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FT8 Announcement

To: All RBN Node-Ops and Users

Subject: FT8 spots

As some may be aware, we've been debating for some time about whether the RBN should handle FT8 spots. A few weeks, ago, several prolific RBN nodes began spotting FT8 signals, using the combination of WSJT-X and an unreleased Aggregator, version 5. The purpose of this limited Alpha test was to get a feel for the load and other implications of carrying FT8 spots on the RBN; it has been very revealing.

The most striking characteristic of FT8 spots is their sheer quantity. Here are some weekday statistics from one of the US testers:


CW 4294 14%

RTTY 69 0.22%

FT8 26318 86%

Total 30681


CW 4370 13%

RTTY 46 0.14%

FT8 29298 87%

Total 33714

Whether due to the startling popularity of the new mode, or to the ability to spot stations at 22 dB below the noise level, it seems obvious that adding FT8 spots to our spot flow could have a huge impact on the infrastructure of the RBN. These numbers suggest that if only 20-30 RBN nodes added FT8 spots, those spots could outnumber the total CW and RTTY spots being delivered by the 140-150 nodes currently active on the network, doubling the total required throughput.

We frankly don't know whether the RBN servers will be up to the task, so we decided we had better find out before the fall contest season is upon us. Accordingly, we are taking the following steps on a Beta test basis:

  1. Effective immediately, the RBN’s current spot feed (telnet, port 7000) will be repurposed to handle only CW and RTTY spots. port 7001 will be set up for FT8 spots only.
  2. Operators of "retail" DX clusters are encouraged to offer the option of RBN spots with and without FT8 spots, as they now often give users a choice between spot streams with and without "Skimmer" spots.
  3. A Beta test version of Aggregator Version 5 that can handle FT8 spots received from WSJT-X will be made available on the RBN web site, along with instructions on how RBN node-ops can configure their nodes to spot FT8 on one or multiple bands. Note, please, that doing so will not interfere with your ability to continue spotting CW and RTTY.

We will closely monitor how the RBN servers handle this new load, as more and more nodes begin sending FT8 spots. We also reserve the right to take steps as necessary to protect the core mission of the RBN, including shutting off the FT8 stream on major CW and RTTY contest weekends or, in an extreme case, discontinuing spotting of FT8 altogether. Even in a worst case scenario, FT8 spots will continue to be carried by PSKReporter.

We hope we're not doing this in a vacuum. The RBN team has been collecting the views of contesters and DXers on this, and we hope that we're headed in the right direction. Feel free to let us know what you think of this experiment.


The RBN Team (KM3T, N4ZR, PY1NB, SV5SJ, W3OA)