normal FM vs narrow FM mode

[Fred]

I am wondering what the difference is between normal vs. narrow FM mode is,
on 2m, 1.25m, and 70cm.
Is it just for receiving, or does narrow FM mode help transmitting also.

[RussellHltn]

The deviation of the signal is different between normal and narrow. Narrow
takes up less bandwidth and in theory could allow for more channels in the
same band if everyone used it.

Yes, the setting affects both receive and transmit and should be set to
match the other users of that frequency, otherwise you'll be too loud or too
soft.

-----Original Message-----
From: Fred [mailto:ki4iep-***@public.gmane.org]
Sent: Tuesday, January 11, 2005 6:36 AM
To: TH-F6A-***@public.gmane.org
Subject: [TH-F6A] normal FM vs narrow FM mode


I am wondering what the difference is between normal vs. narrow FM mode is,
on 2m, 1.25m, and 70cm.
Is it just for receiving, or does narrow FM mode help transmitting also.




Yahoo! Groups Links

[Urantian]

Thanks for the information about normal and narrow mode.

How does Narrow FM affect the strength of the signal? If the
modulation is being focused on a more narrow bandwidth, does it also
extend the signal range? This would be great for simplex.

---Michael Reynolds, AE6QC

Post by RussellHltn
The deviation of the signal is different between normal and

narrow. Narrow

Post by RussellHltn
takes up less bandwidth and in theory could allow for more

channels in the

Post by RussellHltn
same band if everyone used it.

[RussellHltn]

Not sure. Since in FM the deviation is the modulation strength, it's comes
across as softer audio unless you switch to the narrow mode. From what I
understand it was created to allow for more channels, not for longer range.

The real question is what does it do in real life? I could be wrong, but I
don't think the TH-F6A is actually using narrower filters when you switch
the mode, just adjusting the audio gain for compatibility so there is no
improvement since there is no real reduction in bandwidth being picked up by
the receiver.


-----Original Message-----
From: Urantian [mailto:ae6qc-***@public.gmane.org]
Sent: Tuesday, January 11, 2005 7:52 AM
To: TH-F6A-***@public.gmane.org
Subject: [TH-F6A] Re: normal FM vs narrow FM mode



Thanks for the information about normal and narrow mode.

How does Narrow FM affect the strength of the signal? If the modulation is
being focused on a more narrow bandwidth, does it also extend the signal
range? This would be great for simplex.

---Michael Reynolds, AE6QC

[Steve]

I'll have to verify this with measurements, but it first should lower
the peak deviation, not the mic gain. There is a difference. With
less deviation, less bandwidth is needed. This will have no effect
on range. It was indeed, done for more channels. With the narrow
deviation, the capture effect will be less pronounced, meaning that a
weak signal under a stronger signal can produce more interference in
the narrow system. I do not know if the receiver filters is
actulally narrowed and need to measure it.

73, Steve <k9DCI

Post by RussellHltn
-----Original Message-----
Sent: Tuesday, January 11, 2005 7:52 AM
Subject: [TH-F6A] Re: normal FM vs narrow FM mode
Thanks for the information about normal and narrow mode.
How does Narrow FM affect the strength of the signal? If the

modulation is

Post by RussellHltn
being focused on a more narrow bandwidth, does it also extend the signal
range? This would be great for simplex.
---Michael Reynolds, AE6QC

[Fred]

Couldn't resist chipping in folks.

Ever heard Capture Effect on your FM Stereo Tuner? You're enjoying the programme you tuned to then suddenly another station totally replaces it. You might even wonder if the frequency jumped or something. Unlike AM, you don't even hear heterodyne whistle and a signal just 2-3db stronger can "capture" the discriminator and make the original signal audio more than 30db weaker - even disappear.

As I understand it, the Kenwood has selectable discriminator and filters. At the intermediate frequency stages, amplitude is limited so that only the FM information (rate of change and amount of deviation) is passed for detection by a discriminator designed to be efficient only in that mode.
Wide FM received within the passband of a Narrow FM filter has a deviation too great for the discriminator to correctly detect and you will hear loudly distorted audio. If narrrow FM and a wide filter, the deviation will be too little, audio level too low and noise high. If correct, loud and clear audio with minimal to fully quieted background noise.

Bandwidth has a direct bearing on noise and to reduce noise you need stronger signals or narrower bandwidth.

Hope that makes sense.

Regards,

Fred.



Steve <noskosteve-/***@public.gmane.org> wrote:


I'll have to verify this with measurements, but it first should lower the peak deviation, not the mic gain. There is a difference. With less deviation, less bandwidth is needed. This will have no effect on range. It was indeed, done for more channels. With the narrow deviation, the capture effect will be less pronounced, meaning that a weak signal under a stronger signal can produce more interference in the narrow system. I do not know if the receiver filters is actulally narrowed and need to measure it.

73, Steve <k9DCI

Post by RussellHltn
-----Original Message-----
Sent: Tuesday, January 11, 2005 7:52 AM
Subject: [TH-F6A] Re: normal FM vs narrow FM mode
Thanks for the information about normal and narrow mode.
How does Narrow FM affect the strength of the signal? If the

modulation is

Post by RussellHltn
being focused on a more narrow bandwidth, does it also extend the signal
range? This would be great for simplex.
---Michael Reynolds, AE6QC

---------------------------------
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[RussellHltn]

I'll have to verify this with measurements, but it first should lower the peak deviation, not the mic gain. There is a difference. <<<

While they might compress or limit the signal more, I'd be surprised if the overall deviation wasn't lowered at least some.

If that was true that would suggest we are running a rather low average deviation in normal mode. It would also suggest that the received volume of the narrow and normal signal when the radio was in normal mode would be nearly the same.

[Fred]

SMC-34 vs SMC-33

What is the difference between these two mics besides the fact that the
smc-34 had a volume control. I am also curious as to why the smc33 costs
more money, and does not appear to have the volume control.

I would also like to know if these microphones improve the transmit audio,
or are they just for convienience.

Thanks
Fred KI4IEP