VK to JA - TEP Observations 28-50-144 MHz

[VK2KRR]

Hi Folks,

Im (and others) currently making observations into Transequatorial Propagation (TEP) between Australia & Japan. The aim is to try and see if I can possibly make the path on 144 MHz band from here, although they say it cant be done. Along with this I would like to encourage other VK & JA operators to try and make the path on 144 MHz in the process.

So far I have been running daily tests on 28 MHz WSPR for about 2 weeks with Jim JG1KGS & Kazu JQ1HDR, with very intersting results.

Have so far noticed a trend with big peaks, early morning, early afternoon and late afternoon.

On Thursday night I tried for my first real Evening TEP test on 28 MHz, between approx 10 and 11 pm local time and was also decoded at very strong levels at both JG1KGS & JQ1HDR! This was quite interesting to see as this is around the time that 144 MHz signals are said to propagate.

Of note with the evening TEP WSPR signals was that it was rather hard to decode via WSPR, I could see JG1KGS signal a number of times with no decodes, as the signal seemed to be spread in frequency a few Hz. This is also said to be a characteristic of the Evening TEP.
An email yesterday from Kazu indicates that he could see my signal numerous times also, but only one was able to decode.

So it would appear that I may have to brush up on my morse code to make the contacts, unless possibly the new JT65 modes that Rex VK7MO has mentioned may work. Especially at 144 MHz I would think the freq doppler and speading would be worse.

I'd be very interested to hear of stations further north trying things regarding TEP esp up at 144 MHz area.

My TEP page is here http://www.vk2krr.com/evening_japan_tep_log.htm

[VK5AKK]

I researched the 144 tep path to the north a while ago and concluded that it should be a possibility for VK2,VK3 and VK5.
Look at the latitude of the South African contacts with the tep path to the north.
Cheers
Phil

[VK2KRR]

Hi Phil

Thats very interesting! Thanks for adding that.

I note that your beaming heading to JG1KGS is 0 deg so ur both directly north south from each other which probably helps too.

I cant see myself sitting here tapping away on a key for hours on end on 144 MHz so I think it would be feasable to use WSPR to create visual signals, if signals are visually seen then a change to voice can be made or CW at that stage.

Other programs may have to be investigated, I think Rex VK7MO mentioned to me that JT4G may work on 2m but im not sure.

[VK5PJ]

Hi Phil,

I researched the 144 tep path to the north a while ago and concluded that it should be a possibility for VK2,VK3 and VK5. Look at the latitude of the South African contacts with the tep path to the north.
Cheers Phil

I can comment from personal experience that the TEP path much south of the VK8 border will be very difficult to do, given our existing modes of operation. The contacts to JA from Alice Springs on 144 were severly distorted due to multipathing on the signal. I had not ever heard anything like it until I experienced some aroura from VK5 many years later, so thats the best description of the signal quality I can give you and being 1500Km further south I can only imagine it will be far worse.
The other difficult thing to find was an operator who understood english well enough to cope with pulling out the distorted signal from this end of the world. I ended up listening for quite a while to the FM simplex channels from JA but while their audio was better on FM, could find no english speaking stations at that time.

The only pointers I found was when 50MHz started to sound extremely distorted and had a real 'hollow' sound about it with all the multipath then signals some times appeared on 144. From memory they have a different calling freq for SSB in JA, so you will need to sort that one out first. I stumbled across a station on 144.110 from memory after calling on 144.100.. oh to be that young and silly again. Jeff, vk5gf also had contacts to JA so you might like to speak with him about his experiences (I left vk8 in 1994)

so we need to find a mode than can cope with an aurora style distortion on the signal and then apply that to the northern path, simple eh!
Peter, vk5pj

[VK2KRR]

Hi Pete,

Thanks for your comments, hopefully Jeff might speak about his experiences with TEP from Alice Springs.

Ive not yet noted the same conditions as were encountered on Thursday night, will advise further when I have some more info.

[VK2ZRH]

I covered this topic in a paper I presented at the 2007 GippsTech Conference, titled "Transequatorial VHF-UHF Propagation: the next challenges for VK".

Fundamentally, the challenges are: (1) to bridge the VK-JA path on 432 MHz TEP, and (2) to extend the 144 MHz TEP world record.

The paper covers the characteristics, haunts and habits of Ducted Mode TEP (aka Evening-type TEP), with a focus on the Australia-Asia sector. I've detailed the technical challenges of terminal locations, path loss and signal distortion.

To make contact, stations at either end have to be within elliptical "zones" - the long axes of the ellipses lying at right angles to the path and placed at 30-35 degrees geomagnetic latitude.

The 432 MHz Challenge
The 'ideal' path is centred on Darwin in the south and the island of Kyushu in the north. Path lengths of 4450 km to 5250 km are attainable here.

Longer paths might be possible, but it would require portable or martime mobile operation from the southern end, at locations around the southern shores of the Gulf of Carpentaria.

Path details are shown in Figure 1, here.

Figure 1.

The 144 MHz Challenge
The Australian 144 MHz terrestrial distance record is 6763 km, set by VK4BFO in a TEP contact with JI7DMB on 15 April 1991.

The one-way 144 MHz TEP record is about 8000 km - a beacon from South Africa copied in Europe (see http://www.vhfdx.info/tep.html). The longest confirmed 144 MHz TEP contacts involve paths around 7200 km - again, in the Africa-Europe sector (ibid).

Paths of 7200+ km to 8000 km are illustrated in Figure 2, here. In the north, the TEP communications zone covers parts of the JA7 and JA8 call areas. In the south, the zone covers from Longreach in central QLD down to Coonabarabran-Narribri-Gunnedah in northern NSW.

Figure 2.

To go any further, you'd need a sporadic-E extension at one end or the other.

Grist for the mill

If you'd like a copy of the PDF (1.53Mb), please email me (details on OpInfo).

Posted as an incentive.

73, Roger Harrison VK2ZRH
Online reference: http://home.iprimus.com.au/toddemslie/eTEP-Harrison.htm

[VK2KRR]

Roger,

Do you know if the VK Record contact was using voice or CW?

[VK2ZRH]

I must apologise, but I can't recall. Perhaps VK4BFO or VK3KM (WIA VHF-UHF records keeper) could enlighten you.

I wouldn't like to speculate.

73, Roger Harrison VK2ZRH