narrow band conversion

CarterB wrote:Clearblock,

Sorry, but that is four year old information.

Thanks for the updated info. I had seen that FCC 07-39a doc but I did not read all the fine print about the application and equipment manufacture dates being moved out to 2011. I got hung up on attempting to understand where they are going with 6.25 kHz migration.

The uncertainty over ultimate migration to 6.25 kHz capable equipment is why I am reluctant to recommend rushing to purchase new equipment capable of 12.5 kHz bandwidth if it does not meet the final FCC 6.25 kHz objective.

Clearblock,

You may want to talk to your FCC frequency coordinator about the migration.

I know for a fact that I-Com has rolled out 12.5 / 6.25 conversion radios. Other manufacturers must surely follow to remain competitive.

I know some of my larger customers are starting to consider I-Com.

A bigger problem, however, could be the modification of licenses issues.
The license holder should not wait too long to modify their licenses from the 25KHz to the 12.5 KHz bandwidths, since there is no guarantee at or after the deadline/s that they will keep any or all adjacent frequencies, particularly in VFH bandwidths.

I am recommending to all my customers who are licensed on the 25KHz splits to start considering a combo of license modification and phasing out old 25KHz not switchable radios.

I agree that if you are in a situation where you need to procure new radios now for growth or replacement you should purchase 25/12.5 switchable equipment.

I also agree that if you need to do any license modification you should coordinate for both wide and narrow band emissions on each channel.

What I do not agree with is a rush to change anything solely due to a pending rule change 5 years in the future. Frequency coordination and licensing for narrow band now may assure you can keep a license for your frequency but not that it will be viable. With the FCC rejection of the AAR plan for exclusive RR frequency assignments, there is no assurance some coordinator will not assign other users on 7.5 kHz adjacent channels on each side of your channel with no geographical separation.

I know AAR is supposed to be able to review any assignments by other coordinators for RR VHF frequencies but they have no veto power. Any belief that the coordinators or the FCC will protect an incumbent from a poorly coordianted new assignment is a total joke as can be seen from the Nextel 800 MHz mess. In my area, there have been several licenses granted on RR VHF channels to a trunked private carrier system and various conventional general business users.

Frequency coordination in other services than RR is no assurance of anything. Coordinators are supposed to minimize interference but it often seems to be more of a random process than an engineering analysis.

In addition to the expense of frequency coordination and license modification, those of us with the misfortune to be near the Canadian border subject to "Line A" have another concern. You can have been on a frequency for 30 years and apply for a modification, such as bandwidth reduction, that will actually reduce possible interference to Canada and still have Canada veto your application under present interference protection criteria. In this case you can loose what you already have and be hit with ridiculous power and antenna restrictions. Railroads have a slight advantage in this area. If the assignment is in accordance with the AAR US-Canada frequency use plan it will usually not be held up by Canada.

You also need to remember that if you apply for new frequencies, FCC Rules require that you certify to the FCC that you have placed the new frequency in use within one year from the date the license was granted or you loose it.

You have many good points that need to be considered by licensees in planning for the future. Doing nothing until 2013 in the hope the problem will go away is not a wise move. My point is start planning now, keep up on developments in 6.25 kHz capable equipment and other trends in technology and be prepared to act based on an assesment of your future communications needs.