24-11-2019, 05:31 AM
Thought I would share some information about finding potential 144 MHz Sporadic E paths using data from 6m WSPR, and also using WSPRView to analyse the evolving sporadic E situation. You can use other signal sources rather than WSPR to identify paths if you can analyse them with enough accuracy and speed.
This afternoon 23.11.19 there was a period of about 30 mins or so where Leo VK2WTF and myself noticed very strong signals over our 633 km path up to +22dB. This would indicate a potential high MUF sporadic E area where our signals are being refracted in the E layer.
To understand this better you must think of the Ionospheric layers as refracting the signals back to earth, rather than a reflection or a bounce as commonly referred to. As areas of the E layer obtain a higher MUF due to the suns radiation and possible other effects, the E layer is able to refract or bend the signals of higher frequencies. The distance of the E layer HOP for a signal path is a factor of the 'strength' or 'charge' or MUF and the E layers height above the earth, 80 to 120 km or so up at times. The approx maximum hop is about 2300 km +- 100 km or so, due to the earth curvature. We assume the MUF to be for a signal around 50 MHz. As the E MUF strengthens, the ability of the E layer to refract or bend signals becomes greater, so a 50 MHz signal distance will shorten as the E layer strengthens and the MUF rises, the E layer is thus has a greater ability to bend signals at a greater angle. So the points where a 50 MHz signal runs can become very short, and in the VK2WTF to VK2KRR example as short as 633 km. At a certain point the E layer strength will be enough to have 144 MHz return to earth at around 2300 km away from the signal source. On 6m WSPR this is usually with very short paths, sometimes as short as 300 km. At these distances though you must be able to differentiate between a direct E signal, an E backscatter, aircraft scatter, tropo etc. The only one that will run a 2m signal to E hop distance is if its a direct E signal of course, so you have to know what your looking at.
[attachment=364]
[attachment=365]
If you look at the attached images you can see that while a 2m path may have been possible across the high MUF area of VK2WTF and VK2KRR, there were no stations in good alignment to be able to test the MUF at 144 MHz. If there was stations on 144 MHz around Birdsville area, then some tests could have been conducted from stations in Tasmania, and Tasmania is the only area from which this path could have been tested, unless the E MUF was very strong in which case stations may be been able to work as little as 1000 km paths if they lined up across the high MUF area. I'll add more info in each photo description.
So for high MUF areas identified in different positions can obviously give sporadic E along other different paths when the right conditions are met. Another common high MUF E area is often generated above the southern areas of the Great Dividing Ranges which provides paths from VK7 to SE QLD and other areas for example. Adelaide to Sydney is another one. Central coast VK4 to VK3 is another and it goes on.
Its not possible to use this method on paths over long spans of water (unless there are transmitters on the water) such as Australia to New Zealand. You would have to observe signals indicators on each side of the 2000 km path and follow the MUF up, such as 50 MHz band then FM Radio band then 144 MHz band.
Hope this helps you understand a little more about what to look for in the lead up to sporadic E on 144 MHz.
This afternoon 23.11.19 there was a period of about 30 mins or so where Leo VK2WTF and myself noticed very strong signals over our 633 km path up to +22dB. This would indicate a potential high MUF sporadic E area where our signals are being refracted in the E layer.
To understand this better you must think of the Ionospheric layers as refracting the signals back to earth, rather than a reflection or a bounce as commonly referred to. As areas of the E layer obtain a higher MUF due to the suns radiation and possible other effects, the E layer is able to refract or bend the signals of higher frequencies. The distance of the E layer HOP for a signal path is a factor of the 'strength' or 'charge' or MUF and the E layers height above the earth, 80 to 120 km or so up at times. The approx maximum hop is about 2300 km +- 100 km or so, due to the earth curvature. We assume the MUF to be for a signal around 50 MHz. As the E MUF strengthens, the ability of the E layer to refract or bend signals becomes greater, so a 50 MHz signal distance will shorten as the E layer strengthens and the MUF rises, the E layer is thus has a greater ability to bend signals at a greater angle. So the points where a 50 MHz signal runs can become very short, and in the VK2WTF to VK2KRR example as short as 633 km. At a certain point the E layer strength will be enough to have 144 MHz return to earth at around 2300 km away from the signal source. On 6m WSPR this is usually with very short paths, sometimes as short as 300 km. At these distances though you must be able to differentiate between a direct E signal, an E backscatter, aircraft scatter, tropo etc. The only one that will run a 2m signal to E hop distance is if its a direct E signal of course, so you have to know what your looking at.
[attachment=364]
[attachment=365]
If you look at the attached images you can see that while a 2m path may have been possible across the high MUF area of VK2WTF and VK2KRR, there were no stations in good alignment to be able to test the MUF at 144 MHz. If there was stations on 144 MHz around Birdsville area, then some tests could have been conducted from stations in Tasmania, and Tasmania is the only area from which this path could have been tested, unless the E MUF was very strong in which case stations may be been able to work as little as 1000 km paths if they lined up across the high MUF area. I'll add more info in each photo description.
So for high MUF areas identified in different positions can obviously give sporadic E along other different paths when the right conditions are met. Another common high MUF E area is often generated above the southern areas of the Great Dividing Ranges which provides paths from VK7 to SE QLD and other areas for example. Adelaide to Sydney is another one. Central coast VK4 to VK3 is another and it goes on.
Its not possible to use this method on paths over long spans of water (unless there are transmitters on the water) such as Australia to New Zealand. You would have to observe signals indicators on each side of the 2000 km path and follow the MUF up, such as 50 MHz band then FM Radio band then 144 MHz band.
Hope this helps you understand a little more about what to look for in the lead up to sporadic E on 144 MHz.