Looking for tolerant low signal digital mode

WSJT 65 (and variants) Discussion
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Looking for tolerant low signal digital mode

Post by VK5PJ » Sat Oct 03, 2015 7:33 am

Hello,
over time I have tried a lot of JT65 on VHF troppo modes and have had problems with it decoding if a meteor ping occurs during the cycle, which is quite often in morning periods.

A recent test with Rob, vk1kw brought to this light again during the week. While Rob's signal was good speaker copy on JT65 we were not able to get much back and forth due to meteor ping disturbing the decodes.

So I am looking for recommendations from others on a digital mode that used on VHF that has some moderately good weak signal capability BUT is tolerant of disturbances like meteors.

I will try ISCAT-B and see how that goes (long time since I have used it) but am curious what others have had experience in.

Regards,
Peter, vk5pj

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Re: Looking for tolerant low signal digital mode

Post by VK7XX » Sun Oct 04, 2015 6:47 am

Hello Peter. Have you tried JT-9 ?? I use JT9 on HF quite a bit and have found that it is pretty good even when other signals, like RTTY come up. I have not tried it on bands higher than HF a lot, having only 2 x 6m JT9 contacts and they were in to VK2 & VK3.

73
John
Last edited by VK7XX on Sun Oct 04, 2015 7:44 am, edited 1 time in total.

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Re: Looking for tolerant low signal digital mode

Post by VK3AMZ » Sun Oct 04, 2015 7:28 am

You could try CW Pete...... :D :D

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Re: Looking for tolerant low signal digital mode

Post by VK3KCX » Sun Oct 04, 2015 8:18 am

Have you tried Opera? This mode is bit like WSPR in operation and primarily used on HF but has been used very successfully on 2M in Europe.

- David - VK3KCX

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Re: Looking for tolerant low signal digital mode

Post by VK3BJM » Sun Oct 04, 2015 2:28 pm

Peter,

Perhaps you could try running 30 second periods, instead of the full (standard) 1 minute periods?

This might lessen the impact of a stray rock or two.

73,
Barry
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Re: Looking for tolerant low signal digital mode

Post by VK3ZYC » Sun Oct 04, 2015 6:08 pm

Hi,
Perhaps JT9 is a possibility, seems to work ok on the balloon tracking out to several 1000 km on hf with lighting crashes
Willing to try with you anytime, can run it just below the wspr freq on 2m with 1000 Hz mod freq.

jim VK3ZYC

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Re: Looking for tolerant low signal digital mode

Post by VK5PJ » Wed Oct 07, 2015 6:43 pm

Hi Jim
VK3ZYC wrote:Hi,
Perhaps JT9 is a possibility, seems to work ok on the balloon tracking out to several 1000 km on hf with lighting crashes
Willing to try with you anytime, can run it just below the wspr freq on 2m with 1000 Hz mod freq.
jim VK3ZYC
Would love to give it a bash on VHF and see how it handles the disturbances like meteors and Aeroplane Doppler, I am around more now that the weather has improved so if you have a favourite night / morning am keen

Regards,
Peter

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Re: Looking for tolerant low signal digital mode

Post by VK3ZYC » Wed Oct 07, 2015 9:01 pm

Hi Peter,
Will look for you on the logger over the next few nights.
There are few stations here in gippsland with JT9 installed as part of wspr-x, was testing with norm vk3dut a few nights ago.

jim, VK3ZYC.

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Re: Looking for tolerant low signal digital mode

Post by VK3DXE » Wed Oct 07, 2015 11:12 pm

I'm keen to give it a go too. Good to see more activity on the bands after the winter hibernation.
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Re: Looking for tolerant low signal digital mode

Post by VK2ZIW » Thu Oct 08, 2015 5:43 am

Meteor pings are often very short, under 1/2 sec. So, a fast bit rate mode is needed to get a "packet" through.
On 6m, we tried FSK315 but the gut feel was, FSK441 was better.

But, the bigger problem is, few people are running the latest software.
Here, I download and compile WSJT and WSJT-X, weekly or sooner.

Also MSHV works well.

Alan VK2ZIW

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Re: Looking for tolerant low signal digital mode

Post by VK5PJ » Thu Oct 08, 2015 9:40 am

Hi David
VK3KCX wrote:Have you tried Opera? This mode is bit like WSPR in operation and primarily used on HF but has been used very successfully on 2M in Europe.
- David - VK3KCX
From what I can read about OPERA it appears to be a beacon mode transmission a bit like WSPR and not intended for a QSO, maybe you were thinking about ROS ? I think Waldis, vk1wj (now SK) was experimenting with ROS a few years ago.

