Satdump software & wxsat reception

[Terryl]

I reloaded and it's working for now, now, what do most of you have the FFT size set to? I see a list, but no details about some of this stuff.

 

[Terryl]

OK, I don't think satdump is working with my RTL dongle, I started a pass on satdump looking at NOAA 15, saw it start to pass over, got nothing, so it stopped it and loaded SRD console, and it saw the satellite and decoded it.

Photos below.

So whats wrong? Is there a detailed users manual for satdump?

Photo of satdump looking at NOAA 15





Photo of SDR console looking at NOAA 15



What am I doing wrong??

 

[pontiend]

You are not on your own Terry .I am up and running.It is taking some sorting out this.I need some numbers.
Edit by up and running I mean satdiump is running There is a lot to sort out yet.It is somewhat complicated.

 

[ozumo]

There are some guides by one of the SatDump developers here:

Articles | Jacopo's Lair

Useful guides and texts on many subjects

www.a-centauri.com

 

[s-band]

@Terryl Don't give up with Satdump, is can be reliable, I used it continuously for a month or more when STA was close. Most of the following is based on other use of Satdump but I found an RTL stick and looked at that. One problem is that there is no IQ correction to remove the zero term in Satdump's pre-demod plot hence the big spike in the middle on your plot. It appears that NOAA is present there but you need to adjust the FFT length, try 65k, and sample rate or decimation so you see about 500kHz. Then play with the FFT levels to get a better view (i.e. expand it vertically). Other SDRs (e.g. Airspy, Pluto, USRP) seem to have inherently better IQ balance than the RTL hence lower DC term.

The examples in @ozumo 's link show IQ correction enabled on the SDR++ plots and DC blocking (METEOR). In the case of Satdump, it might be better to offset the wanted signal to clear the DC spike in the middle. Remember that the RTL only has 8 bits resolution so it has restricted dynamic range and needs careful amplitude adjustment to keep it in the sweet area. Don't use AGC.

 

[pontiend]

Getting there slowly.Got some recordings.I just have to workout how to view them.I will have a look at those guides I need all the help that I can get.

 

[Analoguesat]

What I found when I started playing with SD.

I couldnt get the frequency plot to populate. SD was seeing the RTL-SDR & everything seemed to be ok but when I hit run nothing seemed to happen. Until on one occasion I happened to to restart SD & be watching the frequency plot just as I clicked start. The frequency plot appeared BUT it then rapidly sank right down till it was out of view off the bottom of the plot!

After a bit of head scratching it turned out you change this in the FFT tab. These are the settings that are currently working here for me from top to bottom in the FFT tab

FFT SIZE 1024
FFT RATE 50
WATERFALL RATE - waterfall not enabled - its too intensive for this processor & it bogs down
FFT MAX -20.0
FFT MIN -87.8 - my noise floor is around -75dB
AVG NUM 66.3

When I start SD now with these settings the frequency plot now appears at the top of the frequency screen & sinks down stopping in view at -75db


@pontiend you can remove Meteor M2 if you dont have 1.7GHz antenna capability - the VHF is broken on that one. You also need to set the frequency in SCHEDULE & CONFIG like this



also click on the little CONFIGURE tab to the right of LIVE & set the NOAA number for the NOAA birds.

If you have a DC spike on the middle of the frequency you can ENABLE DC BLOCKING in the satellite CONFIGURE tab. There is a second instance of this somewhere - when I remember where it is I'll edit it in



EDIT - its in the OFFLINE PROCESSING

 

[Terryl]

Found one of my problems, I had a LO offset that was the same frequency as the satellite I was viewing, thus the big spike in the frequency, I set that to zero and I now have it working for the most part.

Now I have about an hour before the next set of satellites comes over.

 

[Terryl]

OK got the thing working and recording, but...Now cant get it to view anything that was recorded, all I get is ""SPS is invalid must be above 1""..

Looked in everything and can't find anything for SPS....

 

[pontiend]

I think that I am getting there.Still somethings to sort out yet though.Recording format I have tried f32 this one is S8.
NOAA 19 scan just finished it is looking promising.Elevation was set at 25.000 I will lower it for the next scan

Cropped the pic

 

[Analoguesat]

OK got the thing working and recording, but...Now cant get it to view anything that was recorded, all I get is ""SPS is invalid must be above 1""..

Looked in everything and can't find anything for SPS....

SatDump Basic Usage about twothirds of the way down - samples per second (effectively Hertz)

 

[Terryl]

OK I see that, but my samples per second is set to 2.4 Msps as needed for my SDR dongle.

One last question, how do you widen the frequency scale, my display is too narrow, I would like to widen it out to get rid of the junk on either side of the channel.

As you can see it's too wide, it starts at 137.52M, and ends at 137.72M, I want to widen the scale.

 

[Terryl]

I don't know what I did but this one is perfect...

 

[Analoguesat]

NOAA19 0958uk 16/3/24 82 degree elevation

Nice to see the uk partially free of cloud for a change!



137MHz turnstile antenna
upotronics 137MHz filter
satdump software

 

[Analoguesat]

17/3/24 NOAA19 0946uk

 

[Terryl]

OK...Something has gone fubar, all I'm getting now is a black line on any satellite.

Analoguesat, can you post your settings, (screen shots will work) I can then compare with what I have, something changed somewhere overnight.

Getting nice waterfall display, and recordings, but when I go to decode them all I get in some folders is an empty file or black lines.

 

[Analoguesat]

@Terryl any settings in particular you need?

Here is the general overview of the RECORDER tab





Adjust your noise floor using the FFT MAX & FFT MIN lines.


M2-4 is currently not operational so you dont want to be trying to decode that one.

 

[Terryl]

Thy only difference I see is the FFT size, mine is set to 65536, maybe that is too large, I will try your setting on the next pass of NOAA 19 in 14 min.

I'm also not getting the display at the bottom of your photo

 

[Analoguesat]

The bottom panel only appears when its decoding something.

This is my tracking setup



For the NOAAs go into CONFIGURE next to LIVE & set the NOAA number

 

[Terryl]

My recording setting are set to S16 format, what one are you using?