yn0t
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Which yagi do you have? Homemade? Purchased?
RRBlog: Decoding NOAA APT Weather Images
- Thread starter blantonl
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Which yagi do you have? Homemade? Purchased?
eorange
♦Insane Asylum Premium Member♦
Purchased - see my post #12 in this thread:
http://www.radioreference.com/forums/showthread.php?t=88625&highlight=arrow
http://www.radioreference.com/forums/showthread.php?t=88625&highlight=arrow
yn0t
Member
- Joined
- Jun 25, 2008
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- 6
Thanks for the info. I'm considering building my own handheld yagi and tuning it to somewhere around 137 MHz.
Heard the weather sats pass by many times on the 137 MHz band and have always wanted to try to decode them. I have a discone that I recently re-engineered, so to speak. The threaded ends are only crimped to the main long elements, so I wanted to make them tighter. Thought of solder, but couldn't find an alloy to use on aluminum. Could have swore I had seen something in Ace for radiators. What I ended up doing was just wrapping the two ends together tightly with some 22 gauge non-insulated bell wire. Then I used regular alloy solder to somewhat secure that together. Then, using my surgeon skills, and using a wizard tool to grind and polish the solder. It's more like a cap on the bell wire. :lol: Hard to explain..
This program might be of interest. Takes some getting used to. Tried it to match the GPS sats with my handheld, and it appears correct. Correct time is important!
http://www.satscape.co.uk/iweb/Satscape/Front_page.html
Click for larger
In case you were wondering what the background was from. :lol: http://usera.imagecave.com/Poltergeist/notebook.jpg
This program might be of interest. Takes some getting used to. Tried it to match the GPS sats with my handheld, and it appears correct. Correct time is important!
http://www.satscape.co.uk/iweb/Satscape/Front_page.html
Click for larger
In case you were wondering what the background was from. :lol: http://usera.imagecave.com/Poltergeist/notebook.jpg
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Clicking the 12 gives you a link... http://www.radioreference.com/forums/showpost.php?p=675848&postcount=12
Similar results...
Hi all, I'm getting this:
http://85.189.75.141/images/first.jpg
I can see that it's a NOAA sat, but it's very grainy and at a strange angle.
I made a QHA: http://www.cidb.co.uk/images/DSC03751.JPG
(it's finished, touched up and up a 20ft pole now).
Is there something obvious that I have missed and that's why I'm getting really poor pictures?
The reciever I am using is an ICOM PCR1000 - there is a GND screw on the back, but I'm on the fourth floor and haven't grounded it as yet - do you think that might help?
Hi all, I'm getting this:
http://85.189.75.141/images/first.jpg
I can see that it's a NOAA sat, but it's very grainy and at a strange angle.
I made a QHA: http://www.cidb.co.uk/images/DSC03751.JPG
(it's finished, touched up and up a 20ft pole now).
Is there something obvious that I have missed and that's why I'm getting really poor pictures?
The reciever I am using is an ICOM PCR1000 - there is a GND screw on the back, but I'm on the fourth floor and haven't grounded it as yet - do you think that might help?
dchruch24
That's how my images looks. i tried twice yesterday and go hte same results.
vince48
That's how my images looks. i tried twice yesterday and go hte same results.
vince48
Well, I've taken all the dodgy soldering off of the [home made, a friend did the soldering and he was worse than I would have been at it!] antenna now and resoldered it taking extra, extra care not to have any touching stray coax wires etc..., and have wound the coax around the pole in a tight spring-like formation about 6 times. I am also going to reverse the direction of the coax that connects the antenna to the icom, as it seemed to be a clearer signal that way around.
I will also ground the icom somehow this evening and see if that makes a difference.
I will post the results here tomorrow.
We must be able to get this working! ;-)
I will also ground the icom somehow this evening and see if that makes a difference.
I will post the results here tomorrow.
We must be able to get this working! ;-)
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dchurch
I'm in the San francisco bay area, northern California. I belive i'm looking at 17. I think i tried all three for awhile yesterday. same results. I see the recording action, but the image is grayscale and no detail. I'm aslo using my detector output, which maybe the wrong output to use.
I'm in the San francisco bay area, northern California. I belive i'm looking at 17. I think i tried all three for awhile yesterday. same results. I see the recording action, but the image is grayscale and no detail. I'm aslo using my detector output, which maybe the wrong output to use.
Well - that was a failure!
It sounded good when I listened to it, but when I converted it all I got was that gibberish.
I am now at a complete loss.
I might make a new antenna - it can only be the antenna I think.
I did make this one to these dimensions though: http://www.jcoppens.com/ant/qfh/calc.en.php
There is a pole with electric cables on feeding our flat, but the antenna is a lot higher - could this cause all the noise?
