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Author Topic: What Digital Mode on 18.103 Mhz at 23 Zulu  (Read 5550 times)
KB3MDT
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Posts: 193




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« on: August 02, 2012, 04:10:56 PM »

Hi,
   Anyone know what digital mode is being used on the 17 Meter band between 18.103 and 18.104 Mhz, around 23 Zulu Time?   It Sounds like MFSK and a few others but I've never been able to decode it with fldigi.  The sound is like several notes, played slowly over time. 

I'[m hearing it right now on 2 Aug 2012.  Thanks.

Ken
73
KB3MDT
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AF6WL
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Posts: 129




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« Reply #1 on: August 02, 2012, 07:23:15 PM »

Have you compared it to the samples here : http://www.w1hkj.com/FldigiHelp-3.21/Modes/index.htm

DominoEX and Thob sound fantastic  - they deserve more air time because of their musical qualities alone.
Would it be in breach of one' s license to send meaningful messages that just happened to sound like nice tunes  Grin
« Last Edit: August 02, 2012, 07:46:24 PM by AF6WL » Logged
NM3G
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Posts: 46




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« Reply #2 on: August 03, 2012, 05:03:39 AM »

Sounds like JT-65HF, based on the frequency. JT-65HF has a 48-second transmission window, 12 seconds of decode time (and a few seconds of forgiveness in computer clock accuracy), and then the other station starts.

Hope this helps.

73
Rick
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N7SMI
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Posts: 315




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« Reply #3 on: August 03, 2012, 09:56:44 AM »

18102.0 USB is the JT65 frequency. That's almost certainly what you heard. To me it sounds like someone playing a depressed electric keyboard with one finger.

It's an odd, yet strangely appealing mode. Because it is works so well with almost no power, you can make contacts at very long distances even in very poor conditions. The primary drawback is that it takes 7 minutes to make a very basic QSO exchange of grid square and signal report.
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VE3FMC
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« Reply #4 on: August 03, 2012, 12:31:06 PM »

7 minutes? The only way it would take 7 minutes is if the signal reports had to be repeated. 4-5 minutes depending on whether the RRR is exchanged.

I have over 1100 QSO's using JT65, great DX mode.
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N7SMI
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Posts: 315




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« Reply #5 on: August 03, 2012, 04:15:57 PM »

This is the standard JT65 exchange, each step taking one minute:

1 - CQ N7SMI DN41
2 - N7SMI VE3FMC EN92
3 - VE3FMC N7SMI -06
4 - N7SMI VE3FMC R-11
5 - VE3FMC N7SMI RRR
6 - N7SMI VE3FMC 73 (or freeform response)
7 - VE3FMC N7SMI 73 (or freeform response)

With this exchange, while someone could jump in and call you in the 8th minute, it is usually silent before you call CQ again on the 9th minute. This makes the QSO 7 minutes at best.

You could do an abbreviated version...

1 - CQ N7SMI DN41
2 - N7SMI VE3FMC EN92
3 - VE3FMC N7SMI -06
4 - N7SMI VE3FMC R-11
5 - VE3FMC N7SMI 73 (or freeform response)
6 - N7SMI VE3FMC 73 (or freeform response)

You could then call CQ again on the 7th minute, making the QSO 6 minutes.

Maybe I'm missing something, but I don't see how it's possible to have a 4 or 5 minute QSO unless you're not exchanging signal reports (I think this is typical for EME) or you're not confirming receipt of the signal report. If you call CQ again without responding to the signal report, I'd think many people would assume that you did not receive the report and they won't log the QSO.
« Last Edit: August 03, 2012, 04:17:54 PM by N7SMI » Logged
VE3FMC
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« Reply #6 on: August 04, 2012, 07:41:13 AM »

Just timed a JT65 QSO with all the exchanges trasnmitted
First call from the station calling me was at 14:31:33
I sent his report
He sent my report
I sent RRR
He sent 73
I sent 73
QSO ended at 14:36:45

Maybe it is the Canadian atmosphere that makes it faster  Grin

Either way it is a good mode to work DX, or North America and do so with low power. Guys should try turning the output down to under 5 watts and see what happens. I just finished working Mexico and FL with 4 watts to a dipole that has an apex of 28 feet. So hardly a big gun antenna. I have worked VK's on 40 M early in the morning with 10-15 watts to a dipole. Amazing mode. But yes, not for everyone.
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WD4ELG
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« Reply #7 on: August 04, 2012, 08:14:33 AM »

JT65 is an amazing mode.  (No disrespect to the other digital modes)

I have made some incredible QSO's with low power and dipoles.  I sometimes use the miles per watt rating (although a better measure would consider the antenna gain and effective radiated power, because 5 watts and a yagi is going to get a LOT better response in most cases than 5 watts and a single wire).  Anyway, 1000 miles per watt is my typical benchmark, and I have done this many times....working into Europe, Asia, Oceana with just 5 watts.

And just last night, I did my first Earth-Moon-Earth QSO's using JT65.  Granted I was using 350 watts and a 9 element yagi on 144 MHz, but the round trip distance was about 750,000 miles.  So that still comes out to more than 2000 miles per watt.

