That sounds like a jolly good idea....but why only 7dB improvement? Wouldn't
you recover all the loss from 5 slots=-14dB?
And how about increasing to 600Hz width and 10 slots? Another 2X would
probably be worth it and still stay below 1000 offset.
Just think of how many QSOs they could have done at full power and 10 slots.
For the few times I saw them only saw 2 slots running.
de Mike W9MDB
On Tuesday, July 3, 2018, 8:27:13 AM CDT, Joe Taylor <j...@princeton.edu>
wrote:
Hi Grant, Take, and all,
I think the Fox operators are learning to manage their pileups
reasonably well. I listened and watched the show on 40m this morning
for ~2.5 hours, with good signals from Fox. The Op was doing a good
job: he was using 2 slots, thereby keeping the queue moderately short.
He must have been running ~100/hr.
Most Hounds are learning the proper operating techniques, too. On 40m
today there were very few calling below 1000 Hz or on the wrong sequence.
I am looking forward to "de-briefing" the Fox operators after they
return home!
As long as we use the present scheme of frequency-multiplexing multiple
slots, there's not much we can do about power levels. Fox is already
transmitting the strongest undistorted signal he can generate, in each
slot. It's up to the operators on both sides to watch the signal
reports, recognize and take advantage of the dependence of signal
strength on Nslots, and decide accordingly when to call.
There exists a potentially attractive design alternative. Rather than
transmitting up to 5 signals spread over the range 300-600 Hz, we could
generate one signal with information payload large enough for (say) 5
QSOs. Of course this would require more bandwidth -- indeed, roughly
the same 300 Hz total bandwidth as Fox uses presently. But the
generated waveform would be constant-envelope and therefore could use
the full (Average=PEP) capability of the transmitter. This would yield
a link-budget improvement of 7 dB at NSlots=5.
-- 73, Joe, K1JT
On 7/2/2018 11:09 PM, Tsutsumi Takehiko wrote:
> Grant,
>
> I am thinking that it is reasonable interpretation to consider CQ
> message, i.e. “CQ, CQ EU, CQ NA, CQ AS…..” is our “paging message” or
> “congestion control message” to allow certain group to send their access
> message such as “KH1/KH7Z JA5AEA PM95” at access channel i.e. above
> 1,000Hz~4,000Hz. However, the power should be limited to the minimum
> power to be able to communicate at individual message exchange as I
> said. However, CQ period should not be fixed and it should be only
> transmitted when “QSO queue” is becoming empty. (I think this type of
> information is described in FT8 DXpedition Mode User Guide)
>
> Well, for JA wise, KH1/KH7Z is the first exposure to DX Pedition Mode
> without any trial opportunity, so, it is a fan to see the windows in
> WSJT-X and imagine what we should do next.
>
> Yes, It may be the time to wait the chairperson’s summarization and for
> a while, we should chase KH1/KH7Z last day operation. I am expecting
> they will expand their service at high and low bands.
>
> Regards,
>
> take
>
> de JA5AEA
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
> ------------------------------------------------------------------------
> *From:* Grant Willis <vk...@bigpond.com>
> *Sent:* Tuesday, July 3, 2018 7:05:09 AM
> *To:* 'WSJT software development'
> *Subject:* Re: [wsjt-devel] Observation on Expedition Mode
>
> Everyone,
>
> The thread hi-jacking has been interesting but time to bring it back to
> my original question perhaps please?
>
> Take,
>
> Yes – the problem with varying power is I might hear him CQ when he
> transmits with only one channel but when -14dB of power reduction
> results from 5 responses I could loose him )and did do so several
> times). The CW and the power of the channels I am listening to of him
> calling everyone else needs to remain constant as an individual channel
> otherwise this wildly varying link budget just breaks contacts.
>
> A worthy modification would be to resolve the varying individual channel
> power dilemma I feel. I would be interested in Joe and Steve’s thoughts
> on this?
