[K3PZN-List] New NBFM spacings & BW?

Thu Dec 2 12:49:04 EST 2010

So if 25KC bandwidth is =/- 5KC or Where we are now!
 and  12.5KC  bandwidth is +/- 2.5kc 
 than 6.25KC bandwidth is  +/- 1.75 Deviation. Or where they want to end up.
That isn't much talk power! But remember this would be digital, so your existing radio is still sending analog voice. Most newer commercial radio's are being sold with 12.5 KC bandwidth. Many are advertised to be 6.5KC capable. Many of the reduced modulation/bandwidth radio are actually using a Vocoder (A Device using a look up in a table to manually reproduce human voice) to give you the message! So if they (the FCC) want to convert the HAM to a lesser level of Modulation, say 12.5 than you could get by with just turning your deviation back. But to be able to go to the 6.25kc level you would really need the vocoder making your older radio's obsolete and unusable. 

-----Original Message-----
From: k3pzn-list-bounces at mailman.qth.net [mailto:k3pzn-list-bounces at mailman.qth.net] On Behalf Of Steve
Sent: Thursday, December 02, 2010 12:12 PM
To: k3pzn-list at mailman.qth.net
Subject: Re: [K3PZN-List] New NBFM spacings & BW?

Of course there's more to this than just turning down the deviation. Public safety and commercial  use digital modulation P25 variants to reduce the bandwidth. Phase II P25 is also in the works and it will reduce bw by half again (6.25KHz). Following this path means all new hardware for base and individual users. There are amateur P25 systems around though in major Motorola employer areas of the country.

73;
Steve
NY3A

Dec 2, 2010 11:46:11 AM, k3pzn-list at mailman.qth.net wrote:

I saw this article as well. Commercial and Public safety moving to 2.5KHz has been in the works for a long time. 

That doesn't have any bearing on amateur regs and I've seen nothing that would indicate a move to require 2.5KHz on amateur frequencies and such a rule would be a significant reversal for the FCC that has explicitly rejected regulation by bandwidth for amateur bands. 

As for the FRC 

Having 1st hand knowledge of that group from my time in FL as a repeater owner/trustee my personal take is that the 2.5KHz proposal originated from the Miami/Dade area where there is a large population center that has no available 2m (likely 70cm as well by now) pairs. This would allow the FRC to coordinate more repeaters in the heavy population centers where there has been a long waiting list. 

I don't think the cent and north FL FRC delegates would be inclined to support the proposal since they don't have the same pressure for pairs that south FL has and it would upset a lot of repeater owners. 

In addition unless you have a radio that can adjust the bandwidth in s/w once you hardware modify a user radio for 2.5KHz you won't be able to use a 5KHz machine effectively so now you've broken compatability between users and the some (if not most) of the repeaters in the area. I'd expect opposition from ARES/RACES on thses grounds - we've just taken the universal 2m radio that every ham has and is the most widely interoperable piece of equipment in the go-kit and made it much less useful. 

If it were adopted I would also expect an eventual revolt from many long established repeater owners. There isn't any requirement to have your repeater coordinated, and many would just continue to operate as-is which would then create a mess for anyone trying to coordinate a new 2.5KHz repeater. FRC couldn't just ignore a now uncordinated repeater that has been on the same freq same location for 25 years and coordinate someone new down the road - I don't think that would fly with the idea of the coordinator doing their job to prevent interference. 

Just my $0.02. 

Andy 

----- Original Message ----- 
From: "Philip Karras" 
To: "ccarc" 
Sent: Thursday, December 2, 2010 8:53:24 AM 
Subject: [K3PZN-List] New NBFM spacings & BW? 

Has anyone read/heard/know of this? 

I was sure I'd read about this in one of my magazines (print or online) but can't find it now, but if I remember correctly the FCC has mandated a closer channel spacing & narrower bandwidth on the NBFM presently used for business & public safety NBFM bands. 

Also in the article I read the Florida Ham Repeater Coordination Group was proposing the same kind of action by something like 2015? for all repeaters, I think they proposed a grand fathering in up to 2020 but after that no wider NBFM would be re-coordinated automatically & would have to give "good" reasons for wanting to stay at the +- 5 KHz BW & not move to the +-2.5 KHz proposed new BW.. 

Is this for real or did I dream this one up? 

tnx & 73 de ke3fl 
Phil 

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