SDS100/SDS200: P25 trunking failed

[n1moy]

16 December 2025

Just an observation..

Finally got around to updating the firmware in my SDS200.
1.23.20 Main 1.03.15 Sub (10/17/2025)
Was driven by the upgrade to the new Sentinel version. [3.00.01]

After the firmware upgrade, a "P25 Trunk" favorite list failed to lock onto the control channel. The solution was to enable the attenuator.

Previously the favorite list had worked correctly with or without attenuation.

Not seeing any comment about signal reception improvements in the "SDS200 Firmware Update Change Log".

 

[jasonhouk]

16 December 2025

Just an observation..

Finally got around to updating the firmware in my SDS200.
1.23.20 Main 1.03.15 Sub (10/17/2025)
Was driven by the upgrade to the new Sentinel version. [3.00.01]

After the firmware upgrade, a "P25 Trunk" favorite list failed to lock onto the control channel. The solution was to enable the attenuator.

Previously the favorite list had worked correctly with or without attenuation.

Not seeing any comment about signal reception improvements in the "SDS200 Firmware Update Change Log".

Thanks for sharing that observation—sounds like a quirky post-update behavior.

The latest firmware (1.23.20 Main / 1.03.15 Sub) primarily focuses on fixes like resolving NAC display issues during P25 Phase 2 transmissions, improving WX Alert and SAME decoding, enhancing squelch sensitivity for WFM/FMB modes, and addressing no audio output on certain P25 3600 baud systems.

What trunk system are you monitoring?

 

[n1moy]

Massachusetts CoMIRS

 

[ecps92]

16 December 2025

Just an observation..

Finally got around to updating the firmware in my SDS200.
1.23.20 Main 1.03.15 Sub (10/17/2025)
Was driven by the upgrade to the new Sentinel version. [3.00.01]

After the firmware upgrade, a "P25 Trunk" favorite list failed to lock onto the control channel. The solution was to enable the attenuator.

Previously the favorite list had worked correctly with or without attenuation.

Not seeing any comment about signal reception improvements in the "SDS200 Firmware Update Change Log".

Which Site/Zone for ComIRS?? was the issue with ?

 

[n1moy]

CoMIRS - Metro Boston Overlay Simulcast [Quincy]​

 

[jasonhouk]

Massachusetts CoMIRS

I'd recommend to roll back the Main FW to 1.23.07 and see if that fixes the issue.

https://info.uniden.com/twiki/pub/UnidenMan4/SDS200FirmwareUpdate/SDS200_V1.23.07_Main.zip

Let me know how that works out.

 

[n1moy]

Unaware that there was a procedure to roll-back to previous firmware versions.

 

[jasonhouk]

Unaware that there was a procedure to roll-back to previous firmware versions.

Download and unzip the file from the link I previously provided.

Connect the scanner to the computer and enter MSM on the scanner.

In windows explorer locate the scanner drive and copy the firmware file to the firmware subfolder.

Safely eject the drive then reboot the scanner.

 

[n1moy]

Rolled back to Main FW 1.23.07, SW remains at 1.03.15

P25 Trunk favorite list will not lock on the control channel with or without attenuation. Noticed that the favorite list takes a long time to load at radio scanner start-up.

The Main and SW firmware was my only change.

 

[werinshades]

Dial back to 1.03.05 Sub with that firmware:

https://info.uniden.com/twiki/bin/view/UnidenMan4/SDS200FirmwareUpdate

 

[n1moy]

Rolled back to..
Main FW 1.23.07
SW 1.03.05

Favorite list locks with and without attenuation.

Enabling attenuation is not a problem with the new firmware.

 

[werinshades]

Rolled back to..
Main FW 1.23.07
SW 1.03.05

Favorite list locks with and without attenuation.

Enabling attenuation is not a problem with the new firmware.

So you're good now?

 

[n1moy]

Waiting for jasonhouk's reply before returning to the current firmware version.

Thanks for your comment.

 

[ecps92]

CoMIRS - Metro Boston Overlay Simulcast [Quincy]​

the 700 has always been spotty even down into Weymouth
or Revere into Chelsea

 

[jasonhouk]

Waiting for jasonhouk's reply before returning to the current firmware version.

Thanks for your comment.

If Main FW 1.23.07/SW 1.03.05 is meeting your needs I’d stick with that for now.

If UJE requests logs, I’ll be in touch though a private message.

 

[n1moy]

I'll return to 1.23.20 Main 1.03.15 Sub (10/17/2025) and use attenuation which appears to work properly.

 

[jjn555]

16 December 2025

Just an observation..

Finally got around to updating the firmware in my SDS200.
1.23.20 Main 1.03.15 Sub (10/17/2025)
Was driven by the upgrade to the new Sentinel version. [3.00.01]

After the firmware upgrade, a "P25 Trunk" favorite list failed to lock onto the control channel. The solution was to enable the attenuator.

Previously the favorite list had worked correctly with or without attenuation.

Not seeing any comment about signal reception improvements in the "SDS200 Firmware Update Change Log".

I had similar problems earlier this year. I then learned that I could get much better reception/decoding by enabling my attenuator, too.

 

[jjn555]

Rolled back to Main FW 1.23.07, SW remains at 1.03.15

P25 Trunk favorite list will not lock on the control channel with or without attenuation. Noticed that the favorite list takes a long time to load at radio scanner start-up.

The Main and SW firmware was my only change.


View attachment 194036

Interesting. Are you suggesting this is a problem, or simply a possible change that wasn't noted in the release notes?

 

[Ubbe]

Uniden did this change:

• Fixed an issue where the P25 Integrated Voice & Data control channel was incorrectly recognized.

There's always a possibility that a firmware change break things that earlier where working fine. It could have made the decoding of a control channel much harder now and will skip it at the slightest error in the data received. Using the attenuator to solve it indicates some interference issues, that it is now much more sensitive to, and might be solved by using a different filter setting or setting IFX to the control channel frequency, by doing Channel+frequency+Channel and then Function+7, if attenuation can not be used or are ineffective.

/Ubbe

 

[KevinC]

Uniden did this change:

• Fixed an issue where the P25 Integrated Voice & Data control channel was incorrectly recognized.

There's always a possibility that a firmware change break things that earlier where working fine. It could have made the decoding of a control channel much harder now and will skip it at the slightest error in the data received. Using the attenuator to solve it indicates some interference issues, that it is now much more sensitive to, and might be solved by using a different filter setting or setting IFX to the control channel frequency, by doing Channel+frequency+Channel and then Function+7, if attenuation can not be used or are ineffective.

/Ubbe

Except the version he tried didn't have that change in it. That was in FW 1.24.00.