I've had a contact on the wireless with someone in Australia!

Feek · 07-03-2011, 02:19

Now before I start, yes I have heard of telephones. Yes I have heard of VoIP and yes I know all about Skype.

As you know, radio is a hobby of mine. I've always been interested in the Very High Frequencies, that's generally accepted to be 50MHz and above but the band that has had my attention is 144MHz where the length of the radio waves is 2 metres. That's limited to what's generally accepted to be line of sight communication and although the waves can carry a fair way, they generally only go a couple of thousand km at most but more commonly will travel just a few hundred km.

The High Frequency bands, those between 1.8MHz and 28MHz where the length of the radio waves go from 160m to 10m respectively have always been a bit of a mystery to me. I've never used them and up until last year I've had little experience of them. I've always been of the impression that one can switch on a radio at any time of the day and providing you get the right frequency for the time of day, you can 'work' the world.

Well, I became active on the HF bands around six months ago and quickly learned that I was mistaken. Perhaps with a super large station with lots of power and big aerials that might be possible but it's far from the norm. Because these bands have very long wavelengths, getting any decent size aerial up is quite a challenge and most HF aerials are a compromise.

My aerial for the HF bands consists of a random length piece of wire with a 'smart tuner' at the end. For a radio to transmit efficiently it has to have a tuned aerial and the smart tuner fools the radio into thinking that the aerial attached to it is a good match and so the radio can transmit full power. Of course, the aerial is still a poor match and so some of the power gets dissipated as heat in the tuner and isn't radiated. This is quite important because if I say that I'm transmitting 100 watts, the chances are that I'm probably only actually pushing 40 watts through the tuner into the aerial.

Over the last few weeks I've been getting back into data communications over the radio. There are many forms of data modes from Radio Teletype which is exactly the same as the old teleprinters you used to see punching up the football scores on a Saturday afternoon on the television up to advanced forms of IP routing, all done over the radio. I've been experimenting with weak signal transmissions where the idea is that you transmit a weak signal at certain intervals and there are grabber stations around the planet who can receive this signals and provide signal reports. Because it's all done electronically it's possible to use these very weak signals, often weaker than the ear can hear to provide propagation reports, to see how the radio bands are working and to get an idea how ones equipment is performing.

For example, if I'm running 20 watts and my signal is measured at -20dB in New Zealand, it's possible to calculate how much power I'd need to run in order to get a nice strong signal using the same aerial. It can get quite complicated but it's also a good way to test and evaluate different aerial systems by comparing the signal received at the far end.

I'm getting quite technical here and I applaud anyone who has got this far without falling asleep but I find this stuff really interesting and exciting and can talk/type for hours about it!

I've recently discovered a mode called JT65-HF. This uses a technology similar to the weak signal propagation but by using it, it's possible to exchange data and have an actual contact between two people. It's not just one station transmitting and looking on the internet to see his signal reports. Using JT65-HF, callsigns, locators and signal strengths are exchanged.

I've been using it for a few days now and earlier this evening whilst calling on the 7MHz band where the wavelength is 40m I noticed a new trace appearing on the far right of my screen. It decoded as a station located in Western Australia, about ten miles east of Perth.

I had to retune my radio slightly because he was almost just outside the passband and once I'd done that I called him. When I say I called him, I don't mean that I picked up the microphone and shouted, I mean I clicked on the appropriate buttons which would send the tones from the computer to the radio which would in turn transmit those tones.

JT65-HF uses a 47 second cycle. The tones are transmitted over a 47 second period and there is no decoding done until the end. Data doesn't get displayed if it's corrupted, it's either a full decode or nothing.

Once I'd spent 47 seconds transmitting, I had to wait for his reply to see the outcome. So another 47 seconds later the decoded data appeared on my screen. He'd heard me and replied! He was receiving my signal at -18dB which is far from the weakest I've ever been seen at. I replied with his signal report, -12dB and then we exchanged '73' which is a telegraphy shortcut for 'best wishes'.

