My go at WXSAT

[pontiend]

NOAA 19 1513.
A bit of detail on this one.No cigar yet though.
I will try altering the volume on the next pass at 1653.

 

[Analoguesat]

That looks more promising - there are hints of the synch bars on the top image

 

[Terryl]

Is that a metal roof on top of the building I see in that photo?? That can affect things a bit.

And on that antenna design, I cant put together the correct combination of numbers you posted to equal a 1/4, 1/2, 5/8 or 3/4 wave antenna for 137.5 MHz.

2181.81 MM is a full wavelength for the center frequency of 137.5 MHz, you divide that by 2 or 4 to get the 1/2 or 1/4 wavelength needed for the antenna.

Full wave = 2181.81 MM
1/2 wave = 1090.90 MM
1/4 wave = 545.45 MM

My question is what combination of those numbers did you use to make up one set of radials?

 

[Terryl]

Also the coax used is for TV and satellite signals, it's 75 ohm, I think (check you input spec's for your dongle) it needs to be 50 ohm cable, if so then your loosing 2 to 3 dB on your incoming RF to the dongle.

Now 3 dB does not sound like much but it the RF world its 1/2 of the available signal.

If the incoming signal was 1 micro watt or -30 dBM at the antenna output, (micro watt or dBM used for RF signal measurement) and you had a -3 dB of loss due to an impedance miss-match you would have .5 micro watts or -33 dBM at the dongle, add the coax attenuation at 137 MHz and it total lenght, the incoming signal can be below the receive threshold for the dongle.

 

[pontiend]

The roof is asbestos.The measurements I got the measurements of the internet.
how to build a QFH.tinhatranch.com

 

[pontiend]

I have install the software on a clean w7 image on my other pc.After a lot of cable, settings adjustments I may be getting somewhere.I am beginning to think that my signal is not strong enough.These images are from NOAA 18 89E 1 W neally overhead I think. My longitude is 1.47 W

 

[pontiend]

NOAA 19 50W 10 E 1541
I think that I may have cracked it..
The antenna is back on the patio table it needs finishing.
I think that the signal loss was because of a bad cable.It was from the front of the house that I took down a couple of weeks ago it had been there over 10 years.Time to play with the image settings now.

 

[Analoguesat]

Woohoo!!! Yup thats a good first picture. Now you can play with antennas amps cables & antenna placement.

Some passes will be better than others so dont get disappointed if you get a few duff images. At my location easterly passes are better as the house gets in the way of westerly passes

 

[Terryl]

Good job Pontiend.....

Yes good cable is a must, one solid run from antenna to the RX is the best, I'm looking around for a ground block for my setup and should be reporting back in the other thread. (when nap time is over)

 

[pontiend]

Having mixed results just now.I keep upsetting things with all my messing about with the settings.Waiting for the next pass now to see if I have got things back on track.The problem with this software is if I change a setting I have to wait a couple of hours to see what it does.I have two straight connectors in the cable to the antenna.A 30 meter roll of WF100 is on order to replace it.next pass is NOAA 19 15.33.

 

[Analoguesat]

NOAA 19 is passing atm - its not a great pass but its showing up here right now.

Get yourself a copy of "wxtrack by David taylor"and you can visualise the passes nicely. Ive got it set up to show the 3 noaa's, 2 meteors and the ISS

 

[pontiend]

Better, the volume was a bit low 52%.I will raise it for the next pass.17.15.There is that much water in the air that It would not surprise me if water has got into the cable joints..

 

[Analoguesat]

Thats excellent - the middle noise bars are very typical - probably local pager interference. If you watch the waterfall spectrum during a pass you will see the bursts of interference.

Noise bars at the beginning & end are almost inevitable too - looking at the pics from the experts on the APT group on fb they normally have noise bars too.

 

[pontiend]

Thank you.I was going to ask what was causing those I though that it could be a cable fault.I do get a regular odd burst of frequency's.That I have wondered about.

 

[Analoguesat]

If you want to have a go at pagers you need the PDW software & tune to around 153MHz

 

[pontiend]

Is that what those bursts are then Analoguesat.Re, having a go at pagers I think that I have enough on my hands with the weather sat software.
Edit might still have a go though.I may have a brain cell or two spare.

 

[Analoguesat]

PDW is simple - just set it up, change the sound input to your Virtual Cable and tune to the regular bursts around 153MHz. Most of the messages I receiver are just test mesages though - boring as hell!

 

[Terryl]

NOAA 19 is passing atm - its not a great pass but its showing up here right now.

Get yourself a copy of "wxtrack by David taylor"and you can visualise the passes nicely. Ive got it set up to show the 3 noaa's, 2 meteors and the ISS

View attachment 116341

Try this one, it gives you the ground tracks for the three birds and also a choice to add the footprint for the bird going over your location, also a ten day pass prediction. (click all passes)
www.n2yo.com/?s=33591|28654|25338

 

[Terryl]

I have a suspicion that the mid photo noise bars you are seeing, are due to signal phase changes as the satellite passes over, as I am seeing the same thing here, and I'm in an RF dead zone, nothing around me to interfere. (except me)

The antennas we are playing with are mostly linear polarized, (horizontal, diagonal or vertical) a linear antenna can pick up a circular polarized signal but not as good as a one that is correctly polarized, when a circular polarized signal from a moving object (like a satellite) passes the center point of the linear antenna it will cause a short signal fade due to an out of phase condition, this due to the orientation of the antenna.

I have tried may differant designes for a true circular polarized omni-directional antenna but have found nothing that works good enough.

 

[Terryl]

Better, the volume was a bit low 52%.I will raise it for the next pass.17.15.There is that much water in the air that It would not surprise me if water has got into the cable joints..
View attachment 116346

Try to keep the volume at or around 75% to 80%, it works the best at that level.