NOAA Weather Satellites and RTL-SDR Dongles, Part II

Arrrggghhh!!!

I raised the antenna yesterday to 20', and now I'm getting a SOLID signal. Some directions I pick it up at 2*, and other directions from about 6*.

The spectrum display in SDR# looks solid, and I figured out you need the squelch DISABLED, other wise you get 'popping' noises that mess up the recorded audio, and the filter set to 48kHz.

Here's a screenshot of the last session I recorded:

The highlighted area of the spectrum is the filter width, and you can see in the display panel below it that all of the signal is within the filter's bandpass. I was cutting it off before, and losing some sync and telemetry information from the satellite.

With the antenna at 20', these birds are LOUD, well out of the noise by about 20dB.

With SDR# you manually have to adjust for Doppler Shift, but it's pretty easy to check it every minute or two, and 'nudge' the frequency a bit.

The recordings I've made so far sound great, BUT WXtoImg doesn't process them correctly. All I get is the proverbial "Black Cat In A Coal Bin" pictures, with a bunch of white noise thrown in for good measure.

So, I'm able to record the audio files, but I still have to figure out what I'm doing wrong to decode and display them.

I might have a sample rate error between how I'm recording them, and what WXtoImg expects, or some other problem. I'm still hesitant to setup my Virtual Audio Cable paths to feed WXtoImg directly, as if I mess it up, I'll wind up spending more time than I want to getting them squared away for use with my Flex 5000 SDR transceiver.

Oh, well.....I'm about done for this weekend.

See you all later.

Can't Fill Jimmuh Cahter's Shoes

Says it all.....

Saturday Morning "Get Yer Feet MOVIN!" Music

If this doesn't do it, maybe you're not among the living anymore!



Just got back from the World Famous W6TRW swap meet.

Got 200' of "550 paracord" for $10

Got 10 clipboards (nice ones) for $10

Bought a bunch of double-banana plugs-to-BNC adapters for $1 each

Bought 500 paper/plastic CD sleeves for $2

AND...bought a very clean Kenwwod R-2000 Communications Receiver for $75, an amazing bargin.

These are good little receivers, and the only thing "wrong" with this one is that the top shell of the case has the paint scratched up pretty badly in one place.

Since various vendors sell the correct color Kenwood paint in spray cans, it'll be a simple matter to pull the case, wash it, hit with my orbital sander, and respray it.

Now to get that antenna raised another 10' and continue with my FUNCube/RTL dongle experiments!

It's a beautiful day here in SoCal. Clear, cool, and there's a bit of snow in the local mountains.

Have a good day, everybody!

NOAA Weather Satellites and "RTL" dongles

This morning I decided to try and hear one of the NOAA "APT" satellites using the eggbeater I got going yesterday. I was going to raise it another 10', and anchor it to the eave, but it was raining all night long, and continued to rain until this afternoon, so I spent the time just using the antenna on a single 10' section of mast.

The NOAA "APT" (Automatic Picture Transmission) satellites have been around since the 1960's, and I used to record the audio from a modified scanner, and then process it with some free software, but I never had a dedicated antenna, so it was more for curiosity than anything useful.

This antenna works very well for receiving them, and they're LOUD! Unfortunately, the HDSDR software I use doesn't have bandwidth settings high enough to accommodate the wide signal the APT satellites use, so when I try and process the resulting audio file, I keep getting "Telemetry Not Found", and the program I use (WXtoImg) doesn't process the audio into a picture.

The SDR# software allows much wider received bandwidth, but by the time I finished messing around with HDSDR, all the high elevation passes were finished for today, so I'll have to wait until tomorrow afternoon to try recording the signal using SDR#.

There's a tutorial on the RTL-SDR webpage on how to use SDR# for APT reception, but I'm a bit hesitant about mucking around with my Virtual Audio Cable settings, as I use those for digital modes with my Flex 5000, and it took quite a while to get them set up correctly. I'm pretty sure I wrote everything down about getting it working with the Flex, but I'll have to go through the binder I keep for the Flex, and make sure I have the settings properly documented before I start trying to use VAC with another program!

Between the two programs, I prefer HDSDR, even though the documentation is scant. It just seems more friendly to use, and if they included some wider filter options for things like the APT satellites, it would be just a killer program to go with your $20 RTL dongle. There's a fairly comprehensive "HOWTO", but it's written for an earlier version. Just ignore some of the screenshots, read the verbiage, and you'll be well on your way to using it effectively.

This is from the first time I tried using it on the NOAA satellites:

And this is a pass of NOAA 18 as it went over:

SatPC32, my satellite tracking program is running in the upper left corner showing where the satellite was when I grabbed this screenshot.