The contact was over. I had my first contact with someone on the other side of the world. I don't know how much power he was running but JT65-HF is normally transmitted with quite low power, I was transmitting just 30 watts.

I said at the start of this huge wall of text that I know all about telephones, VoIP and Skype but this is a major achievement for me. Radio isn't outdated, it isn't old fashioned, it's still a very valid form of communication and as a hobby, I absolutely love it. I'm on a massive high right now and have been for the last few hours since I had this contact.

I've written a more techy version of this on my blog which you can see by clicking here if you're interested.

/edit Here's an image of what JT65-HF looks like when it's running:

In that I'm just finishing a contact with M0TZO. The 'waterfall' display is where the output from the radio is displayed, the line up the centre is just some noise on the band, there are two signals shown, one either side. The contact I've just had is on the left and his signal was -13dB with me. The one on the right around the 0 marker is OM7OM who was much stronger at -6dB. The red highlighted windows are M0TZOs replies to me and you can see all the buttons on the right that select the appropriate messages. There's a custom message all queued up saying '20W LW TU 73' which translates to me saying that 'I'm running 20 watts to a long wire, thank you and best wishes'.

Looking further down in the window you can see RV6HFA was calling CQ (which is an invite for someone to call him) from the locator square LN05 (which is in the bottom part of Russia, around 100m north of Georgia) at 00:04, then G3IOI replied with his locator, JO01 (he's in Wickford, Essex). I was transmitting myself so I didn't spot RV3HFA send a signal report to G3IOI, you then see G3IOI send a signal report of -08 at 00:09. I missed another transmission because I was transmitting and then G3IOI sent the two callsigns and 'RRR' at 00:11 which means 'yup, all copied'. That can sometimes be left out and just '73' sent instead. Then at 00:15 the RV station is being called by K1LPS in the locator square FN34 which I happen to know is in the US State of Vermont. K1LPS was very strong with me at -4dB.

I think it's quite cool

Psymonkee · 07-03-2011, 02:46

Quite cool?

That's awesome

(I don't think I understood much though. Didn't fall asleep mind

)

Stan_Lite · 07-03-2011, 09:45

I won't pretend to understand the science behind it but I did, sort of, understand things as you explained them. I can most definitely understand your excitement at communicating with someone on the other side of the world on a system you have built and tweaked yourself.

You mentioned the tones you sent and then the '73'. Are there different tones you send and do they have a decodable syntax - like Morse code? If so, could you have a basic conversation using the codes or are they purely intended to convey information regarding signal strength etc.?

Feek · 07-03-2011, 10:01

I've been thinking more about this and the thrill comes from (as you say) getting my signal to the other side of the world with no assistance. With the phone, with VoIP etc then the signal is repeated and regenerated many times en route. With radio, the same signal that's transmitted from my end is received on the other side of the world with absolutely no assistance, except from bouncing off the ionosphere.

It's possible using the custom entry field to change the standard text that's sent - You can see in the image I posted that I used a custom message to end the contact. Normally these tones aren't readily decodable by ear but it is possible to use 'shortcuts' which produce a very distinctive audible pattern.

For example, here's an audio file I just recorded with two samples of the full 47 second transmission periods. The first one is me calling CQ and the second one is the shortcut for RRR.

The first one can't be read by ear, the second is somewhat distinctive.

Stan_Lite · 07-03-2011, 10:26

Ah. Missed the bit about the custom message in the OP

So you have 13 characters in which to convey whatever information you want - presumably, there is a list of standard abbreviations (like 'LW' for long wire etc.) which are universally recognisable?

Jingo · 07-03-2011, 10:30

Quote:

Originally Posted by Feek

The first one can't be read by ear, the second is somewhat distinctive.

What do you mean by "can't be read by ear" ?

I can hear both 'tunes' (

) although they are clearly quite different...

