Can Mot Type ll SmartZone P25 handle analog TalkGroups?

[Retired911Guy]

RR site page shows this:

Marin, County of (MERA - Public Safety)

System Name: Marin, County of (MERA - Public Safety)
Location: Various, CA
County: Marin
System Type: Motorola Type II SmartZone
System Voice: Analog and APCO-25 Common Air Interface <------- Look at this

The above would seem to answer my question, but does anyone know for SURE that it can, and if so, is the control channel programed to tell the mobiles of the analog talk group the change to analog mode, or do all the mobile units have to be re-programed to be analog on that one or two talk groups?

Also would the mobiles still be able to switch to other talk groups that were P25 and still communicate?

Thanks

[KS4VT]

In a mixed mode system like this one the radios are programmed in the CPS as to the type of modulation to expect and transmit. The CC only does the channel assignment.

[jim202]

Let me add a little more to the comments from KS4VT. When the radios are programmed, you have to
tell them on a per talkgroup basis which mode to use. You can have one talkgroup set to digital and
the next one in line set to analog.

Part of the answer also is driven by which version of software the actual system is using. What I
mean by this is the older levels of the system software use the 3600 data rate control channels
and can be mixed. Once the system migrates to the 9600 data rate control channel, mixed mode
operation is no longer available. It will then be a total digital operation. This is normally
called the version 7 upgrade. This will involve a total equipment replacement of both base
and user radios. This is a major upgrade and is very expensive.

Jim

Originally Posted by KS4VT

In a mixed mode system like this one the radios are programmed in the CPS as to the type of modulation to expect and transmit. The CC only does the channel assignment.

[N_Jay]

The confusion comes from over reliance on "brand names" like Smartnet and SmartZone to define the technical attributes of the system.

As started earlier, Type II (and Type I Smartnet before that, as well as Privacy Plus) are based on the Motorola proprietary 3600 BPS control channel. These systems can carry analog or digital (Astro and P25) voice channels.

Systems using the P25 control channel (from any manufacturer) use only P25 digital voice channels.

A "Type II P25 System" is a bit of a misnomer.

[Retired911Guy]

Thanks for the replies, that does answer my question.

Now the followup question, the reason for this question is, I am a close friend of a Fire Chief who has some P25 dead & fringe areas in his District (this affects the local Police also).

I've read many posts here and other sites that have said that digital drops off at a higher level than if someone were using analog.

Not to say it would completely clear up the dead zones, but MAY allow for some communications in those areas. I've suggested to him that he should change just one of his TAC channels in his mobile and on his HT and drive around the P25 dead/fringe areas and do some radio checks.

Anybody have direct experience with P25 vs Analog coverage, I know a San Francisco Fire Capt. and he tells me that when the SF system was originally put in, it was set up as a P25 system. They had great coverage in most areas, but some areas sounded like a bad cel phone connection, the system was switched to analog and FD and PD have used analog ever since.

I don't want start a big argument here about whether P25 or analog is better, but some input as to whether analog MAY help SOME in the dead or fringe zones.

Thanks

[N_Jay]

Try it and reportr back.

[KS4VT]

Originally Posted by Retired911Guy

Now the followup question, the reason for this question is, I am a close friend of a Fire Chief who has some P25 dead & fringe areas in his District (this affects the local Police also).

Thanks

The question is when your say dead zones do the radios loose the control channels and go "out of Range"? If so then changing it to Analog from Digital would show no difference to the end user as they would be using the same CC. If it just audio quaity, then yes in some situations they might see some improvement, but with the more updated vocoders I find the coverage to be quite equal, if not better with digital.

Mark

[Retired911Guy]

Mark,

Thanks for the thoughtful reply, took a while to get back on this, got together with the fire chief last night and discussed this.

Think we came up with what the prom is, our county is divided my mt ridges between our eastern and western areas of the county.

The eastern area which the urban area (approx qtr million pop) is only about 30 miles long south to north, and Zero to 6 miles wide east to west. The zero part being water and the 6 part being the mt ridges to the west side of the county.

The eastern area has many mts, ridges, valleys, canyons, etc from south to north that make radio comms difficult.

We had low band simplex prior to this UHF P25 system and it worked very well, when Motorola & GE stopped making low band the county admin people panicked and decided we needed a new countywide P25 system. They were at least smart enough to realize that 800 wouldn't work at all here, so they went with 400 (on low band we had 3 mt top tx-rx and it covered all, the UHF we 6-7 site and covers about 80%).

Unfortunately we are in the San Francisco bay area and not many UHF freqs were available so they had to reuse the freqs on six sites in the 30 miles long area.

They put the sites at lower elevations with lower output wattage and set the mobiles to lower levels. The chief says his mobile is set for 10 watts and the tx site is set for 25 watts. The county radio shop says that the wattage of the sites, nor the mobiles can be turned up due to interference with the other sites reusing the same freqs.

So you can see where the higher lever tx sites would be able to hit the mobiles, but the mobiles would at 10 watts would not be able to get back to that site.

The radio shop had requested 10 new freq sets from the FCC, but they were in the conventional pool rather the trunking pool so the FCC denied their license request. So sounds like we're stuck way...

Dave

[wayne_h]

Originally Posted by Retired911Guy

System Voice: Analog and APCO-25 Common Air Interface <------- Look at this

FWIW, it indicates analog because a very small number of TGs are configured that way as they send signalling data (telemetry) to open up devices, trigger alerts at stations, etc. MERA does not operate with any analog voice TGs and probably can't be persuaded to.

I agree with the others regarding P25 and analog. Using analog isn't a cure-all.

[Retired911Guy]

Originally Posted by wayne_h

FWIW, it indicates analog because a very small number of TGs are configured that way as they send signalling data (telemetry) to open up devices, trigger alerts at stations, etc. MERA does not operate with any analog voice TGs and probably can't be persuaded to.

I agree with the others regarding P25 and analog. Using analog isn't a cure-all.

Hi Wayne,

I was aware that MERA was using the analog for station alerting and knox box release, and that they probably can't be persuaded to change to analog. We were thinking more along the lines of just one or two TG that were analog could help in the bad areas, but now that the chief has told me his mobile only puts out 10 watts I too don't think it help at all.

The most upsetting thing for the chief is, he sits on the MERA board and the other members (including the PD chief in the same area) are in favor of doing something to fix the problem, the radio shop says they can't fix it without about 10 more freq sets, which are not available in our area.

The MERA system is also so overloaded that every agency is complaining about system busy beeps, it made the local paper in the form of a cartoon of a PD car trying to talk to dispatch with tin cans and a roll of string.

MERA did obtain 5 new freq sets by buying them from FleetTALK but plan to use those just for the overload problem.The Fire Chiefs' Assoc has grabbed up all the old VHF DPW and EMS channels in Marin and converted them to a VHF Fire system for MERA failure/overload and out of county mutual aid units system.

I will post them within a day or two in the Bay Area forum.

Thanks for the reply.