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Wideband vs Narrowband

Posted: 05 Jan 2013, 08:38
by AshtonMobileScanner
When programing radios what is the difference between narrowband and wide band and what frequencies do i use them on.

Im programing pmr frequencies into a Baofeng UV5RA+

Re: Wideband vs Narrowband

Posted: 05 Jan 2013, 09:33
by radiogaga
Wideband (WFM) is generally (very few exceptions) used in broadcast FM, Radio 1, Classic FM etc. It's used where quality transmissions are necessary, such as stereo FM on broadcast frequencies. Bandwidth is general 150Khz +, I think broadcast stuff id 200Khz

Narrowband is used for amateur radio, PMR, marine (don't get confused with the channel spacing).

You're going to be programming Narrowband 99% of the time.

Does that help?

Re: Wideband vs Narrowband

Posted: 05 Jan 2013, 09:58
by AshtonMobileScanner
Does it matter if there programed as wide tho

Re: Wideband vs Narrowband

Posted: 05 Jan 2013, 10:05
by radiogaga
Yes. You'll need to select NFM for everything but broadcast band 88-108.

Using WFM for a NFM will mean you'll notice the audio will be much quieter and you may well hear adjacent transmission.

Re: Wideband vs Narrowband

Posted: 05 Jan 2013, 11:37
by nerdsville
Don't get confused on the Baofeng transceivers the term wide and narrow isn't the same as on a scanner.

If you look in the manual I think you will see wide setting has an FM deviation is +/- 5kHz (10kHz in total) and +/- 2.5kHz (5kHz in total) on narrow setting.

A 'narrow' transmission it will sound quiet on a 'wide' receiver and a 'wide' transmission will sound distorted on 'narrow' receiver.

The channel spacing is usually 12.5kHz in the UK, so most transmissions will be 'wide' however some new equipment now uses 'narrow' there have been several threads about quiet broadcasts and this is the primary reason.

Re: Wideband vs Narrowband

Posted: 05 Jan 2013, 13:15
by RogerD
There are many combinations of deviation, modulating audio bandwidths and resulting RF bandwidths, so 'narrow' and 'wide' are relative terms that always need further specifying - as it will vary from one radio to another depending on whether it's a two-way radio, or a scanner (with FMW Broadcasting or not).

In this case, 2.5 or 5 kHz deviation result in somewhere around 11 or 16 kHz radio bandwidths, as used with 12.5 or 25 kHz channel spacings.

Almost all two-way radio is 2.5 for 12.5 (dev./spacing), except Marine VHF which is 5 for 25 (and other old systems, such as die-hard amateur radio simplex). CB is 2 for 10, broadcasting is 75 for 200.

Re: Wideband vs Narrowband

Posted: 05 Jan 2013, 18:56
by BK
The 70cm amateur band still uses 25kHz channels, except for simplex echolink/IRLP nodes which are mostly 12.5kHz - these can be found on the RSGB band plan. VHF marine band still uses 25kHz channels, except for the land SAR (mountain rescue) allocation which fits pairs of 12.5kHz channels into the 25kHz raster (i.e. offset by 6.25kHz). Everything else I hear on VHF/UHF is 12.5kHz now.

Re: Wideband vs Narrowband

Posted: 13 Mar 2017, 01:57
by rpcomms
Terminology can be bad and misleading esp on internet and forums ie Wide fm can be broadcast to some or FM wide\Wide FM as in Land Mobile Radio systems.

Channel Bandwidth and deviation is preferred term rather than 25khz channels as you can have a 25 khz channel steps with narrow deviation ie 145.550mhz (NFM 2.5khz\9khz Bandwidth) or FM/FM-W
I have seen this happen

There are currently 6 bandwidths\deviations used

FM Broadcast Wide Band FM -100 khz bandwidth@75khz DEV

Commercial 2 Way Radio\HAM
FM(sometimes called FM-wide or FM-W or wide FM in USA this can be called FM narrow!)16khz Bandwidth@5khz deviation Max
Mid FM-14khz Bandwidth@4khz deviation (mainly USA commercial land mobile used)Max
Narrow FM 9 khz Bandwidth@2.5khz deviation Max

CB radio ETSI spec
Narrow FM-9 khz Bandwidth@2.0khz Max ESTI specs current (sometime quoted on MPT specs 2.5khz max-note)

to work it out thumb of rule,
cb is limits the max audio freq up to 2.5khz,max dev 2.0 for 10 khz spacing.
so bandwidth=2.5(max audio freq)x2=5 then add 2.0 (dev)x2=4.0
5+4=9 khz bandwidth!

channels steps on radio equipment do not determine channel spacing\dev .

