2.5Khz/narrowband rx programming?

[jparks29]

Anyone know what amateur HTs support NB/2.5Khz channel spacing?

vx5?vx6?vx7? etc etc

[gewecke]

Not sure about others but the vx-5 does not support the 6.25khz. steps but does support 2.5khz.deviation.
N9ZAS

[jparks29]

anyone got any more info?

No even the VX-8 is supporting 2.5/7.5 steps..... Is there none out there>??

[DaveNF2G]

Where would you need 2.5 kHz steps?

Narrowband (what would be called "supernarrowband" under pre-narrowbanding nomenclature) is done at 7.5 kHz spacing on VHF and 6.25 kHz spacing on UHF.

As noted by gewecke, 2.5 kHz is the specification for bandwidth of the signal, not distance between carrier center frequencies.

BTW, the VX-7 does tune in 7.5 kHz steps, but uses only one bandplan for 2m and the rest of its VHF receive coverage. This means that, outside the ham band, you can't tune VHF narrowband frequencies correctly in most band segments. For the 6.25 kHz spacing on UHF, this is not an issue with that radio because there is only one FCC bandplan for everything above 420 MHz.

[gewecke]

Originally Posted by DaveNF2G

Where would you need 2.5 kHz steps?

Narrowband (what would be called "supernarrowband" under pre-narrowbanding nomenclature) is done at 7.5 kHz spacing on VHF and 6.25 kHz spacing on UHF.

As noted by gewecke, 2.5 kHz is the specification for bandwidth of the signal, not distance between carrier center frequencies.

BTW, the VX-7 does tune in 7.5 kHz steps, but uses only one bandplan for 2m and the rest of its VHF receive coverage. This means that, outside the ham band, you can't tune VHF narrowband frequencies correctly in most band segments. For the 6.25 kHz spacing on UHF, this is not an issue with that radio because there is only one FCC bandplan for everything above 420 MHz.

He might be talking about when the industry standard will change for commercial fm in 2013 to 6.25khz. channel spacing for BOTH vhf and uhf. There is already equipment on the market for this but it's commercial fm.
N9ZAS

[nd5y]

Originally Posted by DaveNF2G

Where would you need 2.5 kHz steps?

2.5 kHz is the specification for bandwidth of the signal, not distance between carrier center frequencies.

Don't confuse deviation and bandwidth. Let me clear some of this up.

In the private land mobile radio world, radios are specified as having:
2.5 kHz deviation = 12.5 kHz bandwidth = narrowband
5 kHz deviation = 25 kHz bandwidth = wideband

In the scanner world:
2.5 kHz deviation = 12.5 kHz bandwidth = FMN or NFM = narrowband
5 kHz deviation = 25 kHz bandwidth = FM
75 kHz deviation = 200 kHz bandwidth = WFM or FMW = wideband (FM and TV broadcasting)

All Part 90 certified VHF high band land mobile radios made recently have 2.5 kHz tuning steps so that they can operate on the 7.5 kHz spaced channels used on VHF High Band in the USA. The FCC channel allocations are spaced 7.5 kHz apart, but there are some gaps and you can't use 7.5 kHz tuning steps from one end of the band to the other.

Most FM only VHF/UHF ham gear made for the USA market won't do less than 5 kHz tuning steps because it isn't needed.
Almost nobody uses 2.5 kHz deviation on ham radio in the USA.
In Europe they do, because the 2m band only goes from 144-146 MHz and the repeater channels are spaced at 12.5 kHz apart.

Some ham rigs will transmit 2.5 kHz deviation but don't have narrow receive filters. My FT-7800R and VX-6R are like that.

You can still listen to NFM stations on 7.5 kHz channels with the average VHF/UHF FM ham rig with 5 kHz tuning steps because they have 25-30 kHz wide receive bandwidth. The filters in the receiver are so wide that you won't notice being 2.5 kHz off frequency.

There was a thread about this a while back. Somebody pointed out that at least one relatively new FM ham rig tunes in 2.5 kHz steps. I don't remember what radio it was.

If you want a radio that does 2.5 kHz steps, you need to download the owners manuals from the manufacturers' web sites and check the specifications.

[gewecke]

Right what tom said. A couple exceptions to this would be the frs radio channels which are supposed to be 2.5khz. deviation. Also the MURS channels would be the other exception.
Some ham repeaters have been known to "clip" the audio a bit if 4-5khz.dev. is used so that may be the reason some of the newer ham rigs include a menu option to switch the tranmitted audio to 2.5khz. deviation.
Just a little FYI here.
N9ZAS

[DaveNF2G]

Originally Posted by nd5y

Don't confuse deviation and bandwidth.

You are absolutely right. I was thinking of the correct concept and typed the wrong word. Mea culpa.

[Wyandotte]

With my Icom V8, I can select wide or narrow transmit. Does this mean I'm selecting between 5Kc wide and 2.5Kc wide? Not sure. There is one ham repeater (that I know of) in Metro Detroit that is 2.5 kc.
So find the specs for the Icom V8, it may be what you are looking for. Seems like I had a dual bsnd Icom mobile that would select wide or narrow also. You may want to take a look at the different Icoms.

[N1BHH]

Originally Posted by Wyandotte

With my Icom V8, I can select wide or narrow transmit. Does this mean I'm selecting between 5Kc wide and 2.5Kc wide? Not sure. There is one ham repeater (that I know of) in Metro Detroit that is 2.5 kc.
So find the specs for the Icom V8, it may be what you are looking for. Seems like I had a dual bsnd Icom mobile that would select wide or narrow also. You may want to take a look at the different Icoms.

Again as stated by a previous poster, don't confuse deviation with channel steps. Your radio does 5 kilohertz steps but is capable of narrow band deviation voice transmission. When discussing this topic the use of the term narrow band gets tossed around without the addition of a proper explanation of the term. Narrow band should have the word deviation attached to it. Narrow band deviation and frequency steps are two different puppies.

[W9RXR]

Originally Posted by nd5y

In the private land mobile radio world, radios are specified as having:
2.5 kHz deviation = 12.5 kHz bandwidth = narrowband
5 kHz deviation = 25 kHz bandwidth = wideband

Actually, you are trying to relate deviation to channel spacing, not bandwidth.

According to Carson's Rule, FM bandwidth is equal to two times the deviation plus the modulation frequency. In two-way communications, the highest modulation frequency is generally accepted to be 3000 Hz.

So, for 2.5kHz deviation:

BW = 2 ( 2.5kHz + 3kHz) = 11kHz

And, for 5kHz deviation:

BW = 2 (5kHz + 3kHz) = 16kHz

If you look at the specifications for land mobile (Part 90) radios, these theoretical bandwidths appear in the transmitter emission type. You'll see 11K0F3E for "narrowband" and 16K0F3E for "wideband". The first four characters of the emission type is the bandwidth.

Bandwidth is a specification for the signal that the radio transmits. Channel spacing is an arbitrary number based on bandwidth that spectrum managers and frequency coordinators use to assign channels. They are not the same thing. You can have an 11K0F3E signal on 25kHz channel spacing. However, 16K0F3E signals on 12.5kHz channel spacing would result in some adjacent channel overlap and interference.