Apr 1, 2001 12:00 PM, By D. A. Keckler

When Lonnie Danchik looked for a business strategy to continue to grow as a commercial radio service provider in the Dallas metropolitan area, he saw a range full of 800MHz and UHF wranglers. His solution: Try the VHF narrowband trunking brand.

‘Git analog, l'il doggies.’

Texas is cowboy country, and every good drover knows that you have to keep your herd moving. If you don't, you'll never get to the market. It also helps to constantly improve your breed.

For nine years, Lonnie Danchik has been looking for new opportunities to keep growing his CommNet Communications operation in the Dallas — Fort Worth metroplex. He sells equipment, provides dispatch radio, installs and services, and resells paging, cellular, PCS and ESMR. Danchik keeps looking for the “next good thing” to differentiate his herd, such as fleet management, mobile data, computer-aided dispatch or GPS/AVL. In the process, CommNet has become the largest independent SMR trunked-system operator in the city. [For Danchik's viewpoint on the challenges facing dealers, see “Point-of-Sale Perspective” on the back page.]

Changes across the land-mobile prairie, including spectrum scarcity and the domination of 800MHz by a few coyotes, caused Danchik to reexamine his market, to review FCC rules changes and to reevaluate his business plan. The result: Danchik took hold of the opposite ends of the trunking spectrum “rope,” 900MHz and VHF, and lassoed Dallas with it.

The first move, made attractive by the availability of exclusivity, was into 900MHz. However, the repositioning came with technical challenges in combining and audio quality. CommNet's 900MHz system has the technical bugs worked out and now has mature loading. It generates a nice income, maintains low churn and even picks up “returnees” from ESMR who just want traditional dispatch. But there were still goals that Danchik wanted to achieve for users including better propagation characteristics, simpler and less-expensive mobile installations, and higher-power portables. Looking five years down the road, Danchik saw that FCC “refarming” offered opportunities for UHF trunking, but he held back, based on the lack of exclusivity, fierce competition and interference problems he observed in the Dallas market.

Old breed, new variety

“My goal was to compete with Nextel's dispatch feature — not their phone feature,” Danchik said. “I said, ‘What technology exists, so that we can do that?’ What the customer wants is so far away from what we've been able to provide, we've either got to get innovative, or go do something else.”

Looking for that something different, Danchik recognized that other refarming changes could create opportunity back at the place where land mobile started: VHF.

The FCC's refarming order, effective at the end of 1997, also authorized trunking in the shared 150MHz — 174MHz band, where channels were previously 30kHz wide and spaced every 15kHz. The FCC added new interleaved channels between each existing channel and promoted a move to narrowbanding down to 7.5kHz bandwidths. Great: new, exclusive channels. However, the order restricted operations to equipment that could operate on channel bandwidths of 12.5kHz or less. Not so great: time to wait for the manufacturers to catch up.

By fall 1999, a few manufacturers, including Kenwood Communications, which CommNet selected, were ready to market type-accepted mobiles and portables.

The coordination started smoothly. “In the early days of filing, in the Dallas area, getting the new, narrowband frequencies was actually pretty easy.” Using Forest Industries Telecommunications as his coordinator, he was able to process several applications for five-channel blocks throughout the Dallas and north Texas area.

The situation was rosy — until — the larger coordinator camels stuck their noses under the tent. Frequency Advisory Committees cooperate, but they have also been, to be blunt, competitors ever since the FCC pooled their jurisdictions.

Some FACs started inspecting and criticizing the work of other FACs, and they also began alerting their VHF clients to possible interference from the new VHF trunking licensees. This set off a flurry of radio hypochondria, often eliciting complaints about interference received from systems that had not even been constructed yet.

2000: Year of decision

When the dust settled, in mid-2000, two issues were decided: First, operators like Danchik got the coordinators to back off from inflammatory statements that implied that new licenses are not in compliance with the FCC rules.

Second, all the FACs agreed to solve the controversy by treating adjacent-channel frequencies just like co-channel frequencies, which means to get a VHF trunking frequency now, concurrence has to be obtained for a 39dBu (70-mile) contour from co-channel and adjacent-channel incumbents. This will impede, though not entirely restrict, the possibility for new systems in urban areas.

Danchik was already managing about 50 channels before the cow pie hit the fan. He has added 13 more, to date, by accepting difficult coordinations — mixing exclusive channels with shared frequency, non-interference-basis channels. “We take them to fill,” he said.

Operators wanting to deploy new VHF trunking in major urban areas will now have to run a longer gauntlet, but there are frequencies in markets where VHF hasn't caught on yet, and there are still plenty of VHF frequencies available in rural markets.

So, with the initial coordinations, and the fill-in channels set up to monitor and handle any interference, CommNet's framework was in place. But, as with 900MHz, there were technical hurdles.

Fences across the range

Channel pairing was the first stumbling block. With few exceptions, no natural pairings exist in the VHF bands. Danchik asked FIT to try for about 5MHz of separation, transmit to receive, and at least 250kHz between transmits.

The second hurdle was the capability of the newly available equipment. Although all the VHF frequencies are being assigned at the 7.5kHz split, the available manufacturers' receivers are, at a minimum, 7.5kHz narrow. “Sometimes at 15kHz over, there's some 400W and 500W paging channels out there.” Danchik said. “This has caused us a real problem because you do have combining, duplexing, and multicoupling.”

The biggest problem encountered was talkback capability. Talkout was “absolutely wonderful,” but the LTR radios weren't getting the handshake to go ahead. Not only the portables, but even 25W mobiles with 3dB antennas, were being difficult.

