NFM vs FM?

[N_Jay]

Band---------------------------------------------Channel Step-----------Emission Width--------Deviation
Old FM LMR (1950's, 1960's) VHF --------------60 kHz------------------60 kHz------------------10kHz
Standard VHF-------------------------------------30 kHz------------------25kHz------------------5kHz
Offset VHF-----------------------------------------15 kHz------------------25kHz------------------5kHz
Standard UHF-------------------------------------25 kHz------------------25kHz------------------5kHz
Standard 800 MHz--------------------------------25 kHz------------------25 kHz------------------5kHz
NPSPAC 800 MHz-------------------------------12.5 kHz------------------20kHz------------------4kHz
Narrowband VHF (w/offsets)-------------------7.5 kHz------------------12.5kHz------------------2.5kHz
Narrowband UHF-------------------------------12.5 kHz------------------12.5kHz------------------2.5kHz
900 MHz-----------------------------------------12.5 kHz------------------12.5kHz------------------2.5kHz
FRS----------------------------------------------12.5 kHz------------------12.5kHz------------------2.5kHz


CRAP!!!!!!

Anyone good at making tables here?

EDIT:
Fixed (So-So)

Ok, so who wants to define "Wide", "Regular", and "Narrow"?

 

[zz0468]

20 K is WFM?? 5K Is NFM? Etc...

You're mixing occupied bandwidth (the 20K) with deviation (the 5K).

The FCC emissions designator depicts bandwidth, NOT deviation. They are not the same thing.

O

kay, so 1-5 is considered NFM 5 and higher is WFM? :lol:

If that floats your boat. But the real definition is based only on modulation index. By that standard, the old standard 5 KHz deviation FM, and 4 KHz deviation NPSPAC, and 2.5 KHz deviation channels are ALL "narrow band fm".

 

[slicerwizard]

CRAP!!!!!!

Anyone good at making tables here?

Phear my skillz!

Band                            Channel Step  Emission Width  Deviation
Old FM LMR (1950's, 1960's) VHF    60 kHz         60 kHz        10 kHz
Standard VHF                       30 kHz         25 kHz         5 kHz
Offset VHF                         15 kHz         25 kHz         5 kHz
Standard UHF                       25 kHz         25 kHz         5 kHz
Standard 800 MHz                   25 kHz         25 kHz         5 kHz
NPSPAC 800 MHz                   12.5 kHz         20 kHz         4 kHz
Narrowband VHF (w/offsets)        7.5 kHz       12.5 kHz       2.5 kHz
Narrowband UHF                   12.5 kHz       12.5 kHz       2.5 kHz
900 MHz                          12.5 kHz       12.5 kHz       2.5 kHz
FRS                              12.5 kHz       12.5 kHz       2.5 kHz

 

[poltergeisty]

Cool! Thanks for the explanation here.

Wondered about it because a I do have a two-way VHF that has two FM modes. The only difference I found is that the NFM ( I think it was ) causes the voice to be lower, but maybe more defined. (?)

 

[rfradioconsult]

Band---------------------------------------------Channel Step-----------Emission Width--------Deviation
Old FM LMR (1950's, 1960's) VHF --------------60 kHz------------------60 kHz------------------10kHz
Standard VHF-------------------------------------30 kHz------------------25kHz------------------5kHz
Offset VHF-----------------------------------------15 kHz------------------25kHz------------------5kHz
Standard UHF-------------------------------------25 kHz------------------25kHz------------------5kHz
Standard 800 MHz--------------------------------25 kHz------------------25 kHz------------------5kHz
NPSPAC 800 MHz-------------------------------12.5 kHz------------------20kHz------------------4kHz
Narrowband VHF (w/offsets)-------------------7.5 kHz------------------12.5kHz------------------2.5kHz
Narrowband UHF-------------------------------12.5 kHz------------------12.5kHz------------------2.5kHz
900 MHz-----------------------------------------12.5 kHz------------------12.5kHz------------------2.5kHz
FRS----------------------------------------------12.5 kHz------------------12.5kHz------------------2.5kHz


CRAP!!!!!!

