Narrow Banding

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800mhz

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I read that by Jan 2013 all Public Safety must be narrow banded. I have not seen anything about our local fire departments. I was woundering about Anne Arundel County and Baltimore City, 154.010 Disp and 154.415 Disp. The only county I have seen that has rebanded their Simulcast channel has been Queen Annes County. Does anyone know whats going on.
 

ka3jjz

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Not only those, but AA, Howard, Montgomery and PG counties all have VHF fire dispatch, and Harford is, I think, UHF. And we have the DNR (which is, if memory serves, not all narrow band yet) and MSP as well.

Very important question...Mike
 

W2NJS

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The frequencies you list are probably "legacy" channels that the departments keep in use for the convenience of casual listeners, like the scanner in your mother's kitchen, and are not the primary dispatch channel for the departments. Even so, if they are now wideband they will have be narrowbanded by January 2013, as they are Part 90 FCC licensed, if the departments choose to keep them in use.

If you do a search on this board under "narrowbanding" you will find literally hundreds of posts regarding this subject.
 

800mhz

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AACO I would think would have to. Their using 154.010 for fire paging. The City I was told uses the 154.415 as a back up. It will be interesting to see what and when it happens.
 

ka3jjz

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Not all of these freqs are 'legacy' channels - PG county just moved to this frequency after many years, and at least some of the DNR's radio setup is a year or two old (having absorbed older VHF channels from other jurisdictions that moved from VHF to 800 - Howard county for example).

To anticipate the unasked question - if your scanner is an older one that can't tune the new offsets, as long as the signal is strong, the only thing you'll likely notice is that the audio is softer (on VHF, anyway- UHF is going to be a problem). If the signal is weak, you may not be able to hear it. For the newer scanners, a bit of reprogramming will be needed...Mike

[edit] Here is our wiki article on narrowbanding - and note that we're not talking about rebanding here...

Narrowbanding- the RR Wiki
 
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dpcain

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Can't speak for the fire departments, but I know us at UMBC are waiting for the FiRST system to come online- the plan is to buy 700P25 radios for that rather than replace our ancient boxload of HT1000s, which aren't 7.5kHz capable.
 
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dpm797

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in Anne Arundel Fire, yes 154.010 will be narrow-banded in late spring early summer. It will still be 154.0100, but with the transmission emission as dead on center as possible but with no bleed over. going from 25 khz spacing to 12.5 khz spacing on the emission. the audio may be "softer" as stated in an earlier post. also 154.340, 154.280, and 154.295 will be narrow-banded at that time as well. The county has a capital budget item to pay for the re-tuning of the transmitters at the seven VFH sites and the base sets in the fire stations and the purchase of about 450 Motorola Minitor V pagers to replace some of the existing pagers in use by staff personnel and the volunteer fire fighters.
 

dpm797

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I have heard that Baltimore City is narrow-banding all of their VHF frequencies. 154.415 and 154.145 as well as the others they are licensed for.
 

dpm797

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actually the dead line for narrow-banding is 12/31/2012......on Jan 1, 2013 those transmitters not narrow-banded face being fined and or shut down by the FCC.
 

ka3jjz

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I would imagine this would include the BWI fire dispatch 154.10...and I would also assume that they're going to keep the current channel assignments via some sort of grandfathering? I don't believe any of these freqs fit the new 7.5khz offsets...
 
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ResQguy

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Some VHF and UHF frequencies can be left wide band by waiver if they are used for paging, I know of one hospital that already has received the waiver. All others do have to be replaced or if qualified reprogrammed for narrow operation by 1-1-2013.
That won't come into play for most public safety entities.
FCC said:
Are paging-only channels exempt from Narrowbanding?
Yes, however, there are only 14 paging-only channels.

152.0075 and 157.4500 MHz in the Public Safety Pool
152.480, 157.740, 158.460, 462.750, 462.775, 462.800, 462.825, 462.850, 462.875, 462.900, 462.925, and 465.000 MHz in the Business Industrial Pool.
 

dpm797

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the spacing is NOT 7.5 khz it is going from 25 khz to 12.5. do not know where 7.5 came from. the next split would be 6.25 again not 7.5
 

ka3jjz

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Did you read the article I linked to earlier? That's pretty clear where the splits are going to be - remember I'm not talking about deviation, but splits between frequencies (yes, they're related, I know that...). UHF splits would be 6.25 khz, down from the current 12.5 khz splits- and that's where the problem lies for some older scanners that tune in only the old 12.5 khz splits. Any freq that conforms to the new UHF 6.25 khz splits could not be properly tuned...I would guess then that only land mobile channels would go to 7.5 khz splits, while the public service channels do something else?

Mike
 
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dpcain

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I think from what I've gathered VHF narrowbanding in general restricts to 7.5 step. I know our current 25kHz radios won't be able to reprogram to it.
 

dpm797

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I apologize I misunderstood the relationship between channel spacing and bandwidth used. This means that current licensed frequencies stay.....new frequencies would end up being .0075 away from current frequencies...so the BWI Fire.....154.1000 would stay...but a new user could get licensed for 154.1075....AACo 154.010 stay but someone could get licensed for 154.0175..now I understand the 7.5 spacing you referred too. I thought the exact spacing was 12.5 khz apart... thus with the old 25 khz the assigned frequencies are .0150 a part. Now I have a better understanding bandwidth vrs channel spacing and how they are inter-related. Thank You ka3jjz
 

ka3jjz

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Yes, that's my understanding. And we do have one or two UHF fire dispatches in the area - Harford uses 460.6, for example. But I guess where I'm confused is that if a current allocation doesn't fit in the new bandplan, does it have to move or can it stay where it is? I know the Feds have been moving freqs around now for awhile due to this. But hey, they can do what they like...

I would imagine this would be a fairly minor tweak if the transmitter can handle the new split - if not, I assume it would have to be replaced, which given county budgets these days, wouldn't be a pretty sight...Mike
 

radioman2001

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When it comes the the VHF part of the spectrum, for 12.5 kc spacing there really won't be any new allocations we have to wait for 6.25. The coordinators have gotten together and stated publicly that "unless the new frequency meets the same interference contour standard (38dbu) as is now in effect that channel will not be allowed". So on VHF side I don't see a lot of activity coming, so here we have another Federal mandate that does nothing.
On the UHF side with Motorola beating the bushes getting people to go MOTOTRBO which is 6.25 channel equivilant with 2 time slots for 12.5 it kinda negates the 6.25 requirement and the possibility for additional channels. As a result you won't see a lot of 6.25 licenses coming out unless they go IDAS or NXDX, and some of the NXDN and IDAS users are actually putting their center frequency closer to one side or the other of the 12.5 channel to ensure no one else licenses next to them, which interestingly BTW is allowed.
Getting back to non-specific paging channels I was talking about a hospital who uses a standard Part 90 2-way voice frequency for paging, not a paging channel, and they did get a waiver to stay wide band. Apparently it's not as hard to get as keeping your voice channels wide band.
As far as scanners most will pick up both side channels at the same time, since they are not 12.5 specific and no where near 6.25 specific. So when everyone has to go 6.25 which will have to be digital anyway, you going to need to update you scanner.
 

zerg901

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There are also spacing requirements for transmitters IIRC. Possibly a 154.10 repeater and a 154.1075 repeater would have to be separated by 10 or 15 miles maybe. Although 1 radio tech told me that 154.10 and 154.1075 could both be used as repeater outputs at the same location with some fancy engineering.
 
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