FM, Wide or Narrow

[rohare]

Hello all. This is my first post here and I just wanted to clear up a couple of simple (I think...) technical questions. I set up a chirp image for emergency communications frequencies and of course noticed that a lot of them are designated as narrow FM while a few are designated wide FM. I understand the difference between the two, but wanted some guidance when selecting a frequency where the available data doesn't specify one or the other. Let's say I want one of the memories to tune to a local repeater in the amateur radio band but there is no information on whether it's wide or narrow. Which is better to choose? If I am listening "narrow" but the signal is wide will I run into trouble? Or vice versa? And what about if I want to set up a memory that is not in the amateur band? Is is more likely to be wide or narrow? Thanks much!

 

[WA0CBW]

As of January 1, 2013 part 90 licenses and radios were changed to narrow band. There are a couple of exeptions. The change only affects part 90 VHF and UHF users with the exception of the UHF "T" band (470-512 Mhz). The change reduces the bandwidth from 25Khz to 12.5Khz. The FCC has granted some waivers that extended the date to convert but for the most part everyone should have changed to narrow band on January 1, 2013. Unfortunately there are some users that haven't heard of the required change or are hoping the FCC doesn't catch them. A narrow band signal only has 2.5Khz deviation so the audio is lower when received on a wide band receiver. A wide band signal has 5Khz deviation and will sound loud and distorted on a narrow band receiver. There is some debate as to the effectiveness of changing a scanners bandwidth to narrow. Some scanners do not have the narrow filters and have chosen something that will receive both wide and narrow equally poor.
BB

 

[rohare]

So, if I understand this correctly, I should assume that any frequency between 150 MHz and 512 MHz is narrow unless otherwise specified and that frequencies outside of that range (like 140-149Mhz and 513-520 MHz) will be wide unless otherwise specified. Using this rule of thumb I should be right most of the time. Does that make sense?

 

[WA0CBW]

You can go to the FCC Web site for the exact frequencies and the wording of the rule as it pertains to part 90 radios but for the most part you would be correct.
BB

 

[ecps92]

470-512 aka T-Band was Exempted at the last minute
However some agencies did NB as it was funded and they had 450/460 freqs in the radios so they had to touch them anyway... YMMV as to who has done it for T-Band

So, if I understand this correctly, I should assume that any frequency between 150 MHz and 512 MHz is narrow unless otherwise specified and that frequencies outside of that range (like 140-149Mhz and 513-520 MHz) will be wide unless otherwise specified. Using this rule of thumb I should be right most of the time. Does that make sense?

 

[rohare]

Oh, I just realized. Isn't amateur radio in FCC part 97. That means amateur radio frequencies are not required to be narrowband. Is it common or uncommon for amateur radio operators to use narrowband?

 

[cabletech]

As most ham equipment was never designed for narrow mode, you will find that hams use wide band.

 

[zz0468]

Oh, I just realized. Isn't amateur radio in FCC part 97. That means amateur radio frequencies are not required to be narrowband.

Correct.

Is it common or uncommon for amateur radio operators to use narrowband?

It's uncommon. One notable exception is 900 MHz, because the vast majority of radios used on that band are commercial radios, which are narrow band.

Most amateur grade radios that do "narrow band" are ONLY reducing the deviation of the transmitter, and don't change the receiver IF filter bandwidth like a commercial radio would.

 

[nd5y]

As most ham equipment was never designed for narrow mode, you will find that hams use wide band.

Somebody forgot to tell that to Kenwwod, Icom, Yaesu and Alinco.
The 2 meter band in Europe has been narrowband with standardized 12.5 kHz channel spacing for decades.

 

[zz0468]

The 2 meter band in Europe has been narrowband with standardized 12.5 kHz channel spacing for decades.

The channel spacing and the occupied bandwidth are two different things. I've seen European versions of various amateur radios, and will agree that the band edges and step sizes can be different than what's used here. But the radios I've seen were all 5 KHz deviation TX, with a corresponding wide band IF on the receiver.

 

[Darth_vader]

So if I was to blind-search any of the narrowbanded part-90 spectra, what would be the best step length to set my rig for; 2.5, 5, 6.25 or 12.5 kHz?

A radio-geek coworker insists 12.5 especially on 400 MHz, I say 6.25 on all. We actually have lunch riding on this.