RRBlog: Decoding NOAA APT Weather Images

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blantonl

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There are a lot of things in the radio communications hobby that are exciting... but for many monitoring satellite communications is at the top of the list. One of the more interesting satellite monitoring targets are the NOAA low earth orbit satellites, which fly in sun-synchronous polar orbits around the earth and continuously transmit satellite photos. These picture transmissions occur in the 137 MHz band and are easily monitored with a scanner and easily decoded with free software. In this post, I'll review how I was able setup a process to receive and decode these pictures using an AOR AR5000 Radio, a computer with a sound card, and free decoding software.

http://radioreference.blogspot.com/
 

reedio

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optional receiver

Any other electronic device that will receive frequencies? I thought I saw a kit or
a small module that only received these freqs. DR
Sorry, posted in wrong place and found info in sat monitoring page.DR
 
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kd5dga

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I ran APT decoder two years ago with good success and using only one discone antenna and Icom PCR1000. Its fun but takes a while to get everything up and running right. The program is excellent.
 

SEMTTP

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Ok,

Ran the software with a Discone and BC780xlt and everything went through the motions, however at the end all I ended up with was a black screen. I will wait for the next pass and try again...


Well, disregard....I thought I had it hooked up correctly and it turns out that I did not.....I had it in the "tape out" on the 780 and the wrong port on the sound card....gesh...so I have it hooked up correctly now....

Many thanks for the software Lindsay......
 
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ki4rvh

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They had an article in QST a couple months back for a 137 MHz antenna to receive the Sat. If I can find a link to an electronic copy I'll post it.

You did a great job on the blog. I've been wanting to try this since I read the article in QST. I'll get to it one of these days.

73

Chris
 
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SEMTTP

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Yeah I may have to build one of those antenna's. I am using a discone, and according to Lindsays blog, a discone should be ok to use. However, I get nothing but grey and black lines. No picture whatsoever.

I thought maybe it would work, but its not. oh well.....off to get a parts list I guess...
 

SEMTTP

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Eric,

Are you hearing a signal on your scanner? How about sound card and levels?
Yes Lindsay I am hearing the satellite noise. I thought I had the settings adjusted accordingly. I will over look it again and try again until I can get a different antenna.....did you use a discone for your pictures?
 

Caesar

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Yes Lindsay I am hearing the satellite noise. I thought I had the settings adjusted accordingly. I will over look it again and try again until I can get a different antenna.....did you use a discone for your pictures?
Thanks for the blog. I too am hearing the sat, however not to terribly strong, will work on another antenna later or pointing a 2 meter beam into the sky one, but how significant it is for the 30khz bandwith? I am listening on a BCT-15 and wondering if that is sufficient or if maybe i should try on some of my ham gear instead..
 

SEMTTP

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Right now, I am using a Discone antenna on top of the house, a BC780xlt. I have tried the discriminator tap, and the external speaker plugs, but have not had any luck with it decoding a picture. I hear the sat just fine, but all I get is black/grey lines.

I followed exactly what Lindsay posted on the blog, but it no not work! :)

I am just going to keep trying until I can get a different antenna built.
 
D

DaveNF2G

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You might be better off using older scanners for this. The APT signal bandwidth is wider than most "wideband FM" signals. The newest scanners have narrower bandpasses and other interference rejecting enhancements that, while making them superior for receiving terrestrial two-way radio signals, tend to screen out wider signals like satcom. It isn't much of a problem when listening to voice traffic on satellites, but the video modes require the full signal to be decoded.
 

KevinGC

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No luck here

Sigh. I have not had any luck receiving any of the satellites on either of my radios. Have listened on my GRE PSR500 with duckie and also hooked up to my dual band (2M & 70cm) J-Pole antenna mounted on roof. Also have not been able to hear them on my Yaesu FT-60 dual band amateur HT.
With the PSR500 have tried both FM and AM mode,
Has anyone had any luck with the PSR500? Or any hams had any luck with their rigs?
Any suggestions?
 

eorange

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Well, last night I heard the satellite w/ no problem, which was cool in itself. But I couldn't decode anything. I am pretty sure I had all the levels set correctly. (I have done tons of soundcard decoding before - HF FAX, PSK31, PDW, POCSAG, ACARS, APRS, ad nauseum).

I used a VR-500 first with NFM, via the discone on the roof. Then I tried WFM, although it was a little too wide - I actually didn't hear the signal any more and started to hear what sounded like broadcast FM!

Like Caesar, the signal wasn't the strongest thing in the world, and I may also try to take my handheld sat antenna outside with a laptop.

The software is very cool, though - a good find there.
 

yn0t

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Ok,

Ran the software with a Discone and BC780xlt and everything went through the motions, however at the end all I ended up with was a black screen. I will wait for the next pass and try again...


Well, disregard....I thought I had it hooked up correctly and it turns out that I did not.....I had it in the "tape out" on the 780 and the wrong port on the sound card....gesh...so I have it hooked up correctly now....

Many thanks for the software Lindsay......
Hey all. Completely new to this forum. And I decoded my first glimpse from a NOAA weather satellite today thanks to the post.

Eric, I too am using the BC780XLT. I was hoping you could post an example of how your images are turning out and which antenna you're using. I'm hoping to clear my images up A LOT! :)

Thanks guys! Great community here!
 

eorange

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Update: I tried the BC780 and the discone, and at least this time I got the grayscale colored bars, but no usable map.

While this was going on, I took the VR-500 outside with my hamsat yagi, and what a difference in the signal! Very strong, well defined, and full quieting between the "beeeeps". Next time I get a chance, the laptop is coming outside.
 

yn0t

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Update: I tried the BC780 and the discone, and at least this time I got the grayscale colored bars, but no usable map.

While this was going on, I took the VR-500 outside with my hamsat yagi, and what a difference in the signal! Very strong, well defined, and full quieting between the "beeeeps". Next time I get a chance, the laptop is coming outside.
Bummer, so you're not getting a good result with the discone. I have the BC780XLT and I was planning on getting a discone to test it out. I probably still will because I currently have my scanner hooked up to the TV antenna on top of my roof and I'd like to get a better scanner antenna up there. I wasn't expecting much. he TV antenna performed a lot better than I expected. I am able to receive a pretty good range of frequencies.

Here's an example of what I'm able to receive with the BC780XLT and my rooftop TV antenna. This is one of the better passes. When the satellite happens to be in the direction of my TV antenna and has high enough altitude I get better results. However, most the time, mainly static.
http://www.postyourimage.com/view_image.php?img_id=o8h0JCsdzhWoQ6W1214580541

Can anyone else post some examples of what they're getting with the BC780XLT?
 

eorange

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That's about what my picture looked like with the discone/BC780, except I didn't even have that rough horizontal lighter area - just the grayscale bars. I am counting on the awesome signal I heard via my handheld yagi to give me way better results.

Long audio cable -> I actually thought of that, but I need to see the software running. I will end up using a long cable anyway so I don't yank the cable/laptop.
 
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