Note 1.
Also beware some radio equipment by well know mfr's only switches the transmit deviation side,not the receive side and that can mislead operators into thinking NFM is sounding quiet to them,they then make assumption the person talking to them has low deviation and in some cases they turn it up in error!,but that's a whole other story to tell.

If a radio\scanner does the full switching on both TX and RX you should not notice the audio level drop at all between wide and narrow fm (note 1.) on both tx and rx assuming both bits of equipment are fully switching
The RX filter correct bandwidth
The RX audio level =either from the fm discriminator or at the demodulator audio side on Wide\Narrow
The tx deviation level

As other users have commented as a general rule in UK using my terminology

25.60-28 Mhz 10 Khz Steps NFM (default ESTI standard) CB band UK\EU-Note I have seen FM-Wide used by ops in UK and USA on some occasions ie old\new ham kit,or operator error not knowing radio will switch to NFM
as a note.

28-29.700Mhz FM-Wide (USA HAMS sometimes referred too as Narrow FM in USA) NFM mainly Europe

25-50 mhz Lowband VHF USA FM-Mid 20 khz steps (mainly Motorola/GE/Vertex/Kenwood kit in 29.7 to 49 mhz band)

66-88Mhz Lowband VHF UK\EU inc 4m band is NFM (with exception to some MOD,GOV uses FM(Wide) in some cases due to history) 12.5khz steps.

2m band can FM(Wide) and NFM mixed in my experiance mainly NFM for repeaters and FM on simplex,but ops can vary depending on kit in use and understanding generally 12.5 or 25khz steps and wide\narrow fm operation of kit.
(THis has caused a lot of problems i can personally vouch for and in
my personal opinion
was badly handled and not thoroughly throughout and implications ie old & new radio kit.
Bad information and info on repeater internet sites not clearly stating as to if actually the repeater is truly running wide or narrow fm and yes have seen this happen even recently with System Confusion Yaesu kit,regardless as to what the RSGB were saying or publishing inc Note 1)
Again these are my own personal opinions I have experienced,hobby wise,job role in radio comms and may this may not be the same for other ops reading this.

Marine VHF 156 Mhz FM-Wide 25Khz steps used.
Land Mobile Radio 138-144 Mhz & 147-174 mhz is usually NFM (MOD,GOV sometimes use FM-Wide)12.5khz steps used.
Trunking Band III 174-220 Mhz NFM 12.5khz steps.

MIL UHF 220-400* Mhz AM-Wide FM-Wide @25khz channel steps *subject to current changes
UHF LO 400-430Mhz generally NFM 6.25khz &12.5khz steps
70cm 430-440Mhz FM-Wide and some NFM used (GOV,MIL use FM-Wide shared spectrum)
PMR 446 Mhz-NFM 6.25khz steps
462/467 Mhz FRS\GMRS NFM USA Only
449 Mhz NFM Business Band 3 channels 12.5khz steps
440-470mhz generally all NFM,some FM-Wide sometimes used for GOV,MIL uses in this band.6.25khz,12.5khz,25khz steps can be used.

list is generalised from experiance but sometimes a odd one comes along,hope this help explains a few things on narrow,mid,wide and FMBC wide is used.
I have seen and commented on quite a few forums as this subject seems a popular question asked a lot.

Just be a little careful when discussing interpretations\meanings of wide fm and narrow FM,esp americans on Ham forums,topics can become quite heated for some reason as well??lol
I blame text books and certain technical books don't explain it very well for the beginner entering the radio world and esp china\english manuals for radio equipment sometimes can leave you very confused. :?
Hope this provides a little help guide.


