Hi Ned,
Your picture of the future FT8 pileups of the top-ten DXpeditions is very realistic but very scary. As a DX'er, I realize that
none of the usual pileup cracking techniques that I use in CW and RTTY are going to work in this scenario, and I will have very
little control over the things. All I will be able to do to improve my chances of a QSO is monitor my TX frequency and QSY when
necessary to stay in the clear. This is the nature of FT8: one cannot pick the right time for sending his call since the time
intervals are fixed, and one cannot pick the right frequency because all frequencies are decoded simultaneously. Perhaps
multiple 2-kHz slots will add an extra dimension to the picture and allow the DX'ers to do something intelligent.
On the bright side, the FT8 mode is not only capable of multi-channel reception, but, with proper modification of the software,
it could do multiple transmissions as well. It is possible to send, say, 10 messages within the 2-kHz slot at the same time, and
improve the QSO rate by a factor of 10. A 400 W linear amplifier will easily transmit 10 x 40W signals if it is linear enough. A
rate of 1000 QSO per hour, or more, may be possible, which will beat all other Ham modes.
73 Alex VE3NEA
P.S. Thank you for the RTTY QSO with VP8STI and VP8SGI! I tried different techniques in these pileups, but tail-ending was the
only one that really worked. I used the waterfall display of CW Skimmer to track your tuning pattern, perhaps that's why I
succeeded with my modest station setup.
On 2017-08-20 12:25, Ned wrote:
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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