[I'm ignorant to most of this but find it interesting enough

]

Feek · 07-03-2011, 10:42

Spot on Stan, most abbreviations are pretty straightforward to those in the know, LW is Long Wire, DIP is a Dipole, RV is a G5RV which is a type of dipole aerial, Vert is a vertical aerial etc etc. The main body of the contact will always be the same though because there's certain info which has to be exchanged for the contact to be valid, that's callsigns, locators and signal reports.

Jingo, I'll see if I can record a weak signal off air later and you'll see how quiet they are in real life. I've got my radio in pieces at the moment and am about to replace 20 diodes to reduce the base noise level of the receiver. It's also interesting in that the space that would be taken up by a single voice contact can be used for around seven or eight of these data contacts so it's very bandwidth friendly.

Feek · 07-03-2011, 22:29

I put the cover back on my radio after making that post this morning and took it to the radio shop where the mods were done for me. I didn't fancy the work. If you want to see what the inside of a wireless set looks like, click here.

I was calling CQ on 40m again this evening and noticed a trace right on the edge of the 'waterfall' display again. It was the same station I worked yesterday only much stronger. This time I took a screen capture:

You can see he's finished off a contact with US3MW in Ukraine and is calling CQ. I quickly grabbed my iPhone and recorded the audio, you can hear it here.

The modifications done to the radio today have really lowered the base noise on received signals, there's much less crud about now.

Feek · 19-03-2011, 01:13

I worked him again this evening, I was calling CQ and saw a very weak station reply, you can see his trace on the waterfall in this image...

His signal was 20dB below the noise - That's weak! Compare that with the station in Monaco who is very loud around at just -8dB and very visible on the waterfall.

