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Leasesed circuit varied signal quality.

This forum is for discussions regarding System Infrastructure and Related Equipment. This includes but is not limited to repeaters, base stations, consoles, voters, Voice over IP, system design and implementation, and other related topics.

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emtprt
Posts: 128
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What radios do you own?: Astro Specta CDMS XTS3000

Leasesed circuit varied signal quality.

Postby emtprt » Thu Jul 26, 2012 8:35 pm

We recently moved our comaparator to a firehouse in town instead of the dispatch center 15 miles away. Our systen consists of 2 receiver sites and 2 repeater sites ( a primary and a backup).
The dispatch center has the ability to switch repeater sites via a DTMF code transmitted via a control station and a second in-cabinet repeat Quantar at the comparator location.
The primary issue I have is a 4 wire circuit running a the comparator to the primary repeater. This circuit has been out of service about 50% of the time since it has been installed due to a humming sound the comes and goes. I have had the phone company with techs at both end and a tech in the central office working on this problem. I have been told a number of reaseons for the noise including a poor pole ground, jumpers in the wrong position and line issues. This 4 wire circuit has smart cards on either end instead of two 2 wire pairs of copper.

The 2 repeaters in our system are MTR2000s with a SPECTRA-TRAC COMPARATOR. Prior to the comparator move the repeater in question had two 2wire pairs instead of the smartcard 4 wire sysle. The previous circuit run was 12 miles and requiring 2 phone company switching offices. The new system has 4 miles of circuit and only 1 phone company station utilized.
The last phone comapny tech found 10v A/C on the circuit in question and -18 to -20dB point to point. After service the circuit was at -16dB and everthing worked well for 12 hours.

Does anyone have an idea why we have chronic issues on this circuit Changing dBs and A/C running through the circuit or has anyone had a similar problem.
All of the radio equipment has been checker for function by the Motorola shop.
I am now working on a 9th service call regarding this issue.

Mark

Al
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Re: Leasesed circuit varied signal quality.

Postby Al » Thu Jul 26, 2012 9:24 pm

"due to a humming sound the comes and goes". Sure sounds like you have an intermittent low resistance to ground or an intermittent high resistance on one side of your pairs. That would explain the high level of 60 Hz that was measured across at least one of the pairs. When the pair goes low resistance to ground, that unbalances the pair allowing AC noise. If you can eliminate the source of the unbalance and discover why you're seeing 18 to 20 Db loss on the pair I'd guess that'll fix your problem. 18 Db sounds high for only a 4 mile run.
Last edited by Al on Thu Jul 26, 2012 9:26 pm, edited 1 time in total.

RFguy
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Re: Leasesed circuit varied signal quality.

Postby RFguy » Thu Jul 26, 2012 9:25 pm

I find that fewer and fewer telephone techs know much about lease lines. Everything is digital in their world. I suspect you have bad copper and the telco has the inabilty to identify the issue and resolve it.

Tell the telco that you don't want any techs under 50 yrs old to work on it. The old guys should have the skill to resolve it.

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Bill_G
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Re: Leasesed circuit varied signal quality.

Postby Bill_G » Fri Jul 27, 2012 5:28 am

Do you have a PUC (public utility commission) to turn in a complaint to?
Does the agency have a contract for guaranteed service and uptime on these lines (three nines, four nines, five nines)?
Have you considered DSL or PTP microwave as an alternative?

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kb4mdz
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Re: Leasesed circuit varied signal quality.

Postby kb4mdz » Fri Jul 27, 2012 7:22 am

Off the wall suggestion; if the SPECTRA-TAC comparator FAILS the problem site when the noise is happening, you might figure some circuit to tally the amount of time it's failed; (never worked on SPECTRA-TAC; does it have an output lead that changes state when the site fails?). Or, less reliable and more time consuming have a real live person keep a log of when and how long it happens...

Among other things this is ammunition to tell the telco that their line sucks monkey-toes.

Maybe another tactic could be to use a PC and a program like Audacity (http://audacity.sourceforge.net/) to record all the traffic on the line; bridge the line at the comparator end with a Hi-Z transformer, feeding the soundcard's line input. Audacity now has the ability to have VOX recording; record traffic in say 8 hour shift chunks and the analyze it for faults. If you do it in stereo, one telco line for Left Channel & one telco line for Right Channel, you can easily make comparisons.

Audacity is very powerful & flexible sound recording & editing package, pretty easy to use with just a little effort.

What I'm suggesting does involve effort & a learning curve on your part, but it's been my experience that you have to provide telco with a LOT of data to back up your statements that it's their problem & not your equipment. You practically have to hold their hand, turn on the test equipment, & such. Sad, but true.

emtprt
Posts: 128
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Re: Leasesed circuit varied signal quality.

Postby emtprt » Fri Jul 27, 2012 10:23 am

I am working with an IT person to have each site recorded and time stamped. I have communicated all the way to the third tier of support at the phone co. They respond quickly but the problem reappears within a day of service. The State of CT has been very critical of utilities since the last hurricane and a recent bill was passed which minimizes down times for services and the public.
Use of a canopy or microwave system is being looked into but is not in the present budget.

