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Spacing

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rankin6

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Looking at the different types of scanners that cover Mil-Air now that some of them have the 8.33 spacing,has anyone heard or know if the military will be changing the 25khz spacing in the near or distant future? Are we still safe if we invest in some of the older scanners?

Mike
 

wa8vzq

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The 8.33 KHz spacing only applies to the VHF ATC channels. When implemented here in the US, the most likely scenerio will be that the super high altitude channels will switch to that spacing. That will minimize the impact to the general aviation community. The FAA is currently replacing both VHF and UHF comm radio equipment nationwide under two separate programs.

The VHF radio's are ITT(Park Air) MDR's (multimode digital radio) They are capable of both analog and digital modulation and 25 KHz or 8.33 KHz channel spacing.

Coincident to the VHF replacement is a totally independent UHF radio replacement program. Those radio's are made by General Dynamics, CM-300 series. Those are analog modulaiton only and 25 KHz channel spacing only.

See these links for additional reading

Dan

http://www.parkairsystems.com/index.asp?id=116
https://www.arinc.com/aeec/general_session/gs_reports/2001/nexcom.pdf
www.gdc4s.com/documents/D-CM300-10-0706.pdf
 

Yokoshibu

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wa8vzq said:
Coincident to the VHF replacement is a totally independent UHF radio replacement program. Those radio's are made by General Dynamics, CM-300 series. Those are analog modulaiton only and 25 KHz channel spacing only.
That surprises me considering the ARC-210's the dod uses do the 8.33khz on vhf... I have to check on UHF but they are not planned to be replaced and I am 90% certain the uhf does the 8.33khz, I would have thought the dod would roll uhf into the 8.33khz with the faa cause I know for LMR they have to push from 25khz to 12.5khz... I know the FCC has been hitting up on the faa and dod to release bandwidth so they can make some money and farm it out...
 
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wa8vzq

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Well all that I can say is that the model of UHF a/g radio that are being installed do not channel in 8.33 KHz steps. I'm sure that the ARC-210 VHF channels in 8.33 since they fly into european airspace. Could be that the UHF end does as well but the FAA units are can only do 25 KHz spacing. The only reason for the change to the 8.33 Khz spacing on VHF is the need to expand. There are only 720 channels available in the VHF spectrum with the current 25 KHz spacing. Lot's of areas are having freq congestion issues. There are approx 7000 channels in the UHF with 25 KHz channels so there isn't as much pressure to pursue the issue. (not counting backing out the LMR assignments)

Dan
 

Yokoshibu

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Yeah... and thats what has me confused as to why the fcc didnt press the dod/faa to reband uhf to 8.33k and release the uhf spectrum that they could (imho they could) But who knows its all politics, they did push some of the trunked lmr systems off of 410-420 for 380-390 ish
who knows
 

wa8vzq

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Most of those parts of the VHF & UHF bands that are used by FAA and DOD are not under FCC control. Freq ranges under government control are sliced up by several differnet controlling agencies including NTIA, NCA and IRAC. Each has a role in the decision as to how things play in those segments. Basicly as far as aviation is concerned, they have authorized these bands for FAA and/or Dod use and they leave them alone to slice it up as needed.

The only jurisdiction that FCC has in those freq ranges are for licensing any civilian organization that has a bonafide need to operate there. In those bands, the FCC regulates licensing for example the fixed base operator at an airport. But it does not regulate how the FAA spaces channel assignments. When FAA switched from 50 KHz channels to 25 KHz channels in the 70's, it was an FAA decision not FCC. Dito with the switch to 8.33 KHz. As far as DoD @ UHF, they may already be operating on 8.33 KHz spacing but as far as air traffic control is concerned, there won't be a switch to that spacing.

Dan
 

Yokoshibu

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I thought ntia and fcc shared it all ... didn't realize nca and irac had a stake in it.

the faa decided on thier own to switch to 8.33.... yeah not like the EU and FCC didnt have anything to do with it!

That's why I was wondering why the ntia (dod) / faa didnt splice up into 8.33 only reasoning I could see is to protect some assets in the spect. considering the building up of ufo, its not like you would want to press any commercial users into those freq's.
 

NAVCAN

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nd5y said:
Currently 8.33 kHz spacing is only used in Europe on the VHF air band.
I don't think the US will change anytime soon.

same as in Canada
 
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