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n3mvf
08-18-2003, 01:17 PM
Wireless Growth Hinders Rescuers
FCC Vows to Fix Radio Interference
By Christian Davenport
Washington Post Staff Writer
Monday, August 18, 2003; Page A01


The explosive growth of the mobile phone industry has crowded and tangled the nation's airwaves to such an extent that wireless company signals are increasingly interfering with emergency radio frequencies used by police and firefighters, public safety agencies said.

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Emergency departments across the country -- including some in the District, Maryland and Virginia -- report unsettling stories of officers who can't call for backup, dispatchers who can't relay suspect descriptions and firefighters who can't request ambulances because of radio "dead spots" believed to be caused by wireless phone interference.

"Just by the grace of God or good luck, we've been able to avoid a major problem," said Gary Manougian, a police officer in Portland, Ore. "But I don't think we can go on like this indefinitely."

The Federal Communications Commission has vowed to find a solution, even if it has to reorganize a large swath of the radio spectrum -- a massive and controversial task, potentially costing hundreds of millions of dollars and taking years to complete, industry officials said.

FCC Chairman Michael K. Powell said in a speech last week that "it is one of my top priorities . . . to ensure that public safety has the reliable spectrum resources it needs to do its lifesaving work." He warned that solving the problem "may be one of the most challenging spectrum policy proceedings" to come before the agency.

No death or catastrophe has been attributed to such communication problems, said Robert Gurss, director of legal and government relations for the Association of Public Safety Communications Officials International, a nonprofit organization representing emergency communication officials.

But dozens of agencies large and small -- from New York City to Androscoggin County, Maine -- have registered complaints, and one public safety coalition estimates that interference is a problem in at least 27 states.

The issue has its roots in the 1970s, well before the popularity of mobile phones, when the FCC assigned channels in the 800 megahertz band to public safety departments. In the 1980s, wireless companies began to acquire, with federal approval, space adjacent to the emergency radio frequencies. Soon, the wireless phone industry started to grow. Last year, there were an estimated 140 million wireless phone subscribers, the Cellular Telecommunications and Internet Association said.

An increasing number of public safety agencies moved into the 800 megahertz band as well, and as the agencies and wireless companies occupied more spectrum space, airwave conflicts intensified.

Communication officials said many factors cause interference. A common problem arises when a police officer, for example, is close to a wireless phone company transmitter but far from a tower that carries the signals for emergency radios. In that situation, the wireless phone tower overpowers the officer's radio, rendering it useless, the officials said.

To solve the problem, the FCC is considering reshuffling channels in the 800 megahertz band. The idea is to separate the wireless companies from the public safety departments, so they inhabit different ends of the band.

None of the companies is doing anything wrong, FCC officials said. As organized, the spectrum, which is a limited resource, simply can't accommodate everyone.

There are several wireless companies operating in the 800 megahertz band, including Verizon, AT&T Wireless and Cingular, the FCC said. Most of the complaints that the agency has received have been caused by Reston-based Nextel Communications Inc. because many of its band frequencies abut those of emergency radios.

Mindful of the mounting pressure, Nextel has teamed with a broad coalition of partners -- including the Association of Public Safety Communications Officials International and the International Association of Chiefs of Police -- to develop a proposal to reorganize the spectrum, which, if approved, would give Nextel some prime real estate in the airwaves.

Nextel also has offered to pay $850 million for the cost associated with reshuffling the channels if its plan is adopted. The company's proposal is just one of many the FCC is reviewing.

Many communication experts said that a complete reorganization of the spectrum is unnecessary, too expensive and too time-consuming. Meanwhile, public safety officials said the situation is urgent. "If we don't fix this now, it's only going to get worse," Gurss said.

Anne Arundel County police officer Patrick A. Fisher said he ran into the problem one day this spring. The call from his partner that came over the radio was crackled and fuzzy, and Fisher could make out only two words: "start . . . fire." Fisher sensed a tone of urgency in the other officer's voice and rushed to the street he knew his colleague was patrolling.

When he arrived, he saw the other officer futilely fighting a house fire with a garden hose. Fisher reached for his radio, but its reception was too weak until he drove a few blocks away. Finally, firefighters arrived. "If it was another couple of minutes," Fisher said, "the whole side of the house would have been gone."

About two years ago, police officers in Portland were chasing a man after a carjacking attempt when their radios went dead. The man ran through a suburban area, then hid in the woods. About a dozen officers dropped into formation around him. "We were trying to set up a perimeter, but our radios wouldn't work," Manougian said. Some officers had to run into nearby homes to call in information to the dispatcher.