Immediately underneath the waterfall display you can see the spectrum of the satellite transmission. It looks like the bandwidth should be sufficient, BUT, due to my excitement at seeing the signals this strong, I was messing with the settings while recording the audio, resulting in a file the WXtoImg couldn't read.

Sigh......maybe tomorrow.

Eggbeater Satellite Antenna Istallation and "Dongle" Success!

I spent most of today, up to Dinner Time, that is, refurbishing and installing the M2 Antennas EB-144 "Eggbeater" antenna that I had hanging in the garage rafters, along with one of my "spare" SSB Electronic 2 Meter preamplifiers.


This is the antenna, with the radial kit, after I cleaned it up, treated all the connections with an antioxidant:

I swept it over several frequency ranges, and was amazed at how flat this thing is. I almost thought something was wrong until I went significantly outside of the 2 Meter band, and saw a more "normal" sweep result, looking like a very broadband antenna.

An "Eggbeater" type antenna is, very basically, two vertical loops, rotated 90* to each other, and fed 90* out of phase to produce a circular polarization.

Each loop by itself would have an impedance of about 100 Ohms, and fed in parallel, that gives you 50 Ohms, a good match for commonly available coax.

Since satellite signals are fairly weak, a good low-noise preamplifier, mounted close to the antenna, makes a significant improvement. So, I pulled one of my "spare" preamps off the shelf, and mounted it in a Rubbermaid tote box:

The little box to the lower right corner is a Bias Tee, which I use to extract the DC power for the preamp from the incoming coax. There's a matching one down at the receiver where I insert the power. I usually run a separate cable for the power, but I wanted to try this since I have a bunch of those little AVCOM bias tees around. Yep, that's a good old PL-259 used for a power plug on the preamp!

I made up a cable connecting the antenna to the preamp input with a PL-259 on the antenna end, and a Type-N on the preamp end. Since this is going to be outdoors, I put a large piece of adhesive-lined heat-shrink tubing over the connection at the antenna, and shrunk it down:

After all the cabling was finished and checked, I tilted it up vertically, and cable tied the mast (a section of 1" rigid conduit) to a big aluminum saw horse I have:

Some of my other satellite antenna mounts are slightly visible behind this new one.



Does it work?

Well, for the first time I was actually able to copy two people having a chat on the VO-52 linear transponder satellite!

Looking at the middle panel of the display in the screenshot below, you'll see a red line, with a blue 'band' next to it. The red line is the center frequency, and the blue 'band' is the passband for an SSB conversation.

The top panel shows a "speckled" area, and that's the display of the two Hams I was listening to.

If you look carefully, you'll notice that there's a definite shift downward in frequency as time passes, indicated by the bottom of the display (newest information) being to the LEFT (lower frequency) compared to the top of the display.

This is the Doppler Shift, going LOWER in frequency as the satellite was moving away from me.

The sideways "Vee" to the right of the guys I was listening to is most likely somebody "ditting" their VFO to try and find their own downlink. Since the transponders on linear satellites use differnet uplink and downlink frequencies, most conversations are full-duplex, where you can hear your own signal coming back through the satellite, with a slight delay. Generally what people do is to find a clear frequency to listen on, and transmit a series of "dits" while adjusting the transmitter frequency back and forth until they hear their own signal.

The only other satellite passes that were "good" before I started this post were from FO-29, which has a UHF downlink, and this antenna doesn't work (well, actually the preamp filters everything out) on UHF, so I'm waiting until 0456 UTC for AO-73 to pass over, and maybe I can (finally!) capture some telemetry.

Tomorrow I'm going to raise this antenna to it's more permanent height of 20', and anchor it to the side of the house. The extra ten feet of elevation will get it above the ridgeline of our roof, and should make quite a bit of difference.

Hope y'all had a very Happy Thanksgiving!


WELL.....I didn't hear any telemetry, but I copied W9ND talking to several stations on AO-73, The Satellite Formerly Known As "FUNCUBE-1"!

This time all the activity is on the right side of the top display, and you'll notice (well, some of you will....) a curving, slanted line near the top of the display. This was somebody "swishing" their VFO trying to find themselves, and they "swished" right through the conversation I was listening to, and it was neat to see it even though I've heard it many times when operating satellites.

2110 local time here, and I'm going to hit the rain locker, and then hit the hay.

Good night, all......

Happy Thanksgiving!

May you and your families enjoy the day.

We're having my wife's oldest son over, and I'm going to work on getting the Eggbeater antenna up and operational.

I'm going to redo all the bolted and screwed together connections with some Penetrox, and then weatherproof them with some electronics grade RTV.

Then I'll mount the antenna and preamp on the mast I bought today, and enclose the preamp in a Rubbermaid tote box I picked up.

Hopefully by this time tomorrow I'll have a better antenna installed for the "Dongle" project that I've been reporting on.