“So we asked, ‘What's going on?’” Danchik said. “You go back to the site, get your spectrum analyzer, you look at the noise floor, and you begin to see there are paging channels, there's all sorts of VHF, there's God knows how much unlicensed stuff running around there. They're all over the place, and no one's receivers are tight enough to eliminate this.”

CommNet's repeater supplier, DX Radio Systems, finally came up with the solution: a narrow, crystal receiver filter. “You order it specifically to your exact frequency, you tell them you want it to be a 7.5kHz window, and you put it right on the front end of your receiver. That's the good news,” Danchik said. “The bad news is they cost $400 dollars apiece. So, if you've got a five-channel system, you just spent another $2,000 you weren't planning on spending.”

Delivery time for the precious solution also became problematic. “You can imagine what must have happened at these crystal filter manufacturers,” Danchik said. “They were probably selling 10 a year of these things, and all of a sudden they had orders for hundreds of them.” Four-week delivery time soon became a 16-week backlog, but “We had finally managed to get them and put them on, and that's been a big, big difference,” Danchik said.

One system that was constructed, but not loaded, was used for a customer demonstration just as the solution was being worked out. The prospective client wanted to switch back from ESMR to traditional dispatch, looking for portability in a clear system — that wasn't one-to-one and wasn't cellular — and would cover Dallas. The sale hinged on the demo.

Danchik approved the demo use of one channel. “They're not going to trunk anywhere,” he told his staff, “because there's nobody else on the system anyway. Let's see how that works for them.”

He decided to monitor the demo from his office.

‘They're not going to buy this’

On demo day, the prospective client passed out four or five portables to its field crew, and by mid-morning Danchik was gloomy. “They were talking on it, and I'm listening to them. About half the transmissions were OK, about half were less than OK. Some of them were crappy, quite frankly.” The users were also making unfavorable comments: “I don't think this is going to work for us, you're not too clear.”

“So, I'm sitting there listening to them, and I was shaking my head, saying ‘This isn't going to work. They're not going to buy this. They're not going to be happy,’” Danchik said.

“They'd been demonstrating since 8 o'clock that morning, I'm half-listening to them on the radio while I go about my day's business. About 10 o'clock, my receivables person from the back comes to the door with the inventory list and says ‘We just got in the first five crystal filters.’ I grabbed my tech and said ‘Go put ’em on, go put ’em on. Right now — go put ’em on.’

Making things XTAL clear

Fortunately, the users from the company trying the demo went to lunch around noon, while Danchik's technician finished the install. “The conversations that I heard the rest of the afternoon — it just cleared up. It was just night and day. They said ‘I don't know what happened. I guess these things have to warm up or something.’ They ended up buying. They have a base, and they have 20 or so Kenwood VHF narrowband trunking hand-helds. They use them all over the Dallas area. They're happy.

“Now, when someone's in my office and I click the radio on, they go ‘Wow, what kind of system is that?’ And I say that's our new VHF narrowband trunking system.”

The addition of the filters also allowed CommNet to reduce the attenuation settings on the site amplifiers. “We're really pleased with where it's headed. All the channels don't have all of the problems. For some of them, the crystal filter helped, but it's not the final solution. There's a lot of things you've got to do to your sites,” Danchik said. That list includes careful antenna matching and using exposed-element antennas.

In addition to using Decibel Products' four-dipole DB224 antennas at its repeater sites, CommNet's VHF narrowband trunking setup includes DX Radio Systems' Millennium series narrowband repeaters and Trident Micro Systems' trunking logic controllers for LTR. The system rings the metroplex with rooftop and tower sites in Dallas, Fort Worth, Richland Hills, Denton, McKinney, Sherman, Greenville, Cedar Creek Lake, and a newly constructed 1,600-foot tower site at Cedar Hill.

For subscriber units, CommNet is exclusively using Kenwood Communications' TK-280 portables and 25W TK-780 mobiles.

“The propagation of VHF is pretty darn good,” Danchik said. As an example, he cited one five-channel system he has placed at a rooftop site managed by Retcom/Trott Communications. The site sits atop Dallas' 550-foot Cityplace building, two miles north of downtown. “I'm operating a VHF trunked system there with 100W power, and typically about a 6dB antenna. I'm also operating several 900MHz systems in downtown Dallas on a 922-foot building, where I'm putting out 150W power per channel. The range is as good or better on the VHF than it is on the 900MHz, even though I'm 400 feet shorter.”

Rounding up customers

“From the perspective of propagation, it's the best we've ever had,” Danchik said. “And I've never had a mobile — that wasn't digital — that sounded this good.”

Danchik said that although VHF trunking only represents about 5% of current loading of all CommNet's radio customers, in the future it will represent about 75% of loading, exceeding the 900MHz commitment.

Keckler is technical editor.

Global VHF trunking

VHF trunking is finding adherents around the world. SmarTrunk Systems, Hayward, CA, has developed a 52-site SmarTrunk II system for the Estonian Railroad, operating throughout Estonia. All 52 VHF repeater sites will be linked so that the dispatch center, located in Tallinn, will be able to communicate with trains anywhere in the country.

Previously, the railroad had been using GSM phones for communications between the trains and the dispatchers. Working with the local Motorola distributor in Tallinn, SmarTrunk and its Argentinian partner, I-SATEL, designed a system using the I-SATEL ISX-510 switch to link the 52 sites together. Now the crews can talk to Tallinn dispatch, any local station on their routes and any track workers along the way. The system also is capable of telephone interconnect.

The network system is in the process of being installed, and there is a great deal of interest from other Eastern European countries in this low-cost solution to a networked communications system, SmarTrunk said.

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