P25 Techs from a Different View

General P25 discussion
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Project25
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P25 Techs from a Different View

Post by Project25 » Sun Mar 04, 2018 5:19 pm

Not too long ago I got to spend some time with a Harris tech. Me being an Astro 25 tech (who's potentially building an Atlas system as well) it was very interesting having the opportunity to sit down and talk differences in systems. For him, they were just getting into adding sites from their primary simulcast system (sub-cells as he put it) in areas where they were lacking coverage. I guess I should also mention, this is city system that has been morphing into a county wide system. On the other hand, I come off of a multi-zoned, multi-band (as in VHF and 7/800) Astro 25 system. It was very interesting for him to hear some of the differences in how the various manufacturers build their trunking systems. One of the greatest examples of this how Harris typically assigns each site a different RFSS where Motorola uses the RFSS for their Zone provisioning. Us having 100+ sites per zone was an interesting concept to him and the functions that need to be enabled on Astro 25 and APX subscribers to allow for site expansion and roaming to and from Zones were different from what they are currently building out.

One of the things we both agreed on however, the MASTR III and MASTR IV receivers aren't the best things out there. It was interesting to sit down and be able to talk about it all. Anyone else had that opportunity to have such a conversation? Potentially good talking points for those attending IWCE this next week as well.
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Re: P25 Techs from a Different View

Post by ASRM » Sun Jul 08, 2018 6:46 pm

Our county is using UHF MASTR III conv. repeaters and has coverage for ####. Almost all the other PD's cover their towns and counties, our county barely covers 2 towns. Sad...
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Project25
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Re: P25 Techs from a Different View

Post by Project25 » Sun Jul 08, 2018 9:58 pm

When I tested a VHF MASTR III and compared it side by side to a MASTR IV I was not all that impressed. Note, my understanding is the only real difference between a MASTR III and IV is that the IV has an optional modem card which allows it to handle P25. In talking with several Harris techs, adding the modem card and upgrading the firmware would allow a MASTR III to be field upgraded to a MASTR IV (similar for the old MTR2000 to MTR3000 field upgrade). For reference though, VHF Quantar's tend to have a receive sensitivity of -122 to -124 dBm in my experience for both 12 dB SINAD and 5% BER. The MASTRs I checked both hit 12 dB SINAD around -112 dBm (these models did not have the optional pre-amps).
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Re: P25 Techs from a Different View

Post by ASRM » Mon Jul 09, 2018 12:10 pm

Interesting that a III can be retrofitted to a IV and gain P25. Of course too late for the county since they went the subscriber route and going StarCom21 here.
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Re: P25 Techs from a Different View

Post by NavyBOFH » Mon Jul 09, 2018 6:51 pm

I have always wanted to have a similar sit-down with various LMR techs/engineers from the different manufacturers to discuss the realistic pros/cons of each brand's products. I have always known a Quantar has a HOT receiver compared to a MASTR, and most of the ham/CERT/private second-hand owners know that as well. However, I wonder what EF Johnson, Kenwood (before the merger), Tait, etc can offer in that ability.

For example, there's a nice and clean TB8100 VHF P25 repeater sitting on eBay forever for $775, while Quantars sit at around $1,700 for the comparable model. I have also seen older EFJ Atlas repeaters running under $600. They seem to be passed up for the typical Motorola brand loyalty, but on paper seem to be pretty similar performers as well.
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