Admin0140434
Member
any help appreciated
difference between FM and NFM
- Thread starter Admin0140434
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Admin0140434
Member
THANKS!!!
Admin0140434
Member
ok, another dumb question...
how can i tell if a frequency is FM or NFM? is there a "rule of thumb"?
how can i tell if a frequency is FM or NFM? is there a "rule of thumb"?
Frequency Range Mode
(MHz) (kHz)
25.0000 - 27.9950 AM
28.0000 - 53.9900 FM
54.0000 - 71.9500 WFM
72.0000 - 75.9950 FM
76.0000 - 87.9500 WFM
88.0000 - 107.9000 WFM
108.0000 - 136.9750 AM
137.0000 - 161.9950 FM
162.0000 - 173.9875 FM
174.0000 - 215.9500 WFM
216.0000 - 224.9950 FM
225.0000 - 399.9500 AM
400.0000 - 512.0000 NFM
806.0000 - 823.9875 NFM
849.0125 - 868.9875 NFM
894.0125 - 956.0000 NFM
1240.0000 - 1300.0000 NFM
(MHz) (kHz)
25.0000 - 27.9950 AM
28.0000 - 53.9900 FM
54.0000 - 71.9500 WFM
72.0000 - 75.9950 FM
76.0000 - 87.9500 WFM
88.0000 - 107.9000 WFM
108.0000 - 136.9750 AM
137.0000 - 161.9950 FM
162.0000 - 173.9875 FM
174.0000 - 215.9500 WFM
216.0000 - 224.9950 FM
225.0000 - 399.9500 AM
400.0000 - 512.0000 NFM
806.0000 - 823.9875 NFM
849.0125 - 868.9875 NFM
894.0125 - 956.0000 NFM
1240.0000 - 1300.0000 NFM
N
N_Jay
Guest
crashcrew said:
How are you defining "FM" and "NFM"?
......Uniden scanner manual
N
N_Jay
Guest
crashcrew said:
Well in that case should it not be.
Frequency Range Mode
(MHz) (kHz)
25.0000 - 27.9950 AM, SSB
28.0000 - 53.9900 FM
54.0000 - 71.9500 WFM, AM/VSB (video)
72.0000 - 75.9950 FM
76.0000 - 87.9500 WFM, AM/VSB (Video)
88.0000 - 107.9000 WFM
108.0000 - 136.9750 AM
137.0000 - 161.9950 FM, NFM
162.0000 - 173.9875 FM, NFM
174.0000 - 215.9500 WFM
216.0000 - 224.9950 FM
225.0000 - 399.9500 AM
400.0000 - 512.0000 NFM, FM
806.0000 - 823.9875 NFM, FM
849.0125 - 868.9875 NFM, FM
894.0125 - 956.0000 NFM
1240.0000 - 1300.0000 NFM, FM
So, I guess I messed up then....just trying to help the guy out. Sheesh... :evil:
N
N_Jay
Guest
crashcrew said:
No prob.
There are no good rules-of-thumb.
This topic is going to keep everyone confused for a long time.
When LMR went from 50 kHz to 25 kHz it was easy as the new channels ended in xxx.xx5, and when the old channels converted the audio was way low. (and there were no scanners)
With the new narrowbanding plans it will not be as easy.
Maybe the Scanner companies need to add a "Modulation Analyser" feature?
You set a frequency within the signal, and it reads out the center frequency, bandwidth and type of modulation. (Don't hold your breath for it!)
K5MAR
Member
crashcrew said:
Hey, crash, if you copied your info straight out of the Uniden manual, you gave the best info you could. As N_Jay pointed out, this particular topic is in a state of flux. Not only are the standards for what is being used in a particular band changing, even the terms are not consistant. What some books call FM, others call NFM. And some places refer to NFM as SNFM (super narrow FM). It gets hard to keep up! :lol:
That's the nice thing about this forum, we all share our information, and learn from each other.
Mark S.
Thank you, K5MAR...copied verbatim from page 3 of Uniden BC796 manual..
Admin0140434 said:
Despite those saying otherwise, there are a couple reliable rules of thumb that will work in 99.9% of the cases.
On VHF, yes. If a frequency ends in 15x.xxx5, it's very likely NFM. If it ends in a 0, it's most likely FM.
Oh UHF, it's a little more complicated. If the frequency is in the T-band and ends in 4xx.xxx0, it's very likely NFM. If on T-band and ends in a 5 (4xx.xxx5), it's likely FM.
On regular UHF, if it ends in a 0 (4xx.xxx0), it's probably FM. If it ends in a 5 (4xx.xxx5), that's where it gets iffy. If it's a low power operation that's been around a while, it's most likely FM. If it's a higher power repeater or a newer license, it's most likely NFM.
Another way to tell pretty well is the FCC license. If it shows an emmission designation that starts with 11, it's NFM. If it shows 16, it's probably FM, but could be NFM.
That's two rules of thumb - one for each hand.
As a bonus, try programming everything FM. If a user sounds particularly weak in audio on all units, it's likely because it's NFM.
BTW, Uniden is the only one who calls NBFM (NarrowBand FM) "FM" and SNFM (Super Narrow FM) "NFM". The choice of 'NFM' is very confusing to most, especially those in the industry, since it's so close to NBFM, but means the exact opposite of the two most popular voice modes.
Most companies call NBFM "NFM" and SNFM "SFM". True FM is rare, but does still exist. No modern scanner truly receives the FM mode. There is also WFM (Wide FM) that is used in FM and TV broadcast. FYI, there is also WAM (Wide AM), AM (at least there is one standard mode that is still used), NAM (Narrow AM), and SAM (Super Narrow AM)
Joe M.
K5MAR
Member
Gee, Joe, it's all so clear now! :lol: (Just kidding)
Something you might know, has the FCC ever mandated any kind of change on the VHF band? You know, if a system upgrades, they have to go to SNFM; or all systems have to change by the year 20xx? I know the Feds (inc. the CAP), have to change, but what about current public safety, local government and private sector licensees?
Mark S.
Something you might know, has the FCC ever mandated any kind of change on the VHF band? You know, if a system upgrades, they have to go to SNFM; or all systems have to change by the year 20xx? I know the Feds (inc. the CAP), have to change, but what about current public safety, local government and private sector licensees?
Mark S.
K5MAR said:
Yes, there 'is' a mandate to switch to some form of narrowband by some date, but that date keeps changing. That only affects below 470 MHz, BTW. The FCC hasn't learned yet that you can't regulate technology.
With so many businesses going to NexTel and the like, and the resulting ease of spectrum congestion, it's becoming harder for them to justify forcing everyone to buy NEW equipment. Since 9/11, it's easy for public safety entities with all the grant money, but businesses don't qualify for grants to purchase new fleets of equipment. But, the FCC is still trying.
The feds are in the same boat. It's easy when money is given to you, but when YOU have to pay for a change, it's not as easy to do.
There was a cutoff date after which you couldn't get a NBFM license, but that too keeps changing. Obviously, the vast majority is still on NBFM - especially when you don't count the 'HSA grant' systems that have popped up.
Joe M.
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