NFM or FM

[MasterPo]

Notice something today on my scanners I had SIPD(482.8875) on myBC125at in NFM mode on the SDS100 I ad same frequency but in FM mode, it sounded a lot better in NFM so I switch the SDS100 to NFM and still works and sounds just s little better, so just what is the difference between the two modes and what mode should it really be in, thanks in advance

Bill

N2YQC

 

[nd5y]

NFM is 2.5 kHz transmit deviation.
FM is 5 kHz transmit deviation.
The receiver should have matching bandwidth and audio level, but they don't always. It depends on the type and quality of receiver.
For a scanner use whatever works best.

 

[wtp]

{\displaystyle {\begin{aligned}y(t)&=A_{c}\cos \left(2\pi \int _{0}^{t}f(\tau )d\tau \right)\\&=A_{c}\cos \left(2\pi \int _{0}^{t}\left[f_{c}+f_{\Delta }x_{m}(\tau )\right]d\tau \right)\\&=A_{c}\cos \left(2\pi f_{c}t+2\pi f_{\Delta }\int _{0}^{t}x_{m}(\tau )d\tau \right)\\\end{aligned}}}

where {\displaystyle f_{\Delta }=K_{f}A_{m}}

, {\displaystyle K_{f}}

being the sensitivity of the frequency modulator and {\displaystyle A_{m}}

being the amplitude of the modulating signal or baseband signal.

OR
if it sounds better use it.
narrow FM is just that, it is more narrow a signal, to fit more channels in a given band.
kind of like fitting more small cars in a parking lot than station wagons.
if you use FM on a NFM signal it will sound lower in volume
if you use NFM on a FM signal it might get choppy.
most things are now narrow FM.

 

[littona]

NFM=Narrowband FM. So it's wideband vs narrowband.... so 25kHz spacing versus 12.5kHz. Most stuff these days was narrowbanded via FCC mandate.