>
> Regards,
>
> Grant VK5GR
>
> P.S. The CQ calling is nice – and KH1/KH7Z could make better use of it
> and free text to control their pile more – but blocking people calling
> as proposed by others here until certain preconditions are met – based
> on my observations of the traffic patterns I don’t see it helping the
> situation at all.
>
> *From:*Tsutsumi Takehiko [mailto:ja5...@outlook.com]
> *Sent:* Monday, 2 July 2018 3:09 PM
> *To:* WSJT software development
> *Subject:* Re: [wsjt-devel] Observation on Expedition Mode
>
> Grant,
>
> Allow me to write my comment on your topic as I have same topic interest
> writing “FOX adaptive power control” in this thread.
>
> Concerning your proposal, i.e.“to have the setting of number of channels
> vs the number of active channels maintain a constant PER CHANNEL TX power”
>
> My comment is
>
> 1. When fox sets 5 slot mode and it activates 5 slots, the average
> power per channel is -20*LOG(5) dB=-14dB. This means about 20W per
> channel if fox uses 500W linear.
>
> 2. When active channel is actually 1 slot, What does fox obtain the
> benefit to maintain link with a particular hound keeping 20W instead
> it can transmit 500W? Please keep in mind fox uses his channel to
> send his message to particular fox such as “VK5GR KH7Z -05”, “VK5GR
> RR73”. It is not the messages to me JA5AEA.
>
> 3. Instead, I agree to keep CQ message to be fixed, i.e. 20W as this
> is a broad cast message. If fox sends 500W, it is disastrous.
> (KH1/KHZ may be confusing us and creating lengthy arguments by this
> high power CQ feature??)
>
> Regards,
>
> take
>
> de JA5AEA
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
> ------------------------------------------------------------------------
>
> *From:*Grant Willis <vk...@bigpond.com>
> *Sent:* Saturday, June 30, 2018 9:47:02 PM
> *To:* 'WSJT software development'
> *Subject:* [wsjt-devel] Observation on Expedition Mode
>
> Joe,
>
> An observation if I may about expedition mode. I see with KH1/KH7Z that
> the number of Fox TX channels varies – I presume as they place more
> stations in the queue. As expected, the power per channel drops the more
> channels running so that the amplifiers can keep up. However, this has
> an unintended consequence perhaps of potentially breaking QSOs. A few
> times now I have started calling KH1/KH7Z on 20m when I am receiving
> them around -09 (but with pretty low S-meter signal strength). Usually
> this is with 1-2 channels running on their downlink. If they go to 3
> channels I can still receive but it falls to say -15. If they bring up
> channel 4 and 5 I loose them. There just isn’t the link budget left to
> receive them when the power is split between more than 3 channels in
> this example.
>
> Now the issue is, if they answer me by adding the 4^th channel – I wont
> hear them under those conditions. If I am part way through a QSO I can
> loose the RR73 for the same reason if they answer someone else on the
> 4^th channel– simply because the link runs out of steam.
>
> Now if I couldn’t hear them in the first place I wouldn’t have tried
> calling. In this case however, they can disappear under load effectively
> and I loose them mid QSO.
>
> For future consideration perhaps is to have the setting of number of
> channels vs the number of active channels maintain a constant PER
> CHANNEL TX power rather than the variable situation we have now. Ie I
> enable my fox station to run say 4 channels, but only reply on 1
> channel, then the output power should be the equivalent of the power
> that would be in that channel if all 4 were in fact on air but aren’t.
> At least that way I have a constant link budget I am working with on my
> comms channel with the fox station rather than one that can have them
> drastically cut power mid QSO without reference to the conditions on the
> path I am working them via.
>
> If what I am describing is not how it is supposed to work already then
> there is another factor at work somewhere in the chain to be explored. I
> would be happy to discuss this further and use the KH1/KH7Z expedition
> to observe and learn more about how the multi-channel nature of the mode
> works.
>
> Regards,
>
> Grant VK5GR
>
>
>
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