07-03-2011, 02:19	#1
Feek ex SAS Join Date: Jun 2006 Location: JO01ou Posts: 10,062	I've had a contact on the wireless with someone in Australia! Now before I start, yes I have heard of telephones. Yes I have heard of VoIP and yes I know all about Skype. As you know, radio is a hobby of mine. I've always been interested in the Very High Frequencies, that's generally accepted to be 50MHz and above but the band that has had my attention is 144MHz where the length of the radio waves is 2 metres. That's limited to what's generally accepted to be line of sight communication and although the waves can carry a fair way, they generally only go a couple of thousand km at most but more commonly will travel just a few hundred km. The High Frequency bands, those between 1.8MHz and 28MHz where the length of the radio waves go from 160m to 10m respectively have always been a bit of a mystery to me. I've never used them and up until last year I've had little experience of them. I've always been of the impression that one can switch on a radio at any time of the day and providing you get the right frequency for the time of day, you can 'work' the world. Well, I became active on the HF bands around six months ago and quickly learned that I was mistaken. Perhaps with a super large station with lots of power and big aerials that might be possible but it's far from the norm. Because these bands have very long wavelengths, getting any decent size aerial up is quite a challenge and most HF aerials are a compromise. My aerial for the HF bands consists of a random length piece of wire with a 'smart tuner' at the end. For a radio to transmit efficiently it has to have a tuned aerial and the smart tuner fools the radio into thinking that the aerial attached to it is a good match and so the radio can transmit full power. Of course, the aerial is still a poor match and so some of the power gets dissipated as heat in the tuner and isn't radiated. This is quite important because if I say that I'm transmitting 100 watts, the chances are that I'm probably only actually pushing 40 watts through the tuner into the aerial. Over the last few weeks I've been getting back into data communications over the radio. There are many forms of data modes from Radio Teletype which is exactly the same as the old teleprinters you used to see punching up the football scores on a Saturday afternoon on the television up to advanced forms of IP routing, all done over the radio. I've been experimenting with weak signal transmissions where the idea is that you transmit a weak signal at certain intervals and there are grabber stations around the planet who can receive this signals and provide signal reports. Because it's all done electronically it's possible to use these very weak signals, often weaker than the ear can hear to provide propagation reports, to see how the radio bands are working and to get an idea how ones equipment is performing. For example, if I'm running 20 watts and my signal is measured at -20dB in New Zealand, it's possible to calculate how much power I'd need to run in order to get a nice strong signal using the same aerial. It can get quite complicated but it's also a good way to test and evaluate different aerial systems by comparing the signal received at the far end. I'm getting quite technical here and I applaud anyone who has got this far without falling asleep but I find this stuff really interesting and exciting and can talk/type for hours about it! I've recently discovered a mode called JT65-HF. This uses a technology similar to the weak signal propagation but by using it, it's possible to exchange data and have an actual contact between two people. It's not just one station transmitting and looking on the internet to see his signal reports. Using JT65-HF, callsigns, locators and signal strengths are exchanged. I've been using it for a few days now and earlier this evening whilst calling on the 7MHz band where the wavelength is 40m I noticed a new trace appearing on the far right of my screen. It decoded as a station located in Western Australia, about ten miles east of Perth. I had to retune my radio slightly because he was almost just outside the passband and once I'd done that I called him. When I say I called him, I don't mean that I picked up the microphone and shouted, I mean I clicked on the appropriate buttons which would send the tones from the computer to the radio which would in turn transmit those tones. JT65-HF uses a 47 second cycle. The tones are transmitted over a 47 second period and there is no decoding done until the end. Data doesn't get displayed if it's corrupted, it's either a full decode or nothing. Once I'd spent 47 seconds transmitting, I had to wait for his reply to see the outcome. So another 47 seconds later the decoded data appeared on my screen. He'd heard me and replied! He was receiving my signal at -18dB which is far from the weakest I've ever been seen at. I replied with his signal report, -12dB and then we exchanged '73' which is a telegraphy shortcut for 'best wishes'. The contact was over. I had my first contact with someone on the other side of the world. I don't know how much power he was running but JT65-HF is normally transmitted with quite low power, I was transmitting just 30 watts. I said at the start of this huge wall of text that I know all about telephones, VoIP and Skype but this is a major achievement for me. Radio isn't outdated, it isn't old fashioned, it's still a very valid form of communication and as a hobby, I absolutely love it. I'm on a massive high right now and have been for the last few hours since I had this contact. I've written a more techy version of this on my blog which you can see by clicking here if you're interested. /edit Here's an image of what JT65-HF looks like when it's running: In that I'm just finishing a contact with M0TZO. The 'waterfall' display is where the output from the radio is displayed, the line up the centre is just some noise on the band, there are two signals shown, one either side. The contact I've just had is on the left and his signal was -13dB with me. The one on the right around the 0 marker is OM7OM who was much stronger at -6dB. The red highlighted windows are M0TZOs replies to me and you can see all the buttons on the right that select the appropriate messages. There's a custom message all queued up saying '20W LW TU 73' which translates to me saying that 'I'm running 20 watts to a long wire, thank you and best wishes'. Looking further down in the window you can see RV6HFA was calling CQ (which is an invite for someone to call him) from the locator square LN05 (which is in the bottom part of Russia, around 100m north of Georgia) at 00:04, then G3IOI replied with his locator, JO01 (he's in Wickford, Essex). I was transmitting myself so I didn't spot RV3HFA send a signal report to G3IOI, you then see G3IOI send a signal report of -08 at 00:09. I missed another transmission because I was transmitting and then G3IOI sent the two callsigns and 'RRR' at 00:11 which means 'yup, all copied'. That can sometimes be left out and just '73' sent instead. Then at 00:15 the RV station is being called by K1LPS in the locator square FN34 which I happen to know is in the US State of Vermont. K1LPS was very strong with me at -4dB. I think it's quite cool __________________ Last edited by Feek; 07-03-2011 at 09:23.

