Who was I hearing on Capitol Area FG 6 doing a radio check this AM?

tede911

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Good morning! I was in the truck in Waltham MA this morning having coffee listening to my HP1 around 0810. Radio stopped on the Capitol Area NH system on Fireground 6 (154.370) which I do not normally hear. I listened along to a typical fire dept morning radio check.

The dispatcher identified as "400". The engine companies were numbered at least as high as 14. Also heard "Combo 21", "Combo 22", "Air Cart One". It was a repeated system and sounded very P-25ish. The HP-1 display was not showing a PL/DCS when receiving the transmissions.

Any ideas who I was hearing? It's probably something everyone else has heard before but it is new to me.

Stay cool,
- Ted
 

n1das

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Nashua, NH
Isn't Haverhill DPL ?? which would generally bleed over/splash as it does well into the South Shore with the DPL
It might have been Haverhill w/DPL but no DPL decoded due to the signal being received slightly off-frequency.

DPL is sensitive to frequency errors in the transmitter and receiver. DPL is less tolerant of frequency errors than CTCSS. A signal received off-frequency introduces a DC offset on the DPL data which can block the decoder from seeing the data. The decoder sees a step function instead of DPL data. The symptoms are very slow decoding or failure to decode. In this case the received signal is received 2.5kHz off-frequency, enough to cause blocking in the decoder.

EDIT: Looks like it's not Haverhill according to KB1VLA's post.
KB1VLA said:
Haverhill is P25 NAC 641. Haverhill Fire Alarm is "400" on the radio, from their license WPKR400.
 
Last edited:

n1das

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It might have been Haverhill w/DPL but no DPL decoded due to the signal being received slightly off-frequency.

DPL is sensitive to frequency errors in the transmitter and receiver. DPL is less tolerant of frequency errors than CTCSS. A signal received off-frequency introduces a DC offset on the DPL data which can block the decoder from seeing the data. The decoder sees a step function instead of DPL data. The symptoms are very slow decoding or failure to decode. In this case the received signal is received 2.5kHz off-frequency, enough to cause blocking in the decoder.

EDIT: Looks like it's not Haverhill according to KB1VLA's post.
My bad, just realized Haverhill on 154.3625 is 7.5 kHz away from 154.3700, not 2.5 kHz away. D'Oh!
It's unlikely to be Haverhill even if they were still analog.
 

ecps92

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I previously got Haverhill, and also the DPL, on the Adjacent channel which is why I was also thinking it was Not Haverhill as Ted had No PL or DPL
Unless he had an issue with the RX at the time...

AS to KB1VLA are they Fulltime now P25 or still dual-mode/mixed mode
My bad, just realized Haverhill on 154.3625 is 7.5 kHz away from 154.3700, not 2.5 kHz away. D'Oh!
It's unlikely to be Haverhill even if they were still analog.
 

DannyM86

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Was listening to this on the way home from work this morning, definitely Haverhill Fire 154.3625 N641. Very long radio test, every mobile and portable, reserve apparatus, air cart etc....
 
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