Denver has identified at least 24 dead spots in its communications system, and the police officers know where they are, said Dana Hansen, superintendent of communications for the city's police department. It's particularly troubling, she said, that many of the dead spots happen to be at major intersections where many traffic accidents occur.

When Fairfax County first purchased an 800 megahertz radio system, it had interference problems, said Mernie Fitzgerald, a county spokeswoman. Nextel and Cingular agreed to reconfigure their systems in the county, and they were able to solve the problem, she said. "We haven't had any problems in the last two years," she said.

Montgomery County recently spent $175 million on a communications system that includes an 800 megahertz radio network. The county took care to ensure there wouldn't be any interference problems, said Lt. Dallas Lipp of the county fire and rescue department. The county's system is on a different part of the spectrum than local wireless phone networks, he said, so its system is less susceptible to problems.

"But we're always monitoring how our system is performing," Lipp said.

The District filed an interference complaint last spring with the Association of Public Safety Communications Officials International. Now, having been awarded a $40 million grant from the federal government, the city plans to build seven transmitters and receivers to strengthen its radio system's signal.

Anne Arundel County plans to spend $15 million over five years to build more towers and to update its equipment. And last year, county officials passed a zoning law that required wireless companies to certify that their signals would not interfere with the county's radio system.

Cingular asked the FCC to strike down the ordinance. Last month, the commission did so, saying that the county was trying to regulate the airwaves through its zoning code. The county, which has appealed the FCC's decision, has worked with the companies to reduce the interference. The effort appears to be working: The number of known dead spots has dropped from more than 60 to about 20, county officials said. Still, they said, 20 is too many.

Meantime, Fisher said many colleagues on the Anne Arundel County police force have found their own solution: They carry cell phones in case their radios go dead.


© 2003 The Washington Post Company

N5CTI
08-18-2003, 05:53 PM
This issue is addressed (by reference, at least) in the ARRL's ARECC Level 1. The main point (which I didn't see addressed in the WashPost article, which I just scanned) is that cellular phones work on a "strong signal" principle (find the strongest signal (closest tower, essentially), where emergency services operate on a "weak signal" design (mobile transceivers all working off of one (or a very few) centrally located fixed antenna location.

WA2ZDY
08-19-2003, 12:40 AM
What's missing from this article too is that the transmitters causing interference should be required to be fixed. If you were found to be at fault causing TVI, you'd sure get the word to fix your rig or to get off the air.

The problem with this "cell phone" situation is that it involves a company that is NOT a celly phone company. It's a two-way radio company that simply added cell phone type use to its two way radio network. So all these transmitters are in the commercial/public service two-way radio spectrum, not the cell phone spectrum. So adjacent channel and overload are far more likely and aggravated in this situation.

One reason many folks in the land mobile radio industry feel FCC isn't taking serious action with this problem is that this company has many long term contracts with . . . . the federal government. Much fed radio traffic is carried by this company's network. Hmmmmmmmmmm getting the picture yet?

The solution described in the article is that the offending company wants everyone else to move to 700 MHz so they can keep 800 MHz as their own. Do you think for a minute that $850 million will cover the cost of replacing every 800 MHz radio in use? Mobiles, handhelds, bases, repeaters . . . And that $850 million is only going to go to public safety systems. Joe the Plumber who happens to be on 800 MHz is on his own.

Funny, the guy causing the interference is about to make the victims pay. What's wrong with that picture?

Oh well.

K9STH
08-19-2003, 04:28 AM
One thing that enters into the equation is that you are dealing with radio frequency transmissions and that they are affected by things other than interference from other stations. For example, "dead spots" can be due to several physical factors, especially terrain and reflections.

Although the radio horizon is nominally 1/3 farther than the visual horizon, it is very common for things like hills, buildings, etc., to block the signal either partially or completely. Also, signals reflecting from various objects (buildings, cliffs, bridges, etc.) can arrive approximately 180 degrees out of phase with the incident signal (non reflected signal) which will cause a cancellation of the signal. This placing a signal 180 degrees out of phase is how the carrier is removed in many SSB transmitters. When one side is going positive, the other side is going negative and when added the result is zero.

It is very difficult to design a radio system that has any better reliability than "90 - 90". That is, you can reliably communicate over 90 percent of the area 90 percent of the time. This gives a "true" reliability factor of 81 percent (.9 x .9 = .81). With a lot of effort including multiple sites, transmitting and receiving, a "95 - 95" system is about the best that can be had under "normal" situations. This gives a reliability factor of 90 percent (actually .9025).

