WXSat proof of concept

[Archive-8]

The pi uses a program called predict to calculate each passing.

And another one called at scheduler, and a couple of scripts to automate the whole process.

The one called predict works out the time of each passing and then through 3 scripts automatically adds and deletes the information according to the next passing satellite winthin a 20° elevation, or higher.

 

[Analoguesat]

I shall join in the fun again in a week or so when the new pigtail arrives.....

 

[Archive-8]

A slightly better shot of the uk this time around, still using the maplins meter stick.

 

[Archive-8]

Would this be a suitable pre-amp

137.5MHz Filtered Preamp

 

[Analoguesat]

Would this be a suitable pre-amp

137.5MHz Filtered Preamp

Yup

137.5MHz NOAA/APT Filtered Preamp

And its Uputronics too. Same as the 1090 aircraft amps.

 

[Archive-8]

Knocked a home brew aerial up last night using a couple of metal coat hangers & the wire connection box from a dab aerial.



And it works

 

[Archive-8]

 

[Archive-8]

According to predict the next passes are:

 

[Terryl]

OK kids I think I found out what is going on with the RX side of this setup, my FT-847 does not have the wide bandwidth needed for proper RX and signal decode on these satellites, it looks like they need a receiver that can handle at least a 35 KHz IF band width, my FT-847 can only do 25 KHz, so I was a bit short.

(BTW new antenna is still awaiting the finding of the SO-239 connector)

So to fix the IF bandwidth problem I used mt VX-5R handy talky, it has a select-able IF bandwidth and can also be set to priority scan channels, I set it up for all the NOAA satellites that are still broadcasting and set those channels for priority scan and hold till carrier is lost.

Now just going to have to wait till a bird comes by to test.

 

[Terryl]

Chris1979, try bending the radials on your new antenna into an "S" pattern, (center of the S will be the DAB antenna mount) these satellites use circular polarization on the RF signals, it may work a bit better.

 

[Archive-8]

Chris1979, try bending the radials on your new antenna into an "S" pattern, (center of the S will be the DAB antenna mount) these satellites use circular polarization on the RF signals, it may work a bit better.

I will give that a try thanks.

 

[Terryl]

OK dumped the house, garage, barn, junk bin upside down, no SO-239 jack, so I had to order one.

So the new antenna is on hold, but I'm trying out the discone antenna as the last pass was still too noisy, the discone is universal as to the polarization, we will wait and see.


(boy did we hijack the heck outa this thread......Sorry Analog........Dont beat me)

 

[Archive-8]

Been out and bent the wire in to an s shape. Hopefully it improves it.

 

[Terryl]

OK, got impatient and fixed up a connection, so here is the new helical antenna, built to specifications as per some of the web sites for this application.


Now awaiting a pass.....

 

[Terryl]

Works great on the local hard to get FM station.

 

[Terryl]

OK this looks promising, a bit more playing around, and maybe I will have to elevate the antenna a bit, (sitting on deck railing) but it looks like it may be working.

Might work better when the proper antenna connector gets here, and there are a few dead spots and still some speckles, will have to look into that.

 

[Terryl]

OK after some testing I found out that most of these antennas for the weather satellites are directional. (needs a Sat AZ/EL rotor) if you look at the post above you will see two dark bands in the photo, these are where the signals from the satellite are out of phase with the antennas polerization, what is needed is a wide band (1 MHz +) omni directional right hand circular polarized antenna tuned for the center of the 137 MHz band.(this for the three NOAA sats)

Looking into this and trying all sorts of stuff, will be back with more info on this......But it's raining like heck and some roads are washed out so it may be a bit before I can get back into this.

 

[Analoguesat]

The replacement connector for the one I broke must be coming on a rowing boat from China - still no sign of it

 

[Terryl]

Same here....A 16 day shipping time (must be on a boat from somewhere) just to save $7 on postage (free shipping) and $2 on the connector (ordered from a Chinese company)....So I'm too cheap!

 

[Terryl]

The replacement connector for the one I broke must be coming on a rowing boat from China - still no sign of it

By the way Analog, I tried out your antenna, it worked somewhat OK for the North South birds, but the birds off to one side or the other were zip......Got to find (or make) an omni directional circularly polarized antenna with as much gain as possible, this may be a multi element type, the only one I can think of was one we tried back in the 60's, it looked like a spiral shaped Xmas tree, it was to be for TV signals from all directions, but was too costly.

The antenna I made with the PVC pipe was a full wave design, this may cause problems with direction of signal reception, I may modify it for halfwave, then do some sort of phase combination for gain.

You antenna is a quarter wave, you could do a second set of elements to make it a half wave.

Brain is now in design mode.........