Sunday, August 12, 2018

LARC proposes a new DMR repeater for Syracuse

Pretty cool news! The Liverpool Amateur Radio Club is investigating a a DMR repeater and providing DMR tech training sessions In Syracuse.

Press release from LARC on their DMR plans:

Liverpool Amateur Repeater Club (LARC) Plans for Digital Mobile Radio (DMR)
August 6, 2018

DMR has been a hot topic of late and the LARC Board of Directors (the “Board”) has engaged in many discussions on the topic over the last year.  At the August 6 board meeting, the Board passed a motion to bring to the membership at the September meeting a funding authorization, pending successful evaluation (see below), for the purchase, configuration and deployment of a LARC DMR repeater for the greater Syracuse area.  If one looks at some of the DMR footprints in Upstate NY, there is a very noticeable DMR void in the Syracuse area.  Repeaters exist both to the East and West of us.  The Board believes now is an opportune time to embrace the technology as it is clearly here to stay.

The Board has reached out and met with several fellow hams with extensive experience in design and implementation of DMR repeaters.  Very early in that process, it was apparent that creating a successful DMR presence was much more than standing up a conventional repeater.  DMR is not about RF.  It is a highly sophisticated Information Technology project.  Anything installed must be fully compatible with an existing infrastructure.  The programming of compatible radios is, again, highly technical.  One must fully understand both sides of that equation for successful and efficient implementation of a DMR repeater.

There are two primary DMR networks in the amateur radio DMR community, DMR-MARC ( and BrandMeister (  There are some key differences in the networks but suffice it to say, bridges exist between both.  Much of the current local DMR community is using BrandMeister via hotspots (e.g., SharkRF OpenSpot, Pi-Star, etc.) as no local DMR repeaters exist. DMR-MARC on the other hand, does not permit hotspots and is purely repeater based for local traffic with Internet as the backbone for inter-repeater traffic.  Within the DMR-MARC network C-Bridge provides for the IP interconnectivity of DMR-MARC repeaters.  It is important to note that the repeater in question is capable of running on either network. It becomes a “simple matter of programming” as the saying goes.

We were fortunate to obtain a Motorola SLR5700 DMR repeater, at no cost to LARC, for experimentation and educational purposes.  If approved by the membership, LARC will purchase the repeater for production deployment.  Several LARC Board members have formed a working group to integrate all the necessary pieces and create a temporary installation for evaluation purposes.  The Board welcomes any DMR knowledgeable working group membership from the club.  We intend to utilize the DMR-MARC network utilizing the C-Bridge network in Upstate NY which will integrate well with the Upstate NY DMR-MARC infrastructure. 

As the working group moves forward with DMR evaluation and testing, the 443.3 machine will be unavailable as testing of the DMR repeater will leverage 443.3 site, frequency, duplexers and antenna.

Should this evaluation prove successful, the group will present their experiences and recommendations to the general membership at our September meeting.  All hams, members or not, are welcome to attend that meeting.  Should the general membership recommend approval, LARC will then purchase and install a permanent DMR repeater in Syracuse.  Additionally, should the concept be approved, we intend to implement a comprehensive educational program for all hams.  This will explain the infrastructure, provide guidance in radio programming, and offer a programming service for most DMR radios. There are some technical considerations that the Board must consider and, in some cases, membership insight must be considered.

·         Location: The DMR repeater will be a UHF repeater. One option is to replace the 443.3 Fusion repeater with the DMR repeater as that site already has antenna, duplexers and is a prime repeater location.  It is important to note; reliable cell service is important as a cellular modem is required to provide the back end inter-repeater C-Bridge connectivity.  The current 443.3 site has a new AT&T cell tower just outside the repeater building and we get 5 bars inside the building mitigating the need for an external cellular antenna.  The other option would be to leverage the Cazenovia location which currently is VHF only.  Cazenovia coverage is not as good as the 443.3 site and an additional set of duplexers and an antenna would be required. LARC does have a spare UHF duplexer and will have to test it to assess health.  A third option is to relocate the 443.3 machine to Cazenovia and stand up DMR at the current 443.3 location.  This option would require coordination with UNYREPCO (Upstate NY Repeater Council), the frequency assignment body for Upstate NY repeaters.

·         Code Plug Management: DMR radio programming is 100% dependent on use of “code plugs” which provide the radio with its “personality”.  Although code plugs all provide the same capabilities, each vendor has their own software for code plug. The Board envisions a body of subject matter experts that can assist members in programming their radios for those that do not have experience in code plug management.

·         C-Bridge talk group administration and management: As with any complex managed infrastructure, membership may have many wants and/or desires regarding talk group management. Given this is new technology to us, the Board and ultimately the DMR repeater trustee(s) will have to adopt some form of Request for Change (RFC) process by which membership requests can be addressed.  As was stated earlier, this is less about RF and more about Information Technology.
I cannot express the importance of understanding that, at this point, all of this is an experiment.  Nothing will be permanent until the General Membership votes to support this energetic project.  We realize that there is already a plethora of misinformation and unsubstantiated rumor.  Hopefully, this will clarify the misconceptions and offer anyone interested the opportunity to participate and provide their observations.

Thanks for your continued support in advancing Amateur Radio in Central New York.


 LARC Board of Directors

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