Wow that sucks.  :(  Is the signal level just too low?  Is it a matter of interference?

And yeah, I can confirm that the microwave stuff we use includes both FEC (at up to 1/2 rate) and an ARQ system (look at "hw-retries" setting).  These features are common to all WiFi systems too, and they're just carried over into our NV2 TDMA system.

--Bart


On 5/24/2014 10:19 AM, Dean Gibson AE7Q wrote:
Scott Honaker and I have moved forward on this project:
  1. We have installed a gateway (Linksys BEFSR41) between the ID-1 and the internal ARES/RACES subnet (not 44.x.x.x) of the DEM.
  2. We have installed a Digi "AnywhereUSB" box to give us remote access to the ID-1's USB port, and thus remote control of the ID-1 radio.  This not only allows multiple use of the ID-1 (which has useful 1.2GHz FM and digital voice modes as well as Ethernet data), but provides for remote frequency agility and a diagnostic capability.  This works beautifully (eg, to search for and use a low-noise frequency)!

Unfortunately, what does not work very well, is the RF portion of the connection.  PINGs failed at a rate of over 99% when using the 1.2GHz antenna at the 70 ft level on the tower, so we swapped the antenna with the one used for the Icom 1.2GHz repeater (which wasn't seeing any action anyway) at 100 ft.  That made a "dramatic" improvement, as PINGs now only fail at a 98% rate (depends upon the time of day, etc)!

Antenna comparison between 1.2GHz and 5.9 GHz for the two sites:

  1. On 1.2GHz, both antennas are omni-directional.
  2. At the DEM, the 1.2GHz antenna is now at the 100' level, whereas the 5.9GHz antenna is at 150'.
  3. At my home, the 1.2GHz antenna is about 10' above the 5.9GHz antenna, and it's on the same line-of-sight path.

Note that voice communication between the two sites using the two ID-1 radios, is fine (there is a slight bit of noise on FM).

The big difference, in my opinion?  I'll bet that the wireless protocol used by the MikroTik radios includes an aggressive error correction and retry protocol, whereas the ID-1 is like a piece of Ethernet cable, and thus relies on the standard TCP/IP retry mechanism.  The TCP/IP protocols, while "unreliable" in the technical sense of the term, require a higher overall reliability than a typical raw wireless connection.

What this says (and I'm a bit surprised to note this), is that sites considering using ID-1 radios for data communications, may find that even with the tighter siting requirements of 5.9GHz, that the latter may be more successful (whether or not part of HamWAN).  In addition to being a lower-cost radio with a much higher data rate, the MikroTik radios offer a built-in router, which can obviate the need for a separate router.

-- Dean

ps: The callsign and digital code filtering features of D-Star that we previously discussed, are not available (greyed out in the software) for digital data mode.  Huh?  Another fine example of software of the "seven last words" of poor program design: "Why would you want to do that?"



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