locked Aurora - what is the best mode for 50/70Mhz #Yaesu


Mike
 

Other than CW what is the best mode to use via Aurora - My ears arn't the best for speech on Aurora and looking at a variation for 70Mhz mainly. Tried FT4/8 and heard some recommendations of Q65 but would like your opinions/thoughts

Regards

Mike GD6ICR IO74PF73


Reino Talarmo
 

Other than CW what is the best mode to use via Aurora - My ears arn't the best for speech on Aurora and looking at a variation for 70Mhz mainly. Tried FT4/8 and heard some recommendations of Q65 but would like your opinions/thoughts
Hi Mike

On technical point of view FT4 and FT8 have too narrow tone spacing and aurora spred is more than the tone spacing. If you want a short transmission time, then Q65B or Q65C would provide better changes on Aurora paths.
Most probably you need to set a sked to find any other stations.

73, Reino OH3mA


 

I would think that MSK144 might work but haven't had an opportunity to try it.

--
John P.
WA2FZW


Charles Suckling
 

Hi Mike

I doubt that FT4 or FT8 would work well with auroral signals, given the
large frequency spread they have.

Listening to a few web recordings of 50MHz auroral signals, the signal
seems to occupy about 100Hz. I think this can vary a lot depending on the
exact propagation, but as a starting point one could take this and look at
the various Q65 submodes available.

Tone spacings can be seen in a table here
https://physics.princeton.edu/pulsar/k1jt/Q65_Quick_Start.pdf

Q65 works well on EME if the tone spacing is about 0.1 of the signal
bandwidth, so for a 100Hz wide signal you might want to use a sub-mode with
spacing with tone spacing in the region of 10Hz.

Period length is the next to consider. Longer duration periods give the
ability to decode weaker signals, but QSOs take longer to complete. Given
that auroral reflections are usually quite strong, I would opt for a
minimum period length.

Thus , I would try 15A or 15B. Will be interesting to see what resutls you
can achieve!

73

Charlie DL3WDG

On Mon, 28 Nov 2022 at 12:21, Mike <gd6icr@...> wrote:

Other than CW what is the best mode to use via Aurora - My ears arn't the
best for speech on Aurora and looking at a variation for 70Mhz mainly.
Tried FT4/8 and heard some recommendations of Q65 but would like your
opinions/thoughts

Regards

Mike GD6ICR IO74PF73






Charles Suckling
 

Hi John

I once tried MSK144 on EME (own echoes) with spread signals and it only
worked when the spreading was quite low. I recall that MSK144 needs a
coherent channel to work properly, so doubt it would work with auroral
signals on the VHF bands.

73

Charlie DL3WDG

On Mon, 28 Nov 2022 at 17:05, John P <j.m.price@...> wrote:

I would think that MSK144 might work but haven't had an opportunity to try
it.

--
John P.
WA2FZW






 

Charlie, my thought about MSK144 is that the message length is very short (144 bits) and is transmitted at high speed (2KBPS). The tones are 1KHz and 2KHz. My experience with meteor scatter is that it only takes one short ping to get a good decode and the longer the ping, the better the decode. The decoder frequency tolerance can be set as high as 200Hz which can accommodate people's radios being slightly off frequency as well as Doppler shift.

On a longer meteor ping (2 seconds or more) one often sees a frequency difference between decodes as the Doppler changes.

Here's JT's explanation of the mode (https://physics.princeton.edu/pulsar/k1jt/MSK144_Protocol_QEX.pdf), not that I understand any of the theory!
--
John P.
WA2FZW


Jim Brown
 

On 11/28/2022 3:12 AM, Mike wrote:
Other than CW what is the best mode to use via Aurora
I asked this here a year or so ago, and got no answer from anyone who had successfully used any other mode for AU. I worked a lot of AU on 6M from WV, where I grew up in the late '50s, and some from Chicago 40 years later, all CW. Now, 70 miles S of San Francisco's Golden Gate bridge, I'm too far south.

73, Jim K9YC


Alan G4ZFQ
 

On 11/28/2022 3:12 AM, Mike wrote:
Other than CW what is the best mode to use via Aurora
Next best SSB?
If you have ever heard aurora then you would know just how shift there is. CW is like two variations of noise level. SSB a ghostly whisper.

Google finds HDCW V2.2 http://www.dj5hg.de/digitalmodes/digitalmodes.html which seems to use SSB bandwidth.

You may well find more by searching, WSJT-X user guide does not include aurora.

73 Alan G4ZFQ


Charles Suckling
 

Hi Alan

I've been running a few simulations here this morning of Q65-15A, B and C
with 100Hz spreading, which is probably in the ballpark for 50/70MHz.

All three submodes work well when signals are weak, but there is an
increasing penalty in decoding success as signals get stronger, as is often
the case with Auroral propagation.

For stronger signals (tested up to +20dB/2500Hz) to be reliably decoded
with 100Hz spreading, it seems that Q65-15C is a better choice than
Q65-15B. Q65-15A performs worst with strong signals.

The simulator uses a spreading model more aligned to microwave EME than
Aurora, but probably provides a reasonable indication of what behaviour
might be expected in on-air tests.

If Q65-15C were to be tried, then I would recommend TX/RX freq of 700Hz, to
enable the signals to pass through a typical SSB filter without risk of
attenuating the higher frequency tones.

