Just as the title says ... why is Simulcast such an issue for Phase 2 but not Phase 1?
Why is Simulcast such an issue for Phase 2 but not Phase 1?
- Thread starter sefrischling
- Start date
- Status
In my experience there is no real difference between Phase 1 and Phase 2 when it comes to simulcast.
west-pac
Member
- Joined
- Nov 13, 2004
- Messages
- 1,641
It's an issue for both.
- Joined
- Jan 15, 2007
- Messages
- 7,374
In my experience, both at home and travelling, simulcast affects both phase 1 and phase 2 with no noticeable difference.
There is definitely an issue which became more noticeable when the SDS series was introduced due to it's ability to handle simulcast better. It was evident on the x36hp series of scanners, but was easily dismissed because simulcast was problematic.
When 2 transmissions are occurring on the same frequency but different time slots, it will bleed over to the other non-assigned slot and act as if though someone is keying up over the top of the other. I was able to see this when Chicago started using the 800 P25 Phase 2 for CFD and only appears noticeable on busier systems. I don't know if the new beta firmware is addressing this, but someone near a busy system using Phase 2 talkgroups would notice this.
When 2 transmissions are occurring on the same frequency but different time slots, it will bleed over to the other non-assigned slot and act as if though someone is keying up over the top of the other. I was able to see this when Chicago started using the 800 P25 Phase 2 for CFD and only appears noticeable on busier systems. I don't know if the new beta firmware is addressing this, but someone near a busy system using Phase 2 talkgroups would notice this.
The issue I am trying to deal with is that I have two new 996P2 scanners that are nearly impossible to get working on the Connecticut Land Mobile Radio Network (CLMRN) Phase 2 system. I have two older 996P2 scanners that have no issues at all with the system.
The two newer scanners, like the older ones, are working just fine on the Rhode Island RISCON Phase 1 simulcast system as well as on the Waterford (CT) Phase 1 simulcast system.
I have moved around locations, to locations the original scanners work (which is pretty much everywhere, except places my Unication G5 and state issue portable go dead). I have used the same antennas from the same locations. No joy at all with the new 996P2 units on CLMRN. I took a ride out to Rhode Island to monitor RISCON, everything worked on RISCON. I have loaded up Waterford, everything works on Waterford for a 15+ mile radius.
This is baffling to me and driving me nuts.
The two newer scanners, like the older ones, are working just fine on the Rhode Island RISCON Phase 1 simulcast system as well as on the Waterford (CT) Phase 1 simulcast system.
I have moved around locations, to locations the original scanners work (which is pretty much everywhere, except places my Unication G5 and state issue portable go dead). I have used the same antennas from the same locations. No joy at all with the new 996P2 units on CLMRN. I took a ride out to Rhode Island to monitor RISCON, everything worked on RISCON. I have loaded up Waterford, everything works on Waterford for a 15+ mile radius.
This is baffling to me and driving me nuts.
west-pac
Member
- Joined
- Nov 13, 2004
- Messages
- 1,641
You likely outside of the circle of towers for one simulcast system, and are only receiving one tower on that system. The other system you are either inside the circle, or otherwise close enough to be receiving more than one tower on that simulcast cell.
chrismol1
P25 TruCking!
- Joined
- Mar 15, 2008
- Messages
- 1,278
Totally likely wrong and waiting for corrections...I've seemed, in my mind at least...to have slightly more issues with Phase 2 TDMA simulcast than Phase 1 FDMA simulcast.....Phase 2 TDMA may need slightly more simulcast maybe due to sync timing or something, I'm not sure, than that of phase 1 FDMA CQPSK and maybe on the receiving end more, these are just my observations in my own caseon the fringe of both p1 and p2 systems
I have found it to be the exact opposite for me. My HP2 and 436 struggle with P1 at times but for some reason are better decoding P2,
this is all on the same system and site.
this is all on the same system and site.
Different receivers (even the same model), different systems, different physical locations and the specific frequency you are receiving at this moment will each produce different experiences with potential Simulcast issues. You'll compare a single transmission one moment, and then in the next moment it is on a different frequency. It's likely emitting from different antennas on the same towers, which means each signal gets to your receivers at slightly different times than the transmission on the first frequency. You'll go crazy trying to look at it in this manner. Just know that if it happens to be "working for you" at one moment, it doesn't mean the underlying issue is not there.
There is a fairly significant difference in simulcast performance between Phase 1 LSM and Phase II. Phase 2 requires a slightly higher signal strength and a smaller timing alignment window than phase 1. All things being equal, Phase 1 LSM will outperform phase 2. All receivers aren't created equal either. On a dual mode system, it is reasonably possible your scanner will decode the phase 1 and not phase 2.
sfb88
Member
You mentioned that the two newer receivers have problems. Maybe the newer receivers have the newer, changed hardware and it has different receiver characteristics?
I suspect that you may be correct. The 'revised hardware', which necessitated a couple of firmware revisions for the 996P2, was from 2021. There was also a revision, in 2022, to correct receive problems for Vhf frequencies in the ~171 to 174 range.
The fact that the "newer" scanners have issues that the 'older' 996P2s seems to support that.
Not for my Unication G5. It just works perfectly. Thanks Unication. Right tool for the right job. :0))
west-pac
Member
- Joined
- Nov 13, 2004
- Messages
- 1,641
You must've read the Forum name incorrectly. It's 'Uniden' not 'Unication'. I can see how that looks similar.
My Unication G5 works wonderfully, however the issue is with two Uniden 996P2 radios.
Anyone want to swap me two older 996P2 units for two new 996P2 units :0)
Let's continue this discussion in the thread below to keep from having 2 threads discussing basically the same thing...
forums.radioreference.com
996P2 and CLMRN
I asked this in the Uniden group, but maybe local help will be more effective. I have two 996P2s that have been working just fine on CLMRN. I have now programmed three new 996P2 units for a station in town, and they seem unable to pick up CLMRN. I program using ARC XT, I just moved two of...
- Status
