[HamWAN PSDR] 1.2GHz to Paine [was: 44.x.x.x HamWAN network at Paine]

Tue May 27 16:59:30 PDT 2014

ID-1 simply encapsulates an Ethernet frame behind a D-STAR header.  The
header has some correction, but the Ethernet frame is not corrected by
D-STAR.

------------------------------
John D. Hays
K7VE
PO Box 1223, Edmonds, WA 98020-1223
<http://k7ve.org/blog>  <http://twitter.com/#!/john_hays>
<http://www.facebook.com/john.d.hays>

On Tue, May 27, 2014 at 4:28 PM, Bart Kus <me at bartk.us> wrote:

>  There's no protocol I'm aware of that implements these features on top of
> ID-1.  You'd need the ability to receive corrupt frames from the ID1 to
> allow the use of FEC.  How does the ID1 handle corrupt frames?  Is there a
> CRC or something in the framing?  For ARQ, you could keep the TX retrying
> until it hears an ACK or times out.  Custom software would be needed, or
> perhaps pppd can do such tricks, I dunno.
>
> Did you hear any signal when you listened with an FM receiver?  Can you
> use an RTL-SDR or equivalent to see if there's any signal present?
>
> --Bart
>
>
> On 5/24/2014 8:36 PM, Dean Gibson AE7Q wrote:
>
> That's what I figured ("features [that] are common to all WiFi systems");
> it just made sense (although that is not always determinative!).
>
> So, my next question:  Is there an available tunneling protocol that
> employs those features?
>
> Note that with the ID-1 in the *one watt* setting (same omni antenna), I
> can use the 1.2GHz KB7CNN repeater 35 miles away on East Tiger mountain,
> with no noise in the FM signal. The link to Paine (5 miles away) was tried
> at max power (ten watts) on both radios.  I tried two different frequencies
> (that's the beauty of being able to control both radios from one
> location!): 1.250GHz and 1.249GHz (I listened on both in FM mode), with no
> significant difference.  So, in my opinion, it's a path problem.
>
> On 2014-05-24 13:13, Bart Kus wrote:
>
> 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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