Emergency Traffic / button

[hruskacha]

I'm Using SDRTrunk to listen to a P25 Trunked system. What does an emergency message look / sound like? I heard a dispatcher verbally mention it on the dispatch channel, but isn't there something else that goes across the radio to indicate an emergency button activation?

Audio Clip

 

[maus92]

I'm Using SDRTrunk to listen to a P25 Trunked system. What does an emergency message look / sound like? I heard a dispatcher verbally mention it on the dispatch channel, but isn't there something else that goes across the radio to indicate an emergency button activation?

Audio Clip

It is a data message sent by the radio, and it will indicate on the dispatcher's console with a visual (and perhaps an aural) alert. The feature may also cause the emergency radio to continuously transmit, or it may force the radio itself to emit an alert tone (to help find a fire fighter in distress for example.) In my city, the police generally do not broadcast that a radio is in Emergency mode; they will instead call the unit with a code, and expect another code in response as a safety / security measure (Emergency buttons get keyed by accident frequently, lol.) Unitrunker 2 can be set up to blink or sound a tone when a radio goes into an emergency state - not sure if SDRTrunk has a similar feature.

 

[wtp]

my 396T has alerted me to emergency alerts.
from the manual:
Setting Emergency Alert (Motorola and EDACS Systems Only)
J Program System
J L 4 Select the system
J L 4 Edit Sys Option
L 4 Emergency Alert L Off - the scanner does not alert you to emergency transmissions.
Alert 1 - 9 the scanner sounds an alert beep to notify you of the emergency transmission. You can choose any of 9 different beep types.
J Set Level Auto - the scanner automatically sets the emergency alert beep to the master volume level. Level 1 - 15 - the scanner adjusts the volume you hear to the level you select

 

[wgbecks]

This question is way above my pay grade, but then I am retired... I believe that a press of the Emergency Button via programming in the radio will send an Emergency Alarm Request from the Subscriber Unit (SU) on the uplink channel as an ISP message with an Opcode of 0x27.

Now I don't know for sure, and it likely varies somewhat by system manufacturer, but I believe that this would show up on the associated downlink channel (Trunk) as a Group Voice Channel Grant message with the Emergency Bit set in the Services Options octet of packet.

There is also a Motorola Proprietary OSP called "Motorola Emergency Alarm" that perhaps may be transmitted in response to an SU with an emergency activation on Motorola systems?

Hopefully, someone who fully understands P25 trunking protocols will offer a better or more accurate description of the messaging involved with this process. I'd actually like to know for certain myself. I can't tell you if programs like DSD+ or SDRTrunk are capable of flagging these events or not.

 

[slicerwizard]

DSD+ definitely reports P25 emergency events. I've seen it many times.

 

[AM909]

Here's an event log entry from a P25 system:
2021/05/25 22:31:01 NAC=5A8 Emergency; TG=12173 RID=739631
a Con+ system:
2021/05/17 05:04:44 DCC=3 Emerg Enc TXI Group call; TG=11966425 RID=11927222 Slot=2
a DMR TIII system:
2021/04/01 15:40:56 DCC=0 RAS Emerg OVCM Private call; Tgt=13959414 Src=15360597 Ch=1465

 

[maus92]

This question is way above my pay grade, but then I am retired... I believe that a press of the Emergency Button via programming in the radio will send an Emergency Alarm Request from the Subscriber Unit (SU) on the uplink channel as an ISP message with an Opcode of 0x27.

Now I don't know for sure, and it likely varies somewhat by system manufacturer, but I believe that this would show up on the associated downlink channel (Trunk) as a Group Voice Channel Grant message with the Emergency Bit set in the Services Options octet of packet.

There is also a Motorola Proprietary OSP called "Motorola Emergency Alarm" that perhaps may be transmitted in response to an SU with an emergency activation on Motorola systems?

Hopefully, someone who fully understands P25 trunking protocols will offer a better or more accurate description of the messaging involved with this process. I'd actually like to know for certain myself. I can't tell you if programs like DSD+ or SDRTrunk are capable of flagging these events or not.

It's not just P25 systems; it's also available on SmartZone as that is my local system. Sometimes you can hear the console alarm blaring in the background when the dispatcher calls the unit in question.

 

[wgbecks]

It's not just P25 systems; it's also available on SmartZone as that is my local system. Sometimes you can hear the console alarm blaring in the background when the dispatcher calls the unit in question.

Yes indeed! Emergency alerting has been around in many forms (systems types) for a long time.

 

[slicerwizard]

a Con+ system:
2021/05/17 05:04:44 DCC=3 Emerg Enc TXI Group call; TG=11966425 RID=11927222 Slot=2
a DMR TIII system:
2021/04/01 15:40:56 DCC=0 RAS Emerg OVCM Private call; Tgt=13959414 Src=15360597 Ch=1465

Those are highly suspect. Some vendors play fast and loose with the service options bits.

 

[AM909]

Those are highly suspect. Some vendors play fast and loose with the service options bits.

Yeah, I've noticed supposed emergency messages on a law enforcement TG (maybe San Bernardino County 37C) that weren't followed by any expected related activity.

 

[slicerwizard]

Yeah, I've noticed supposed emergency messages on a law enforcement TG (maybe San Bernardino County 37C) that weren't followed by any expected related activity.

That doesn't sound like a DMR system.

 

[AM909]

That doesn't sound like a DMR system.

True. Didn't realize we were talking DMR only. I don't remember if my impression included instances on a DMR system.