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DaveNF2G
Guest
I have noted a second hex code flashing on my SDS-200 screen right after (alongside, not alternating with) the programmed site NAC on a Phase II trunked system. What is the function of the second code?
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Hi Dave when I asked the question I was told the first numbers are the site NAC and the second set that come up are the voice channel NAC, for this to show undersettings you must have Ignore Site NAC. turned on. If you have
Use Site NAC turned on you won't see the second set of numbers. I know my Site NAC is correct but I see both sets of numbers when Ignore is turned on. When Uniden added the feature it was because R/R had some NAC that were wrong.
I forgot about that. In some non-Motorola systems the VC NAC is different than the CC NAC.
slicerwizard
Member
That sounds highly problematic. Citation?
Hopefully I didn't misspeak, but I "believe" Harris system do this. If I'm incorrect I apologize.
I haven't had any problems with it my reception is just fine. If I don't want to see both NAC it turn the option to Ignore off.
slicerwizard
Member
I've monitored the following Phase II networks and it's my understanding that they're Harris setups.
For all monitored sites, P2 DCC = P1 NAC.
Network: 148DE.00A ; Durham Region PS
Network: 458AD.227 ; Monroe/Ontario County
Network: 458AD.228 ; Monroe/Ontario County
Network: 458AD.229 ; Genesee County
Network: 458AD.22A ; Orleans County
I found the same condition with my SDS100 when receiving marginal quality signals. The NAC would be displayed correctly (ex: P25 NAC: 8B1h) when idle on the CC but would shift to displaying "NAC: 8B1h 47Fh" during active TG reception. I verified with UT and DSD+ that 8B1H was the correct NAC on this system. I noted the same condition on another system with marginal reception. One system was Motorola and the other Harris so that was not a factor.
I found that I had the global "Site NAC Operation" set to "Ignore Site NAC" vs "Use Site NAC" . I changed the setting to "Use Site NAC" and the problem went away. It is apparently an artifact of the SDS100/200 firmware.
I found that I had the global "Site NAC Operation" set to "Ignore Site NAC" vs "Use Site NAC" . I changed the setting to "Use Site NAC" and the problem went away. It is apparently an artifact of the SDS100/200 firmware.
slicerwizard
Member
Uniden can't figure out how to do forward error correction properly.
The Oneida County Phase II system here in Central NY also provides alternate NACS. The alternate NACS are often assigned to the Phase I systems for neighboring CNYICC counties (Madison, Oswego, etc.). A typical session on my SDS200 might show NAC 2A5h 2A7h. The Oneida County NAC is 2A5h and the Madison County NAC is 2A7h. With this bit of knowledge, let me pose two questions:
1. Every so often, my SDS200 will display NAC 2A5h 0A9h. According to the RR database, NAC 0A9h doesn’t belong to the neighboring counties. So what is this NAC? Can alternate NACS be assigned to a specific transmitter site within a Phase II system? I know, that doesn't make sense.
2. My second question relates to RSSI values displayed with different NACS. Using the system hold on the Oneida County Phase II system, I have noted the signal strength varies wildly from -80 dBm to -100 dBm. This seems like a normal event for a scanner. But here is the odd thing - when certain alternate NACS are displayed (e.g. 0A9h), the RSSI value no longer oscillates through a range of numbers. When NAC 2A5h 0A9h is displayed, the RSSI is limited to three values (-50, -55, or 60dBm) and nothing in-between. Why does this happen?
1. Every so often, my SDS200 will display NAC 2A5h 0A9h. According to the RR database, NAC 0A9h doesn’t belong to the neighboring counties. So what is this NAC? Can alternate NACS be assigned to a specific transmitter site within a Phase II system? I know, that doesn't make sense.
2. My second question relates to RSSI values displayed with different NACS. Using the system hold on the Oneida County Phase II system, I have noted the signal strength varies wildly from -80 dBm to -100 dBm. This seems like a normal event for a scanner. But here is the odd thing - when certain alternate NACS are displayed (e.g. 0A9h), the RSSI value no longer oscillates through a range of numbers. When NAC 2A5h 0A9h is displayed, the RSSI is limited to three values (-50, -55, or 60dBm) and nothing in-between. Why does this happen?
I moved this to the Uniden Tech forum as it is either a)an issue with the SDS-series decoding the NAC or b)the NAC users think a site should be and what it really is are different.
The short time I had a SDS100 I can confirm it didn't properly display the NAC of a trunked channel a lot of times.
The short time I had a SDS100 I can confirm it didn't properly display the NAC of a trunked channel a lot of times.
slicerwizard
Member
I doubt that those are "alternate" NACs. Every site has one NAC assigned to it. Whether NACs are unique across all sites in a system appears to be up to the system operator. Using unique NACs across neighboring sites would be the correct way of doing things, but there is nothing "alternate" about them. BTW, believing what a scanner tells you is ill advised, IMO.
UpMan - What is the purpose of the second hex code to the right of the site NAC (e.g. 2A5h 0A9h )? I see this all the time on my SDS200 while monitoring a P25 Phase II system.
- If the RRDB NAC does not match received NAC: NAC xxxh --> xxxh (FLASHING)
With all due respect, and I mean that sincerely and not in the usual sarcastic way...let's refrain from making such an iron-clad declaration and allow for the possibility that the scanner is simply displaying/receiving an incorrect NAC.
I happen to know for a fact that the system/site @R0am3r is scanning has the correct NAC of 2A5. This has been verified beyond any doubt. If his SDS200 is displaying 0A9, then it's wrong, simply put.
I would encourage anyone having this NAC issue to read @k2hz post, and to also change your global Site NAC Operation setting to Use Site NAC. This appears to possibly be a firmware bug in the SDS series.
This isn't critical, but I'm still wondering what 0A9h means. The graphic is from ProScan.
It means the firmware is buggy. Ignore it, it means nothing. 2A5 is the correct NAC for the Oneida cell, 0A9 is meaningless.
As suggested, follow the advice of @k2hz with the scanner settings and you will no longer see it.
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