Weather fax on netbook + portable sony radio

[iainhu]

Chart of 7th

Your chart from the 7th is just stunning...as you say, as good as something from 'tinternet.

Have just collected more charts so will post in a little while. These weren’t quite as good as earlier and a little more like your second one. Also I had the charts 'reverse' (white out of black) at one point as a fiddled with frequencies, tuning and aerials. The signal was stronger (no surprise) with ‘whiter whites’ with the external aerial plugged in, but tended to have skipped lines periodically. You’ll see when I post…

 

[iainhu]

Further results

These are more results taken from earlier this evening. At the beginning you can see some 'experiments' with and without the external aerial. The results aren’t as good as earlier and you can see periods of ‘frequency tuning’ often making things worse, at one point even turning the plots into reverse (white lines on black). This was all from tuning the signal and nothing to do with program settings!

One of the main problem seemed to be ‘skipped lines’ where every 5 or so lines, there would be a white ‘missed line’. I also found that while the signal was stronger using the external aerial, with the built-in aerial the charts were darker but less broken. Which though is better? All to be decided as you are trying to receive charts for use…

All three sets of charts were collected simultaneously, so this is with the exact same feed into the one laptop although of course maybe not all programs are setup ideally. SeaTTY for instance includes a squelch control although I’ve not yet been able to use it to any visible good effect.

The main characteristics of the charts seem to be:

• jvComm seems to give the ‘dirtiest’ charts – a lot of ‘black noise’ making the charts hard to interpret
• Mscan in some ways is the clearest but suffers for black horizontal banding and the extremely irritating ‘Unregistered’ banner. A note to the software author…this kind of ‘demo software’ makes me inclined NOT to purchase a license as I can’t properly test the software. Maybe you should think again about the means of restricting your demo copies?
• SeaTTY produced lighter charts and still tends to be my favourite

I have reduced the imagesfrom 1,810 pixels to 1,000px wide and in the case of the Mscan saved as jpeg. This to try and fit on a screen and be read reasonably!

From jvComm

From Mscan

And finally from SeaTTY

More experimentation required and comments/suggestions/ideas welcomed

 

[Pye_End]

Good results. It would be interesting to put all the gear next to each other and see how the receivers compare, as well as the software.

If you look at the Mscan at the small signal graph, there are the two notches marking the light and dark. If you get the 'light' end of the spectrum right over the notch, or even a tadge further on, then it should lighten the image.

Does the SeaTTY autotune? Looks as though it handles the signal very well.

 

[iainhu]

Yes SeaTTY has an Autotune and I've left it to do its own thing. I've played less with the other two but ill have a go getting the white blip (the one to the right I recall) and right-most tick aligned and see if I can improve things. Thanks

 

[st599]

When you create an AM signal, you end up with two sidebands. One is a negative copy of the other. You can therefore remove one. This is SSB AM.

You need to set your radio to receive the correct sideband.

The line out, is at line level. Microphone outputs are tiny compared to line level. It could be you're overdriving the PC input.

 

[iainhu]

Yes I'm aware of the upper and lower bands and the radio is correctly set to USB.

I mentioned the input mic was set right down and that I have considered using the headphone-out instead as a means of controlling (turning down) the input to the laptop, however, this has the disadvantage that I can't listen then to the tone as I attempt to tune and things are generally working at the moment.

Also, talking with a YM Ocean instructor friend, it seems clarity should improve significantly at sea and away from land interference, so things should get better.

 

[Conachair]

I mentioned the input mic was set right down and that I have considered using the headphone-out instead as a means of controlling (turning down) the input to the laptop, however, this has the disadvantage that I can't listen then to the tone as I attempt to tune and things are generally working at the moment.

Also, talking with a YM Ocean instructor friend, it seems clarity should improve significantly at sea and away from land interference, so things should get better.

I've used the mic input from the laptop before, works OK in a quiet place and gets rid of any interference from the laptop going down the cable, though if the laptop isn't charging this isn't really much of a problem. last laptop had a blown soundcard so i just bought a cheapo usb/sound dongle.
Reception is much better offshore, though one of the drawbacks I had was remembering to turn the fridge on afterwards
The images you are getting seem OK, you can tell what's gouing on which is the main thing.
You can use the tuning as a sort of contrast control, tune up a fraction and the picture will get a bit whiter.

