Data on 154.370

Status
Not open for further replies.

krokus

Member
Premium Subscriber
Joined
Jun 9, 2006
Messages
3,909
Location
Southeastern Michigan
While I am driving through the M-14 and I-275 area, I keep hearing a data interrogation happening on 154.370.

I find it odd that a data signal is being used on a fire tone out freq. Does anyone know who the data system belongs to?

Sent via Tapatalk
 

SCPD

QRT
Joined
Feb 24, 2001
Messages
65,126
Location
Virginia
Same thought

I believe it's civil defense siren controllers.
Before I scrolled down and read you response, I thought the same.
I've been told that the siren activations for some of the downriver communities are data burst on the old vhf freqs.
 

pilondav

Member
Joined
Aug 12, 2010
Messages
16
Location
Westland, MI
It's actually DTE Energy. That frequency (actually 154.3785, 6.25kHz splinter channel) is used for interruptible air conditioner and capacitor bank control. It's a one-way, paging-style signal.

A test signal is sent out every few minutes to verify operation, even if there's no control message.

Dave


Sent from my iPad using Tapatalk HD
 

ffexpCP

wizard of odd
Database Admin
Joined
May 15, 2004
Messages
597
Location
Michigan
Before I scrolled down and read you response, I thought the same.
I've been told that the siren activations for some of the downriver communities are data burst on the old vhf freqs.
Some used QCII tones, while others used DTMF or something similar. I don't hear any of those anymore. They're also been eliminating leased telco lines. I've heard those run around $80 / month.

These data bursts started showing up when these other formats started to disappear.

They could be heard everyday at 0300 like clockwork. Eventually the time drifted quite a bit. Some sound like stronger signals than others. All of this led me to believe the siren controls/ polling / status checks.

You can go hours without hearing any of that data. But when it starts it goes on for several minutes.
 

902

Member
Premium Subscriber
Joined
Nov 7, 2003
Messages
2,391
Location
Downsouthsomewhere
Some used QCII tones, while others used DTMF or something similar. I don't hear any of those anymore. They're also been eliminating leased telco lines. I've heard those run around $80 / month.

These data bursts started showing up when these other formats started to disappear.

They could be heard everyday at 0300 like clockwork. Eventually the time drifted quite a bit. Some sound like stronger signals than others. All of this led me to believe the siren controls/ polling / status checks.

You can go hours without hearing any of that data. But when it starts it goes on for several minutes.
I'm not up by you, but your mention of the time prompted me to respond. It used to be pretty common to "retrain" simulcast transmitters daily in the early morning hours when calls are statistically least likely to occur. 3 AM is usually that magic time. Those retrainings would send data stream handshaking from individual transmitters (could explain why some were weaker than others) controlled by Simulcast Solutions interfaces, that lasted for several minutes back to a central receiver and phasing controller unit sync'ing up modulation and timing.

It's a possibility and very likely for fire use, as alerting Minitor receivers usually requires a certain degree of saturation coverage.
 

krokus

Member
Premium Subscriber
Joined
Jun 9, 2006
Messages
3,909
Location
Southeastern Michigan
I am using a wideband radio for monitoring the transmissions. I will try a narrowband capable rig.

Sent from Tapatalk
 
Status
Not open for further replies.
Top