The antenna was made using 75ohm coax - could this be a problem?
Anyone got any suggestions?
It sounded good when I listened to it, but when I converted it all I got was that gibberish.
I am now at a complete loss.
I might make a new antenna - it can only be the antenna I think.
I did make this one to these dimensions though: http://www.jcoppens.com/ant/qfh/calc.en.php
There is a pole with electric cables on feeding our flat, but the antenna is a lot higher - could this cause all the noise?
The antenna was made using 75ohm coax - could this be a problem?
Anyone got any suggestions?
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dchurch,
that's a lot better than what I recorded. I'm going try the audio output and see if it makes a difference.
that's a lot better than what I recorded. I'm going try the audio output and see if it makes a difference.
Several years back I did some decoding with a different hardware decoder and software program. This is my thoughts on your picture. The diagonal wide band in the lower right corner looks like the software timing and the line sync are a little off. Not familiar with the program so I don't know what control you have over the timing. Each scan line is preceded by a sync signal or followed by one I don't recall which. If the course timing is close I would expect the program to lock and keep the sync signal in a straight vertical line which keeps the rest of the picture lined up.
If the signal sounds good before you plug in I would suspect something with the audio input, because it looks like a weak noisy signal but you indicate different. Line in would be better than mic in. Easy to overload the mic input and overdrive the audio input amp. Does the program have any oscilloscope type diagnostic display. In the program are there any contrast or brightness controls? It is not about the screen contrast/brightness, but looking at the audio input. Decoding the high and low part of the signal closer together (low contrast) or further apart (more contrast). Or shifting all of the signal up or down to change the brightness of the signal, like a DC bias shifting up and down.
Take what I have said, "with a grain of salt." It was a long time ago with a different setup. You are very close. If you are really hearing a clean, strong signal I believe you have the radio-antenna configuration set well enough for now to focus on the audio in and processing part of it.
Good Luck!
Mike
Hi guys, thanks for the replies!
You guessed quite correctly that I had the jack plugged into the mic and not the line-in.
Have changed this now, but didn't have enough time this morning before work to wait for a sat pass, so will have to wait until I get home to see if it makes anough difference to the sound.
To be honest, even though it was in the mic it still sounded ok.
There are brightness/contrast controls, but I have been using GIMP to try and lighten the images etc... with varying success. There doesn't appear to be any options to change the timing in wxtoimg.
I've just been re-reading the blog about this (first post in this thread), and it says that the signal should be on FM.
I've been listening for the signal on USB, with any other mode it either picks up nothing but static or is too distorted to hear properly.
Is USB (I'm assuming it stands for Upper Side Band?) not FM?
Please excuse the dumb questions - I really am a complete newbie at this, this is my first scanner.
I have attached a screenshot of the software I am using to control the PCR1000.
In the mode drop-down, I have LSB, USB, AM, CW, UNUSED, NFM and WFM to choose from. I'm not sure what CTCSS is, but I assume it's something to do with two-way radio and squelch? I've been leaving this at 'Off' - it seems to make little difference what I choose there, so I assume it's not relevent to the NOAA transmisions.
Just as a side-note, I am using WXtoIMG running under WINE in Ubuntu 8.04 - not sure if this is relevent, but thought it might be worth mentioning.
Am I right in assuming that the PCR1000 is expecting a 50ohm antenna? I wouldn't have thought using 75ohm coax in my antenna would make that much difference, but I am happy to be proved wrong.
Vince, what antenna are you using? Can you post an image of what you are recieving?
You guessed quite correctly that I had the jack plugged into the mic and not the line-in.
Have changed this now, but didn't have enough time this morning before work to wait for a sat pass, so will have to wait until I get home to see if it makes anough difference to the sound.
To be honest, even though it was in the mic it still sounded ok.
There are brightness/contrast controls, but I have been using GIMP to try and lighten the images etc... with varying success. There doesn't appear to be any options to change the timing in wxtoimg.
I've just been re-reading the blog about this (first post in this thread), and it says that the signal should be on FM.
I've been listening for the signal on USB, with any other mode it either picks up nothing but static or is too distorted to hear properly.
Is USB (I'm assuming it stands for Upper Side Band?) not FM?
Please excuse the dumb questions - I really am a complete newbie at this, this is my first scanner.
I have attached a screenshot of the software I am using to control the PCR1000.
In the mode drop-down, I have LSB, USB, AM, CW, UNUSED, NFM and WFM to choose from. I'm not sure what CTCSS is, but I assume it's something to do with two-way radio and squelch? I've been leaving this at 'Off' - it seems to make little difference what I choose there, so I assume it's not relevent to the NOAA transmisions.
