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Line Noise Questions - connection problems



Q1. What is "line noise"?

A1. Line noise, outside of software configuration errors, is probably the most prevalent problem we deal with in the dial up access world. It can range from the occasional stray character to total loss of control of your session. In most cases it will tend to lean more towards the annoying end of the scale, but sometimes it makes it impossible to work. So, now you're asking, "What is line noise?" Have you ever been on the phone and heard hisses, pops, echoes, or dropouts? All of these are a type of line noise. When you talk on the phone you generally don't mind, or even notice, most of the noise on the line - until it gets to a level that interferes with your conversation. When that happens, you go into a cycle of repeating yourself, asking the other person to repeat what they said, or you just give up and hang up the phone. This is a pretty rare event though. Now you put a modem onto your phone line. A modem is a device that interprets the electronic signals on the line several thousands of times more efficiently than the best hearing human ear will ever be able to do. gain, most of the time everything works fine, but its not a perfect world and the technology is even less perfect, so now the pop you barely hear when you're talking on the phone, becomes a character on your screen when you're in a dial up session. That hiss in the background causes your session to slow down to a crawl. The dropout comes along and now you don't have a session anymore. Line noise can be classified in 2 ways, persistent and sporadic. If you only have problems every now and then, you fall into the sporadic category. If you have problems every time you connect, or most of the time and its always this way, then you fall into the persistent category. Both are annoying, but they are indicative of different problems. What causes line noise? Probably the most common reason is the weather. If it's raining, or has been raining for a number of days, you're probably going to have noise problems as water tends to penetrate phone lines. This is especially true in the winter when ice can force water into the lines, and KEEP it there for extended periods of time. Lightning, even if it isn't close to you can cause problems. Other common causes include poor telephone wiring, electrical interference, or bad computer cabling. What can I do about it? In most cases line noise will take care of itself. You can do a few things to help prevent it though. Here are a few: 1. Make sure the phone cable running between your PC and the wall jack is in good condition and made of high quality materials. If you can get a shielded line or a line with a "level" rating you'll be in good shape. All of the cables we use are level 3. 2. Make sure the phone cable doesn't run close to electrical applicances if possible. The noise created by this could be sufficient to cause you problems. 3. If you use an external modem, make sure that the cable between the modem and the computer is firmly connected and of sufficient quality to carry data at high speeds. If you own a 2400 baud modem you don't need to worry as much as someone who has a 28.8 baud modem. If you start experiencing problems and you normally don't have any, the first thing to do is look out the window. Is it raining? Chances are you're being hurt by some temporary condition. In this case, the best thing you can do is to be patient and give it a few days. If the condition continues, or worsens, contact the Help Desk so we can be aware of the problem and look into things on our end. If you have problems that could be classified as persistent, try moving your computer and connecting to a different jack in your house or school, if this is possible. This can identify wiring problems with a specific jack. If you've moved it everywhere you can move it and the problems still persists, the next step would be to contact your local phone company and have them test the line for noise (it's a free service). If you do this, its imperative that they know that you're using the line for data as well as voice. This would also be a good time to notify the Help Desk so we can check out our equipment as well. We at the helpdesk understand how frustrating line noise can be for you as we've all had to deal with it when we connect. Noise is one of those things that WILL happen to you. If you're lucky it will be so minor that you don't notice, but rest assured that if it becomes a major problem for you we'll do all we can to resolve it as quickly as possible. In the event that you need to contact the Help Desk about line noise, answering the following questions would be most helpful: 1. How long have you been experiencing this problem? 2. Do you have this problem EVERY time you connect to the system? 3. Do you connect to any other systems? If so do you experience similar problems? 4. Have you noticed any pattern to the trouble you've had? An example would be that the problem appears worse between 5 and 7 PM, or only in the morning. This is useful in determining if there is a trunk routing problem. 5. What brand, model, and speed modem are you using? 6. If you connect at a speed higher than 2400, have you tried lowering the baud rate? If so, what changed, if anything? 7. Which number are you dialing to connect to TEN-Nash? What number are you dialing from (your number)? 8. Do you have any other information that you feel is important for us to know?

Q2. What does the message "[connection to tennas aborted:invalid message received]" mean?

A2. It's a message from the communications server, due to "line noise". The communications server interprets the "line noise" as a command which it doesn't know how to handle. As a result, it terminates your connection. The only way to prevent it is to eliminate the "line noise" in your connection, as described in Question 1 above.

Q3. What does the message "You are at maximum allowed processes for your user name" mean?

A3. In order to conserve phone lines, we limit each user to two logins. Sometimes, if you are knocked off-line due to "line noise" or some other uncontrollable circumstance, your process (login) will still be active. If it happens twice, and you try to log in a thrid time, you will get the above message and be denied a login. The first time the problem occurs, immediately go to the "$" prompt and type: $ stop_proc to knock your hung process (login) off the system. This FAQ provides some description of the Tennessee Education Network (TEN) and contains information, help, and tips on the use of the TEN and the Internet. TEN is a project done in partnership with TECnet (Tennessee Education Cooperative Network), the SDE (State Department of Education), and the TBR (Tennessee Board of Regents). This project has made Internet access available to Tennessee K12 users via either a local telephone call or an 800-number call. This FAQ answers the most commonly asked questions concerning the use of the TEN and the Internet. This document contains a numbered list of questions, grouped by subject, that provides an overview of what is available. This particular document does NOT contain the answers, only the questions. Refer to the particular subject area in the previous menu, for the answers.


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