This might be the start of something big

[ChrisSmolinski]

Two more photos:

The rotor. This is an old satellite dish rotor I used with the 250 MHz satcom helical antenna I built, which was destroyed on winter. The rotor used a DiSEqC interface, but that board died. So I removed it, and instead apply 12V DC on the coax cable directly to the motor. I have a box inside the shack with a DPDT switch which allows me to apply voltage of either polarity, to control the motor direction. I have no feedback for position. The motor drive does have an encoder and home switch, so if I was ambitious I could possible rig up something for position. I had to get a 45 degree PVC adapter to handle the weird angle of the rotor shaft. The plate the shaft is attached to rotates, so the pieces of PVC pipe and adapters align the long PVC pipe that attaches to the loop with it, so it can rotate. Yes, very Rube Goldberg, but it works! 




This is the support for the antenna, a rope that goes up over a tree branch, and takes most of the weight. I don't think the rotor would be happy with all of it:

[ChrisSmolinski]

OK, a third photo, the entire antenna, with a lawn chair for some perspective:

[ChrisSmolinski]

OK... I've re-wound the loop AGAIN for resonant mode. It's going to stay that way. 

I've also made some changes to Amalgamated DGPS for a live SDR mode, where it directly talks to the SDR (no need for an SDR app) and decodes the entire DGPS band in real time. Barely seems to run on the old iMac, but it made it through the night.  Now I've got a crude waterfall in the app so I can see where the resonant frequency is and adjust it. I don't have any position feedback on the loop orientation, so I have to look out the window. Which doesn't work when it is dark outside. Which is what it usually is when trying to DX DGPS stations. Maybe I need to add some flashing lights on the loop frame.

[redhat]

You have a lot more faith in PVC pipe than I do 

+-RH

[ChrisSmolinski]

You have a lot more faith in PVC pipe than I do 

+-RH

We have a possible squall line coming through the overnight hours tonight. So that will be the test 

It is supported at the top by a rope, in addition to the bottom support to the rotor (actually most of the weight is taken by the top support).

[skeezix]

Maybe I need to add some flashing lights on the loop frame.

You should put a red light on top anyway, for safety.

To show the direction, put a couple of lasers pointing precisely parallel to it and a smoke generator to see the laser beams.

[ChrisSmolinski]

You should put a red light on top anyway, for safety.

Next thing you know, I'll get in trouble for peeling paint.

[skeezix]

Next thing you know, I'll get in trouble for peeling paint.

To solve that, use red & white PVC in the correct positions, then you'll never have to paint.

[jFarley]

OK... I've re-wound the loop AGAIN for resonant mode. It's going to stay that way. 

I've also made some changes to Amalgamated DGPS for a live SDR mode, where it directly talks to the SDR (no need for an SDR app) and decodes the entire DGPS band in real time. Barely seems to run on the old iMac, but it made it through the night.  Now I've got a crude waterfall in the app so I can see where the resonant frequency is and adjust it. I don't have any position feedback on the loop orientation, so I have to look out the window. Which doesn't work when it is dark outside. Which is what it usually is when trying to DX DGPS stations. Maybe I need to add some flashing lights on the loop frame.

Sounds like a reasonable solution for the tuning.  I use SDR Console which allows me to have a lower pane the width of the SDR span.  I use this for tuning purposes only.  I also display a zoom pane centered on the demod frequency.  This is about 1 kHz wide and allows me to see barbaric CW IDs in a pileup.

[ChrisSmolinski]

One thing I find that is interesting is that ADGPS still decodes stations well outside of the resonant bandwidth. Not with as high of a decode rate, but still reasonably good.