As for navtex, don't think I've ever got that working, means either getting up at some ungodly hour hoping that they are trasmitting acording to their schedule or leave the thing set up all day. I've never had any luck anyway. Weatherfax is possible more useful as a big picture offshore anyway.

The dwd rtty broadcasts might be of interest though

http://www.dwd.de/bvbw/generator/DW...erty=publicationFile.pdf/Schedule_rtty_01.pdf

10.1mHz usually has a signal, the coded reports make no sense though.

Settings from my jvcomm are:

Type - baudot
PTC-II type - baudot
# of bits - 5
Baudrate - 50
shift - 450
rev-800

These are in the configuration/rtty mode editor

Happy receiving

 

[iainhu]

You can use the tuning as a sort of contrast control, tune up a fraction and the picture will get a bit whiter.

That's certainly what I've found...higher pitch = more white.

Many thanks for the other info and the 'warning' over Navtex. Had no luck there and this maybe explains why, but will try the RTTY you mention. Thanks

 

[iainhu]

More experiments

Well I have some more experiments from a little testing earlier this evening (21-Oct-11). Very clear reception tonight, but some interesting results which I throw open from comment/advice.

The following image from SeaTTY shows some interesting sections…

1. Section 1: This was me re-tuning. On first starting reception was excellent, then the broadcast ended and I ‘had a play’ to see if I could pick up Boston (without luck) and then tuned back and the black ‘negative’ section is me getting tuned back in. Interesting switching the radio to ‘narrow’ significantly improved the signal clarity.
2. Section 2: I inadvertently had my laptop on charge during this phase (forgot to unplug!), but it’s interesting to see the effect of the RF noise feeding through into the chart
3. Section 3: This is an interesting section. I ran SeaTTY (from which this image is take) and jvComm together. I then started Mscan Meteo and this was the cause of the banding in section 3 – the periodic missed lines that I also recorded last weekend. As soon as Mscan was stopped the skipped lines stopped (and we’re back to section 2 RF noise)
4. Section 4: Nice clear reception with no mains connected, however, note the changes in horizontal offset. One a prior chart I attempted to correct the offset but seemed to keep getting it wrong, so I left it alone thinking to do it once at the end. What I then got is recorded here, with the horizontal offset changing every minute or so, with the chart ‘stepping’ to the left each time. No ideas why though!
5. Section 5: I started picking up some Morse interference that I couldn’t tune out, hence the noise lines

So the interesting points seem to be the interference between Mscan and SeaTTY + jvComm. SeaTTY and jvComm were happy to play nicely together, but Mscan clearly thought differently. I’ve not yet experimented with Mscan on its own. And the other point was to reinforce the message about RF noise and main-connected equipment.

Now we have a nicer cleaner chart from SeaTTY with no Morse interference and no Mscan either, but look at the horizontal shift. I did nothing but let the machine record during this time, so these shifts were done all by itself!

And finally here’s a sample from jvComm. This is a lot cleaner than jvComm samples from last weekend although I don’t think they are quite as clean as the SeaTTY charts. But notice also the ‘left stepping’ of the chart. Clearly this problem seen on the SeaTTY charts above isn’t something to do with SeaTTY as jvComm working from the same audio feed is producing a near identical results.

Anyone any ideas on why I might be seeing this 'stepping' left shift of the image? This isn’t a problem I encountered last week and it makes me wonder if I should use a graphics program to realign any charts I might receive like this. I could cut a reception into slices than then shift each slice left/right as necessary to build a readable chart.

 

[Pye_End]

Never had one like that before! Looks almost as if it is losing bits of a line, and effectively starting a new chart. Is the lead ok? It's not something to do with another program running, and in some way interfering with the input?

Have you tried re-booting!?

 

[iainhu]

Have you tried re-booting!?

Yes re-booted because SeaTTY didn't seem very happy at some point. Don't believe it was having several program running as I was doing that last weekend with all three running together without problem, although I did uncover that the 'skipped lines' problem I saw last weekend seems to be down to having Mscan run at the same. Maybe Mscan only likes to play on its own

Will experiment some more.