"RTL" Dongle with HDSDR

Well, having played with both of the dongles, and most of the available free software, I've come to a few conclusions, so far.

The FUNCube dongles have a restricted bandwidth, with around 80 kHz of useful display.

This is both good, and bad.

It limits you to how much spectrum can be observed at any one time, which makes it easier to spot a signal in the relatively narrow transponder passband of a satellite (50 to 100 kHz, depending on the satellite), but it sucks for using it as an ersatz spectrum analyzer to see what's popping up in the section of spectrum that you want to monitor.

It also helps cut down "image" frequencies as far as I can observe. (It's probably what's called "aliasing" in digital sampling and Digital Signal Processing, but I'm a Radio Guy, so I'm calling it an "Image"!).

It's also NOT enough to decode Broadcast FM Stereo by a long shot, or even Broadcast Mono, if that's important to you, but then it was never designed to do that, so I'm sure not crying about it now that I know the limitation.

The "$20 RTL" dongles do about 2 Mhz of bandwidth (mine does about 2.15 MHz), which makes sense, as they were designed to receive Digital Television signals.

This is almost twenty-seven times the bandwidth!

It receives FM Stereo very nicely using SDR#, and not so well using HDSDR. HDSDR was coded for "Communications" use, so the demodulators, even the "FM Wide" can't cope very well with Broadcast FM.

BUT....it dows a bang-up job of observing a 2 MHz slice of spectrum, as seen in this screenshot:

The display is centered on 162.550 MHz, which is the strongest of the NOAA Weather Radio broadcasts here.

To the left are the other NOAA broadcasts at 162.400, .425, .450, .475, .500, .525, and ,550.

Off to both the left and right, you'll see some broad, blue bands in the waterfall (top) display. From a casual glance, considering their bandwidth (over 100 kHz), I suspect these are FM "images" caused by the poor filtering in the front-end of these little receivers. Somewhere around here I have an FM band-reject filter, and if I can find it, I'll stick it in and see if this goes away.

Almost all the way to the left, you'll see some activity, which turns out to be the railroad frequencies. There's  quite a few "RailFan" websites out there, and some people are fascinated listening to trains. I prefer to listen to aircraft, but to each his own.

Above the NOAA channels are various services listed as "Mobile", but since I don't usually explore this part of the spectrum, I'm not sure what's up there. I just picked this frequency to center on as I knew NOAA was there.

Here's a shot of 2 MHz worth of the FM band out here in L.A.:

And here's what 2 MHz wirth of the 2 Meter Amateur radio band look like:

So, to wrap up tonight's "experiments", I'm getting more comfortable using these little guys, and learning more about each of them, and the different software available for them. They both have their pluses and minuses, as does the software.

I suspect, and I've read, that to get the best performance out of them they both need some front-end filters for whatever band you want to use them for, but then you can say that about almost any receiver made.

More to come......

Fun with my "FUNCube" Dongle

Although I haven't had any success at all trying to receive telemetry from the new AO-73 satellite launched last week, I did manage to hear some activity on AO-7.

My setup is far from ideal, as I'm using my Comet GP-3 vertical antenna, with no preamp.

Here's a screenshot of the FUNCube dongle running under SDR#, and you can see the activity in the waterfall, towards the bottom of the display.:

**UPDATE**
After looking at this, and doing the post, I realized that "signal" couldn't possibly be traffic on the AO-7 transponder.

Why?

NO DOPPLER!  I'm used to my radio being controlled by SatPC32, which automagically tunes the radio to compensate for Doppler Shift in the received signal. Since this little receiver is NOT getting any tuning correction, a real signal would have a display showing a line starting at the right side of the waterfall, drifting down to the left side as the Doppler Shift affected it.

Straight Line = NO Doppler, meaning this signal was terrestrial in nature.

Oh, well........



And here's another screenshot showing approximately where the satellite was as displayed by SatPC32, in the upper left:

Since I have an "unused" M2 2 Meter "eggbeater" antenna out in the garage, and a receive-only 2 Meter preamp, I might just drag it out over the Thanksgiving holiday and stick it up on the "portable" tower I ginned up for Field Day.

I really need to set up a more permanent satellite station here at the house, but the snag with that is running the cables from where the tower sits in the driveway to the house. I need two runs of coax for 2 Meter and 70 centimeter antennas, two rotor cables for the Azimuth and Elevation rotors, and two runs of power cables for the preamps mounted on the antennas. I suppose I could run a single cable out of the house for the preamps, and split it once it gets to the tower, but the major hassle with this is figuring out a way to either run all the cables along the ground (maybe in a PVC pipe?), or else gin up a cable tray arrangement to keep them well above head level until they get close to the house, and then drop them down.

Or perhaps I could get a couple of section of the stuff we use at work when we have to lay cables in areas where people have to walk.

