WSPR on 144 MHz

[VK7HH]

Hi Nev

At different times of the year you see different amounts of stations on the maps, more so in their summers as you can imagine, particularly on 6m. The VK7JJ site will only show up reported paths, and doesnt show how many stations are on air but not actually been heard or heard anything, but your right, 2m particularly across USA and EU is very lacking.

In European areas, I am aware of some significant reasons why WSPR is not used by a larger amount of people, but I wont comment on it here. This can also have a flow on effect to USA stations on the east coast loosely. All I can say is that it is a great shame when you think about the Atlantic Ocean crossing often talked about.
Across the USA there is often talk of use of APRS as a propagation indicator for 2m tropo & Es. While no doubt this works for strong signals, I have tried it myself and the signal strength required to get it to decode is huge in comparison to a WSPR signal. 

This is true. APRS runs on FM and requires full quieting to decode. The other issue is paths can't be easily determined via aprs.fi as they always reach the quickest way to the internet - and not via RF. If you have a radio listening on the RF channel and can take the time to view the paths then you can determine where it has come from.


You also dont need a real good stable radio to make it work either, but having said that, APRS was not designed to detect DX paths so many people running it are not even chasing DX. So the paths not detected and missed by this method, I would not like to think about. 

In Hawaii though there is a 70cm WSPR beacon beaming towards California, which is regularly RXd by Chris N3IZN & some others near-by to Chris which is in excess of 4000 km.

Still amazes me that not many more stations along the West coast exploit this path.


After using WSPR for a while I realise the potential, but having VK6KXW decode my 2m WSPR signal last week @ 2806 km unexpectedly at -29dB and also hear VK5AKK, is pretty incredible and reinforces its ability to find paths at VHF. 

Not only find paths, but monitor the path SNR as it increases to the point for digital contacts or voice.

You might wonder, well what can I do with a -29dB signal? If using minimal TX power, say 2 or 5W and have a lot in reserve you should be able to make a contact if you can increase your power by say 6dB or more. If already using say 50W and only have about 90W out of your rig u may not be able to do anything really, except marvel at the possibilities and keep monitoring hope that it gets strong enough to be able to use other modes and maybe get a contact. But now at least I know a path to VK6KXW is a possibility and that this particular path could occur when you are least expecting it.

As I commented above


One thing I would say about WSPR, particularly on 2m and to a lesser extent 6m, is that it works extraordinarily well when you get your set up right, and you have a reasonable grasp on signal propagation techniques and characteristics, but its also very easy to get it wrong, especially for newcomers. 

It's also set and forget in most cases in regards to setup. Checking your results regularly (or getting WSPRView to email you) can result in finding contacts that nobody would know about. An example is of a path to VK4 on Sporadic E earlier this year I would've completely missed had I not been running 6m WSPR. Video at the bottom of this post.

The hardest thing for most people to achieve is to have their radio's set up to a high precision GPS type reference signal for oscillator stability and accuracy (we see how hard that is when ICOM cant even get it right with their IC9700). So when people start out with a basic radio, they could be no where near the WSPR bandpass and not even know it, so they dont get any decodes obviously and or their TX signal drifts like crazy.
Having said that, some standard rigs do work extraordinarily well when it comes to stability, and one currently is the IC910 rig that Nigel VK6NI is using, with only a hi-stability option crystal, its working perfectly.

Solutions for the 9700 are coming thick and fast, some easier than others so it's never been easier to try it out.

Comments above in bold in response to Leigh.

[Video: https://www.youtube.com/watch?v=EgCyDPtFsvQ]