In the past, most two-way radio systems were actually designed for more like "70 - 70" coverage which gives a reliability factor of 49 percent. As the use of repeaters with satellite receivers became more common, then the system designs started to get better. But, the majority of commercial systems still are substantially less than "90 - 90".

A while back a company that I owned had contracts with most of the cities and the county north of Dallas, Texas. Our largest municipality had, at the time, three 460 MHz repeaters for the Police Department alone. After we started maintaining the system, we had the officers record any "dead spots" that they ran into including which of the three repeaters was involved (the repeaters were located about 3 miles apart in different sections of the city). One evening an officer "found" over 100 dead spots! Some of them were no longer than the length of the squad car (that is when the car was moved just a few feet the radio worked fine). A number of these locations were within actual sight of all three repeater locations (you could actually see the towers) and all three frequencies were dead! Several of these were within 2 blocks of one of the repeater sites!

There were 2 parking spots at a local MacDonald's restaurant that 100 watt mobiles with the antenna mounted in the center of the roof couldn't even break the squelch of any of the repeaters. Yet an officer using a 2 watt portable could stand at the rear bumper of the squad car and be "full quieting" into all three repeaters!

Whenever someone told me that they were thinking about buying a particular brand of two-way radio equipment because the seller promised "100 percent coverage" I told them to get that guarantee in writing with a "money back" guarantee because I knew that I could find numerous "dead spots" within a very short period of time. Frankly, it was the sales persons of the major manufacturers of two-way equipment that were making the 100 percent reliability claims. Of course they wouldn't put that clause into the sales contract because they knew that the coverage wasn't that good.

Also, foliage ("leaves on the trees") can have a marked effect on the performance of radio systems, especially on 800 MHz and higher. However, "long needle" pine trees, cypress, etc., have a marked effect on the 450 MHz band as well. During the months when leaves are not present, or the "sap" is not "running" into the foliage, coverage on the higher bands will often be very good. But, as spring approaches, things go from good to fair to bad to even worse as the foliage comes out onto the tress.

There are some "overloading" effects that can happen to equipment. However, you really have to be close to the transmitting location for these to be any real problem. Believe it or not, being right under a transmitting antenna actually places you in the "cone of silence" for most antennas. That is, the signal strength is often 60 to 100 dB, or more, less than the signal out say a "quarter of a mile" is. This is due to the radiation "pattern" of the antenna.

Anyway, there is always the possibility that some of the "dead spots" are caused by cellular telephones. But, by and large, the problems come from the fact that such "dead spots" happen because of the inherent problems with the higher and higher frequencies that are now being used by public safety departments and not because of the widespread use of cellular telephones.

Glen, K9STH

N5CTI
08-19-2003, 04:54 PM
The Association of Public-Safety Communications Officials (APCO) has some information about how all this came about, and how they're progressing, on their web site (http://www.apco911.org/frequency/800bpg.html).

The Washington Post article has brought the issue to widespread public notice, but this whole thing has been going on for years, while they search for viable solutions to the interference problems.

08-19-2003, 07:20 PM
And here (http://www.apco911.org/frequency/documents/finaldraftpetforrecon.pdf) is a bit on what is going on with the VHF/UHF public service band.
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">The Second R&amp;O reflects the Commission’s desire to improve spectrum
efficiency in the crowded VHF and UHF land mobile radio frequencies below 800 MHz.
The goal is to move licensees to narrower channels and, in theory, multiply the number of
available channels within the same amount of spectrum. Prior efforts to “refarm” land
mobile spectrum have been ineffective, due in part to the absence of a requirement that
licensees convert to more efficient narrowband radio equipment by a specific date.
Instead, the Commission had merely used its equipment authorization process to force
manufactures to offer narrowband equipment, without any concurrent requirement that
users purchase or deploy narrowband capabilities.2[/QUOTE]<span id='postcolor'>
In a nutshell, the FCC ruled that by January 13, 2004, applications to expand the coverage area of existing
systems would only be approved for narrowband (12.5 kHz) operation. This, of course, just won't work in the real world.

On the other hand, after you've paid your higher taxes to pay for your local public service radio system, we'll have a wonderful supply of Motorola gear to play with on the ham bands.

Another thought: Should we now start looking at setting aside a chunk on 2m and 73cm for 12.5kHz channels, both for simplex and repeaters? Will interoperbility with public service equipment be an issue in the future? I know some SAR folks that have commercial HTs that they use both on ham repeaters and for talking on the public service bands.