BCD996P2: [Bug] P25 Phase II Systems

Status
Not open for further replies.

KC2ZHY

Member
Feed Provider
Joined
Feb 29, 2008
Messages
364
Location
Somerville, NJ
I believe I have identified a (potentially major) bug in the BCD996P2 (and I'm certain it carries over to all Phase II scanners; I know my BCDx36HP also have issues). When a site is NOT broadcasting a band plan, the scanner appears to fall back on the custom band plan that was uploaded to the scanner. However--at least with the BCD996P2--the custom band plans do NOT specify if the band plan block is Phase 1 or Phase 2. This is fine for Phase 1 as the math is simple and it defaults to FDMA. However, with Phase 2, it is treating the calculations like Phase 1 and double-stepping the actual frequency.

For example, blocks 0 and 1 are programmed to be 6.25 kHz steps and is Phase 1 (no issue). However, blocks 2 and 3 are programmed to be 12.5 kHz steps but do not specify that there are 2 time slots, so it miscalculates the voice channel. Furthermore, even if you set the step to 6.25 kHz, the scanner does NOT attempt to decode TDMA; I assume it keeps trying to force FDMA decoding and fails.

I believe a programming option needs to be added (maybe as simple as a boolean value) that specifies if a band plan block is Phase 1 or Phase 2. From there, the scanner can make the appropriate determinations.
 

UPMan

In Memoriam
Uniden Representative
Joined
Apr 19, 2004
Messages
13,296
Location
Arlington, TX
What specific Phase II system do you monitor that does not transmit the band plan?
 

GTR8000

NYS Database Guy
Database Admin
Joined
Oct 4, 2007
Messages
9,306
Location
BEE00
It's a single site of the NJ statewide 700 MHz system (NJICS). Very odd behavior that seems to have started only recently, and does not seem to affect any other sites. I personally verified that it's not broadcasting any band plans entries for that site after KC2ZHY sent me some raw control channel logs.

https://www.radioreference.com/apps/db/?siteId=23015
 

mikewazowski

Forums Manager/Global DB Admin
Staff member
Joined
Jun 26, 2001
Messages
11,675
Location
Central Ontario
I'm not sure this would really be a bug as there really isn't a default bandplan. What you see normally is probably a Motorola default which doesn't apply to other manufacturers systems and even the Motorola bandplan could have been modified. This default bandplan wouldn't apply to other band systems either.

We had a UHF Phase II system stop transmitting its bandplan and we ended up having to manually enter the bandplan.
 

KC2ZHY

Member
Feed Provider
Joined
Feb 29, 2008
Messages
364
Location
Somerville, NJ
I'm not sure this would really be a bug as there really isn't a default bandplan. What you see normally is probably a Motorola default which doesn't apply to other manufacturers systems and even the Motorola bandplan could have been modified. This default bandplan wouldn't apply to other band systems either.

We had a UHF Phase II system stop transmitting its bandplan and we ended up having to manually enter the bandplan.
Unfortunately, none of my three Phase 2 scanners give me the option to specify if a band plan is FDMA or TDMA. It just asks for a Base and a Step and implies FDMA, rendering TDMA tracking null. I consider it a bug because it's a lack of a pretty important feature in these uncommon situations, especially when there is the option to program a band plan; the option is merely incomplete.
 
Last edited:

mikewazowski

Forums Manager/Global DB Admin
Staff member
Joined
Jun 26, 2001
Messages
11,675
Location
Central Ontario
Sorry, my reading comprehension skills are lacking today.

Yes, I agree. Not being able to add whether a channel range is fdma or tdma would be a problem.

Good eye!
 

KC2ZHY

Member
Feed Provider
Joined
Feb 29, 2008
Messages
364
Location
Somerville, NJ
Yeah, it's definitely a problem. Question is: now that the issue is identified and verified, how long will it be until we see a fix?
 

scan-pa

RRDB Admin
Database Admin
Joined
Dec 18, 2002
Messages
996
Location
Lebanon, Pa.
yep, a way to change modulation mode must be added to p25 trunk systems, it shows a audio type column (always blank) on the profile favorite list overview, but not in the favorite list editer, same with talkgroup overview and in the editor for tdma slot (always grayed out)

what gives uniden? please fix this asap.

i have a nearby county that is transitioning from phase 1 to phase 2... tg by tg one at a time
 

KC2ZHY

Member
Feed Provider
Joined
Feb 29, 2008
Messages
364
Location
Somerville, NJ
yep, a way to change modulation mode must be added to p25 trunk systems, it shows a audio type column (always blank) on the profile favorite list overview, but not in the favorite list editer, same with talkgroup overview and in the editor for tdma slot (always grayed out)

what gives uniden? please fix this asap.

i have a nearby county that is transitioning from phase 1 to phase 2... tg by tg one at a time
Fortunately, **most** systems broadcast a band plan on the control channel, so your scanner should readily track appropriately. You should be fine, but I agree that in these uncommon cases, a fix is warranted.
 

jonwienke

More Info Coming Soon!
Premium Subscriber
Joined
Jul 18, 2014
Messages
12,132
Location
VA
yep, a way to change modulation mode must be added to p25 trunk systems, it shows a audio type column (always blank) on the profile favorite list overview, but not in the favorite list editer, same with talkgroup overview and in the editor for tdma slot (always grayed out)
There is a reason for that--A P25 digital trunked system is always digital, and allowing any other settings would make zero sense and screw up reception (e.g. setting AM modulation and DMR audio type). Manually selecting Phase I vs II also makes no sense, as some systems switch between I and II on a talkgroup depending on the capabilities of affiliated radios. A talkgroup may default to Phase II, but revert to Phase I if a Phase I-only radio affiliates with the site.

The problem is that there is no universal "default" bandplan, so if the system doesn't transmit it, the scanner can't calculate it without some user input.
 
Status
Not open for further replies.
Top