Just as a side-note, I am using WXtoIMG running under WINE in Ubuntu 8.04 - not sure if this is relevent, but thought it might be worth mentioning.
Am I right in assuming that the PCR1000 is expecting a 50ohm antenna? I wouldn't have thought using 75ohm coax in my antenna would make that much difference, but I am happy to be proved wrong.
Vince, what antenna are you using? Can you post an image of what you are recieving?
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Now that you are in the Line-in jacket, check the PC setup to make sure that audio is going where it needs to be in the PC. The input might be turned off.
“To be honest, even though it was in the mic it still sounded ok.”
Is that an indication that you can hear the audio from the PC when it is being decoded? That’s a good thing because that gives you a chance to fiddle with the radio tuning and audio volume to hear and see the results.
USB is ‘Upper Side Band’ and it is amplitude demodulation vs. frequency. You will want to be in FM and will have to retune you receiver when you do. When you hear the satellite signal in USB your carrier frequency is offset low or high from where you want to be in FM. I bet that you are hearing a whistling sound in the background. That is the satellite carrier mixing with the injected carrier in you receiver because of the USB mode of operation.
After I responded last night I got to thinking about what I was listen to years ago. It was HF weather charts very much like satellite picture decoding, but with a different output. For the HF weather charts, USB/LSB was the mode to use. For the satellite I am just not sure which it should be without some research. I can’t decide if AM or FM, but you said FM from the blog so go with that.
The PCR1000 has a 50ohm input, but not to worry 75ohm will work just fine.
Timing adjustment might not be needed with today processors speed and memory. With a good signal the program could be finding the sync signal in the data stream and keeping the scan lines correctly positioned.
“I've been listening for the signal on USB, with any other mode it either picks up nothing but static or is too distorted to hear properly.
”
The distortion you heard could have be the result of overdriving the audio input using the mic-in jack. It might have been the very signal you were looking for, but distorted. Look at it like a serial list of events starting at the antenna and ending at the picture on your display. Each input has to be correct to get to the output that is correct for the next input … and so on. One bad output and everything after that is bad and no picture.
Again Good Luck and keep us posted about your results.
Mike
“To be honest, even though it was in the mic it still sounded ok.”
Is that an indication that you can hear the audio from the PC when it is being decoded? That’s a good thing because that gives you a chance to fiddle with the radio tuning and audio volume to hear and see the results.
USB is ‘Upper Side Band’ and it is amplitude demodulation vs. frequency. You will want to be in FM and will have to retune you receiver when you do. When you hear the satellite signal in USB your carrier frequency is offset low or high from where you want to be in FM. I bet that you are hearing a whistling sound in the background. That is the satellite carrier mixing with the injected carrier in you receiver because of the USB mode of operation.
After I responded last night I got to thinking about what I was listen to years ago. It was HF weather charts very much like satellite picture decoding, but with a different output. For the HF weather charts, USB/LSB was the mode to use. For the satellite I am just not sure which it should be without some research. I can’t decide if AM or FM, but you said FM from the blog so go with that.
The PCR1000 has a 50ohm input, but not to worry 75ohm will work just fine.
Timing adjustment might not be needed with today processors speed and memory. With a good signal the program could be finding the sync signal in the data stream and keeping the scan lines correctly positioned.
“I've been listening for the signal on USB, with any other mode it either picks up nothing but static or is too distorted to hear properly.
”
The distortion you heard could have be the result of overdriving the audio input using the mic-in jack. It might have been the very signal you were looking for, but distorted. Look at it like a serial list of events starting at the antenna and ending at the picture on your display. Each input has to be correct to get to the output that is correct for the next input … and so on. One bad output and everything after that is bad and no picture.
Again Good Luck and keep us posted about your results.
Mike
Hi, wow! Thanks for the reply.
The line-in should be on (the mic wasn't, I had to fiddle to get that working - all 3(?) inputs were just labeled 'record', so I turned them all on).
I could hear the signal whilst recording, which was very handy as you suggest.
I've just been reading about USB/LSB/FM etc... on wikipedia, and guess what? You are spot-on with that whistling sound in the background - in fact, it seems to gain in pitch as the satellite approaches and go down in pitch as the satellite is receding. I thought this might be some atmospheric phenomena, but I guess it's 'cos I'm listening to the usb and not the carrier.
So, if you don't mind (like I say, I'm REALLY new to this!) I'd like to just reiterate what I think so far.
I have been listening to the upper side band on 137.620mhz for NOAA17. If I listen on FM (WFM or NFM - I am assuming "Wide" and "Narrow") would the frequency be the same?