And here's a picture of an "Eggbeater" antenna, just in case you've never seen one. The left one is for VHF (130~150MHz), and the right one is for UHF (400~500MHz):

Our "Former" Dogs In Colorado

The soon-to-be daughter-in-law sent the wife some pix of our "former" dogs in their new environment.

The dark brown one with the "eye patch" and red jacket is Coco, and she absolutely HATED to get her feet wet when it rained out here. She'd go pee or poop on the driveway or sidewalk to avoid walking through the wet grass!

The lighter colored ("Fawn") one in the blue jacket is Diamond, who was the biggest (85 lbs!), most lovable "moose" I ever knew. Always wanted to be a lap dog, but geez....EIGHTY FIVE pounds of her?

Groan.....

And the one at the top left is "Obie", who my step-son picked up as a stray, and kept him where he worked as a "watch dog".

Obie only trusted Michael, and my wife, and Michael's GF Jeanine. For some reason he didn't like me, and would very quietly growl when I tried to pet him. The day he snapped at me was the last time I touched him, a few months before they moved.

Good dogs (except for Obie....), and even though we have two more here, I still miss Coco!

*REALLY* Out of it Today

Took yesterday off work to go see the Doctor about these headaches I've been having. I *know* I've needed new glasses for some time now (the ones I have are 4+ years old...shame on me!), and finally called my eye Doctor for an appointment a couple of weeks ago.

They scheduled me for a December 27th appointment, so I figured I'd just grin and bear it.

WELL....the headaches were getting worse, to the point that my neck was hurting, and my eyes were watering, and my wife was starting to bug me about going to the Doctor, so I went to the walk-in yesterday.

The Doctor asked a bunch of questions about my 'eye history', did some simple tests, asked some questions, looked at my eyes, ears, nose, and throat (remember "ENT" Doctors?), and said I was probably right, but just to be sure, she called the Neurology Department to see if they could see me. The Doctor over in the other building was free, so I trudged over there, got checked for any easy-to-spot neurological problems, and got scolded for not taking care of my eyes better!

Since my eye care provider is affiliated with my primary medical group, both Doctors sent over a referral marked "Urgent", and requested they get me in ASAP for a full eye exam, and get me fitted for some new glasses.

I'm to give them a call this afternoon after the referral is 'in the system', and see if they can get me in before my scheduled appointment.

And I got a prescription for some muscle relaxants as the severe eye strain was causing spasms in my neck muscles, leading to some pretty stout headaches.

And I think I'll go back to bed for a while.....

NRA "First Sterps - Pistol" AAR

Well, I assisted in another class today, which included two people I used to work with.

The class went well, and the students were all excellent shots, which is unusual, and we graduated another 12 people.

After the class, my two friends and I went out to the range so they could try various pistols before they decided what to buy.

My former manager was talking "Glock!" all day long, until we got out on the range, and she had the opportunity to load and fire one repeatedly.

Turns out she hated it!

She had a hard time loading the double-stack magazine, and although she shot it very well, she said she just "didn't like it".

Her boyfriend was pretty neutral about the Glock, so I let them try my wife's S&W TRR-8 revolver, which they both loved, praising how easy it was to load (duh....it's a revolver!), how nicely it fit their hands, and how well balanced it was, which are the same reasons I bought it for my wife.

They were firing 38 Special out of it to get used to it, and then we switched to some Fiochhi ammo I had, which are pretty hot loads.

The first couple of BOOMS! were greeted by smiles, but after they'd both fired about 20 rounds each, they were getting tired of the recoil (and concussion....), so we switched to my Kimber 1911.

We spent some time going over the controls and the grip and thumb safeties, and then they took turns firing it.

Surprise, they liked the 1911! They could both load the magazines easily and rapidly, had no problem with the recoil, which they heard was very stout, and just loved the glow-in-the-dark sights it comes with.

Final gun of the day was my SIG P226, in 40 S&W. Again, they didn't like loading the double-stack magazines, and while they could fire it single action quite well, they both had a hard time adjusting to the first shot after using the decocking lever having such a long pull, followed by the second shot being single action. This is the same reason I don't particularly care for the P226, even though I think it's a very fine pistol otherwise.

SO....now that they've had their first class, passed their Kaliforniastan Handgun "Safety" Certificate tests, and fired a number of different '''pistols",what are they going to buy? I don't know, and I don't think they know yet, either. We're planning on some more range time together where I bring the two guns of mine they like the most, and they rent a couple of different types to try.

They both understand that to get proficient with a hand gun requires time on the range learning to use it, and that *whatever* they decide to buy has to fit their hands comfortably, "feel good" to them, be easy to load, easy to operate, and enjoyable to shoot.

I'm looking forward to spending some more time at the range with them, and I'll bring my wife along so the two ladies can discuss guns.