again on eBay. This looks like a better version: <https://www.ebay.com/itm/RG59-RG6-Universal-Adjustable-Compression-Crimp-Tool-Connector-CATV-RCA-BNC-F/232216467664> >I even have a 500 ft spool of the orange cable the >company uses for direct burial. Orange is for TEMPORARY cable drops. <https://forums.xfinity.com/t5/My-Account/ANSWERED-Got-an-Xfinity-orange-cable-in-your-yard/ta-p/2941167> >I bought it the local metal scrapyard. >I suspect someone stole it and then sold it for the copper to the >scrapyard, I hope they didn't discard it because it was defective. Temporary cable is usually not waterproof (gel filled and non-penetrating jacket). >I got a couple of splitters from him before he left, one two way, >-3db, and another with -4.5db tap and the rest -7db. I wanted to insert >just to drop the signal level a little. The two way (-3.5dB) is a splitter. The other one might be a cable tap (directional coupler). You can probably use the splitter as a -3.5dB attenuator if you put a 75 terminator on the unused port. >The cable guy tried to hard wire the computer, I wasn't there then, I >was told they think there is a bad connection in the modem, they had to >keep wiggling it to get a connection, but then they would lose it. He's probably correct. I've seen it all too often. Some drops the cable modem with the RG-6/u coax attached. It lands on the F-connector and breaks the connection inside the tuner. That's usually easy to fix. Tear it apart, lift the lid on the tuner, survey the damage, and solder it back together. Extra credit for securing the F-connector with epoxy (or hot melt glue). > I said "all 4 ethernet connectors?" I can see why. Next time you write "bad connector", you might find it more intelligible if you specify which connector. I'm assuming the F-connector, but it looks like the unspecified modem is actually a cable router or "gateway". >No answer for that. So, I also >want to take my laptop over and my cable and hard wire it. Probably a good idea. Wiggle "the connector", any connector and see what happens. > If it measures slow, I'll suggest we connect the modem outside where >the cable comes up out of the ground and see if it has proper speed. > If yes, then replace the cable in house. Yep. The idea it to plug into the unspecified ISP's cable at the point of entry so as to eliminate the entire house and everything in it. > Cursitor had no effect in my lack of important data. > I did it all myself. FON (fear of numbers) must be contagious. You can check if you have FON. Just count how many product names, model numbers, version numbers, measurement numbers, in your posting. If it's tiny compared to the number of lines in the posting, you're doing badly and are infected with FON. If all you see are numbers, then you are suffering from hyper-FON, and are spewing too many numbers. An average of one number per line is a good compromise. >First it was about 36*F outside and I took the garbage out and saw the >cable truck, so I wondered over to neighbors to supervise. ;-) Got it. The garbage attracted the cable truck. I'll try that next time the cable guy is late. >device and a separate display. they were both in there bag or holder and >I didn't get a good look. By the time we got to a 300MHz bump it was >getting dark. At what temperature do you start functioning normally? > If this goes any further, I'll answer 3 or 4 of your 5 questions. I don't think it can go much further. I still don't know what equipment you're working with or the basic system details. > Yes we have that awareness of product speed , and the cable guy got >70 MBPs on his phone. That would be via wireless. So, the cable speed could 70Mbits/sec or faster as the wireless connection is now the slowest part of the system. > That's still not what he is paying for. > As I said he had 200 MBPs, I talked him down to 100 MBPs, saying, "I >can stream all 3 firesticks and use my computer without buffering. You won't get 200 Mbits/sec on a wireless smartphone. 802.11ac can theoretically do 500 Mbit/sec, but all I've seen is about half of that. > He only has one TV and his wife's cellphone to deal with. He has 3 Amazon Firesticks. One for the TV, but they don't fit in cellphones. Where to the other 2 Firesticks go? > I'll add, I have an old slower laptop, but when I speed test with wifi >on that at my home, I get the full 60 MPBs that I pay for. If you feel the urge, plug your fastest machine into a gigabit port on your router, and run iperf3 -s to setup an iperf3 server. Then run iperf3 on one of your machines and speed test you wi-fi and ethernet speeds. That takes the speed of the cable out of the picture and only measures the speed of your hardware. It should be faster than 60 Mbit/sec or it's NOT your cable ISP that's slowing you down: <https://iperf.fr/iperf-download.php> More: <https://www.google.com/search?q=iperf3> Drivel: I've been replacing older routers (i.e. Linksys EA2700) with newer routers because they can't deliver the speeds that Comcast is now providing. I've seen 300 Mbits/sec recently and the EA2700 can barely deliver 90 Mbit/sec. > He has the combo unit now a Netgear. Find a suitable recycler and buy a new modem (SB6190) and a separate wireless router (Asus RT-AC68u with 802.11ac or better). He won't like the price on the router, but methinks it's worth the price. <https://www.newegg.com/p/pl?N=100158096%204016> >> cable ISP: >> <https://www.newegg.com/arris-sb6190-cable-modem/p/N82E16825694017> > Cable guy a gave a little push to Arris. Arris/Motorola have their problems, but I think they're good enough and generally better than most. I buy quite a bit of refurbished hardware including refurbished Arris cable modems. I have received some lemons, but have always been able to exchange it for one that works. Just be sure to update and test it on arrival. > Usually have to call the cable company and have them ping some info >to the modem when first installing. Baloney. When you swap modems or routers with the neighbor, the cable company thinks that the modem is still at his house. Nothing to change or reset. The unspecified cable company has no way to know if the modem is at the neighbors house or at your house, as long as you're both on the same ISP, CMTS, and segment. > Then I'd have to re ping it back at my house. Wrong. Also, ping is a latency test program, not a programming tool. > I have a different cable company, not positive mine is compatible with >his Comcast service. But I could check. Hold it. If you have a different ISP, you can't move a modem or router to another ISP. Got any more details you failed to mention that might be important. If not, please cease mentioning your setup as it just confuses the issue. We're trying to troubleshoot the neighbors networks, not yours. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| Sergey Kubushyn <ksi@koi8.net>: Jan 22 06:13PM > years, but recently brought it out to sterilize a room where a person > had been sick. However, I don't know if it still emits the germ killing > UVC spectrum. What's a quick way I could tell for sure? Thanks. Wonder what is this all about... UVC germicidal lamp uses Hg vapor discharge. This produces UVC because of the pure physics of that discharge so if you see the lamp lights up you can be 100% sure it produces UVC. It simply can't do otherwise unless that Hg transmutated into another element but one would need a philosophers' stone for that to happen. Intensity is another question but that can be judged from the current that lamp draws. --- ****************************************************************** * KSI@home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * ****************************************************************** |
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