Had some success with NOAA 18 tonight!

[Murphy625]

I've been playing around with satellites this past week.. had some issues with the Amateur radio satellites in that I can't decode anything from them.. (still working on that from my other thread).. But tonight I decided to give the NOAA satellites a shot.

I'm using an RTL-SDR dongle hooked to 100 feet of RG8/U coax running into a G5RV Dipole antenna strung up about 55 feet into a tree.. Ya. that's not a typo.. a G5RV that was originally intended to operate on the 10 to 40 meter bands...

And it worked! Sort of... kind of... I don't know how clear the signal is supposed to be but I started recording about 20 seconds after it entered range and it had just finished (barely) about 20 seconds before the satellite went out of range.. The sat was at an elevation of 24 degrees.. It seems that I downloaded a single image but in 5 formats. I have MCIR, NO, Contrast, Contrast, and Norm

The picture is not perfect and there are some goofy lines of static in it, but I can clearly see the clouds, my state, major bodies of water, etc. THAT was cool..

I think I'm going to build one of those double cross dipole antenna's and maybe purchase a band-pass antenna preselector (was recommended) to get rid of some of the noise the dongle picks up.

I'm not sure if I've figured this all out yet, but are these NOAA satellites in some kind of train behind each other so the software will stack images from multiple satellites? Or do they become totally separate instances? Seems to me that I got a hold of the caboose because there were no more due for another 7 or 8 hours or so.

 

[royldean]

They aren't in a train, per say. I think the sat downlinks a continuous "scroll" image, and you get what you get. I'm sure somebody else will corrrect me if I'm wrong. NOAA 19 has the strongest downlink, btw.

 

[racehorse5000]

I have a setup at my house that I receive the NOAA satellites 15,18, and 19. I use a RTL-SDR dongle attached to a Dipole Turnstile antenna. I located the RTL-SDR at the antenna and used a 20 ft. usb cable to my computer located inside my house. On the computer running win 7. I use SDR# to receive the 137 MHz signal and run Virtual Cable program to pipe the signal to WXtolmg program to decode images direct from the NOAA satellites. I do not use a preamp or preselector. I also use the same antenna and SDR# program using Virtual Cable to receive ISS signals, both audio and data on 145mhz

This setup works 95 to 100% of the images if you start receiving the signal above 16 deg above horizon and stop receiving 16 deg above horizon satellite pass.

 

[Murphy625]

Got my best image yet so far..

Just using a G5RV antenna with an RTL SDR dongle and nothing else.

I've been able to grab images from every sat pass but nothing this good.. Working on building a Turnstile but just gathering materials so far.

 

[jasday]

This is really cool. I have not done anything beyond scanning the local public safety.

 

[devicelab]

Here's NOAA 19 from this morning. Using nothing but Airspy Mini and Diamond D3000N discone antenna:

 

[Murphy625]

Has anyone compared the differences between a makeshift antenna like a discone or my 40m dipole and a purpose built antenna like the Turnstile (double cross)??

 

[devicelab]

Has anyone compared the differences between a makeshift antenna like a discone or my 40m dipole and a purpose built antenna like the Turnstile (double cross)??

If you build it correctly and use an analyzer to confirm its frequency resonance then a turnstile antenna should be much more effective. There are a lot of variables that determine this however.

 

[devicelab]

Here's NOAA 15 during tonight's pass:

 

[Murphy625]

I'm wondering if I should even bother building the special antenna for this.. So what if there are a few static lines in the picture, we can still see what's going on.

Anyone have experience going from a make-shift antenna to a purpose built turnstile or whatever? Is there a significant improvement?

 

[K5MPH]

What software are you using to decode the image,not bad for a dipole and why you are at it try WFM ......

 

[Murphy625]

What software are you using to decode the image,not bad for a dipole and why you are at it try WFM ......

I use SD Sharp with an RTL-SDR dongle and WXtoimg tied to a 40 meter G5RV antenna that's about 50 feet up in a tree and configured as an inverted V.

I do use wide band FM and adjust the bandwidth as the signal improves.. I also compensate for the Doppler shift manually.. about 2 khz every 10 seconds or so.

My bandwidth usually ends up around 40 khz when the signal is strongest.

Just got my hands on 20 feet of 1/2 inch Aluminum electrical conduit.. Thinking of making a turnstile (double cross) antenna but not sure if its worth the effort.

 

[devicelab]

The Airspy Mini can do NFM @ 32,000 b/w which is plenty for the APT signals that I've seen. I adjust about the same for doppler -- mine is 1khz every couple of minutes. The only downside to the discone is that when the sat is overhead there's a bit of dropout. You can see the 4 lines in my latest picture in the middle there. With a proper RHCP antenna it likely wouldn't drop out at all.

 

[racehorse5000]

Latest picture with good antenna.