Forums | USR | Connecting at 28.8K despite decent SNR | Watch |
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MarkN Tl Posts: 5 USA | Posted - 3/25/2002 11:31:59 PM I’m looking for a new ISP and have been dialing in to various ISPs servers to test the line speeds. I’m 7.5 miles from my CO, so my connections to my old ISP are either 31.2K or 28.8K. However, I always get a 28.8K connection to all the new ISP’s I’ve tried (about 12 different numbers). I’ve done line noise tests and based on the results I think I should be getting a faster connection. Here are the nitty-gritty details from a typical test connection: ======================= Chars sent 0 Chars Received 741 Retrains Requested 1 Retrains Granted 0 Data Compression V42BIS 0/0 Disconnect Reason is DISC Received OK Modulation V.34 OK Here’s the modem log from the connection: With an SNR of 37 and an A/D-D/A value of 19 (36-17), I don’t see why my connection is always 28.8K. I know my computer and modem (USR 56K Performance Pro – 3CP5610A) are working fine because when I took my PC to work (1/2-mile from the CO) I was able to get 46K connections every time. I am using the latest drivers for my modem. Is there something else shown in these settings that could explain why my connections are so slow? If anyone has any advice on things I can try to speed up the connection, I’d love to hear about it. The difference from 28.8K to 31.2K isn’t much, but when your speeds are that slow, every little bit helps. Thanks, Mark PS: This is a great site. I've learned a tremendous amount in the past week! |
charles Tl Posts: 5879 USA | Posted - 3/26/2002 1:45:34 AM Have you had a second line installed? If you have tried your pc at another location and got a good connection than it is your phone line. Try unhooking all phones from there jacks.Are you using any type of surg device for the phone line? You could hook to the telco box out side to see if it is in the house line also. |
greggae Tl Posts: 8 USA | Posted - 3/26/2002 5:41:12 AM It was my understanding that your SNR needed to be above 45 to get a v90 connection. You might want to try an RFI filter from Radio Shack. See this thread: http://forum56.com/topic.asp?whichpage=6&pagesize=15&forum_title=USR&topic_ID=2737&forum_id=7&Topic_title=USR+5610A+GARBLED+NOISE |
Troubled_user Tl Posts: 263 USA | Posted - 3/26/2002 1:20:34 PM true. 37 is a marginal SNR, meaning that you would get between 29.2 V90 and 28800/31200 V34. please attach an ATy11 and an ATi11 hyperterminal result, also |
MarkN Tl Posts: 5 USA | Posted - 3/26/2002 3:34:29 PM Thanks for the replies everyone. Here's a little more info: I only have one phone line in my house. The phone line comes in to my garage and feeds right to a jack. A short phone line jumps to another jack, and the line from there feeds throughout my house. I moved my computer to the garage and plugged it into the first jack. That disconnected all the other phone lines/equipment in my house, but I still got the same results. I was expecting a higher speed based on some information I found at http://www.modemhelp.net A chart there shows the following: SNR Expected "Stable" Speed With an SNR around 37, I was expecting a connection from 31,200 to 33,600. I know I won't get V.90 speeds, but I'd be happy with something in this range. I've even gotten an SNR of 46 on a few connections, but the speed is always 28.8K. Responses to other comments: The ati11 and aty11 results are part of my original posts. Any other thoughts/ideas, or am I stuck with 28.8K? :( - Mark |
MarkN Tl Posts: 5 USA | Posted - 3/26/2002 3:34:43 PM Bah, double post. Edited by - MarkN on 3/26/02 3:37:20 PM |
Bob Starnes Tl Posts: 4360 USA | Posted - 3/26/2002 9:46:39 PM Might try disabling V.90 and X2, use S32=98 in the Extra Settings. Then try a connection to see if you get a little better speed.
