Analog line quality 7

[MasterRacker]

What can a basic Joe Twelvepack do to test analog line quality? About all I know is I either have dial tone or not and I can hear audible crackling/noise or not.

I've got a site with a stand-alone analog line for a fax and they're reporting the need to retry a lot on outbound faxes. They seem to receive them fine, but of course, we don't know if the senders had to retry.

I've never had good luck troubleshooting this type of thing and the provider will always say the line is fine. Just looking for something else to try.

Jeff
[small][purple]It's never too early to begin preparing for [/purple]International Talk Like a Pirate Day
"The software I buy sucks, The software I write sucks. It's time to give up and have a beer..." - Me[/small]

 

[Deweyhumbolt]

Your basic assumptions are correct. You could use a Voltmeter, but Nortel supplies a tester that worked very well for this issue. Someone will know the part #. It proves when telcos line conditions are out of whack.

Adversity is Opportunity

 

[resorttech12]

Most of the problems I've encountered over the years have been wiring; either shorts at splices or bad line cords.

Another thing I have seen is the dmarc point, keptel residential style, goes bad on one spot. If you can get good test calls both ways at the point where telco hands it off, I would look at the customer wiring. Not what you want to hear, I know!

To more specifically answer your question, there is a voltage range that a POTS line should be in, for both idle and ringing. Can't remember what that is for the life of me.

Good luck!

mk

 

[SYQUEST]

A TIMMS, like the old Halcyon 701A is very good for testing POTS. (I have a pair of them) It can measure things like, milliwatt level, noise, balance, etc. If you know how to use a Multimeter or VOM that can tell you some useful info also about the loop condition.

Some offices still have the Silent Termination, it is good for noise checking even if you only have a hand testset.

....JIM....

 

[Lostpbx]

The main thing about testing line condition is you need to have all voltage removed or off the line when you are testing or you will get false readings. You can do that with your inside wire easy enough from the mpoe but for testing the pstn lines you either need a pstn tek to do it or know the number to remove line voltage.

 

[ISDNman]

My HUNCH is this may not be the line. Before spending too much more time on this I would suggest doing some testing.

From another office in the same city try sending and receiving faxs with the problem line. If this works 10 out of 10 calls in both directions then the problem is not the line.

Next arrange to try 10 calls to a fax machine that is long distance. Try 10 times and see how many (if any connect). Have them try you 10 times too.

If you have problems LD but can receive LD faxes next try dialing 10 calls with a name brand carrier as a dialaround. For example try one of the following (101xxx1NPAxxxx):

1010288 AT&T
1010222 MCI
1010333 Sprint.

If these work then report the problem to your LD carrier and be sure to tell them you know it is them because faxes using another carrier work fine.

Good luck

-------------------------------------------

TIP: If you ask a better question, you will get a better reply. Be specific so we can help!

 

[jerryreeve]

check this out:

http://h10025.www1.hp.com/ewfrf/wc/...05&lc=en&cc=us&product=2512008&rule=4965&dlc=

1-888-hpfaxme (1-888-473-2963).
the phone number is from the webpage, lets you send a fax and it will be resent to you on the header phone number of your fax transmision.

----------------------------
Hill?? What hill??
I didn't see any $%@#(*$ Hill!!
----------------------------
JerryReeve
Communication Systems Int'l
com-sys.com

 

[hawks]

nice job jerry

 

[MasterRacker]

Without a lot of testing I've also been inclined to think the results are varying by destination dialed. I like that faxback number. It's a good starting point.

Jeff
[small][purple]It's never too early to begin preparing for [/purple]International Talk Like a Pirate Day
"The software I buy sucks, The software I write sucks. It's time to give up and have a beer..." - Me[/small]

 

[jerryreeve]

one of the first tests I normally do when I have a problem with an analog line though is to just go off hook on the phone and dial any number to break dial tone and then listen to see if there is noise on the line to the CO. beyond that it is to continue with the testing at the demark etc to isolate but it is nice to sometimes know that the problem exists obviously. then you can start isolating afterwords.