Jim202
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Re: Leasesed circuit varied signal quality.

Postby Jim202 » Fri Jul 27, 2012 5:16 pm

You might inquire of the telephone techs as to what kind of cable your circuits are being run over. There is still a good amount of pulp insulated cable in service today. With the cost of labor an material climbing all the time, the phone companies are in no mood to be spending money to replace their old cables until there is no other way to keep their circuits up.

You have probably seen the old lead covered cable being taken down along the roads. This is the old pulp insulated cables. Some of it may even have the black outer jacket over it. It may be hard to tell if it is pulp or PIC (plastic insulated) being used. Again I bring up the point to make sure you ask the techs trying to keep your circuits working.

By all means file a complaint with the state about the poor track record of your circuits going out. I don't hesitate to call the state and file a complaint. The state uses these complaints as a way of tracking the telephone company's actions when it comes asking for a rate increase. The more complaints, the less likely the rate increase will even be considered.

Plus you would be amazed at the reaction to the state by the phone companies when there is a complaint. I have called Verizon to put in a trouble call and have been told it will be 2 weeks before a service call can be set up. Hang up with Verizon and call the state DPU. Tell them what just went on and in most cases the problem is taken care of the same day. Maybe the morning of the next day if it was after lunch when the calls were placed.

Will
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Re: Leasesed circuit varied signal quality.

Postby Will » Fri Jul 27, 2012 5:19 pm

Have he telco remove ALL amps from the remote ends, you should only have a 1:1 matching transformer on each pair provided by telco.

On that short of a line the telco transformers may not be needed. Make sure there is NO leakage to ground on the transformers in your equipment.

Will
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Re: Leasesed circuit varied signal quality.

Postby Will » Fri Jul 27, 2012 5:24 pm

RFguy wrote:I find that fewer and fewer telephone techs know much about lease lines. Everything is digital in their world. I suspect you have bad copper and the telco has the inabilty to identify the issue and resolve it.

Tell the telco that you don't want any techs under 50 yrs old to work on it. The old guys should have the skill to resolve it.


Telco techs are not cable people, you need a cable person with a lot of time in grade. We do not allow "techs"on site,
BTDT, had to do my own cable testing.

emtprt
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Re: Leasesed circuit varied signal quality.

Postby emtprt » Fri Jul 27, 2012 7:16 pm

The telco did send out a line crew last week to check pole grounding and jumper issues. I have refused to close out the service ticket due to the issues encountered. I was advised to bring the matter up with 2 State regulatory agencies.
The guys they have sent out have been decent people and seem to encounter corperate stumbling blocks when dealing with complex problems. The copper in our area is 40-50 years old for the most part. I have had better luck using 2 wire pairs vs Smart card which can be adjusted end to end in a central office.

The reason we moved the comparator was due to a telco issue that shut down the system. We now have circuits and backup control stations

emtprt
Posts: 128
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What radios do you own?: Astro Specta CDMS XTS3000

Re: Leasesed circuit varied signal quality.

Postby emtprt » Mon Jul 30, 2012 4:12 pm

What would be an acceptable telco circuit db loss for proper function of MTR2000s and the Spectra-Trac comparatot. Today we were sitting around -16dB when everything was checked at the site.

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Bill_G
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Re: Leasesed circuit varied signal quality.

Postby Bill_G » Mon Jul 30, 2012 7:48 pm

10db is great, and 20db is acceptable. As long as it doesn't become a moving target again, you can align for that -16db loss, and function just fine.

emtprt
Posts: 128
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Re: Leasesed circuit varied signal quality.

Postby emtprt » Tue Jul 31, 2012 4:18 pm

The trouble team is sending out a senior tech. supervisor to resole the issue tommorrow. Minimal changes in dB loss 16.1-16.4 possible grounding issue creating A/C current through the line up to 10v

emtprt
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Re: Leasesed circuit varied signal quality.

Postby emtprt » Sun Aug 12, 2012 9:11 pm

Well our main transmit site has been down since July 5th (except for a few rare hours) 4 days ago the Telco found 1 good 4 wire pair out or 25 attempts and 12 service calls. My service ticket is still open and a continuous monitor was placed on the line to record problems. I brough the site back online Thursday and all seems well. I thank God that I had a DEMARC to DEMARC install from them so they have to eat the costs of serving their own equipment. I am also glad that our back up system provide workable coverage.
Telco administrators don't like when you complain to the state's regulaty agencies and mention the press...

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kb4mdz
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Re: Leasesed circuit varied signal quality.

Postby kb4mdz » Mon Aug 13, 2012 5:10 am

Are they at least pro-rating your bill for that circuit? You could even try charging them penalty fees for outage over a certain limit.

Go get 'em!

rbad
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Re: Leasesed circuit varied signal quality.

