[amsat-bb] Re: OT - Weather satellite antennas
kf6kyi at gmail.com
Thu Jun 12 12:04:26 PDT 2008
Ed Tump wrote:
> Thanks for the response on power. Now I wonder if my Arrow satellite antenna
> will work for these weather satellites or my AL800 HT antenna.
> Any ideas?
> Grid EN52
> AmSat Member
I've done a bit of work recording the NOAA satellites, using the
wideband FM settings on my little Yaesu VX-3R, or the Wide FM mode on my
Radio Shack Pro-60 hand scanner and tracking it by hand with my Arrow
antenna. The arrow definitely provides significant gain around 137 Mhz,
and I am able to get fairly clear recordings. The major problem isn't
actually antenna gain, but the filter bandwidth of the receivers. Wide
FM is actually way too wide: the satellite actually uses about 50khz
bandwidth, and the Wide FM filter bandwidth is more like 200khz, which
means two things: you get about six db more noise, and you can get
interference from other sources, such as other satellites. For
instance, I blogged about this a while ago:
On this pass, I actually used a small preamp, which really doesn't help
with my setup (handheld yagi means coax losses are low). I wrote my
own apt decoder, which still had some bugs in this incarnation, so you
can see that I lost sync a couple of times. The bright rectangle of
noise overlayed is probably an Orbcomm satellite operating on a nearby
frequency: a weather receiver with smaller frequency bandwidth would be
You might ask what you can do with just the normal narrow fm rece[topm
pf upir average HT. I did that experiment too.
You can see all sorts of clipping artifacts at the beginning where the
receiver is set in narrow mode. In particular, you can't actually
reproduce the nice stepped gradient that appears between the images. In
wide band, we get much better dynamic range.
If you nose around my blog, perhaps searching for noaa, you can find
other pictures that I did. All of these were recorded on my Macbook
using Audacity, fed from my Pro-60 or my VX-3R wired to my dual band
Arrow antenna, and then decoded with my own software.
Feel free to hit me with email if you have any further questions:
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