• Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

    We've noticed a huge increase in rants and negative posts that revolve around agencies going to encryption due to the broadcasting of scanner audio on the internet. It's now worn out and continues to be the same recycled rants. These rants hijack the threads and derail the conversation. They no longer have a place anywhere on this forum other than in the designated threads in the Rants forum in the Tavern.

    If you violate these guidelines your post will be deleted without notice and an infraction will be issued. We are not against discussion of this issue. You just need to do it in the right place. For example:
    https://forums.radioreference.com/rants/224104-official-thread-live-audio-feeds-scanners-wait-encryption.html

Are Philadelphia’s 2 P25 sites actually simulcast?

jdm1

Member
Premium Subscriber
Joined
Dec 14, 2015
Messages
9
Location
New York, NY
#1
I’ve been logging activity across all talkgroups in both of the Philadelphia P25 systems labeled as simulcast on RadioReference.

Site 1 doesn’t seem to pick up any police dispatch talkgroups, but does pick up a few talkgroups that Site 2 doesn’t pick up at all (PPA, PHL Emergency). Both sites pick up some activity on Fire and Medic channels.

Is RR wrong? And if so, what are each of the sites used for?
 

u2brent

Member
Premium Subscriber
Joined
Jul 17, 2010
Messages
1,134
Location
KRWDPAXKRS1
#2
I’ve been logging activity across all talkgroups in both of the Philadelphia P25 systems labeled as simulcast on RadioReference.

Site 1 doesn’t seem to pick up any police dispatch talkgroups, but does pick up a few talkgroups that Site 2 doesn’t pick up at all (PPA, PHL Emergency). Both sites pick up some activity on Fire and Medic channels.

Is RR wrong? And if so, what are each of the sites used for?
Each site carries different traffic.
1.3 NAC 3B3 EMS-Zone1
1.4 NAC 3B4 Law Enforcement-Zone2
1.5 NAC 3B5? Underground1
1.6 NAC 3B6? Underground2

Simulcast in this case simply means multiple towers making up each site, Each site (Zone) does not carry all traffic.
Zone 1 is EMS/Fire
Zone 2 is Law Enforcement

The "Zones" cover the same geographic area. Not like a north site and south site in this case..
Almost like two separate systems that co-exist, an overlay.

That's how I look at it anyway.. :) If that's of any help...
 

jdm1

Member
Premium Subscriber
Joined
Dec 14, 2015
Messages
9
Location
New York, NY
#3
Thanks, that makes a lot more sense. Still, there are a few oddities I've seen as I've listened into the two zones this weekend. Sometimes certain things come across one zone but not the other.

E.g. for PHL Police – occasionally (rarely) I'll hear a transmission come across Zone 2, but they always come across Zone 1 (which seems to be primary for this talkgroup). Also seeing this the other way around. Occasionally a PPD district transmission will come across on Zone 1, but it's rare.

Why aren't the talkgroups clearly split between zones?
 

GTR8000

Well Known Member
Database Admin
Joined
Oct 4, 2007
Messages
6,713
Location
BEE00
#4
Setting the system up so that talkgroups are only permitted on one simulcast cell (i.e. site) or the other without exceptions wouldn't be very wise. If one cell goes down, you want to ensure that everyone can operate off of the remaining cell, even if it means a lot of system congestion. That is why P25 systems have the ability to prioritize access at both the talkgroup and even subscriber (radio) level.

Simply put, if a radio happens to wind up on the Zone 2 cell, taking with it a talkgroup that normally is found on the Zone 1 cell, that talkgroup is going to be active on Zone 2 for as long as the radio is affiliated with that cell. As long as the talkgroups are not absolutely restricted to either cell, the possibility exists for that to happen from time to time.
 
Joined
Feb 22, 2007
Messages
781
Location
Bristol, Pa.
#5
I listen to Philadelphia everyday Zone 2 with police and Zone 1 is fire EMS and city services. Citywide like J band, M band, T Band can be heard on both.

The database is incorrect and always has been, it is phase 1 not 2 simulcast and is very affected by LSM. It's best to program two different systems splitting the police and fire/ EMS so that you only have to scan one system at a time as it goes faster that way.

If you're using an SDS there are two different NAC numbers.
 
Last edited:
Joined
Feb 22, 2007
Messages
781
Location
Bristol, Pa.
#6
I just want to add as I see the other 3 post are very informative. You didn't say exactly where you are in the city?

I never had good luck with the x 36 radios and the GRE Whistler radios didn't work well at all on the P1 simulcast systems.

I ended up using an apx 7000 which works terrific all over the city including Underground Transportation tunnels.

I also use an SDS 100 now for Philly. I focus on the far Northeast police district 7 and 8 programmed on Zone 2 and Central Police district 6 and 9. Also on Zone 2. Sometimes I listen to North fire on Zone 1 but it is programmed on a different system.

If you want to hear J band or sometimes called administrative band or emergency band the SEPTA UHF T police frequency simulcast J band.

An interesting note, on the far Northeast and Central Zone 2 site normal filter which is global works fine but on the North fire band which is Zone 1 site works better on wide normal. Who knows? I will say this. The SDS 100 picks up as well as the apx 7000 but of course it doesn't have the loud volume. Hope this helps.
 
Top