Wide/Narrow Band Questions

dbfd588 · Post by **dbfd588** » Tue Apr 10, 2007 2:35 pm

Im not sure what narrow band is. Im sure that we dont use it. So Im setting my radio up for wideband. Im not sure what to go with. I have a choice of 20k and 25k. What that difference?

Jim2121 · Post by **Jim2121** » Tue Apr 10, 2007 3:01 pm

what kind of service is this for? ie: public service, PD, FD, ect... and, what type of radio do you have? any other info would help....
city? state?
________________________________________________
do a search for narrow band above, covers lots of issues

dbfd588 · Post by **dbfd588** » Tue Apr 10, 2007 3:19 pm

Its a county fire dept. VHF. We are in the 150-160 range. We use a variety of brands: Motorola, Kenwood, Vertex, Relm, etc.

Here is our REPEATOR setup:
TX 159.015
RX 154.190
PL 151.4

Mobiles usually around 45-50 watts
And we use alot of 5 watt portables

HLA · Post by **HLA** » Tue Apr 10, 2007 3:54 pm

it looks like it's wideband so just leave the spacing set at 25

spock7230 · Post by **spock7230** » Tue Apr 10, 2007 3:58 pm

It's my understanding that wide/narrow banding refers more to the allowed signal deviation from the assigned frequenc(y/ies). Wide band is allowed +/- 5 kHz on either side of the base frequency and narrow +/- 2.5 kHz.

It's also my understanding that any new licenses are required to be narrow band. My question (on-topic) is how to tell if a license is wide or narrow on the FCC info on-line? The two jobs I work have both had their frequencies for a number of years, so do we have to keep the wide band settings, or do we switch to the narrow? (EMS)

dbfd588 - in reference to your question, I think you're asking about channel spacing, which is different. I think you need to stick with 25kHz, unless you have the option for 12.5k

AEC · Post by **AEC** » Tue Apr 10, 2007 4:00 pm

Narrowband in 'today's' world, means channel spacing that operates in 6.25 Khz. 'slots', unlike older radios using 12.5 Khz or wider.

For narrowband, your frequency would look like this on a counter:

155.10625

For 12.5 Khz systems, it would look like this: 155.1250

You can effectively place more radios into service utilizing narrowband channel spacing than with anything wider in nature, but the radios must be capable of rejecting adjacent channel interference from wide band noises, such as other systems using not only 12.5, but 10, 20, 25 and wider channel spacings based on frequency usage in your geographical area.

The proper filtering in the receivers also makes this a great difference as well, and makes possible a narrower 'split' worthy of considering.

If your agency is not set up to use narrowband channel spacing, and their frequencies are based on the standard 12.5 Khz. spacing, then make sure your equipment is configured to match your agency's system, or you may miss more than you bargained for, especially in fringe areas of operation.

n1das · Post by **n1das** » Tue Apr 10, 2007 5:20 pm

"wide" = 5kHz max deviation with 3kHz max modulation frequency --> 16kHz bandwidth. The emission designator is 16k0f3e.

Some older "wide" bandwidth systems used 5kHz max deviation with 5kHz max modulation frequency and occupied 20kHz of spectrum --> 20k0f3e emission desginator.

Channels in the UHF band are often spaced 25kHz apart, hence the "25kHz" channel naming. Narrowbanding cut the bandwidth down and reduced the channel spacing to 12.5kHz. Future narrowbanding will operate on 6.25kHz spaced channels.

On VHF, the spacing used to be 30kHz many years ago but was later cut in half to 15kHz. Narrowband now cuts the VHF spacing in half again, to 7.5kHz.

On the 2m ham band, early repeater splits were spaced 30kHz apart and the spacing was later cut in half to 15kHz, like the rest of the VHF band. (Example: 146.73, 146.76, 146.79, etc. then later spaced as 146.715, 146.73, 146.745, 146.76, 146.775, 146.79, etc.) The lower half of the 2m band used 20kHz spacing to help aleviate adjacent channel interference problems caused by the 15kHz spacing while signals were still occupying 16kHz of spectrum. It looks like the ham bands could also benefit from being more spectrum-efficient.

"narrow" = 2.5kHz max deviation with 3.125kHz max modulation frequency --> 11.25kHz bandwidth. The emission designator is 11k0f3e. This will fit in 12.5kHz-spaced channels, hence the "12.5kHz" channel naming.

Future narrowbanding will operate with narrower bandwitdh and operate on 6.25kHz spaced channels.

The repeater channels you list appear to be standard "wide" (16k0f3e) channels, so set "25kHz" mode. Note the "25kHz" and "12.5kHz" names for wide and narrow bandwitdth channels are actually misnomers. They refer to the channel spacing in the band and NOT the actual bandwidth. Bottom line is 25kHz spaced channel = "wide" (16k0f3e) and 12.5kHz spaced channel = "narrow" (11k0f3e).