The ISCAT-B mode in WSJT looks to be a contender, it has a low data rate and error correction built in. Some early test on 50 MHz with lots of meteors around showed it could handle variable conditions well and still decode down to the minus 16db signal levels that the faster modes can not do (fsk441 etc)

Regards,
Peter, vk5pj

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Re: Looking for tolerant low signal digital mode

Post by VK3KCX » Thu Oct 08, 2015 9:22 pm

HI Peter, I've not used ISCAT-B, only JT65 / 9 and WSPR, I have used ROS and Opera extensively.
I'm of the opinion that if you want a real QSO mode (not just canned messages) you just can't go passed ROS, apart from it's astounding ability to decode in high noise environments and selective fading, it has a choice of three baud rates (4/8/16) and each message has a good/bad check sum indicator and many features not found elsewhere.

There is much more to digital modes than just PSK31 and JT family of modes.

https://rosmodem.wordpress.com/

- David VK3KCX

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Re: Looking for tolerant low signal digital mode

Post by VK2ZIW » Fri Oct 09, 2015 9:34 am

We need a linux program for Low Power systems eg. Raspberry Pi.
ROS is PE32 executable (GUI) Intel 80386, for MS Windows.

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Re: Looking for tolerant low signal digital mode

Post by VK2ZIW » Fri Oct 09, 2015 10:12 am

Another to lookat: WSQ
http://www.qsl.net/zl1bpu/SOFT/WSQ.htm

Also needs a Linux version.

Alan VK2ZIW

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Re: Looking for tolerant low signal digital mode

Post by VK5PJ » Sat Oct 10, 2015 7:39 am

Thanks Alan
VK2ZIW wrote:Another to lookat: WSQ
http://www.qsl.net/zl1bpu/SOFT/WSQ.htm
Alan VK2ZIW
that mode from ZL looks quite interesting, they state it is very tolerant of long impulse noise as it was intended for MF /LF frequencies where lightning noise if prevalent, so sounds like the meteor pings might not effect it

http://www.qsl.net/zl1bpu/SOFT/WSQ.htm (even has source code)

It is simple to use and configure so even I have a hope as I found using ROS to be a test of my patience to figure out how to make it work.

Regards,
Peter
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Re: Looking for tolerant low signal digital mode

Post by VK4UH » Sat Oct 10, 2015 10:23 am

I also now have WSQ installed and believed working

Happy to run a test when requested. Catch me on the logger

Kevin VK4UH QG62kp
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Re: Looking for tolerant low signal digital mode

Post by VK3KCX » Sun Oct 11, 2015 7:15 am

WSQ sounds very interesting, I'd like to join with you guys in evaluating this.

- David - VK3KCX

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Re: Looking for tolerant low signal digital mode

Post by VK3KCX » Sun Oct 11, 2015 7:50 pm

From the WSQ Readme.txt file - "Remember - this mode WON'T WORK on HF, so don't bother trying! It is an LF/MF mode ONLY."

Hmmm... anybody tried this yet?

- David - VK3KCX

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Re: Looking for tolerant low signal digital mode

Post by VK5PJ » Sun Oct 11, 2015 8:15 pm

Oh !
VK3KCX wrote:From the WSQ Readme.txt file - "Remember - this mode WON'T WORK on HF, so don't bother trying! It is an LF/MF mode ONLY."
Hmmm... anybody tried this yet?
- David - VK3KCX
Thanks for finding that David, not quite sure what would stop it working on HF but he must have had his reasons for putting that in there, will see if I can contact the author.

Ah, he mentions that Doppler shift is the problem with using it on HF, so for my intended use (weak troppo with occasional meteor) it might function. I guess we should set a day / time and a few of us get on 144 MHz with a few of these modes?

Regards,
Peter

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Re: Looking for tolerant low signal digital mode

Post by VK3KCX » Mon Oct 12, 2015 8:20 pm

Agreed Peter, in my personal experience with Opera and ROS over EU - Aus paths, the proof is in the air testing, I have managed to get -34db decodes on 10m using Opera Op4 and Op8 (4 minute and 8 minute cycle) when the author of this mode said it would never work as those slow modes would only work on lowerbands. Similar experience with ROS 2/100 made for 600M use, worked great on 10m -24 decodes which is 2dB better than ROS 4/2000 which is designed for HF.

- David - VK3KCX

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