Excepted the line wrap, it does show the receiver can do a quite nice job. This was with the 7m retractable (windable) aerial.

 

[Bilgediver]

Yes re-booted because SeaTTY didn't seem very happy at some point. Don't believe it was having several program running as I was doing that last weekend with all three running together without problem, although I did uncover that the 'skipped lines' problem I saw last weekend seems to be down to having Mscan run at the same. Maybe Mscan only likes to play on its own

Will experiment some more.

Excepted the line wrap, it does show the receiver can do a quite nice job. This was with the 7m retractable (windable) aerial.

You can run as many as you have sound cards and give each one its own however don t expect perfection if more than one program is sharing the sound card. Usually they will refuse to share.

The smudgy faxes indicate incorrect tuning and the fax signal should be tuned more to the right on both SeaTTy and JVcom if these being used.

Both programs work well with Sony SSB receivers. I use the SW 55.

 

[iainhu]

Smudgy faxes?

You can run as many as you have sound cards and give each one its own however don t expect perfection if more than one program is sharing the sound card. Usually they will refuse to share.

The smudgy faxes indicate incorrect tuning and the fax signal should be tuned more to the right on both SeaTTy and JVcom if these being used.

Both programs work well with Sony SSB receivers. I use the SW 55.

I'm receiving a laptop which will goes to sea so there is no option for multiple soundcards, although someone did mention a plug-in USB dongle? I've not come across one of those before, although a quick search on Google revealed a nice example. However, the reason for looking at several programs is to see how they compare, so I won't expect to run multiple. As it is, jvComm and SeaTTY seem happy together, but Mscan clearly isn't.

Re ‘smudgy faxes’, do you mean section 5 in my example? That was caused by a clear Morse signal that I couldn’t tune out. Excepting this and the strange sidewards ‘walk’ of the faxes (of which more in a while), the reception and white seem pretty good to me?

 

[Conachair]

IExcepting this and the strange sidewards ‘walk’ of the faxes (of which more in a while), the reception and white seem pretty good to me?

Quality seems plenty good, you can see what's going on which is the main thing. I used to get the image jump sometimes as well, never got to the bottom of why. Just takes a few clicks on jvcom to fix though.

 

[iainhu]

More experiments!

Well a few more tests and observations…

This time I only ran one program at a time just to see if that made any difference. First I ran Mscan…

The two obvious issues are:

• The horizontal black lines which have characterised all the Mscan charts I have captured
• The leftwards ‘side step’ of the chart, just as received last night

I therefore stopped the reception and rebooted the laptop. No harm in trying. I then ran SeaTTY…

This again demonstrated the ‘leftwards step’ of the chart, so my conclusion is that the reboot didn’t help, but was worth trying as it eliminates one possible issue. Excepting that, these charts don’t seem too bad. Note how they ‘clean up’ midway down (around the 1020mb isobar). This was my neighbour switching off his petrol mower…an instant improvement without any fine tuning, just the removal of interference. So not perfectly clean, but readable.

I then tried jvComm…

This acquitted itself rather nicely with clean output, at least to start, and a lot nicer than previous attempts with jvComm. Interestingly, it also shows the same leftwards ‘step’ of the charts, so this doesn’t seem to be anything to do with one program or the effects of several programs accessing the soundcard output at the same time. That observation tallies with previous results wher all three worked together without issue, other than the occational ‘blank line’ which I’ve now found comes from Mscan running at the same time.

Towards the bottom of this chart I then experimented with using the headphone output from the Eton G3 rather than the line-out. This was to see if winding the input signal back might help things. jvComm have a very handy input signal meter and even with the mic wound down to the very first click above ‘off entirely’, a level so low it looks like it’s off when you view the mic level slider, the input seems too powerful, however, this made no appreciable difference.

I then switched to using the Eton’s in-built aerial. The dirty section at the bottom showing noise banding top right to bottom left is the result…and that banding looks very like the mains interference I caught last night with my laptop (accidentally) on mains supply. But it makes the point about the job being done by the wind-away aerial. It’s obviously worth having!

