Potential Pitfalls of Broadband Reporting

Last month, we discussed the woes associated with battery backup systems in commercial PBX telephone systems that use ground-start telco lines. This month, we will discuss a number of problems fire technicians commonly encounter incorporating broadband when sending fire signals to a central station.

More and more, fire technicians, as well as security companies, are turning to broadband communications for the transport of alarm, tamper and supervisory signals to a central station. The fact is the fire industry is moving away from traditional plain old telephone service (POTS), gradually replacing it with high-speed broadband.

Some of the more common broadband technologies in use include digital subscriber line (DSL), asymmetric digital subscriber line (ADSL), integrated services digital network (ISDN) and high-speed cable.

Signal transmission using broadband has its advantages. First, it solves the bottleneck in bandwidth that typically exists between the subscriber premises and the network service provider. Second, DSL allows the subscriber to send and retrieve more information in shorter periods of time than is traditionally available over the public switched telephone network (PSTN). Third, it rides in piggyback fashion on the same metallic telephone lines that provide analog telephone service. In a word, when it works, DSL is a real bargain.

Broadband communication technologies and their delivery systems are so specialized that most fire technicians fail to understand the risks involved when transmitting fire signals to the central station. Because a fire technician’s business involves life safety, it goes without saying that it is his or her duty to study and understand all the issues that surround the use of broadband.

Battery Backup Can Be Problematic

Broadband presents a potential problem to fire technicians and the alarm systems they install. This is because no matter what flavor of broadband is in use, it most likely relies on power on the subscriber side of the connection.

The power used by broadband modems and routers usually comes in the form of a plug-in transformer. Thus, when power is lost at the plug, DSL service will likely fail – unless, of course, there is a battery included in the mix. So, essentially, if there is no battery, chances are the fire alarm system will not be able to report to the central station during power outages.

Sadly, in many cases, the broadband installation company will not include a suitable battery backup to address the issue of operating power. This often makes the issue of battery backup even more of a challenge to the fire technician as it means it becomes his or her job to investigate and correct such deficiencies when necessary by installing a suitable, low-voltage power supply.

On the other hand, where battery backup is provided by the broadband installation company, it becomes the fire technician’s duty to ascertain whether the broadband system has enough backup power in reserve to maintain the modem/router for a sufficient period of time (e.g. 24 hours).

Using Uninterruptible Power

“Usually, [broadband companies] use an uninterruptible power supply [UPS] battery backup system on the high side of the router or DSL switch, whichever it might be,” says Nick Markowitz, owner of Markowitz Electric Protection in Pittsburgh.

Uninterruptible power supplies usually are adequate to the task, providing the DSL modem/routers are the only thing attached to them. A UPS typically provides backup power to 120VAC devices when the public electric bus fails. The following passage from Technical Brief #15, “ON-LINE UPS Systems,” by Automated Power Technologies of Lake Forest, Calif., elaborates:

“The true ON-LINE UPS provides full-time, totally conditioned clean power because the UPS is always converting from AC to DC to AC, providing an independently regenerated sinewave output to the load. As a result, the ON-LINE UPS fully protects the computer load from all on-going and often transparent power problems on the utility line.”

An inverter essentially converts low-voltage DC power to high-voltage AC (alternating current), which will operate common, ordinary devices. The problem with using a UPS, however, is many folks will use the same UPS that provides backup power to their DSL for other items, such as personal computers, printers and other accessories.

This can, of course, load the battery in the UPS system to the point where it will not last long enough to comply with NFPA 72, National Fire Alarm Code. Thus, when an outage does occur, the backup time is greatly diminished.

To prevent this kind of problem, the fire technician should install a dedicated UPS for just the DSL modem/router. This will ensure backup power is there for the required time period so the fire alarm system can send fire signals to the central station when called upon to do so.

Backup Outside Fire Tech’s Control

Inside a subscriber’s premises is not the only place batteries are found. Truth be known, there could be a dozen batteries or more that stretch between the protected premises and the central station. This is especially true where the central station also uses broadband, such as T1 service. Typically, cable service requires the use of batteries at the pole when T1 telephone service involves batteries in underground vaults, where fiber feeds metallic trunks.

With DSL over T1, for example, it is necessary to position repeaters along the telephone line at 3,000- to 6,000-foot intervals. This is necessary because of attenuation, a common problem when sending signals along metallic lines for any appreciable distance. Once the signal arrives at the central office (CO), the remainder of the trip is usually performed using high-speed fiber-optic cable.

With cable-based digital telephony (digital telephone systems), the cable company usually positions a series of batteries on the poles in the cable boxes along the road.

“Those amplifiers must be turned on at all times along the telephone poles. If even one is not working, thousands of customers will not have broadband service,” says Markowitz. This was the original problem cable companies encountered when they tried to use their cable system to report alarms many years ago.

According to Markowitz, “There have been cases where thousands of people were left without protection because one or two amplifiers failed during a local outage. Power was intact at the subscriber’s home or business, as well as the central station, but it was between the two points where a small, seemingly insignificant local outage disrupted central station monitoring.”

The telephone and cable companies are aware of this problem and have generally provided a means of battery backup at each repeater along the line. However, with all those batteries and the relatively long periods of time subscribers are often without power, service may not last long enough to satisfy NFPA’s requirements.

Of course, there is only so much a fire technician can do to see that fire alarm signals arrive at the central station intact. Where it is within the technician’s capability to assure proper battery backup at the premise side of the connection, it would be unreasonable to expect the fire technician to do the same outside the subscriber’s facility.

Perhaps the best way today’s fire tech can assure central station response is to use an entirely different reporting technology for the second signal path to the central station.

In this case, especially with DSL, an ordinary digital alarm communicator transmitter (DACT) on board the fire alarm panel can be used to transmit relevant fire signals to the central station over the analog portion of the telephone connection. The good thing about DSL, in this instance, is if DSL service is lost for any reason, th

If you enjoyed this article and want to receive more valuable industry content like this, click here to sign up for our FREE digital newsletters!

Security Is Our Business, Too

For professionals who recommend, buy and install all types of electronic security equipment, a free subscription to Commercial Integrator + Security Sales & Integration is like having a consultant on call. You’ll find an ideal balance of technology and business coverage, with installation tips and techniques for products and updates on how to add to your bottom line.

A FREE subscription to the top resource for security and integration industry will prove to be invaluable.

Subscribe Today!

Get Our Newsletters