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Dx. What comes in when?

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ACL

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#1
Hi I'm based in England and wanted to know if there is a website that gives a rough indication of what countries could be received and at what time[roughly] from my location on HF. I also wondered how the HF signal actually works. I know HF skips off the ionosphere but wanted to know how far ground wave generally goes before disappearing. Is the shortwave signal made up of two parts, a groundwave and skywave/skip signal? Any feedback would be great.
 

SCPD

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#2
You can go to the Wiki section, HF radio topics, plenty of info there. As far as finding out what is on the air and what time you could check out Short-Wave.Info, you could also search the internet for more info.
 
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#3
Ground wave only travels a few wavelengths which is why the early transmitters used low frequencies, your 198kHz transmissions cover most of Europe and occasionally get to the US. Unfortunately they also need lots of power and large antennae. HF broadcasts use the sky wave almost exclusively. HF broadcasters don't waste power by transmitting 'blind', they try to forecast propagation conditions and tailor their frequencies and times to hit their target audience.
If you go to the EiBi site (http://www.eibispace.de/) and download the EIBIview program (a zip file) and the current data ("sorted by Frequency" text file) it will show you which frequencies are currently on the air and hopefully you should hear the ones that are targeted to the UK - the data changes frequently, daily sometimes, even though the "B13" number remains the same. Listening in the evening will produce the best results, stay up all night if you don't need to sleep! Best results are when both stations are in the dark, although when both are at dawn or sunset you get unexpected results too!
Propagation changes daily too, so what you hear tonight you may not hear tomorrow. High frequencies during the day, lower at night although your 49m band will be a cacophony of noise in the evening! I regularly hear Radio Espana International on the 49m band late in the afternoon - I can't get any further than that!
 
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ka3jjz

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#4
As majoco implies, the subject of HF propagation is very complex - not only does it get affected by the receiver (you) and the transmitter's daylight situation (both being in day, both being at night, and yes, there are cases at dawn or dusk where things can get interesting) but it's also greatly influenced by solar activity. This is a subject that would easily exceed the character limits on this message, so I will leave that thought with a link that's an excellent beginning point to understanding this. Note that you will need Flash player to be active to view it (blue text is always a link)

Propagation Primer - Flash Movie by AE4RV

Now as to how to hear what - there's a very old and well established club in the UK known as the British DX Club. Been around a very long time, and well known to many in our field. Among the things they have are their own accumulated B13 skeds (and it looks like their website has just been updated) as well as 1 or 2 Yahoo groups where, I'm willing to bet, fellow members share logs. Study these carefully - you will get a very good idea of how propagation works in the UK and when you can hear certain areas. The link is below...

bdxc.org.uk

HTH...Mike
 
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#6
That's a very good question, and as you might assume, has a complicated answer: It depends.

Mostly, it depends on what band you're listening to.

I'll give you some example from where I live, here in the midwest USA. Maybe someone can fill in the blanks for where you are.

19 meters and up - open to Europe in the mornings, South America in the afternoon, Asia in the evening. My best band to hear Voice of Korea (north) in the evenings.

25 meters - similar, but afternoons are South America and Africa and deep Asia. Early afternoon is a great time to look for All India Radio for example.

31 meters - DX does a flip flop here, mornings are Asia/Pacific, evenings are Europe, middle of the night South America. In addition, during sunset Asia comes through via greyline. Radio Australia just screams in here until well after dawn, until 9am or later usually.

41 meters - Same as 31 meters but greyline is really pronounced and the band may be filled with Chinese stations simply BOOMING in. After they fade, Europe dominates.

60 meters and down - Africa in the evenings, Pacific in the mornings. Best band for Africans until their sunrise, then it's South and Central America until near dawn when the Pacific Islands can be heard on a good day.

Hope that gives you an idea. Following the ham DXers might help.

Here's a page showing a map of what DX the hams are working: QSO/SWL real time maps - EU - 50
 

ACL

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#7
Thanks. That's exactly was I was looking for. Just a rough blueprint of what areas of the world come in on what frequencies at certain times.

