Once you have the basic hardware and software functional, you’ll quickly find the limits to those technologies.

Both vendors suggest (or require in the case of Kenwood) a router that can support VPN’s and connections between every repeater that is to be connected too via a specific connection… Each software only support 16 IP addresses, so you can quickly exceed that limited with just a very small network.  And out of the box, both systems require a fixed IP address, again as it applies to Amateur Radio a very limiting feature.

While at the RF side, both vendors are inter-operable, that’s pretty much where the interop stops.  Neither support the same protocol over the Internet and neither protocol is covered in the NXDN specification.  As a result, we’ve had to reverse engineer those protocols to allow us to extend the features.

Enter the NXREF (NXDN Reflector), it’s a simple piece of software that runs on any form of Linux platform (except for the one in the repeaters which we don’t have access too).  The job of the NXREF is to take information from one repeater and send it to the others.  By doing it this way, any given repeater only needs to know about one IP address and we can overcome the limit of 16 repeaters being able to talk back and forth.  However we didn’t stop there.

Below is a simple listing of the features that we’ve enabled so far.  These are unique to the Icom for the moment, but I’ll cover that in another post.

– 200 IP address. While just an arbirary limit, we do have a finite amount of time that we can process information before we run the risk of missing or dropping an incoming packet of information from a repeater.  200 IP addresses on any give NXREF should be way more that we actually architect a system to use.

– Cluster support.  The NXREF’s are fully configurable such that they will allow for nesting or clustering.  This is only limited by our imagination.

– STEALTH IP support. This is support for an IP address that may be behind a NAT’d firewall, one that has a DYNAMIC public address and or one that may have a PRIVATE public IP address. There are configuration options that can be turned on to set a *heartbeat* interval and allow data to move between the Repeater and it’s STEALTH upstream NXREF. This feature is great for running a repeater behind a 4G wireless setup either as a temporary or permanent setup.

– RAN translation – This is a very early feature, but it allows a repeater or a group of repeaters to be on a different RAN code than the primary one. As a packet transitions a NXREF, it’s translated both from and to whichever RAN code it needs for its next hope. While not very efficient, it should also allow for multiple translations to occur if so built or desired.

– Remote Console – a Basic reporting console for local reporting and configuration.

– APRS support. This is a very early implementation.  It will watch for a Data packet, capture the entire GPS string, and then send it to the rotating IP address of the APRS-IS or APRS2 server.

– Talk Group support. This allows for traffic to be segregated between the Local use of the repeater and it’s link to the internet.  When in Local mode, the internet traffic is blocked until an activity timer expires and then at that time, the Linked traffic will again start to be heard.  As we move forward there will be more and more uses for this type of *routing*.

As it relates to equipment that is needed to utilize this technology, I’ll try to give you the basics from both Major vendors.  In either case, make sure you get the right *split*… for the Ham frequencies that you are going to utilize.  I’m not going to go into the pros and cons of this technology, I’ll leave that to your investigation.  Suffice it to say at the highest level, it supports both analog and digital on the same hardware, that part is fairly seamless. It will only support digital over the Internet connection, there is not way to deal with anything but the digital version when linked via the NDXN linking… Each repeater has a DB25 connector on the back which allows connection of other peripherals.  In fact all of my repeaters also have AllStar Link connected to them so they can link in either Analog or Digital mode.

Icom – http://www.icomamerica.com/idas625/
– IC-FR5000/6000 repeater, these come in one of 2 flavors. either the model numbers listed which gets you a full rack size unit with a nice display and buttons and knobs, or the UR-FR5000/6000.  The later is the module that is inside the rack case, it doesn’t have the display, buttons or knobs, but it will also save you about $500 over the price of the one with.  There is no other differences, the same software, programming etc is utilized to make just the module work.  These are very small, about the size of a hard cover book, but about 4-5″ thick.  They both are 50W output at 50% duty cycle and 25W at 100%… with other levels of power setting available through programming.  The 5000 being the VHF version and the 6000 being the UHF version.

– UC-FR5000 linking board – this is a small Linux based computer that is mounted inside the top of the repeater or module above. It has an Ethernet connection point and 2 other ports for simple connection to other modules, repeaters, radios, etc.  (we won’t go into the later as we don’t use those)

– CF-FR5000MC Multi-Site Conventional Linking compact flash card.  This includes the basic software that is utilized to get the Icom repeaters on the internet and at a basic level of connected to the WW NXDN network.

That’s it for Icom, if you shop hard, you can usually find the above for around $1000-$1100 all in.

Kenwood – http://nexedge.kenwood.com/
– NXR710/810 – You don’t need the 700 or 800 models, while almost 2X the price, they include no feature that would be appropriate for Amateur Radio.  There is no module only version of the Kenwood that’s sold specifically that way.  The 710 is the VHF version the 810 is the UHF version

– KTI-3 – this is the internet connection module for the Kenwoods, it has Ethernet and what they call N_SYNC ports, the latter being a form of RS-485 and are used for interconnection to other equipment similar to the Icoms.

There is no Compact flash card for the Kenwoods, that is included in the software functionality of the KTI-3.

Both of the above will require the Icom or Kenwood programming software and cable, these are easily found through other Ham groups that may be supporting the technology or through your favorite ham friendly dealer.

Note, all of this equipment is Part 90 certified, and as such, while it supports 25khz spacing and 5khz of deviation today, the Mandate in that space is going to require the vendors to limit it to 12.5khz spacing and 2.5khz deviation on January 1 in the US.  We don’t know what implications that will have for analog usage going forward, but will keep you posted as we learn that.

Thanks to Bill – KI4SWY for pulling together and hosting this site!!

While this is just the starting post, I’ll attempt to go back through time and catch up on the developments that have taken place so far. As well as capture some of the information shared to date.

For the newcomers. We are attempting to create a WW NXDN network for Amateur Radio. Given the prices of the NXDN equipment and the fact that they will do analog as well as digital it simply makes no sense to look anywhere else. Even at list commercial prices, this equipment is cheaper and more robust than other new commercial equipment and much simpler to maintain and support than the aging equipment that Hams normally use.

Both Kenwood and Icom support the technology and the with the NXDN-FORUM now releasing the full specifications, it should just be a matter of time before others do as well.

Until you hear and experience the benefits of NXDN, it’s hard to describe, but in a nut shell. A 20-30% extension to your existing coverage footprint, both analog and digital support seamlessly for simple transition and the added benefit of being ready for the the 6.25khz spacing that we’ll all be forced too at some point.

Package that up with existing amplifiers, duplexers and antennas, it’s a very simple drop in upgrade with lots of room for expansion.

Then along comes the internet and connecting these repeaters together via the internet. Both Icom and Kenwood allow that, but their methods are extremely restrictive and cumbersome hence the need for this blog.

How do you take a WW network of repeaters and connect them together such that you don’t have a monolithic network, you have a dynamic one. And how do you do that easily and inexpensively.

That’s what we are all about!

Follow along, it should be a fun ride…