change in MARCS freq

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wa8pyr

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Has anybody heard about the change of frequency from 800 to 700?
They are not exactly changing frequencies so much as combining. The new system being constructed (MARCS-IP) currently operates on 700 MHz and will replace the existing system (MARCS) which uses 800 MHz frequencies; the 800 MHz frequencies will then be moved to the new system.

Since the new control channels are all on 700 MHz, you must have a P25 capable digital scanner which is capable of trunking 700 MHz as well as 800 MHz.
 

wa8pyr

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When will they combine?
The new system is supposed to be fully on line by early summer of this year. Existing users will then start to migrate to the new system and once they're all moved (about a year), the old one will go away.

However, if everyone gets migrated sooner, the old system could go away sooner.

The new system will continue to use 700 MHz control channels, so all the 800 MHz frequencies will do is increase voice capacity.
 

firemantom26

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The new system is supposed to be fully on line by early summer of this year. Existing users will then start to migrate to the new system and once they're all moved (about a year), the old one will go away.

However, if everyone gets migrated sooner, the old system could go away sooner.

The new system will continue to use 700 MHz control channels, so all the 800 MHz frequencies will do is increase voice capacity.
Thanks for the info. What is the advantages of this new system over the older MARCS system?

Tom
 

W8RMH

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The main advantage of the new system is it is state-of-the-art "IP" (connected via the internet). Also it is a P25 digital system, whereas the old system is a Motorola Type II system which uses digital voice, plus the new system will have the ability of TDMA Phase II, however this is not being used yet at this time.
 
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firemantom26

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The main advantage of the new system is it is state-of-the-art "IP" (connected via the internet). Also it is a P25 digital system, whereas the old system is a Motorola Type II system which uses digital voice, plus the new system will have the ability of TDMA Phase II, however this is not being used yet at this time.
When you say IP (connected via the internet) what does this mean?
 

budevans

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When you say IP (connected via the internet) what does this mean?
The short version, P25 systems can connect to each other using the same internet standard protocols that computers, VOIP, etc.. use. So MARCS-IP (P25) can connect to a County P25 system or systems.

Here's the Wiki definition: The Project 25 Inter RF Subsystem Interface (P25 ISSI) is a non-proprietary interface that enables RF subsystems (RFSSs) built by different manufacturers to be connected together into wide area networks so that users on different networks can talk with each other.
 

budevans

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Will the same radios handle MARCS/MARCS-IP or will agencies be buying yet more new equipment?
It depends on how old the equipment is. If I'm not mistaken most Moto XTS radio's purchased since the mid 2000's should work (at least for Phase I FDMA). Newer radio's like Moto ATX can handle both FDMA and TDMA.
 

wa8pyr

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When you say IP (connected via the internet) what does this mean?
Sites, controller, consoles and so forth for a single system are all are connected via standard Internet Protocol using routers, switches, firewalls and so forth. Old systems had all that connected via dedicated telephone or data lines ("circuit switched").

In addition, Internet Protocol can also be used to connect different P25 systems together for interoperability.
 

wd8chl

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And before anybody gets the wrong idea, no, this does NOT mean that the sites are connected over the internet (that would be VERY bad!) It's still a closed network, some might be leased lines, some microwave, some could be other source. But NOT internet that you and I know.
 

budevans

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And before anybody gets the wrong idea, no, this does NOT mean that the sites are connected over the internet (that would be VERY bad!) It's still a closed network, some might be leased lines, some microwave, some could be other source. But NOT internet that you and I know.
Actually it is the Internet that you and I know. The old dedicated switched lines (T1 & T3) are (over priced) left overs from the last century. Metro Area Ethernet Networks and IP/VPN solutions are the cost affective (closed network) alternatives that have been deployed since the mid to late 90's.

Sorry, didn't mean to get off topic. But as a retired Director of IT, I couldn't let that post go without a response.
 
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