DSDPlus not decoding P25 aliases

[maus92]

I'm still unclear of their purpose since RIDs are already related to a preprogrammed label - perhaps it's an interim measure to ID a radio between codeplug updates?

 

[mtindor]

Radio aliases also show up on many NXDN systems and some DMR systems too. Of course, they will never show up if you aren't using FMP* + DSDPlus and have CTRL --> Combined CC/VC Monitor set. That's because the aliases (when available) are transmitted over the voice channels and not the CC.

Before SW comes along and corrects me, I should say that talker aliases will not show up unless you are actively monitoring a voice channel that is sending talker alias traffic. Usually that would mean running in Combined CC/VC mode. But it could mean running SDR# or SDR++ or FMP* + DSDplus in Passive Digital Monitor mode while parked on a voice channel freq. Bottom line -- the aliases come from the voice channels.

 

[GTR8000]

I'm still unclear of their purpose since RIDs are already related to a preprogrammed label - perhaps it's an interim measure to ID a radio between codeplug updates?

You're not sure what the purpose of over-the-air aliases is? Fairly self-explanatory; they provide the subscribers on the system with a means to easily identify other subscribers by showing an alias rather than a raw UID. They eliminate the need to maintain alias lists (aka UCL) in each codeplug, which becomes outdated in about a month on most systems. Since not every system has OTAP, believe it or not, it can be years between codeplug refreshes. OTA aliases provide the ability to update aliases assigned to an existing UID and to have the updated alias hit subscribers the very next time that subscriber keys up. It allows newly added UIDs to be aliased instantaneously for all existing subscribers without having to touch a single codeplug.

 

[GTR8000]

And yes, OTA aliases are encoded exclusively on the traffic channels as part of the voice transmissions. This is true for P25 (MSI and L3Harris), NXDN, DMR T3, etc.

 

[maus92]

You're not sure what the purpose of over-the-air aliases is? Fairly self-explanatory; they provide the subscribers on the system with a means to easily identify other subscribers by showing an alias rather than a raw UID. They eliminate the need to maintain alias lists (aka UCL) in each codeplug, which becomes outdated in about a month on most systems. Since not every system has OTAP, believe it or not, it can be years between codeplug refreshes. OTA aliases provide the ability to update aliases assigned to an existing UID and to have the updated alias hit subscribers the very next time that subscriber keys up. It allows newly added UIDs to be aliased instantaneously for all existing subscribers without having to touch a single codeplug.

So basically confirming what I assumed. Thanks.

 

[GTR8000]

So basically confirming what I assumed. Thanks.

Sounds like you're assuming that every radio already has a preprogrammed list of aliases (UCL), and that OTA aliases is a stop gap measure of showing updated aliases until the codeplugs are updated. That's not accurate; OTA aliases is a feature intended to eliminate static lists in codeplugs, as OTA aliases are dynamic and instantaneous, something that a codeplug certainly is not.

Anyway, their purpose should be quite clear to you now.

 

[maus92]

Nope, I only assumed it was an interim solution between codeplug versions. Even if it was ultimately designed to eliminate RID lists in subscribers and consoles(?), new codeplug editions would still be required for other reasons. But I can understand why it would ease some administrative housekeeping. Is this feature described in the TIA-102 specs (which I do not own). Is it a P25 standard or vendor-specific?

 

[GTR8000]

If you've never personally dealt with managing alias lists in thousands of codeplugs of large systems, you can't even begin to fathom how beneficial OTA aliases are.

I believe OTA aliases are in the P25 standards, or are actively being worked on if not yet fully codified. MSI "Group Services" is currently using a proprietary method of encoding the aliases, while I believe L3Harris is following the standard. No, I don't know if MSI will eventually follow the standard.

 

[slicerwizard]

I believe L3Harris is following the standard.

I haven't seen mention of aliases in the P25 standard, but that doesn't mean much.

What I've seen of Harris systems and OTA talker aliases is "talker alias header" messages followed by "talker alias text" messages; both message types use opcodes that are in the vendor-specific opcode ranges and IIRC, the MFID byte values are set to 0x90, which if I'm not mistaken is Motorola's MFID!

So Motorola got some talker alias messages that use MFID 90 into the standard, just like they did with their patch notification messages, then Harris implemented those "standard" talker alias messages, only to have Motorola go and implement a proprietary/obfuscated OTA talker alias scheme? So pretty much on the money for Moto...

 

[GTR8000]

From August of 2022...



Note that MSI's OTA aliases have been functional since early 2016 on ASTRO 25 trunked systems (both FDMA and TDMA). Harris was late to the game.