NARROWBAND 150-512 MHz deadline

FCC establishes January 1, 2013 deadline for migration to 12.5 KHz technology.

http://apcointl.org/frequency/documents/NarrowbandOrder.htm

How does this effect our older scanners? Can someone explain the "steps" when refering to spacing as noted here:

http://support.radioshack.com/support_electronics/doc59/59447.html

Will my Pro-75 still work after this FCC change?

Thanks!!

Both of your links seem to be dead.

Hmm, something the board did to the links... lets try:

apcointl.org/frequency/documents/NarrowbandOrder.html

support.radioshack.com/support_electronics/doc59/59447.htm

You will have to copy and paste them.

http://apcointl.org/frequency/documents/NarrowbandOrder.html

http://support.radioshack.com/support_electronics/doc59/59447.htm

Linkified...

http://apcointl.org/frequency/documents/NarrowbandOrder.html

http://support.radioshack.com/support_electronics/doc59/59447.htm

Linkified...

And yes, that fateful day in 2013 when everything switches to the 12.5 kHz spacing or some time before it would mean that scanner you have is simply useless for monitoring that particular frequency chunk between roughly 148 MHz and 174 MHz. Your scanner already receives frequencies from 380 to 512 MHz with the "proper" 12.5 kHz spacing (the UHF band, basically), but the VHF band (VHF-Hi) would go quiet except for some off-frequency stuff you might pick up. Some frequencies would still be picked up as long as they matched precisely - meaning at 5 kHz spacing, you could pick up every even multiple of 12.5 x 2 = 25 kHz, so that's a huge gap of lost coverage.

That last part can be even more confusing so I'll break it down a bit. Right now your scanner can tune things like the following set of frequencies in sequence:

155.0000
155.0050
155.0100
155.0150
155.0200
155.0250

Those are channels spaced .005 MHz = 5 kHz apart, which is the standard for a while yet. Everyone has till that day in 2013 to make the change to the 12.5 kHz spacing as defined in that FCC order. Now, when a scanner with 12.5 kHz spacing starts scanning at 155.0000 MHz and goes up in frequency, the jumps look like this:

155.0000
155.0125
155.0250
155.0375
155.0500
155.0625

I'm sitting here looking at the decimal points there and praying I'm getting this right, just one of those moments where I'm leery of posting this for fear I'll be wrong, but I'm pretty sure I'm right.

Anyway, as you can see, because of the larger spacing between the frequencies, your scanner will "get lucky" about every other frequency: your Pro-75 can pick up the 155.0000, and it could pick up the 155.025, and even the 155.0500 there, but the other frequencies would either be totally silent to your radio or you might get some signal bleed depending on how sensitive it is to off-channel reception.

Soooo... while you've got nothing to worry about right now, in a few years you might find yourself with a scanner that is just a bit more quiet than it used to be simply because it can't pick up the broadcasts anymore for that reason.

Hope I got this right, if not I'm sure someone will pounce on me for it.

OK, that makes sense, especially after I tried to enter the bottom set of freq's you listed into my Pro-75 - 155.0625 becomes 155.060.

But I guess I am still confused....

The page says this:
Q – Will we need to change frequencies?
A – No. You merely reduce the bandwidth of the channel(s) you are now using.

So if I monitor 155.5200 now what will happen? Will they be 155.500?
How about 154.7850? Will it become 154.75?

If so, then how is this not a change in frequencies? What is "reduce the bandwidth"?

So if the stuff I monitor will be forced to switch to Narrow Band I can still scan them. For instance... at a step of 12.5 MHz you would have this:

155
155.125
155.25
155.375
155.5
155.625
155.75
155.875

All of which my scanner will take now....

That information is for companies that use transmitters - they are being required by FCC order to change or upgrade their hardware to equipment that satisfies the new bandplan of 12.5 kHz channel spacing. That entire FCC document has no bearing on you as a listener with a scanner other than to let you know in a roundabout way that in the coming years that scanner you have might not pick up anything on specific frequencies, that's about all.

And you're off by one decimal place with those frequencies. They should look like this:

155.000 <<<--- You can pick this up
155.0125
155.025 <<<--- You can pick this up
155.0375
155.050 <<<--- You can pick this up
155.0625
155.075 <<<--- You can pick this up
155.0875

5 kHz spacing is represented by 3 decimal places, like .005 .010 .015 .020 .025, etc. 12.5 kHz spacing is more accurately represented by 4, like .0125 .0250 .0375 .0500, etc. So you will be able to monitor every other frequency on that 12.5 kHz bandplan, basically, because every other frequency falls on a multiple of 5 kHz (.005).

