Question about Narrowbanding: Do I need to care about it?

[Redshirt]

Ignorant technician guy here: I'm seeing more and more narrowbanding notices on web pages for comm gear, and I wanted to get some feedback here as to whether it is something that I will ever run into as a problem.

My understanding is the NB is a set of rules requiring that radios use a 12.5khz "step" frequency efficiency. What precisely does this mean?

Will older radios be able to listen to these bands in the future? (aka, should I be worried about buying HAM gear used that might not work for listening to public safety/business comms anymore?)

Does this affect HAM users as well operating within the 150-512Mhz bands?

I hope I don't seem too silly worrying about these things. I'd have done more research myself, but I've been so swamped with studying I haven't had a chance to actually dig into it.

[KJ4VOV]

Does not apply to amateur radio bands.

[Redshirt]

Ok, that is what I thought, but I figured asking and making certain was a good plan.

[ImfromtheGovt]

It only applies to Business Communication bands as far as I know, and even some Public Safety bands are exempt from the rebanding requirements. What it does mean, though, is that a whole lot of used quality gear should be turning up on eBay and other sites for pretty decent prices... gear that can be easily reprogrammed to work on the amateur bands.

[Commo141]

NTIA is requiring it as of last year.

[zommoz10]

My understanding is the NB is a set of rules requiring that radios use a 12.5khz "step" frequency efficiency. What precisely does this mean?

+++ When a signal takes up 12.5kHz of bandwidth instead of say 25 kHz, you can squeeze more signals into the band without them interfering with one another.

At least that's the theory. I just had a new *very busy* EMS system show up on a splinter frequency that is bleeding over on to one of the business frequencies that my business is licensed to operate on. I don't know WTF they were thinking but poorly coordinated to say the least and I'm wondering if their repeater is programmed for wideband.

Will older radios be able to listen to these bands in the future? (aka, should I be worried about buying HAM gear used that might not work for listening to public safety/business comms anymore?)

+++
Maybe not. It depends on the frequencies and if the frequencies change or are new systems are added. You'll still be able to hear the narrowband signals if the radio will accept direct entry of their frequencies or will land on it during a scan. Although if you can't adjust the steps and you go to enter something like 154.2575 and instead it pops over to 154.265, then you might have a problem. Chances are you have been hearing narrowband signals for years anyway although most of the narrowband commercial radios nowadays have built in audio companders to improve the audio so it sounds as good as it would have before the reduced bandwidth. You're not going to have that.

Although as for using your ham gear to monitor public safety and businesses, your days of being able to monitor that are numbered anyway as public safety has mandates of it's own and more of them are transitioning to digital systems. Businesses often get oversold radio systems and many of them are going to digital systems also. Some of them you can monitor with a digital scanner or digital tranceiver and some of them you can't.

Does this affect HAM users as well operating within the 150-512Mhz bands?

+++The mandate does not.

[TacAir]

"I just had a new *very busy* EMS system show up on a splinter frequency that is bleeding over on to one of the business frequencies that my business is licensed to operate on. I don't know WTF they were thinking but poorly coordinated to say the least and I'm wondering if their repeater is programmed for wideband."

DO you use a repeater?

Can you hear the new signal if the antenna is off of your receiver?

Do you hear the signal all the time? That is to say, do you get multiple, full length transmissions? Or just bits and pieces of transmissions?

Have you contacted the repeater owner? Always better then going to the FCC right off.

Lastly, do you have access to a good spectrum analyzer?

I had co-channel interference on a system I 'owned' a while back - the solution was...interesting.

[Redshirt]

Zommoz10 and Imfromthegovt, thank you for the insights and more in depth explanations!

[nacho]

A little bit more on the NB topic.

Back in the go-go 90's FM radio systems by and large operated at 5KHz deviation or a 25k bandwidth (business, public safety, amateur radio, etc) until "we ran out of spectrum", so the FCC decided we should all cut our deviation in half to ease the congestion. By 2013 everything* under part 90 operation (business, public safety, govt) that operates from 136 - 470 MHz must operate at a deviation of no more then 2.5k (12.5k bandwidth) This is what is commonly called "Narrow Band". The NTIA frequencies (federal government) has been operating NB for several years. Amateur Radio as well as CB / GMRS is not regulated under part 90, and is thus not required to narrow band. Recently the "T-band" (470-520MHz) got a temporary exemption while congress pulls it's head out of it's ass, but that's another issue...

The FCC mandate, DOES NOT require public safety to "go digital" although many agencies took advantage of federal grant money and decided to go digital when they bought new narrow band equipment.

Another huge misconception with narrow banding regards channel spacing. Back in the good old days radios operated on multiples of 12.5k or 5k channel steps, this has nothing to do with a 12.5k bandwidth, so pay attention and don't get all confused like 90% of the people out there.

In California for years we have used 3 frequencies for Mutual Aid

154.2650
154.2800
154.2950

You will notice these frequencies are spaced .015Mhz or 15KHz apart. The FCC has decided since we are going to be operating narrow band why not add "interstitial" frequencies in between these older ones, so now where there were three channels their can now be six!

So now we now have...

154.2650
154.2725
154.2800
154.2875
154.2950
154.3025

Most older radios and amateur radios will only operate in 30/25/15/12.5/5KHz channel spaces. You will notice that the first and third italicized frequencies is not divisible by 12.5KHz or 5KHz. (154272.5/12.5=12341.8) so many old radios that are part 90 approved, and will do the 12.5k Narrow Band will not be able to accept these new frequencies. Only commercial radios and scanners built in the past decade or so will do 6.75/2.5KHz channel spacing, so as the FCC and NTIA assign more and more new frequencies you will have issues using older radios on these new frequencies.

So I know you are asking yourself, What the Hell does this have to do with me?

If you are planning on using an old scanner or a ham radio to listen to public safety traffic, not only are you going to have low volume issues, and possibly issues with interstitial frequencies, you will also not be able to monitor the new frequencies.

IE, I tested my FT-60R and when I punch in 154.2725 it rounds down to 154.2700