BCD436HP/BCD536HP: FM/NFM

[JethrowJohnson]

Hello all,
I have a BCD436HP and it receives analog channels pretty well, except that a few channels are really quiet. I can hear them just fine usually, until we have the heater running in the car, or something else that just drowns it out and I can only hear a word or two. I was looking through the forums this morning and I came across one about the SDS100/200 allegedly receiving analog signals terribly, and @trentbob said that's what the filters are for and you just have to figure out how to make them work the way you want 'em to, and @werinshades added that you could also change the modulation to FM, but set the volume offset to +2 or +3 because FM will reduce the audio. So, MARIETTA PD 1 is 460.3 MHz DCS025 (FM) and MARIETTA SVC is 453.15 MHz DCS025 (FM) Will the audio be louder if I change those to NFM? Thank you 🙂

 

[a417]

Have you tried it yet with the positive offset? What was the result?

 

[JethrowJohnson]

I've always had the offset on +3 but it's still quieter than some of the other channels.

 

[IAmSixNine]

Those two channels should be narrow band. If your scanner is set to FM and the agencies are using NFM then your audio will be reduced on the scanner.

 

[a417]

PD's entry & listing



...and the Svcs entry and listing.


Little discrepancy there, but the PD should be in narrowband (FMN) , and it appears the other one is licensed both FM/FMN

 

[JethrowJohnson]

Okay. So should I also ask the DB admin to change the chart to FMN so others know to set it that way?

 

[JethrowJohnson]

I set them on NFM and it seems to work. Thanks for the help guys. 🙂👍

 

[Ubbe]

I have a BCD436HP...... I came across one about the SDS100/200

Keep in mind that many things mentioned about SDS scanners are for making specific steps to those scanners and do not apply to scanners using conventional receivers like a 436.

The reason to change from NFM to a wider FM setting in SDS scanners are that they have increased modulation noise in comparison to other scanners as their filters have been set more narrow, probably to try and mitigate interference issues, and the squelch will then cut out a wide modulated data signal too early at lower signal strengths, even when the data signal are transmitted using the correct NFM modulation.

/Ubbe