Date
1 - 16 of 16
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/thoughtsHi 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
toggle quoted message
Show quoted text
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 |
|
|
|
Charles Suckling
Hi John
toggle quoted message
Show quoted text
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 |
|
|
|
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 AuroraI 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:Next best SSB?Other than CW what is the best mode to use via Aurora 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
toggle quoted message
Show quoted text
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:Next best SSB?Other than CW what is the best mode to use via Aurora |
|
|
|
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 |
|
|
|
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
toggle quoted message
Show quoted text
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 |
|
|
|
Svend, OZ7UV
60 seconds is an awful long time with strong aurora signals.
toggle quoted message
Show quoted text
How does 15 second periods cope? \Svend, OZ7UV lør. 3. dec. 2022 18.53 skrev Charles Suckling <g3wdg1@...>: Hi Bo |
|
|
|
Charles Suckling
Hi Svend
toggle quoted message
Show quoted text
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. |
|
|
|
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 400HzAny meaningful test of the best mode for AU should include CW, which has long been known to work well. 73, Jim K9YC |
|
|