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GatesAir FMXi 4g Importer/Exporter

March 15, 2021

Corporate mandate: Install this on your station. Reason: Old Importer runs Windows XP, security reasons.

I accept the reason, but I do not understand the mandate for a specific manufacturer’s equipment, especially when my transmitter is a different manufacturer. Making a GatesAir FMXi 4g work with a Nautel NV20. Well, I do, but money should not always be the answer to everything.

This can be done. What I did discover is quite interesting, and is not a very good way to determine proper operation. To make this whole picture come together imagine your choices of installation location for a combination Importer/Exporter. If you put it at the transmitter site, the Exporter sits on its own subnet with the Exgine. Now you need to get your audio for your HD2s and 3s to the site, in addition to metadata. If you install the combination at the studios, then you have your Exporter and Exgine on different subnets, or you are forced into VLAN fun. I have been running Exporters from the studio site successfully for years, so it can be done, but the FMXi gave me quite a start.

Per the manual, I configured the management NIC and the E2X NIC on the FMXi. I saved the PSD/IMP NIC as the last thing to worry about. When configuring the device GatesAir wants you to configure a routing table so traffic knows where to go. E2X is a simple UDP stream, so this should be simple enough. No HD. Head scratch. Example: E2X NIC given the 192.168.10.10 address. Exgine is on 192.168.20.X network, so the routing table is configured to send data to the 20.x network, use 192.168.10.1 gateway. Simple enough. No work. Discussion time #1.

Take the unit to the transmitter site. Basic troubleshooting principles. Drop it on the same subnet. After a quick configuration still nothing. Poked at the Exgine and verify ports are correct. Sheesh, haven’t changed those in so long, but verification away. After about 10 minutes of this, I noticed the FMXi was now happy, Exgine was detected. So, it can talk with the Nautel Exciter and Exgine. Cool. Back to the studios to contemplate why. Discussion #2.

Discussion #2 with Gates revealed a very important, yet minor detail about the Exgine being “detected”. I was curious about how a UDP connection got confirmation that “presence”, as Gates calls it, is determined. The surprising answer was the ARP table. The FMXi creates an ARP table just like any computer or switch. If the Exgine IP address is in the ARP table, then the Exgine is considered present. Guess what? If you are on a different subnet, you will NEVER get that “presence” indication, and your FMXi will report visually that the Exgine is not present.

As I had the FMXi working, as in creating an E2X stream at the site on the local subnet, I knew I could get this to work from the studios, so back to configuration and poking. Again, I made sure the routing table had the route required to get the E2X stream to the site. This time, I kept refreshing the ARP table until I saw with my own two eyes that the gateway configured showed up. Bam, HD was on. Here’s the kicker. The FMXi still reported that the Exgine was not present. So, now I have a box that is working, but reports that it is not. Here’s the proof:

Exgine Fault but HD Carriers on Transmitter

Apparently GatesAir will have to come up with a “better” way to inform the end user that the E2X stream is being sent to where it is designated to go. In all this, I also discovered that the FMXi has no built in diagnostics such as ping or trace route. If I was able to ping from this device I would have confirmation that my route was correct and that the ARP table had correct entries without having to go through these extra hoops hoping to see the HD carriers and hear audio.

There you have it. Intermingled manufacturer devices working together. The Nautel HD Multicast+ was not this difficult to setup. I will address metadata in my next post, as another interesting discovery was made regarding PSD data. Until then!

Cheers!

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