Listening on 14076...

Mark Lunday
WD4ELG
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N7SMI
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Posts: 315




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« Reply #8 on: August 05, 2012, 11:31:15 AM »

Just timed a JT65 QSO with all the exchanges trasnmitted
First call from the station calling me was at 14:31:33
I sent his report
He sent my report
I sent RRR
He sent 73
I sent 73
QSO ended at 14:36:45

Of course this omits the one minute of you calling CQ and the one minute it takes for him to answer your call. That would bring the entire time required to 7 minutes.
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W5DQ
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« Reply #9 on: August 06, 2012, 12:27:54 PM »

Just timed a JT65 QSO with all the exchanges trasnmitted
First call from the station calling me was at 14:31:33I sent his report
He sent my report
I sent RRR
He sent 73
I sent 73
QSO ended at 14:36:45

From your posted times, it appears your clock wasn't sync'ed properly, if your times include start at 33 seconds and end at 45 seconds???

From the JT65-HF spec, if clocks are properly sync'ed, TX will start at xx:xx:01 and end at xx:xx:48 with decode time from xx:xx:49 to xx:xx:59 and then 1 second of delay and starts again with other station.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
VE3FMC
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« Reply #10 on: August 06, 2012, 03:54:33 PM »

Just timed a JT65 QSO with all the exchanges trasnmitted
First call from the station calling me was at 14:31:33I sent his report
He sent my report
I sent RRR
He sent 73
I sent 73
QSO ended at 14:36:45

From your posted times, it appears your clock wasn't sync'ed properly, if your times include start at 33 seconds and end at 45 seconds???

From the JT65-HF spec, if clocks are properly sync'ed, TX will start at xx:xx:01 and end at xx:xx:48 with decode time from xx:xx:49 to xx:xx:59 and then 1 second of delay and starts again with other station.

Gene W5DQ

My logbook clock is synced with my JT65 clock, which is synced to a national time server from your country.

I must be doing something right with JT65, I have well over 1100 contacts on that mode with casual operating over the past 1 1/2 years.

Plus I don't really pay any attention to the time it takes to start and finish a QSO, I just work em and log em!
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W5DQ
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« Reply #11 on: August 07, 2012, 08:42:06 AM »

Just timed a JT65 QSO with all the exchanges trasnmitted
First call from the station calling me was at 14:31:33I sent his report
He sent my report
I sent RRR
He sent 73
I sent 73
QSO ended at 14:36:45

From your posted times, it appears your clock wasn't sync'ed properly, if your times include start at 33 seconds and end at 45 seconds???

From the JT65-HF spec, if clocks are properly sync'ed, TX will start at xx:xx:01 and end at xx:xx:48 with decode time from xx:xx:49 to xx:xx:59 and then 1 second of delay and starts again with other station.

Gene W5DQ

My logbook clock is synced with my JT65 clock, which is synced to a national time server from your country.

I must be doing something right with JT65, I have well over 1100 contacts on that mode with casual operating over the past 1 1/2 years.

Plus I don't really pay any attention to the time it takes to start and finish a QSO, I just work em and log em!

I too have many JT65-HF QSOs, but probably not 1100+ like you. But doing something 1100+ times wrong doesn't make it right, does it??? I also see folks running in what is basically referred to as 'all knobs right'. Their waterfall trace looks like someone used a 3" paintbrush to make it. Usually the s/w will NOT decode them properly unless you roll back the RF Gain and do some DSP filtering on them and then it might work.

I'm not saying that the time is super critical and being off a few seconds doesn't work. I have see signals on the waterfall starting several seconds early to ending several seconds late and the software seems to decode them ok (caveat : sometimes). I simply stated that if you read the specification, the cycle SHOULD start at xx:xx:00 followed by 1 second delay and then 47 seconds of tones (1 to 48 seconds) followed by 11 seconds of decode period for a 60 second cycle window. Then it repeats.

I know that my JT65-HF clock starts EXACTLY at xx:xx:00 with PTT ON and at xx:xx:48 PTT goes off. I am also synced to the Boulder, CO Time source (I don't recall offhand exactly which server I am pointed at). I use TIMESYNC utility and have a 5 minute resync window.

But if you're making contacts then keep after it. Since it seems being accurate on the timing isn't too important to you, I truly hope your not one of the signals made with the 3" paintbrush?

I too enjoy JT65-HF, but I use it when nothing else is on I want to try to work or when I have alot of time to waste. Much prefer RTTY or CW.

73

Gene W5DQ

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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
VE3FMC
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« Reply #12 on: August 08, 2012, 03:55:32 PM »

Hi Gene

No my signal is not the 3 inch wide paint brush on JT65. No ALC showing at all, no power out put above 20 watts (and that is rarely used except to work some DX) Most of the time I run 10 watts or less. You won't see me signing with 50W YAGI 73  Wink

I have seen the signals you talk about, but that is not how mine look.

Yes at times the timing might be off a little bit. The time could be like that because I do not always get right to the answering of someone who has called CQ.

But as I said something must be working or it would be hard to log as many QSO's with that mode as I have.

I will have to check my log to see if I have worked you in the past.

73, Rick VE3FMC

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