Narrowbanding: Helpful Tips from Spokane
Wednesday, January 06, 2010 | Comments
By John Larribeau
With the deadline for VHF and UHF narrowbanding just three years away, it’s time to get your implementation plan in order. In Spokane, Wash., the monumental task of modifying almost 1,650 city-owned radios falls on the small city radio shop. With only two technicians and a technician aid/installer, starting early and planning ahead are critical if we expect to meet the deadlines.
Our city communications system consists of numerous VHF and UHF repeaters with a system of voted receivers spread across 12 different remote sites. The numerous remote sites are necessary to address coverage issues with the mountainous terrain. Our radios consist of about 1,000 for public safety (fire, police and EMS) and slightly more than 650 for utilities (water, sewer and streets).
Public safety (VHF and UHF) will transition to a new 700 MHz trunked/VHF simulcast system during the next two to three years. This new system will be shared by the city and county of Spokane, as well as some outlying cities. For financial reasons, the city utilities will transition to VHF narrowband as an interim step before making the ultimate leap onto the trunked system. While the public-safety infrastructure, mobile and portables radios have various funding methods — stimulus, grants and a 0.1 percent sales tax initiative — the utilities must procure their own mobile and portable equipment. Because of the costs involved, it’s best to do this through attrition rather than buy all the equipment at once. Also, as the demand for new Project 25 (P25)-compliant trunked radios increases, the cost per unit will decrease.
With the large-scaled projects identified and before the rush to install the new trunked system, we analyzed the narrowbanding mandate and decided to approach it in four phases:
Phase I: This phase covers all the planning and research associated with modifying our system. Although our main focus is on the utilities, we also looked at police and fire in the event the new public-safety trunked system is delayed or suffers unforeseen problems. The better the information you have going into the project, the better your results will be. Items that will help you gather the necessary information include:
1. Form a “super department” to cover the associated time and cost. This cost is shared by all the departments that use the city’s communications systems and is billed proportionately.
2. Obtain an accurate inventory and departmental breakdown of existing radio equipment. This critical element will help eliminate missed equipment, meet planning time lines and minimize weak signal calls down the road.
3. Identify the existing equipment that is narrowband capable and how the switch from wideband to narrowband can be accomplished — software or hardware modification.
4. Identify the units that must be replaced because they aren’t narrowband capable and identify recommended or specific replacement units.
5. Identify and inventory associated support hardware — test equipment, programming cables and software, hardware modification kits, etc.
6. Prepare briefs and handouts for the various department heads and other people who will either be involved or need to know what’s going on. Keep It Simple, Stupid (KISS) works well here. Don’t drown the upper echelon with techno-speak. Few people have a problem with my “We have to re-slice the pie so more people can get a piece” analogy.
Phase II: This phase covers the initial procurement of specialized tools and equipment required to make the shift, as well as installing and testing the various equipment modifications prior to the switch. Tasks associated with this phase include:
1. Initial procurement of radio programming cables and software. The software can be copied and saved; however, the cables can’t. Make sure you have at least two of every programming cable because one can go bad in the middle of a switch. Everyone is counting pennies, so look around. Google the cables. At, I found programming cables for Motorola, Vertex Standard, Kenwood Communications and others at a cost savings of up to 90 percent compared with the manufacturer prices. Some of these programming cables even include software — not the latest version of the software, but it worked fine in our radios. Some manufacturers say that not using their cables and software will “fry” a radio. We tried every cable and the software on some spare radios, and they worked fine. The bottom line here is to test, test and retest before you begin the switch. Don’t wait for the switch to find out how a radio responds.
2. Initial procurement of hardware modification kits. We have a lot of GE MASTR II repeaters and voted receivers, which aren’t narrowband capable. Communications Specialists, a company in California, makes numerous modification kits for various makes and models of base radios. The kit for the MASTR IIs includes new crystal filters and a capacitor, which converts it to narrowband. In bench tests before and after the modification installation, we gained 1 to 1.5 dB of quieting on the SINAD.
3. Test and verify narrowband-capable radios to ensure they will switch to narrowband. In bench tests, we found a couple of radios that the service manual said had both capabilities, but we discovered that they must be ordered set up from the factory for either wideband or narrowband. They can’t be changed in the field.
4. Test and verify that narrowband-capable radios will simply switch to narrowband. Although most of our radios simply divide the XMIT deviation in half when switched to narrowband, some were too high or too low. Our tests identified which radios require an additional deviation alignment to the modulation/deviation within specs. We also identified the approximate time it takes to modify one radio. This helps us plan about how long we have to spend on each vehicle/radio and allows us to check our progress along the way.