I've gone through the links but had one more question. If I send out an HF Tx in my city I know there will be a skip zone, ie maybe the south of England wouldn't hear me but France might as a result of skipping but would my next door neighbour's or people in my city be able to hear me before it bounces up and skips or will it immediately skip? Sorry I may not have worded that particularly well but hopefully you get what I mean.
 

ka3jjz

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#8
Well from k9rzz's perspective his answer is perfectly valid. From the UK, it's going to be rather different, due in large measure whether it's day or night in your part of the world, and the frequency being used. Looking at the propagation site I gave you earlier will make this clear. Studying the BDXC logs carefully will give you the answer to your question as to what to hear when.

As to your question - it depends (I know you're getting tired of hearing that, but propagation is a very complex subject, and there are rarely simple answers). Many things would influence the answer to your question, including the frequency used, the antenna being used to transmit and receive the signal, the power, and several other factors. There is a 'ground wave' with many designs, which would generally extend within a couple of hundred meters or so, so your neighbor, in theory, could hear it. However getting that signal across the city would greatly depend on the frequency chosen - if you were in the Euro 2 meter band (144-146 Mhz, which is well above the HF spectrum) it's common to use repeaters which does exactly as it sounds - it takes an input signal and repeats it on another frequency. On HF, it's possible without the use of repeaters

Mike
 
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#9
Yeah, it's easy for me to do that off the top of my head because I've been listening to shortwave from the same location the past 40 years.
I'm sure it would also be a simple task for some old timer in the UK. Otherwise, just take it day by day and learn as you go
 

ACL

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#14
Thanks a lot for all the feedback and the links. I guess learning about all of this is a progressive thing.
 

ka3jjz

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#15
You are absolutely correct. HF as a hobby is not simple - there are many facets to it, and understanding how propagation works from your corner of the world is really the key to understanding what you might hear, and what is out of reach. It doesn't matter whether you're talking broadcast (where you can use schedules as a first step), ham or utilities, the rules don't change with the service.

As I mentioned before, propagation is not a simple science - as you have seen, even something as simple as changing your location may change what you can / can't hear.

Take it slow and ask lots of questions. Make like a gopher and dig :.>> - beyond scanning the BDXC logs, these are the best ways to learn, apart from actually spending time at the dials

Mike
 

ka3jjz

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#16
I might point out that we have some very good links for HF Propagation resources here...

HF Propagation - The RadioReference Wiki

I see the popular GeoClock utility has been updated for Win7 (I have no idea whether it will run in Win8), and there are 2 others - Sun Clock and even an applet for the Logitech Squeezebox - that look to do something similar. What I'm concentrating on are simple programs and websites that show daylight and darkness patterns anywhere on earth.

I'm sure there are other sunrise/sunset apps (I wouldn't be a bit surprised if there were something for a smartphone by now) out there. Let's hear from the membership - if they aren't on the website, please give a link. Remember keep it simple. There are a few sites in our list that are, frankly, for the more advanced hobbyist that understands a bit more about solar physics. Let's not scare the newcomers (not just yet, anyway...)

Mike
 
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cj5

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#17
This is more for amateur operators who want to talk to a specific region, but I refer to it as well for receiving, VOACAP Online - professional-grade high-frequency (3-30 MHz) point-to-point propagation predictions

Play around with it and see what results you get.

I also have a site of various HF/Shortwave loggings, http://apps.qualsh.com/hflogs. It maps out most of the logs, and you can query what's on now on any given day, or on the current day. It's a shameless plug, but if I get enough use from the community, I plan on extending it with more features.
 
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ka3jjz

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#18
Yes, we have that one, but I don't believe this is set up for showing sunrise/sunset areas around the world - and for a newcomer, it might not be so simple to use. (Hint: in this context, SSN does not mean Social Security Number)

Still it's a very popular site...let's stick to the easy to use (read simple) sites to get folks feet wet and not overwhelm them. Mike
 

cj5

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#20
This may not be a site that tells you what may be on, and where, but in my early days of listening, I would refer to the VOLMET broadcasts (as well as WWV). VOLMET is fairly dependable, and if you plug these frequencies HF Volmet Broadcasts into your radio of choice, you can do a quick scan through, and listen for the good signals. Then based on what frequency you're on you can tune around and find possible stations on or near that band. And the VOLMET regions will give you a better idea from where the signal paths are deriving.
 
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