Hi Take,
Thanks again for sharing your opinions. Perhaps your ideas for a
single-carrier OFDM mode for high capacity (more than 10x) FOX station
(and a congestion control mechanism applicable for emergency and
disaster communication) will become part of some program in the future.
-- 73, Joe, K1JT
On 5/15/2018 2:09 AM, Tsutsumi Takehiko wrote:
Hi Joe,
Thank you for providing your comments.
My “development schedule is controlled by DXCC marketers” comes from
Bill’s (I am sorry not to mention as Bill in my previous memo. It is my
typo.) comment, i.e. “but overall under time pressure to get the
modeworking” and your February 02 First DxPedition Mode announcement
saying “We have been working together with members of the Baker Island
(KH1/KH7Z) group. Their planned expedition will take place in June-July
2018.” I also have not realized such kind of liaison arrangement between
weak signal favorites and conventional DX pedition society.
If we can maintain development schedule for ourselves, I strongly
suggest you will pause the project now and announce “Call for Proposal”
to the floor. Proposals stated by me and Bill in this thread is all
coded in the past WSJT programs, such as JT65, WSPR in the past. Thus,
they are proven technology for us.
Yes, it will be great to widen the door to participate the development
activity from the core development team to WSJT-X mailing list
participants. Then, I will propose charming “single-carrier OFDM to
realize high capacity (more than 10x) FOX station and congestion control
mechanism which is applicable for the emergency and disaster system
such as earthquake, Tsunami, wildfire, flood as well as Dxpedition.
I hope you will make your action now.
Regards,
take
de JA5AEA
Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows 10
*From: *Joe Taylor <mailto:j...@princeton.edu>
*Sent: *Tuesday, May 15, 2018 9:07 AM
*To: *WSJT software development <mailto:wsjt-devel@lists.sourceforge.net>
*Subject: *Re: [wsjt-devel] DxPediton Mode Development utilizing Weak
signal favorites Resource
Hello Take,
On 5/14/2018 7:14 PM, Tsutsumi Takehiko wrote:
> Hi David,
>
> Thank you for disclosing and sharing the motivation of the current FDM
> frame architecture of Dxpedition mode.
I believe you are responding to comments made by Bill (G4WJS), not by
David (K2LYV). Bill's comments were made in the spirit of sharing
information, since you had expressed some interest.
> Then, the following is my words to the person behind you, not you.
>
> It is obvious that DxPedition mode specification is written for high
> power conventional DX peditionists and development schedule is
> controlled by DXCC marketers.
There is no truth to your speculation that our "development schedule is
controlled by DXCC marketers". Whatever schedules we maintain are
determined wholly by our own interests and our available time for
playing at Amateur Radio.
We are perfectly aware that the current FT8 DXpedition Mode is not
necessarily the best long-term solution to all tasks it addresses. It
is a good solution, however. Development and testing could be completed
in reasonable time, with resources at hand; and with the exception of
one new message type the mode is backward compatible with normal FT8.
This guarantees that a knowledgeable base of potential users is
available and ready to use it.
> Therefore, it does not make sense to use
> the resource of weak-signal favorites for system design, code
> development, operation frequency allocation and field tests.
> > Regards,
>
> take
>
> de JA5AEA
Thanks for sharing your opinions. We are always happy to receive
comments and advice from other radio amateurs. Perhaps you will be the
one to design and develop an even better solution!
-- 73, Joe, K1JT
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
> ------------------------------------------------------------------------
> *From:* Bill Somerville <g4...@classdesign.com>
> *Sent:* Monday, May 14, 2018 4:46:54 PM
> *To:* wsjt-devel@lists.sourceforge.net
> *Subject:* Re: [wsjt-devel] Signal variation during latest test
> Hi Take San,
>
> you are quite correct and a different protocol using a higher symbol
> rate for the Fox has been considered, this would allow a single constant
> envelope signal to be transmitted without any need for power adjustments
> to compensate for IMD products. It also has another benefit in that the
> Fox callsign need only be encoded once for any transmission period
> rather than the current protocol where each individual message slot
> needs messages including the the Fox callsign or a hash representing it.
> This last encoding gain is indeed attractive along with the constant
> envelope attribute but overall under time pressure to get the mode
> working, developing a whole new source encoding and protocol for Fox
> messages was considered too big a step. For now the Fox messages use
> near identical source encoding as other FT8 messages and are sent at the
> exact same symbol rate with identical FEC and checksum attributes, the
> only difference other than message content is the use of one of the
> three spare payload bits added when FT8 was initially developed.
>
> 73
> Bill
> G4WJS.
>
> On 13/05/2018 23:31, Tsutsumi Takehiko wrote:
>> Hi Dave,
>>
>> I do not have any intention to hijack your mail but I hope you allow
>> me to state again that we should not concede "signal would drop around
>> 12dB when 3 channels were used" as weak signal favorites.
>>
>> By my simple spread sheet calculation, we can achieve 4-3dB
>> degradation range at 5 channels maintaining symbol length longer than
>> 64mS, which is sufficient for multi-path interference guard under
>> shortwave ionospheric propagation model, with simple single carrier
>> TDM frame architecture. Keep in mind that RTTY or PSK31 symbol length
>> is around 22mS - 32mS. Thus, I do not see any significant reasons to
>> adopt FDM frame architecture.
>>
>> Regards,
>>
>> take
>>
>> de JA5AEA
>>
>> On 5/13/2018 1:53 AM, David Birnbaum wrote:
>>> Hi Joe
>>>
>>> Bands were not helpful this morning, but I did notice something that
>>> might be important.
>>>
>>> Aside from the QSB there appears to be some variation in your
>>> transmitted signal even if only one frequency is being used. I would
>>> see K1JT call CQ and then the response with a RR73; K2xxx -yy <K1JT>
>>> response would be down about 3 dB. I did see that the signal would
>>> drop around 12 dB when 3 channels were being used by the Fox which is
>>> expected but I did not expect to see a response with a single channel
>>> being down relative to a CQ.
>>>
>>> dave
>>> k2lyv
>
>
>
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