5. Procure and test additional modification ancillary equipment. We are outfitting our two service vehicles so they can be mobile radio shops that can perform all the reprogramming and alignments in the field. It’s easier to have two service trucks go to the yard where the trucks are parked than have hundreds of trucks come to the shop. We’re putting a service monitor, laptop computer, in-line wattmeter, and all the associated cables and tools to perform a complete service in the field. An AC inverter is installed to allow easy access to power for the test equipment and any power tools required. A 20-foot Cat-5 cable with a straight-through coupler on one end and a 20-foot RF cable with various RF adapters to fit all the radios are included. This will allow us to drive to a vehicle, hook up to the radio (RF and programming connections) without dismounting the radio and completing the modification from inside the service vehicle. The coupler in the Cat-5 cable allows us to disconnect the programming cable and hook up a spare microphone for modulation and over-the-air tests.
6. Schedule initial meetings with the various departments to explain the switch to narrowband. This brief includes a handout of radio assets, what narrowbanding is and why you have to do it, how it will impact the department and what is or will be expected of them. The sooner everyone is informed and involved, the better.
7. Put together a preliminary modification schedule broken down by department or subdepartment as determined by the number of units to be modified and the time factors involved. We elected to try the “surge” method where we will work through the weekend to get an entire department switched to narrowband by the following Monday. This plan, although hard on technicians, will allow the least amount of impact to operational units — with the exception of emergency crews, most of the city utilities are closed over the weekend.
An alternative method we considered was a “phased conversion” where we would convert half of our voted receivers to narrowband and assign them a different PL/CTCSS tone. As the portable and mobile radios are modified to narrowband, they are given new XMIT PL/CTCSS tones. This would allow only narrowband-modified radios to talk to narrowband-modified voted receivers. The difference in audio levels associated with the decrease in deviation would be compensated for at the receiver so that the dispatcher wouldn’t notice the difference between wideband and narrowband calls. It would also allow for more time to complete the switch, which is easier on the technicians. The problem with this plan is that it would adversely affect coverage for both wideband and narrowband radios until the whole department — all voted receivers —completes the switch. That fact was the tiebreaker for us.
8. Procure dots. Those 1-inch diameter, colored, self-stick, paper dots at office supply stores are a quick and easy way to get a status at a glance. We’ll place them on the outside of the upper-driver’s-side corner of the windshield. Green dot means modification complete; red dot equals modification attempted and failed and repair required; no dot means waiting modification. You can also put them on portable radios.
9. Draft departmental work orders. One for each department that uses radios that require modification. This will ensure that a specific department is charged for the time and materials to modify only its associated equipment. Some equipment requires more time to modify than others.
Phase III: The modification phase covers all the final or last-minute steps required for the actual modifications, as well as the modifications themselves. Tasks include the following:
1. Final planning meetings with each department prior to the actual change. These meetings include finalizing the time and dates for the switch and making sure all the vehicles and portables restaged in prearranged locations to minimize travel time. It includes making sure all the associated keys are available and that large trucks are parked nose out so we can drive to the front of the vehicle and not have to get in, start it up and move it to get access — air brakes take time to come up to pressure. The meeting outlines the parent department point of contact on hot standby if unforeseen problems arise.
2. Final load out of the service vehicles. This includes a supply of common repair parts — antennas, antenna mounts, RF cables, spare microphones, various connectors and their associated crimp tools, power wire with terminals and but splices — a few pre-programmed and checked out spare radios.
3. Final modification schedule. Some departments may want some vehicles or radios done first. These will be identified and localized for priority modification.
4. A rough plan to get the problems and/or misers. No plan is perfect, so we’re planning for everything that is missed or fails to switch for one reason or another. Our technician/aid will be on call to address and correct any wiring, antenna or RF cable issues.
Phase IV: Relicense your wideband channels to narrowband. This will not happen automatically. If this step is not accomplished, you risk losing that channel and/or having it reassigned to another organization. It may be easier to think of it this way: Every current license in the VHF and UHF bands will expire Jan. 1, 2013, regardless of the date printed on the license itself. The FCC is currently investigating extensions to this date, to be issued on a case-by-case basis as requested by the licensee.
That’s our plan. We will shift the first department to narrowband this spring. Because we’ve done as much due diligence and advanced planning as possible, I’m hoping that the actual switch will go smoothly. This is by no means a catch-all, must-do, one-size-fits-all plan. However, I hope it gives you a starting point and maybe even one or two of those forehead-slapping, “Why didn’t I think of that?” episodes. Good luck, and I hope to report on how it went next summer.
Editor's Note: For more information on narrowbanding, visit For discussion on the narrowbanding mandate, join the LMR Narrowbanding Yahoo! Group here. You can also search on "narrowbanding" in the ONLY Online Library at
Your comments are welcome, click here.

John Larribeau is a communications systems technician for the city of Spokane, Wash. He has 26 years of service in the U.S. Navy and worked for 15 years as a senior manager for Radio Shack. Contact Larribeau at

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