NFM/FM Modes

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w2lie

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Thank you @RaleighGuy for reposting the YouTube video. Keep in mind, that the 12.5kHz spacing as shown in the video is missing the fact that the center frequency remains valid and usable. The same is true for the 6.25kHz spacing.

This is a very early video in what I hope will become a weekly segment on my YouTube channel called "Two Minute Tech Tips", where I explain one Scanner Radio topic in 2 minutes or less.
 

Ubbe

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You might find this short explanation from Scanner School's @w2lie helpful.
He made a little mistake with the FM 25KHz channel and had that as a 250KHz wide channel.

For something like a SDS100/200 scanner it might actually decode a digital signal better using FM on a NFM channel. The SDS scanner makes a fully modulated data signal a little distorted in the correct NFM mode if the signal isn't at full strength.

/Ubbe
 

dlwtrunked

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You might find this short explanation from Scanner School's @w2lie helpful.


Not completely accurate...Does not deal with the difference between channel step site and modulation bandwidth (not clear to me that the author knows) and "the part of the FM signal" part is extremely misleading as it is not part of the other signal. In technical publications, it is rare to see terms of "FM" and NFM" as they are used specific to certain types of communications--and time changes them. Some thing s are best left as numbers. Numbers given his talk are generally not accurate in many circumstance.
 

w2lie

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I appreciate your feedback and comments, but that wasn't the point of the video.

This was a quick explanation on the differences as to why we see FM and NFM (or FMN) as options on the scanners and what the differences are. This is a very common question posted on forums like RR and also on the vast majority of scanner groups on social media.

My goal was to answer this question in 60 seconds. Why? Because that is the time limit of a YouTube "shorts" video.
So, much of the video ended up, as they say, on the cutting room floor.

Just the basics of the explanation was included. The video was never meant to be a full on RF Engineering course on FM Modulation or spacing. The entire goal was to quickly explain FM and FMN in less than 1 minute.

I'll admit, there are a few errors in the drawings. I'm new to creating these types of videos and just like everyone else, you have to start somewhere and hopefully these will get better as I get better at making them.

In the meantime, your feedback is greatly appreciated as that will help me to improve on these on future short form tutorials.
 

w2lie

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I just wanted to correct the above statement because my mind was focused on 60 second videos when I replied. (It's too late to edit my prior post)

The FM vs FMN video is part of a series I'm calling "Two Minute Tech Tips", which is exactly what it sounds like.
So even though I have 2x the amount of time to explain things than I said prior, a lot of the info still remained edited out.

What have I learned so far? That 1 or 2 minutes is not enough time to *fully* talk about a topic. But - there are many out there that want direct and do the point answers and I will try to help those people as well. Many don't want to hear the science behind something. It bores them and makes their eyes roll in their heads. Delivering on the information quickly will help them learn.

The great thing about making content and putting videos online, is that there are many different ways to share the same information. So while I just skimmed the surface of FM in 2 minutes, this still gives me an opportunity to create a 2nd or 3rd (or more) videos to explain even more on the topic. Or - I can also go back and remove the "offending" video and replace it at a later date with an updated version on the topic.

A HUGE issue I found while podcasting for nearly 5 years is that most of the times, when I review the podcast before publishing, I always wished that I added another example, changed the way I explained something, or had another idea to add. But - if we continuously sit there and modify the content, it would never be released since there is always room for improvement. And that is what makes any hobby fun ;). There is always something new to learn, to try, and to experiment with.
 
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