Rebanding

Rebanding (also called Reconfiguration) refers to changes to the 800 MHz band plan that is taking place nationwide starting in 2006. Detailed information about rebanding can be found at http://www.800ta.org, but this page gives a brief overview and basic FAQ's.

History

When the 800 MHz band was originally created. Two segments of the spectrum were set aside for Cellular Telephone. Public Safety was assigned a set of frequencies, and "SMR" and "ESMR" services were allowed on the remainder of frequencies. However, unlike in other bands where licensee types were allocated to contiguous blocks of frequencies, in the 800 MHz band, Public safety, SMR, and ESMR services were allocated on adjacent frequencies. This has resulted over time in situations where relatively low-power public safety channels (typically 125 - 300 Watts) are adjacent to relatively high-power ESMR services (up to 3kW). When a 3kW channel is next to a 125 W channel in the same geographic area, it is almost impossible for the 125W channel to be free of interference.

In the late 1990's, the FCC realized that they had a problem. The number of interference complaints were rising, and the popularity of the ESMR services that were primarily blamed for the interference was also rising, with no end in sight. Something had to be done. The FCC solicited input from the various users groups to determine the best course of action. Over the course of many hearings, replies, counter-replies, and conferences, the FCC has issued a Report and Order directing the "rebanding" of the 800 MHz spectrum. The result of the rebanding will be a contiguous block of frequencies reserved for Public Safety and a separate contiguous block reserved for SMR/ESMR.

So, Where the Heck does Nextel come into this?

Nextel, contrary to popular belief, is not a cellular telephone company. They operate an "Extended (or Enhanced) Specialized Mobile Radio" service (ESMR). It does look like a cell phone, and it operates like a cell phone...but it really isn't. It is a business radio with telephone interconnect, and does not operate in the "cellular telephone" part of the 800 MHz spectrum.

As the largest licensee of ESMR channels, they are also responsible for the largest number of interference complaints to public safety.

What does Rebanding Actually Do?

Before rebanding, Public Safety and ESMR's both operate in the 851 - 861 MHz range. ESMR has exclusive use of the 861 - 866 MHz range, and Public Safety has exclusive use of the 866-869 MHz range.

After rebanding, Public Safety will have exclusive use of the 851 - 854 MHz range. ESMR's will have exclusive use of the 862 - 869 MHz range, and both public safety and low-power SMR's will share the 854 - 860 MHz spectrum.

This is shown graphically here:

Continued in the next section...

Why won't my scanner work after rebanding?

Well, depending on what you listen to, it might work. If you listen to EDACS or LTR (or conventional), you will just need to reprogram the new frequencies and logical channel numbers. However, if you listen to Motorola analog systems (which still comprise the largest number of public safety systems), your scanner will have a problem.

As part of the original spectrum allocation, each "slot" that public safety could operate on was assigned a channel number. Channels 1-120 were each 25 kHz apart, and started at 851 MHz.

Now, after rebanding, this part of the spectrum will have channels that are only 12.5 kHz apart.

Scanners track Motorola systems by monitoring the control channel. When the scanner detects a TGID that the user has programmed in, it gets from the control channel the channel assignment for the communications, then jumps to that frequency. At no time does the control channel actually pass the frequency information...just the FCC Channel assignment.

So, today if the scanner is told to go to Channel 66, it calculates the frequency as (851 + 66 * 25 kHz) and jumps. After rebanding, the scanner will perform this same calculation and jump to that same frequency. The problem is...since the channel spacing has changed (from 25 kHz to 12.5 kHz), the scanner will jump twice as far as it should and will miss the comms.

Even if you enter in all of the frequencies for the system, the scanner relies on the above calculation and will miss the comms.

How will I make my scanner work?

Well, now we get real fuzzy. Since no system has, at the time I'm writing this, been rebanded, no one knows what Motorola will do to their control channel. They could:

1. Just change their channelization and make no other changes to the data.

2. Use the control channel format used for P25 systems.

3. Use a completely new control channel format specifically for rebanded systems.

4. Something else...??

In all cases, the Uniden scanners that are expected to support rebanding will require a firmware update that the user will be able to apply themselves. It should be understood, though, that option 3 or 4 could require substantial analysis in order to determine the new format...not a 1 or 2 day job!

For RadioShack, it looks like only the scanners that allow for extended tables will operate, and then only if option 1 is used. If the change involves options 2-4, it looks like the only way the scanner will work is if RS sets up a board-exchange program to swap out the logic board with one that has the rebanded code installed.

FAQ

Well, the answers anyway.

1. This has nothing to do with 700 MHz.

2. This has nothing to do with cellular telephones.

3. No one knows anything for sure. Until a system is rebanded, anything you read that says "This is absolutely how it will be" is speculation (this article, included).

4. Please, someone add to this...I've got to go home. :*)