73

Charlie DL3WDG

On Tue, 29 Nov 2022 at 10:01, Alan G4ZFQ <alan4alan@...> wrote:

On 11/28/2022 3:12 AM, Mike wrote:
Other than CW what is the best mode to use via Aurora
Next best SSB?
If you have ever heard aurora then you would know just how shift there
is. CW is like two variations of noise level. SSB a ghostly whisper.

Google finds HDCW V2.2
http://www.dj5hg.de/digitalmodes/digitalmodes.html which seems to use
SSB bandwidth.

You may well find more by searching, WSJT-X user guide does not include
aurora.

73 Alan G4ZFQ






Mike
 

These digital mode programs have not been updated since 2012 I think. HDCW i tried a long time ago with no success. I agree its methods, good but with more modern decoding techniques it seems that Q65-15A/B from looking at WSJT methodology it predicts that these methods would seem best, Thanks to G3WDG/DL3WDG Charles for the link, I will be active again next week on 70Mhz and hope that with the quite high incidence of Aurora recently with the help of KST I will look for suitable occasions to test in the forthcoming month. Dont hesitate to call/email me to organize skeds

TIA
Mike GD6ICR IO74PF73


Andy Talbot
 

JT4G has the widest shift tones. But it is only available in 60s cycle
time.
You could try JT9H with 222Hz tone shift, or the fast version, JT9H-Fast

Those wide shift modes work well with 10GHz rainscatter that has hundreds
of Hz of spreading

Andy
www.g4jnt.com


Bo, OZ2M
 

Hello

I know that Jan, LA3EQ, and John, G4SWX, ran some QSO experiments using various modes. As far as I recall JT4G and PI4 worked on 2 m where the spreading can easily be 400 Hz. To the best of my knowledge Jan is the guy to consult on aurora and digital modes.

Bo
www.rudius.net/oz2m :: www.rfzero.net


Charles Suckling
 

Hi Bo

I've been doing some simuations today comparing Q65-60E to JT4G with 400Hz
spread signals. Both had similar sensitivity on a CQ message with unknown
call and grid. Q65-60E did very much better than JT4G when the callsign was
known, as would be the case with a sked.

73

Charlie DL3WDG

On Sat, 3 Dec 2022 at 10:35, Bo, OZ2M <groups.io@...> wrote:

Hello

I know that Jan, LA3EQ, and John, G4SWX, ran some QSO experiments using
various modes. As far as I recall JT4G and PI4 worked on 2 m where the
spreading can easily be 400 Hz. To the best of my knowledge Jan is the guy
to consult on aurora and digital modes.

Bo
www.rudius.net/oz2m :: www.rfzero.net






Svend, OZ7UV
 

60 seconds is an awful long time with strong aurora signals.
How does 15 second periods cope?

\Svend, OZ7UV

lør. 3. dec. 2022 18.53 skrev Charles Suckling <g3wdg1@...>:

Hi Bo

I've been doing some simuations today comparing Q65-60E to JT4G with 400Hz
spread signals. Both had similar sensitivity on a CQ message with unknown
call and grid. Q65-60E did very much better than JT4G when the callsign was
known, as would be the case with a sked.

73

Charlie DL3WDG

On Sat, 3 Dec 2022 at 10:35, Bo, OZ2M <groups.io@...> wrote:

Hello

I know that Jan, LA3EQ, and John, G4SWX, ran some QSO experiments using
various modes. As far as I recall JT4G and PI4 worked on 2 m where the
spreading can easily be 400 Hz. To the best of my knowledge Jan is the
guy
to consult on aurora and digital modes.

Bo
www.rudius.net/oz2m :: www.rfzero.net










Charles Suckling
 

Hi Svend

Yes, totally agree with your sentiment about 60s periods being totally
unnecessary with relatively strong signals! This is the reason I looked
into Q65 15s periods initially.

Earlier in this thread I mentioned some simulation results for 100Hz spread
signals, that may be typical of 50/70MHz, as was being discussed at the
start of this thread.

A quick look at Q65-15C with 400Hz spread signals also looks very
promising, with decodes possible well below what might be achieved with
CW. Strong signals (+20dB SNR) are also decoded without problems.

73

Charlie DL3WDG

On Sat, 3 Dec 2022 at 18:59, Svend, OZ7UV <spanget@...> wrote:

60 seconds is an awful long time with strong aurora signals.
How does 15 second periods cope?

\Svend, OZ7UV

lør. 3. dec. 2022 18.53 skrev Charles Suckling <g3wdg1@...>:

Hi Bo

I've been doing some simuations today comparing Q65-60E to JT4G with
400Hz
spread signals. Both had similar sensitivity on a CQ message with unknown
call and grid. Q65-60E did very much better than JT4G when the callsign
was
known, as would be the case with a sked.

73

Charlie DL3WDG

On Sat, 3 Dec 2022 at 10:35, Bo, OZ2M <groups.io@...> wrote:

Hello

I know that Jan, LA3EQ, and John, G4SWX, ran some QSO experiments using
various modes. As far as I recall JT4G and PI4 worked on 2 m where the
spreading can easily be 400 Hz. To the best of my knowledge Jan is the
guy
to consult on aurora and digital modes.

Bo
www.rudius.net/oz2m :: www.rfzero.net














Jim Brown
 

On 12/3/2022 9:53 AM, Charles Suckling wrote:
I've been doing some simuations today comparing Q65-60E to JT4G with 400Hz
spread signals. Both had similar sensitivity on a CQ message with unknown
call and grid. Q65-60E did very much better than JT4G when the callsign was
known, as would be the case with a sked.
Any meaningful test of the best mode for AU should include CW, which has long been known to work well.

73, Jim K9YC