Anyone good at making tables here?

EDIT:
Fixed (So-So)

Ok, so who wants to define "Wide", "Regular", and "Narrow"?

Way back when radios had dynamotors and vibrators (more radio porn) I remember deviation as 15 KC not 10. Motorola provided "narrow banding kits" that contained several new parts including numerous resistors, capacitors and a new splatter filter for the TX and a new permakay filter for the RX; also you were supposed to replace the old black bakelite crystal ovens with the new gold ovens. The also provided you with a new FCC type acceptance sticker and a new dot sticker to indicate the deviation was to be set to 5 KC.

 

[N_Jay]

Way back when radios had dynamotors and vibrators (more radio porn) I remember deviation as 15 KC not 10. Motorola provided "narrow banding kits" that contained several new parts including numerous resistors, capacitors and a new splatter filter for the TX and a new permakay filter for the RX; also you were supposed to replace the old black bakelite crystal ovens with the new gold ovens. The also provided you with a new FCC type acceptance sticker and a new dot sticker to indicate the deviation was to be set to 5 KC.

You are probably right. 60 kHz was before I was playing with radios.

Yes, all my old Mocoms had those stickers.

 

[rfradioconsult]

A little known fact, first gen (AMPS analog) cellular used channels spaced 30 KHz apart but transmitted voice at 15 KHz deviation.

 

[nd5y]

A little known fact, first gen (AMPS analog) cellular used channels spaced 30 KHz apart but transmitted voice at 15 KHz deviation.

No, it was 12 KHz deviation.

 

[rfradioconsult]

12 indeed, but not 5 as most folks think.

 

[N_Jay]

12 indeed, but not 5 as most folks think.

The deviation is set to a peak value, but the average is quite a bit lower.

Additionally the average telephone is much further below peak than the average radio audio signal.

That is why you could get 720 channels of telephone traffic on a 600 channel analog microwave link.

 

[zz0468]

That is why you could get 720 channels of telephone traffic on a 600 channel analog microwave link.

That takes me back quite a ways...

Don't forget to mention that those 720 channels crammed onto a 600 channel radio were measured in RMS deviation, not peak. And hopefully, the OP is not hopelessly confused.

Bessel nulls, anyone?

 

[poltergeisty]

They still use analog microwave links? I'm think public safety in rural areas perhaps.

 

[N_Jay]

They still use analog microwave links? I'm think public safety in rural areas perhaps.

There is still some out there, but I don't think anyone sells it (or has for years).

Microwave radios run for a LONG time.

 

[rico47635]

Band---------------------------------------------Channel Step-----------Emission Width--------Deviation
Old FM LMR (1950's, 1960's) VHF --------------60 kHz------------------60 kHz------------------10kHz
Standard VHF-------------------------------------30 kHz------------------25kHz------------------5kHz
Offset VHF-----------------------------------------15 kHz------------------25kHz------------------5kHz
Standard UHF-------------------------------------25 kHz------------------25kHz------------------5kHz
Standard 800 MHz--------------------------------25 kHz------------------25 kHz------------------5kHz
NPSPAC 800 MHz-------------------------------12.5 kHz------------------20kHz------------------4kHz
Narrowband VHF (w/offsets)-------------------7.5 kHz------------------12.5kHz------------------2.5kHz
Narrowband UHF-------------------------------12.5 kHz------------------12.5kHz------------------2.5kHz
900 MHz-----------------------------------------12.5 kHz------------------12.5kHz------------------2.5kHz
FRS----------------------------------------------12.5 kHz------------------12.5kHz------------------2.5kHz


CRAP!!!!!!

Anyone good at making tables here?

EDIT:
Fixed (So-So)

Ok, so who wants to define "Wide", "Regular", and "Narrow"?

Wide would be my MIL's backside, regular would be wifes, and narrow would be my son's. Mine is just perfect.