San Diego Trolley SDTI 1 Blue -- seems they changed the tone, can anyone confirm?

[TeeJayZee]

I'm located about 3 miles south from the Coronado Bridge (San Diego).

I've noticed that in the past couple of days the following channel's audio has become either inaudible or choppy.

San Diego Trolley​

Frequency	License	Type	Tone	Alpha Tag	Description	Mode	Tag
160.665	WRY938	RM	131.8 PL	SDTI 1 Blue	Ch 1 Rail Operations - Blue Line	FM	Transportation

RRDB reference: Subcategory: Railroad/San Diego Trolley (San Diego County)

So I made a scan for the tone and it seems to always land on the following tone: C 100.0 -- and the audio sounds extremely better or at the very least audible.

Can anyone confirm this? Thanks in advance.

FYI: I used the following scanners (and radio) to help me search and confirm the tone: Uniden BCD325P2, Uniden SDS100, and a Radioddity GM-30.

 

[inigo88]

Thanks for the note. I monitored Blue and confirmed as well that they’re on 100.0 PL. Database has been updated.

For future reference if you’ve confirmed with multiple scanners feel free to make a submission directly, since it will be seen sooner than on the forums.

Kind regards!

 

[TeeJayZee]

@inigo88 I noticed you also changed the mode (modulation) setting for Blue.

Before it was set to just FM, now it's changed to FMN in the RRDB. Subcategory: Railroad/San Diego Trolley (San Diego County)

Is this correct?

 

[K6CDO]

All should be listed as FMN, as that is a FCC requirement.

 

[inigo88]

Fixed. I didn’t touch the modulation last time, it was already like that.

 

[TeeJayZee]

All should be listed as FMN, as that is a FCC requirement.

Are you referring to this mandate: Narrowbanding Overview

If yes, would this apply to all railroad frequencies states and nationwide? Since they are mostly within the 150-174 MHz frequency bands.

As for me, now monitoring the San Diego Trolley frequencies with the applied FMN setting changes on my scanners, to me they sound a bit more clear and stronger.

 

[tvengr]

As for me, now monitoring the San Diego Trolley frequencies with the applied FMN setting changes on my scanners, to me they sound a bit more clear and stronger.

When set to NFM (FMN), the scanner reduces the bandwidth and increases the audio gain to make up for the decreased deviation of the narrowband signal.

 

[K6CDO]

Are you referring to this mandate: Narrowbanding Overview

Yes. The mandate was effective 10 years ago (2013).

If yes, would this apply to all railroad frequencies states and nationwide? Since they are mostly within the 150-174 MHz frequency bands.

Yes.

As for me, now monitoring the San Diego Trolley frequencies with the applied FMN setting changes on my scanners, to me they sound a bit more clear and stronger.

As it should.