Rob 73's

Re: Wideband vs Narrowband

Posted: 13 Mar 2017, 07:46
by paulears
I agree - so much well meant but confusing data. It might be better understood if manufacturers also explained the consequences of getting it wrong.

Years ago, 50KHz channel spacing was pretty common, and one of the reasons it got stuck there was that channel centre accuracy was pretty poor. Radios for comms were crystal controlled and to get your frequency set needed a small trimmer - which would often be temperature sensitive, low when cold and then high when hot. With higher deviation settings the systems didn't really suffer. The hams started up their repeater networks using this type of gear, and the Home Office, OFCOMs equivalent then, had 25KHz channels. My first radio to use on the repeater network was a Pye Pocketfone - a receiver for one hand, and a transmitter for the other. It was always nearly on the right frequency. 434.950MHz might have been 434.940, but we managed.

(interestingly, these radios were bought at the ham rallys - and you could buy them on the frequency of your local Police - who had just upgraded, so I had quite a few labelled channel 47 - which worked fine on their old owner's channel.)

When frequencies became clogged in the big, busy areas, 25KHz channels were reduced to 'narrow band', and deviation was lowered.

From this point, frequency accuracy became critical - a few KHz either side and nobody could understand you - but practically the way radios managed over-deviation was quite different. Icom, for example had radios, like the H16 and U16 that would not open the squelch if the received signal was too wide. Very annoying, as many of my old customers had older Icom business radios and replacing any with new ones was horrible - even when there were no other users in the area on the next channel up or down. Reducing the deviation wasn't too tricky, but in the receiver, the narrow band mod meant new filters. Listening on scanners at this time - late 70s/early 80s - meant some users were very loud, and others very quiet when people were mixing systems or in transition. Volume settings a real pain! Range also dropped too - in the fringe areas, weak but workable reception was worse with lower deviation.

A few old boats have old radios and because they workfor the couple of channels the owner uses, are damn annoying to others, as they are always very loud. Users, getting complaints over the years developed the knack of speaking a foot away from the mics, which made their transmissions more tolerable to others. NowI note locally one of these now has a new radio, but still speaks from a foot away, and constantly gets told he is quiet! Probably thinks his new radio is rubbish!

The air scene is the same - they have gone very narrow, squeezing 3 channels into the space of 1, and until everyone had refitted,volume levels are low for some, high for others. For listeners, looking for distance, range is also dropping on wider band receivers.

I'm not certain that the wide/narrow/very narrow setting does anything in cheap radios apart from change the deviation. The receive setting remains at the widest option, hence why these radios aren't very good at adjacent channel rejection - the filters are wide to cope with the wide setting, and that is that!

My scanner wide setting lets me listen to my radio mic channels happily - which means VERY wide, but my portable radios seem to think that 25KHz is wide, and 12.5KHz is narrow, and very narrow is 6.25KHz is very narrow. So is 8.33KHz nearly very narrow or narrower?

If they gave a number that would make so much more sense, but they don't!

Re: Wideband vs Narrowband

Posted: 30 Nov 2017, 20:20
by rpcomms
Proper receiver's/transceivers if done correctly will switch IF filters and the fm discriminator audio level,normally a resistor across the descrim coil or resonator via a transistor switch.
Reason being to keep audio level correct and audio fed to fm noise squelch, as narrow filters reduce noise so more white noise required to compensate.
Often this is overlooked in some designs and can cause operator having to turn volume up more on fm narrow/super narrow transmissions,most of this is routed from USA marketed FCC NFM(USA terminology) 5khz dev/16khz bandwidth 60% dev=3khz dev from past.
Where Uk and Euro in pmr bands tend to use the 2.5khz dev max/11khzbandwidth system (except marine band/MOD)60% dev=1.5khz
cb uses 2.00khz dev max /9khz bandwidth (ETSI/EN specs)60% dev=1.2khz dev

So can see audio gain must change in receiver as you change fm systems otherwise maximum audio will not be achieved giving the effect of low audio gain,cranking volume control right up to compensate.
Some scanners/rx do have a audio compensate in menu,but generally this is automatically controlled by fm mode switch WFM,FM,FM-Mid,FM-Nar,FM-Super Nar

I have seen some mfr cheat and only switch filters but not audio!

Hope that helps explain