Rich,
I would like to add some perspective of what might happen when what is
called a "Top Ten" DXpedition (a DXCC entity that is in the Top Ten
slots in published need lists...examples being Bouvet and Baker Island
that will be QRV early next year) takes place on RTTY (or any digitial)
mode. Having been the "RTTY guy" on both VP8STI and VP8SGI last year
(both on the Top Ten at that time), the pileups are hard to describe.
RTTY operation on these two DXpeditions was confined to 2 bands,
basically, in order to prevent issues that arise in the use of Clublog
Leaderboard. So the DXpedition leadership opted to limit RTTY to two
bands (30 and 15 meters) in order to maximize the number of ATNOs (All
Time New Ones) on the digital modes. As a result, the pileups were huge
and stayed huge until we left both islands.
When I called CQ the very first day on South Sandwich Island (VP8STI),
the pileup was 30 KHz wide and hundreds deep. I have been in many RTTY
contests and other DXpeditions (27 so far), but I had never experienced
anything like this before. Using MTTY from within N1MM, the logging
application for the DXPedition, it was virtually impossible at times to
find complete calls in the pile. Over half of the time, I had to work
QSOs in the same manner as one does on CW where I would type in a
partial call and fix it when the station would send their report. There
seemed to be few chances for me to use a mouse to pick a call out of an
area on the computer screen. My hands were literally glued to the
keyboard to make QSOs at a high rate. I manually spread the pile by
trying to randomly pick calls across the breadth of the pile to prevent
"tailending". I could never pick out one call in a tailend pile. So,
while I was sending my QSL/QRZ message, I literally spun the dial of the
receiver either up or down to a new frequency to work the next station.
After doing this a while, everyone in the pile stopped trying to tail
end and the rates settled into the best that could be done. FT8 is
perfect for doing this, BTW.
The only real tool in the hands of the DXpedition operator is to spread
the pile until calls could be copied and making it easy for the
DXpedition team operator to briskly sweep the spreadout pile to find
calls. What Rich is suggesting below is spot on. FT8 operation at a Top
Ten DXpedition might only be possible if the operator can make QSOs at a
good rate, otherwise they will go back to RTTY. Rate is king. My fear is
that the piles might get so deep that the decoders produce nothing and
the rate goes to zero. Bad things happen when the rates go to zero on
DXpeditions. Blistering emails and jamming are a few of the normal
byproducts when confidence in the DXpedition team is lost. I am of the
opinion that a Top Ten DXpedition will need more than one 2KHz slot to
thin down piles at times...maybe all the time.
Here are a couple of suggestions...I am a frequent user of FT8 and have
been using JT65 on EME DXpeditions for years, so these are hopefully
framed correctly...
1. Create a DXpedition mode in FT8 (similar to Contest Mode) where the
appropriate information is used in an exchange. I don't think grid
squares are needed. Signal reports are dubious in my mind. Some are
saying that signal report info might be useful in analyzing propagation.
My experience with FT8 so far is that the report has something to do
with SNR in code space, but has nothing really to do with the strength
of the signal in the radio. Propagation models might not really benefit
from these reports, so I am of the opinion that their value is questionable.
2. Create DXpedition roles...either you are the Fox or one of the
Hounds. The Fox sends his transmission in 1st slot, all Hounds in the
second. Maybe other tailoring options set up when you select your role.
3. Create DXpedition "Channels". These are chunks of spectrum that fit
in current radios. 2 KHz might be right. 4KHz works in my K3 but maybe
not your TS-520. So, settle on one. It would be nice if everybody's
radio were an SDR radio and we could define a wider channel, but that is
years away.
4. Make it easy for either the Fox or any of the Hounds to select which
channel to TX in or RX in. Maybe the Fox always stays in one channel and
hounds spread out over one or more channels.
I really think it best for Fox to be frequency agile within a channel.
If not, the whole operation could be brought to its knees with a few
jammers. Another concern that I hadn't thought much about until just now
is pirates. It might be difficult to authenticate the station you work
as being the real DXpedition group and not some bogus station. Maybe
Hounds will listen on their headsets to use audible info to confirm that
the signal "sounds" right like they currently do on RTTY...not sure.
Thanks for reading this far.
73,
Ned/AA7A
One of the ops on the upcoming KH1 Top Ten DXpedition
On 8/20/2017 3:27 PM, Rich - K1HTV wrote:
Additional 20 M FT8 frequencies for DXpeditions & general DX use
------------------------------------------------------------------------------------------------
The question has been posed as to the best frequencies for DXpeditions
while operating the FT8 mode.
Lets focus on 20 Meters, which will probably be the most heavily used
DX band as we approach the bottom of the solar cycle.
From the IARU Region 1,2 & 3 Bandplan documents:
IARU Region 1:
14 060 – 14 070 (200 Hz BW) CW,
14 060 kHz – QRP Centre of Activity
14 070 – 14 089 (500 Hz BW) - Narrow band modes – digimodes
14 089 – 14 099 (500 Hz BW) -Narrow band modes - digimodes
automatically controlled data stations (unattended)
14 099 – 14 101 - IBP, exclusively for beacons
14 101 – 14 112 (2700 Hz BW) - All modes – digimodes, automatically
controlled data stations (unattended)
14 112 – 14 125 (2700 Hz BW) All modes
* * * * **
IARU Region 2:
14060-14090 (500Hz BW) - ALL MODES, DIGIMODES
14100.5-14125 (2700Hz BW) - ALL MODES, FAST DIGIMODES, AUTOMATIC
IARU Region 3:
Considering the dramatic increase in data mode usage on the 20 meter
band, it is recommended that the sub-band for
these classes of signals be 14.070 MHz to 14.112 MHz (with +/- 500 Hz
at 14.100 MHz for beacons), and within that
data sub-band the current practices of traditional data modes may
continue up to 14.095 MHz with 14.095 to 14.112 MHz
being reserved for other data modes including Packet.
- - - - - - -
In IARU Regions 1 & 2, both indicate ALL modes up to 14.125 MHz. Only
in Region 3 are the digital modes recommended
between 14.070 and 14.112 MHz.
For major DXpeditions in Regions 1 & 2 is there any reason why
frequencies above 14.112 MHz can't be used for the FT8 mode by
DXpeditions or for FT8 DXing in general? It has been less that 2
months since WSJT-X software with the FT8 mode has been made available
to the general Ham population. But already the frequency range between
14074.2 and 14076.4 KHz is very often packed with hundreds of stations
simultaniously using that small segment. And the congestion will only
get worse in the months to come, especially when DXpeditions start
using the new digital mode.
I would strongly suggest that serious consideration be given for the
use the FT8 mode on 20 Meter frequencies between
14.112 and 14.125 MHz.
73,
Rich - K1HTV
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