The distortion was there even when I listened to the output directly from the scanner using it's internal speaker :-(
However, I do feel really encouraged by this. The USB signal was really clear the last time I recorded it - I tried to upload to my site so I could post a link here, but the resulting WAV file was over 100 meg, so thought that it was probably a bit much.
I must have some setting wrong somewhere and the fact that the USB signal is getting clearer (certainly a lot clearer than my first attempts) leads me to believe that the main FM signal, once I have the settings correct, should be clear too.
Are the USB and LSB picked up on the same frequency? i.e. 137.500 etc...
I like the analogy about the signal from the antenna to the screen.
If I can pick up the USB clearly, does that imply that I have build the antenna more-or-less correctly? This is the only *real* unknown - I have never made an antenna before (short of putting a coat-hanger in my car radio!) and everything else is a proven (I have seen the software produce excellent results on web pages, and have seen websites where the ICOM PCR-1000 has produced excellent results using the same software I am using).
Just for your information, the antenna is just about the highest thing in the village now - our flat is about the highest building in the highest part of the village - even at the roof level (where I can see out of the windows), you can visibly see the horizon in all directions, so there should be little in the way of 'blockages'.
The line-in should be on (the mic wasn't, I had to fiddle to get that working - all 3(?) inputs were just labeled 'record', so I turned them all on).
I could hear the signal whilst recording, which was very handy as you suggest.
I've just been reading about USB/LSB/FM etc... on wikipedia, and guess what? You are spot-on with that whistling sound in the background - in fact, it seems to gain in pitch as the satellite approaches and go down in pitch as the satellite is receding. I thought this might be some atmospheric phenomena, but I guess it's 'cos I'm listening to the usb and not the carrier.
So, if you don't mind (like I say, I'm REALLY new to this!) I'd like to just reiterate what I think so far.
I have been listening to the upper side band on 137.620mhz for NOAA17. If I listen on FM (WFM or NFM - I am assuming "Wide" and "Narrow") would the frequency be the same?
The distortion was there even when I listened to the output directly from the scanner using it's internal speaker :-(
However, I do feel really encouraged by this. The USB signal was really clear the last time I recorded it - I tried to upload to my site so I could post a link here, but the resulting WAV file was over 100 meg, so thought that it was probably a bit much.
I must have some setting wrong somewhere and the fact that the USB signal is getting clearer (certainly a lot clearer than my first attempts) leads me to believe that the main FM signal, once I have the settings correct, should be clear too.
Are the USB and LSB picked up on the same frequency? i.e. 137.500 etc...
I like the analogy about the signal from the antenna to the screen.
If I can pick up the USB clearly, does that imply that I have build the antenna more-or-less correctly? This is the only *real* unknown - I have never made an antenna before (short of putting a coat-hanger in my car radio!) and everything else is a proven (I have seen the software produce excellent results on web pages, and have seen websites where the ICOM PCR-1000 has produced excellent results using the same software I am using).
Just for your information, the antenna is just about the highest thing in the village now - our flat is about the highest building in the highest part of the village - even at the roof level (where I can see out of the windows), you can visibly see the horizon in all directions, so there should be little in the way of 'blockages'.
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Sorry, just re-read that.
Does that mean, that as I am picking up USB on 137.620 (noaa17) that I would have to find the frequency for the carrier up or down from 137.620 - or do I just change the mode to either WFM or NFM.
(sorry if I am not explaining this very well, I'm starting to get a little confused - sensory overload I think, I've been reading about Frequency Modulation all morning!)
Vince, make sure you set your AR5000 to 30K IF Bandwidth - and use the headphone output or high-level tape output from the AR5000 - not the detector output.
Thanks Lindsay
I’m using the 30K filter. I will use the headphone jack. That should do it. One thing I have noticed, I get maybe a 1-2 minutes pass by the satellite until the signal fades. Is everyone else experiencing the same duration for transmission??
I’m using the 30K filter. I will use the headphone jack. That should do it. One thing I have noticed, I get maybe a 1-2 minutes pass by the satellite until the signal fades. Is everyone else experiencing the same duration for transmission??
I'm getting that on occassion, but not when the sat passes more-or-less directly overhead - then it lasts for up to 15 mins.
Which prediction program are you using? You should be able to see a 'footprint' of when the signal is available to you.
I'm using gPredict, but I'm sure there's a windows version too.
Also, can you output the signal to an external speaker and bypass your PC? If so, does the signal sound noisy or clear?
Which prediction program are you using? You should be able to see a 'footprint' of when the signal is available to you.
I'm using gPredict, but I'm sure there's a windows version too.
Also, can you output the signal to an external speaker and bypass your PC? If so, does the signal sound noisy or clear?
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