Also double check the FCC license for the repeater to be absolutely sure of the bandwidth authorized. Narrow mode operation is possible on channels having the "old" spacing in the band, so the frequencies listed can be misleading although they look like older "wide" channels. Look at the emission designator (11k0f3e or 16k0f3e) on the license to be absolutely sure. 16k0f3e or 20k0f3e = "wide", 11k0f3e or narrower = "narrow".

Good luck.

n1das · Post by **n1das** » Tue Apr 10, 2007 5:41 pm

spock7230 wrote:It's my understanding that wide/narrow banding refers more to the allowed signal deviation from the assigned frequenc(y/ies). Wide band is allowed +/- 5 kHz on either side of the base frequency and narrow +/- 2.5 kHz.

It's also my understanding that any new licenses are required to be narrow band. My question (on-topic) is how to tell if a license is wide or narrow on the FCC info on-line? The two jobs I work have both had their frequencies for a number of years, so do we have to keep the wide band settings, or do we switch to the narrow? (EMS)

dbfd588 - in reference to your question, I think you're asking about channel spacing, which is different. I think you need to stick with 25kHz, unless you have the option for 12.5k

The emission designator on the FCC license describes EVERYTHING about the type of modulation and bandwidth. The format of the emission designator has been internationally agreed upon. It may seem kind of cryptic but there IS an order to it all.

16K0F3E --> "wide" (16kHz of spectrum occupied)
11K0F3E --> "narrow" (11.25kHz of spectrum occupied)

These are probably the two most common ones you'll find for plain old "wide" and "narrow" FM voice systems.

I forget exactly how to decode the emission designator and don't have any info handy (I'm at work right now). The first two digits before "K" refer to the bandwidth in kHz. "K0" I think refers to the carrier being continuous for the duration of a transmission and "F3E" refers to FM voice modulation. Hopefully fellow Batlabbers who are more familiar with the emission designators will chime in.

The emission designator tells all!

dbfd588 · Post by **dbfd588** » Tue Apr 10, 2007 7:12 pm

OK. Thanks guys. Im starting to understand it now. We have had our frequencies for many years now, so Im gonna go with 25k. I just checked on the FCC site. It said 20k

n1das · Post by **n1das** » Tue Apr 10, 2007 7:42 pm

dbfd588 wrote:OK. Thanks guys. Im starting to understand it now. We have had our frequencies for many years now, so Im gonna go with 25k. I just checked on the FCC site. It said 20k

That's probably 20k0f3e in the emission designator.

The best choice to go with in the radios is 25kHz spacing (16k0f3e bandwidth).

Good luck.

Wes · Post by **Wes** » Tue Apr 10, 2007 9:44 pm

Anybody remember what the deadlines are for everybody to be switched over to narrowband? I was thinking it is 2013 for buisness band and 2015 for public safety.

Wes

libuff · Post by **libuff** » Wed Apr 11, 2007 9:57 am

n1das wrote: "F3E" refers to FM voice modulation.

What is the modulation "code" for p25? or even hybrid systems?

spock7230 · Post by **spock7230** » Wed Apr 11, 2007 11:53 am

libuff wrote:
n1das wrote: "F3E" refers to FM voice modulation.
What is the modulation "code" for p25? or even hybrid systems?

After a PM to n1das, I googled for the emissions designators. The best info I found was at APCO International's site on this page. Scroll down to the bottom of the page and there are some examples. Still not a lot of info, but all I've found so far...

dbfd588 · Post by **dbfd588** » Wed Apr 11, 2007 3:54 pm

OK folks. Here is what it says on our emission page. 20K0F3E . Im assuming I go with 20k. Am I wrong. Whats the differnce in 20k and 25k. My software ask me for (WIDE BAND TYPE) and gives me a choice of 20k and 25k. Help me please. I dont wanna go with 25k if we are not licensed for it.

Will · Post by **Will** » Wed Apr 11, 2007 5:00 pm

dbfd588 wrote:OK folks. Here is what it says on our emission page. 20K0F3E . Im assuming I go with 20k. Am I wrong. Whats the differnce in 20k and 25k. My software ask me for (WIDE BAND TYPE) and gives me a choice of 20k and 25k. Help me please. I dont wanna go with 25k if we are not licensed for it.

20K0F3E would be the 25K setting.

dbfd588 · Post by **dbfd588** » Wed Apr 11, 2007 5:19 pm

Awesome. Thats exactly what I wanted to know. Thanks for clearing that up.

libuff · Post by **libuff** » Wed Apr 11, 2007 6:34 pm

then what is the 20k setting on the CDM's for??? i've seen some hammies use it, but im pretty sure they live in the 25k spacing world too... someone do tell...

mr.syntrx · Post by **mr.syntrx** » Wed Apr 11, 2007 9:30 pm

20KHz channels are used in some (if not most) parts of Europe, with 4KHz deviation, IIRC. They use the Waris platform there too, albeit with different model numbers and features (Select V, MPT-1327 etc.)