07-03-2011, 02:46	#2
Psymonkee A cat wearing a wet suit Join Date: Sep 2008 Location: St.Andrews Posts: 2,023	Quite cool? That's awesome (I don't think I understood much though. Didn't fall asleep mind ) __________________ Sonisphere FMC Code: 1k949178

07-03-2011, 09:45	#3
Stan_Lite Stan, Stan the FLASHER MAN! Join Date: Jul 2006 Location: In bed with your sister Posts: 5,483	I won't pretend to understand the science behind it but I did, sort of, understand things as you explained them. I can most definitely understand your excitement at communicating with someone on the other side of the world on a system you have built and tweaked yourself. You mentioned the tones you sent and then the '73'. Are there different tones you send and do they have a decodable syntax - like Morse code? If so, could you have a basic conversation using the codes or are they purely intended to convey information regarding signal strength etc.? __________________ Just because I have a short attention span doesn't mean I...

07-03-2011, 10:01	#4
Feek ex SAS Join Date: Jun 2006 Location: JO01ou Posts: 10,062	I've been thinking more about this and the thrill comes from (as you say) getting my signal to the other side of the world with no assistance. With the phone, with VoIP etc then the signal is repeated and regenerated many times en route. With radio, the same signal that's transmitted from my end is received on the other side of the world with absolutely no assistance, except from bouncing off the ionosphere. It's possible using the custom entry field to change the standard text that's sent - You can see in the image I posted that I used a custom message to end the contact. Normally these tones aren't readily decodable by ear but it is possible to use 'shortcuts' which produce a very distinctive audible pattern. For example, here's an audio file I just recorded with two samples of the full 47 second transmission periods. The first one is me calling CQ and the second one is the shortcut for RRR. The first one can't be read by ear, the second is somewhat distinctive. __________________

07-03-2011, 10:26	#5
Stan_Lite Stan, Stan the FLASHER MAN! Join Date: Jul 2006 Location: In bed with your sister Posts: 5,483	Ah. Missed the bit about the custom message in the OP So you have 13 characters in which to convey whatever information you want - presumably, there is a list of standard abbreviations (like 'LW' for long wire etc.) which are universally recognisable? __________________ Just because I have a short attention span doesn't mean I...

07-03-2011, 10:42	#7
Feek ex SAS Join Date: Jun 2006 Location: JO01ou Posts: 10,062	Spot on Stan, most abbreviations are pretty straightforward to those in the know, LW is Long Wire, DIP is a Dipole, RV is a G5RV which is a type of dipole aerial, Vert is a vertical aerial etc etc. The main body of the contact will always be the same though because there's certain info which has to be exchanged for the contact to be valid, that's callsigns, locators and signal reports. Jingo, I'll see if I can record a weak signal off air later and you'll see how quiet they are in real life. I've got my radio in pieces at the moment and am about to replace 20 diodes to reduce the base noise level of the receiver. It's also interesting in that the space that would be taken up by a single voice contact can be used for around seven or eight of these data contacts so it's very bandwidth friendly. __________________ Last edited by Feek; 07-03-2011 at 10:45.

07-03-2011, 22:29	#8
Feek ex SAS Join Date: Jun 2006 Location: JO01ou Posts: 10,062	I put the cover back on my radio after making that post this morning and took it to the radio shop where the mods were done for me. I didn't fancy the work. If you want to see what the inside of a wireless set looks like, click here. I was calling CQ on 40m again this evening and noticed a trace right on the edge of the 'waterfall' display again. It was the same station I worked yesterday only much stronger. This time I took a screen capture: You can see he's finished off a contact with US3MW in Ukraine and is calling CQ. I quickly grabbed my iPhone and recorded the audio, you can hear it here. The modifications done to the radio today have really lowered the base noise on received signals, there's much less crud about now. __________________

19-03-2011, 01:13	#9
Feek ex SAS Join Date: Jun 2006 Location: JO01ou Posts: 10,062	I worked him again this evening, I was calling CQ and saw a very weak station reply, you can see his trace on the waterfall in this image... His signal was 20dB below the noise - That's weak! Compare that with the station in Monaco who is very loud around at just -8dB and very visible on the waterfall. __________________