Postby rbad » Tue Apr 14, 2015 10:25 am

How did this end up?? I am currently experiencing a similar problem with a client quite a long distance away. It's a public safety agency that recently was forced to move from a (very functional for 12+ yrs since the time I had originally installed it) 2-wire DC circuit for remote base control to a 4-wire tone remote when they moved the remote base to a new spot in town where the copper plant was horrible. AND, at the same time, they migrated several agencies (police/fire/ems) together into a group of repeated UHF "T-Band" freq's. vs. the assortment of simplex radios in Low-Band and VHF...
(small town - single site repeaters are giving them roughly 97% portable radio coverage in town, so no remote receivers or voting/comparator issues to deal with -- they were used to almost no in-building portable coverage w/ prior low-band portables and were quite happy to be able to rip out the PAC-RT's out of their vehicles.. LOL)

The problem now lies with the Telco --they could not provide a "unloaded" /"clean"pairs and were unwilling to remove the 2-3 "bridge taps" that were discovered by a splicing crew, so we opted for the 4-wire option. Since the circuits have been down more than "up", you can safely assume that it IS Verizon. :(every time a failure occurs, they send out a spec-services "tech" - term used very loosely - who then swaps pairs at both ends until he finds something working, then leaves.) A few hours/days later, the problems start again. The splicing crews that have come out are very nice and really do want to help, but cannot come close to getting authorization to replace such huge amount of copper plant that is destined for the recycler just as soon as they are done running fiber to every customer. (at the HQ site, at the time of initial install, we had run in 4 total 4" sched 40 pvc conduits @140' ) from the building out to an underground pedestal and had the telco use one for a 100-pair direct-burial "pic" cable and it runs into a 100 pair indoor terminal. at the pedestal, it's just spliced into the old feeder , but everything is at ground level and usually under snow in the winter. when it all melts, the problems increase by 50%, but they won't raise it or enclose the splices in any type of enclosure and the 4-wire copper based T1's for their data ckts are in the same mess, but FORTUNATELY we don't get called when they go "down" -- same % as the radio gear. )

Without the auto-failover that we built-in initially, they would be noticing the issue much more, but during the "failover" process, they go from 110w Quantars at the highest spot in town on top of a water tank w/ 1-5/8" hardline fed DB-420 antennas to locally installed MTR2000's at their HQ with a small low-gain/low-end antennas mounted on the building itself . (was only meant as a means of communicating during a severe catastrophic infrastructure failure... not daily use).

Looking at a major overhaul soon anyway as the agency had migrated all police/fire/ems up from a mix of low-band and vhf simplex frequency operation to T-Band freq's... and, unless smart minds intervene, the "giveback" will be affecting their operations. So they are apprehensive about investing any more funds into what is very possibly going to be an obsolete system within just a few years.

ROIP and Microwave link have been suggested, but the $$ isn't there. As has been mentioned above, the older and more experienced techs are the ones who really do know how to get this stuff working. (sites are 2 miles apart, but each leg of the leased circuits go 15+ miles to the C.O. that handles phone service for 3 adjacent townships... so that's 30+ miles total overall length... and it's paper insulate/lead jacketed unpressurized cable that will never be replaced as "FIOS" is the only term that Verizon is familiar with now)

Numerous calls go unanswered and escalation has failed repeatedly. Regulatory agencies here are extremely apprehensive about even taking a complaint -- it's New Jersey though, so that explains quite a lot.

As a temp "fix", we suggested they use several spare Quantars they have for "emergency replacement use" and use them at HQ with better antennas.

But, long-term, it's tough to recommend that they allocate funds to a system that is destined to go away quite soon. I would guess that if the T-Band Spectrum was not in doubt, a microwave link, or even canopy or aironet (it's not line of sight at building level and a small tower would have to be erected, but nothing substantial) would be up and running and all headaches would disappear.

Does anyone here think that ROIP (over cable-tv company provided internet service -- It's Cablevision/Optimum Online, so is fairly reliable as far as ISP's go) would be a reliable solution to radio connectivity / console to radio connectivity for emergency service functionality? (police dispatch and ops / fire dispatch and ops OTHER than fireground, which is simplex analog / ems dispatch and ops) ? Provided, of course, that backup equipment is in place w/ auto failover in the event of any failure. (very economical solution, as the cable co has to provide internet service to any municipal building under their franchise agreement with the township - the only cost would be for "static ip's" , if desired. --- but very susceptible to environmental factors and probably significantly lower priority service and SLA vs. leased lines.) ?

Just a bit frustrated and want to give a viable option to them without forcing them to squander funds that in rather short supply nowadays.
If I had a crystal ball and could predict the future.... And KNEW that the forces of NY and other large city environments using T-Band spectrum
would be able to force a legislative solution to the "giveback", I KNOW which way I'd go. But, they might just go the route of joining a newly formed "communications consortium" that will be building out a 700mhz "D-Block" phase-II p25 simulcast multiple-town system. No infrastructure maintenance, but
they will have to purchase all new portable radios and mobile radios and pay a "subscriber fee" monthly or yearly to maintain the infrastructure.


Just looking for some thoughts and ideas from the Radio Gods here. :)


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