Hope that helps...

So these are not valid freqs?

155
155.125
155.25
155.375
155.5
155.625
155.75
155.875

I guess I am in over my head here because I am not getting it...

So the question I still have is.... Will my local PD on 155.5200 need to change anything?

fredg said:

So these are not valid freqs?

155
155.125
155.25
155.375
155.5
155.625
155.75
155.875

I guess I am in over my head here because I am not getting it...

So the question I still have is.... Will my local PD on 155.5200 need to change anything?

Click to expand...

People continue to confuse the issue.

EVERYONE must go to 12.5 kHz bandwidth.
Most will stay on their current channel assignment.
When everyone goes to 12.5 kHx ther will be some new channels made available on new channel assignments between teh old assignments.
Some of thse "new" center frequencies are already used at 12.5 kHz or even at 25 kHz.

Bandwith and channel spacing are independant issues.

(Disclaimer: the following numbers and discussion are simplified to illustrate a concept. To use more exact numbers would be speculative as far as what your PD is really doing, not to mention confusing.)

First off, radio communications are not conducted on exactly the frequency discussed -- there is necessarily an overlap with adjacent frequencies. If you PD uses 155.520, really they occupy approximately 155.515 to 155.525 every time they transmit. To hear them properly you tune to the center frequency of 155.520. In this example, the bandwidth would be 0.010 MHz or 10 kHz.

Because technology now permits it and there is demand for new channels, the FCC is directing everyone to use fewer of the adjacent frequencies. So instead of 155.515-155.525, your PD will now use 155.5175-155.5225, for a bandwidth of 5 kHz. Still centered on 155.520.

Let's pretend that someone else near you already uses 155.505, which, using the older channel spacing, would have been the lower adjacent channel available for licensing. Once everyone narrowbands their operations, suddenly there is space for someone a few towns over to use 155.5125 (halfway between 155.505 & 155.520). Subject to proximity issues, you just doubled the number of channels in the affected portion of the band.

What does this mean to you and your Pro-75? It means that you might receive your local PD on 155.520 with slightly diminished quality or strength, since your scanner is set up for the old bandwidth and the PD is using less than that. And by slightly, I mean you may not even notice a difference unless your reception was already marginal.

As far as the new channels, I'll bet you can receive them pretty well. Let's use 155.5125 as an example: this user would actually be occupying 155.5100-155.5150 (5 kHz bandwidth). If you program in 155.5100 in your scanner then your scanner will be listening to 155.5050-155.5150. See the overlap? Reception won't be as strong since you're not tuned to the center of the channel, and even strong signals may sound a little scratchy because the audio is off-center, but it will probably be good enough to put off upgrading scanners for a bit longer.

As to your previous question about valid freqs (really, channels), you've got the decimal place in the wrong spot. Following is a table of the old (left column) and new (both columns) channels:
155.0100 155.0175
155.0250 155.0325
155.0400 155.0475
155.0550 155.0625
155.0700 155.0775
155.0850 155.0925
155.1000 155.1075
155.1150 155.1225
155.1300 155.1375
...

Jim

OK, I think a glimmer of understanding is coming on!

I am still not clear on the last part but I will let that go!

Oh boy, here we go with the misinformation again. "Splinter channels" are nothing new, they've been around far longer than NFM capable scanners, about 1985 or so. With that in mind you'll have no trouble receiving them whatsoever.

Here's how, just program the frequency in and let the scanner barf up or down to the closest standard channel, it will round off the last two decimal places. If it just barfs do it yourself and enter the nearest standard third decimal.

N_Jay as usual has it backward, bandwidth and channel spacing go hand in glove. Half the bandwidth, half the spacing only makes common sense. That's exactly how those four figure channels were splintered off the standard assignments and put in between them in the first place.

N_Jay, maybe one of these days you'll understand the difference between channel spacing and frequency step so let me put you on the path. Think "frequency divider (counter) chip" and you've taken that first step toward learning how a PLL frequency synthesizer works.

I wish you WOULD gently apply common sense before you make such wildly misleading statements and confuse people!

Owners of the scanners such as BCD396T won't have to worry, correct???

With that in mind you'll have no trouble receiving them whatsoever.

DOH!!!!!!!