And as a final 'check', I took the SeaTTY image from above and 'shuffled' the slices back into some kind of order. The results is a pretty respectable chart...but why the recorded shifts? Anyone else seing this at the moment? I wasn't having this problem last weekend!

 

[iainhu]

Just takes a few clicks on jvcom to fix though.

Does it? How? I can a set the left margin, but then that shuffles the entire fax. Does jvComm include some magic to do all the reshuffling into shape automatically? Thx

 

[iainhu]

Just takes a few clicks on jvcom to fix though.

Ah...'stairstep' which isn't mentioned in the PDF manul, but is on the tools once you open a fax. Now this really is smart...and as you say, quick to fix an image. What's more, it fixes any image including ones captured by SeaTTY...it's justy manipulating a bitmap image. Very smart inded!

 

[iainhu]

jvComm tothe rescue!

This is the SeaTTY captured image shown previously 'shuffled' via jvComms's 'stairsteps' function. Shame there's no 'undo' for when you grab the wrong point, but still, very nice, exteremely useful and at least provides a workaround the 'leftwards step' problem I've been seeing...

 

[iainhu]

jvComm only

Neither SeaTTY or Mscan seem to have any image manipulation tools like jvComm's 'stairstep' function. It would seem to me that it's worth having a copy of jvComm even if you want to receive with some other decoder, as this function is a God-send in making sense of these repeatedly shifted images.

 

[jollysailor17]

This is a fascinating thread and I hope it’s not gone quiet as I’m need of some help!

As mentioned, the Sony radio you quote is no longer available, so instead I have purchased an Eton (Grundig) G3 Globe Traveller from Amazon. This seems a capably radio and is even sold in a package for SSB weather info use by YachtCom, e.g. the radio should be capable of doing the business. I also have a 7m retractable aerial (also from Amazon) to try and help things along, plus I’ve downloaded a copy of SeaTTY, however, from this point on things don’t go so well.

So I can tune the radio to 2616/4610/8040/11084 as you suggest. Incidentally, there’s a reminder; “To receive both weatherfax and text broadcast on a USB receiver you may have to tune 1.9 kHz low of frequency.” on the YachtCom site which confirms your; “tune 2KHz down” comment. This page also has a lot of useful info on frequencies and transission times. It seems this offset (-1.9KHz) is for receiving SSB-USB (upper side band). I suspect the offset is different for SSB-LSB (lower side band) which the G3 supports, however, I don’t know the offset or whether USB is somehow better than LSB.

I can get the input into my laptop (an old Dell D600 running WinXP and used solely for ‘nav’ tasks). I can see you point about mic input levels as if I turn the mic right down to nothing, then one click of the up arrow (not even a visible movement on the mic level slider), SeaTTY immediately sees a strong signal, e.g. to the top of the ‘current spectrum’ display at the top of the SeaTTY window. Mic input does seem to be rather all or nothing.

So I have the radio, I have the radio hooked to the laptop, I have SeaTTY working and I have SeaTTY showing me input ‘sound’ (noise more-like!), but there things come to a halt. I don’t seem to be able to get any kind of signal on any of the Northwood (GYA) frequencies. I did manage to get a feint voice message on RAF Volnet (5450 KHz) so know I can receive ‘something’, I just don’t seem to be having any luck receiving an actual weatherfax signal. I am in Norfolk (UK) so don’t know if I’m too close to the transmitter?

I have read that the Northwood transmitter is switched off when it’s not transmitting anything, making it a little more difficult to tune in ahead of time and get things setup, but is there some trick to tuning the radio? Should I only attempt in hours of darkness for instance? Should I try outside with the aerial strung up a tree? I’ve tried with both radio and laptop on battery only, but so far my limiting factor seems to be to actually receive anything that sounds remotely like a fax/data transmission on the radio, and obviously SeaTTY or anything else can’t decode anything until it has a data signal. So any clues on what I’m doing wrong? How do I get the radio to receive the weatherfax signal…what simple bit am I getting wrong?

Many thanks

Perhaps this might help
http://www.users.zetnet.co.uk/tempusfugit/marine/fwoc.htm