----------------------------
Hill?? What hill??
I didn't see any $%@#(*$ Hill!!
----------------------------
JerryReeve
Communication Systems Int'l
com-sys.com

 

[donb01]

I'm going to get flak for this, but here goes anyway....

Some of my worst crappy modem connection issues have been improved significantly if not eliminated by simply reversing the polarity of the phone line at the jack for the device - regardless if it was correct or not to start with.

I know people will say that most of today's analog devices are not really that polarity sensitive and it won't make any difference, but it is one thing I pull out of my bag of tricks when desperate and I have had modem connections that would barely stay online at 14.4K turn around and deliver 33.6K with a decent connection. It doesn't always work, but when it does it seems to make a respectable difference, and it's an easy enough thing to try.

Fax machines work on the same concept as modems, so this should apply here as well.

 

[SYQUEST]

The one component in all of those devices that is the least reliable is the ELECTROLYTIC CAPACITOR and sometimes the TANTALUMs too!

donb01,

Whatever trick works... The modem in a fax machine is a fax modem!


....JIM....

 

[MasterRacker]

donb01,
You'll get no flak from me. Years ago a friend of mine was talking with a friend of his who designed modem chipsets. This gentleman (who was in a position to know) stated that considering what modems are trying to do over a network designed for voice, any time two modems completed a handshake and started communicating, it was magic.

The tricks people learn from actual working experience are the most valuable, regardless what the "book" says.

Jeff
[small][purple]It's never too early to begin preparing for [/purple]International Talk Like a Pirate Day
"The software I buy sucks, The software I write sucks. It's time to give up and have a beer..." - Me[/small]

 

[letman2]

If you go through a slc system with the LEC you might have a timing issue in the slc.

 

[jerryreeve]

it is theoreticaly impossible to send information faster than 4000 bits per second over a 4khz audio channel modem. it says so right here in the lenkurt demodulator. this limit is due to the fact that it takes about 1/4000 of a second for the modem to recognize the highest frequency signal and create the digital representation of that signal. then codex came along with their 4800 and 9600 high speed analog muxes and blew theory out of the water by using the highest speed that was attainable by modems (2400 Baud) and shifting the phaze of the signals to double and quadruple it. I don't remember off the top of my head what coding is being used to get us up to 56K

BTW Baud is an indicator of a digital speed sent over an analog transmission medium and Bits Per Second is an indicator of a digital speed sent over a digital media.



----------------------------
Hill?? What hill??
I didn't see any $%@#(*$ Hill!!
----------------------------
JerryReeve
Communication Systems Int'l
com-sys.com

 

[Howi]

Re- reversing line wires, as most analogue devices are totaly non polarity dependant, what is actually happening is that re-terminating the wires (albeit reversed) is simply remaking what was a poor connection. THIS is what ALL analogue lines are most sensitive to. For normal speech it does not really matter, BUT for a modem, noise is a killer, especially at the speed modern modems can send/receive (33k baud). Here in the UK analogue PSTN lines are only required to guarantee up to 9600 baud.
I have to say at this point, why are you still using faxes?????? They are a pain in the proverbial ass, whats wrong with email or other methods.

 

[MasterRacker]

Faxes are still surprisingly common. There are a lot hard paper documents, pictures, hand drawings, etc. that would first need to be scanned to send another way. Also, as improbable as it sounds, there are a lot of cases where a faxed document with a signature is enough to authorize something.

Jeff
[small][purple]It's never too early to begin preparing for [/purple]International Talk Like a Pirate Day
"The software I buy sucks, The software I write sucks. It's time to give up and have a beer..." - Me[/small]

 

[orypecos]

Rent or get someone with an oscilloscope to look at your line. U can see if it has garbage on it very easily.

And climb into the 21st century and refuse to do faxes anymore. They truly are dark ages. Do U still have a carburetor on your car, no answering machine on your home line and water your grass with a hose????