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greggae Tl Posts: 8 USA | Posted - 3/27/2002 5:49:13 AM Try the filter from Radio Shack. It's only $11 and I bet they'd let you take it back if it doesn't work. I had no dimmers, overhead fans or anything obvious interferring. My SNR was the same as yours. I now get connections of 50.6 almost every time. It may not work for you, but if you read the link I provided you will see that there is clearly a problem with noise on the 5610A and B. |
greggae Tl Posts: 8 USA | Posted - 3/27/2002 5:58:47 AM Also forgot, to really exclude a problem in your house wiring, you need to check at the box on the outside of your house. If it is relatively recent, there should be a jack in the box that you can plug into with a phone and listen for noise. By doing that, you connect directly with the line on the street. Your jack inside your garage is still connected to the rest of the wiring in your house and will likely give you a similar result if there is noise on the line. Unfortunately, it means you have to listen for audible noise and that is sometimes not real obvious. Just listen to the dial tone and see if you hear any static, crackling, buzzing etc. You can do that within your house also. With close attention, mine could be heard through the PC speaker when the modem was connecting. Good luck. |
Troubled_user Tl Posts: 263 USA | Posted - 3/27/2002 1:31:46 PM >34-37 31,200-33,600 connects It is VERY rare to get a V34 connection above 28800. My modems could all hang on to 50-52 with no problem, but they only connect at 28800 in V34 mode. My SNR is 57 |
MarkN Tl Posts: 5 USA | Posted - 3/27/2002 11:04:14 PM Thanks again for the replies. Bob: I used the S32=98 init string and tried several test calls, but it had no affect. I'm somewhat new to modem problems, so forgive me for asking but how could this have helped? I always get V.34 already. Is this one of those secrets that sometimes allows a modem to get better V.34 connections? gregae: I'm going to buy an RF phone line filter tomorrow and see if it has any affect. The tests I did from my garage were. The phone line comes out of the ground, through the garage wall, and into the back of a phone jack -- no splits at this point. A short phone cable jumps from the front of that jack to the front of another. Out the back of that one is the lines that run throughout the house. By plugging my computer into the first jack, all the equipment in my house was disconnected and my PC was the only thing plugged in. Troubled_user: I didn't realize V.34 connections were limited to 33.6K and that those speeds were rarely achieved. I guess I should be thankful that I got 31.2K for a while. Thanks again to everyone -- I've learned a lot from all the information. If anyone has any more tips, please post them. - Mark |
charles Tl Posts: 5879 USA | Posted - 3/28/2002 12:31:54 AM You might get a modem that support K56 and a ISP that supports it.It is a downgrade from V90 but better than V34. |
greggae Tl Posts: 8 USA | Posted - 3/28/2002 5:56:30 AM Good luck Mark. The place in your garage may be the right box afterall. Do you have a box outside? If you don't, then this indeed may be the phone company's box. If you disconnect the jack there and all your internal stuff is disconnected, you have probably tested it in an OK place. That filter may not do the trick, but for me at least it was a $10 gamble that was worth it. I has spent countless hours trying to get that SNR higher. Let me know how it comes out. |
charles Tl Posts: 5879 USA | Posted - 3/28/2002 7:31:34 AM http://modemsite.com/56k/x2-adconversion.asp
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charles Tl Posts: 5879 USA | Posted - 3/28/2002 7:56:17 AM Examine the values of 3300 and 3750 from the Y11 screen. These values indicate the degree of “rolloff” in signal power at the high end of the frequency spectrum. Subtract the value for 3300 and from the value of 3750. If the difference is equal to or greater than 25, that is very good evidence of an additional analog-to-digital conversion If the value is betwen 20 and 25, you MAY have too many A/D, D/A conversions and you may not be able to achieve 56k speeds. signal-to-noise ratio (SNR) A measure of link performance arrived at by dividing signal power by noise power. |
timoch Tl Posts: 16 | Posted - 3/28/2002 10:11:46 AM I have the choice of dialup numbers, one in my town and another a few miles away. The local number gives a SNR of 46 and connects at 45333, and the other gives a SNR of 37 and usually connects at 31200. On the occasions when the latter connects higher, the SNR is up to 42, but the connection becomes unstable and often retrains. I've found that the Radio shack filter doesn't help the SNR, only RF noise. I live in a fairly new house, but did help the SNR marginally by disconnecting all of the wire connections in the phone lines, burnishing them, applying anti oxidant compound, and reinstalling. In the process, I did find a couple of loose connections which may have had some resistance. |
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