Observation 651895: NOAA 15 (25338)


#1

Hey folks, I’m new to all this and I’ve just “logged” Observation 651895

For some reason, it came up as “good” after the scan, but there’s clearly no trace of a satellite anywhere in the recordings/waterfall/data image, so I’ve changed that to “bad”.

I’m pretty confident this was the right thing to do, but that’s mainly because the antenna I’ve got connected to the RTLSDR on the ground station is a rubber duck designed as a 1/4 wave for 868MHz (I’m going to be building a “proper” antenna soon, this was just so that there was “something” on the SDR to avoid any damage to the circuit!).

Did I do the right thing?


#2

I think this is one of the rare occasions where “failed” is the correct vetting. That waterfall is one solid color, something is not right.


#3

Cool, thanks, I’ll mark it as such, I suspect it’s because of the antenna, at least the base station is reporting correctly to the platform.


#4

I have had this happen in the past on my station when the RTLSDR is in error. I suggest unplugging and plunging it back in.


#5

When the antenna is the problem you at least have random noise on the waterfall which is not the case here (-> see “one solid color” above).


#6

ok, thanks both.

Is there a “satnogs approved” script that I might be able to use to test if the SDR is working?


#7

Ah, I did a quick search, found rtl_test, ran it, and it says “device not found”, so I’ll check that and try again.


#8

The pi is dead.

The logs are full of

[15247.713546] usb 1-1-port2: over-current change

and changing the power adaptor has made absolutely no difference whatsoever.

New Pi ordered, should be here tomorrow, then we’ll try again!


#9

was that with the RTL disconnected? If not, did you try switching ports?


#10

I’ve tried all of the USB ports - this is an old pi that I’ve had for a while now, and for some reason the ELEGOO 5" TFT that connects via the GPIO pins has shorted out the power controller ( see https://www.raspberrypi.org/forums/viewtopic.php?t=97858 for other people with similar issues).

I’ve switched the SD card into a Pi 2 B+ for now, and rtl_test returns the expected values, so I’m about to queue up another observation and see what happens!


#11

No luck with the Pi 2, assuming that it’s down to the antenna now, so will build a proper one during the week.

Bought a new Pi 3 from Amazon, it was DOA, so back to Pi Supply for a proper unit.

Is it possible to run SATNOGS via Docker or similar? I’ve got a home server that I can easily map the USB devices from host to container, so that could work…


#12

There isn’t any docker container or something similar. However there are people running client on desktop.

For example you can check the ansible client install for debian stretch at this wiki page.


#13

Thanks, Ill have a look.

I use Ansible everyday for work, so this should be fairly straight forward.


#14

OK, it was the RTL-SDR that was faulty.

I now have what I think is a “valid” scan at Observation 670614

If someone is able to check and validate for me that would be appreciated - now that I’ve got the thing working, I need to start understanding what I’m looking at!


#15

I think that is a “functional” observation, with no visible evidence of the satellite. I would vet this as “bad”, but since I’m not sure what the sat looks like - I’ll leave that to somebody else.


#16

ok, thanks.

I’ve still only got a rubberduck antenna that’s meant to be tuned for 868MHz attached, so I’ll get a proper antenna attached in the coming days and see how well that improves things!


#17

https://network.satnogs.org/observations/670615/ looks a lot better - same antenna, but at least I’m getting a trace all the way down the waterfall!


#18

Again, looks like the station is working, but I would vet that as “Bad”. Here is what NO-84 APRS should look like:

https://network.satnogs.org/observations/634916/

The horizontal lines are the APRS packets. The faint vertical “s” curves (as in your observation) are terrestrial in origin.


#19

I agree with K3RLD. Software is tuning for calculated Doppler, so desired signal should be zero offset (or close) the entire pass. The off-center and S-curve of the signal on the left side of the waterfall is terrestrial. Looks like some of the garbage in my neighborhood. I am wondering if the apparent modulation suggests commercial pager?

I vetted this DIWATA-2 observation as bad: https://network.satnogs.org/observations/666544/ The weird cruft on the right is a new signal I have not seen before, and I think the brief burst +9 kHZ about 10-20 seconds in is from FOX-1C/AO95.


#20

Thanks both.

I’m hoping to get the kit to build a “proper” (non-rotator) antenna in the next couple of weeks - this is currently in my garage, next to my WiFi Access Point, a “SMETS1” Smart Meter, a LoRaWAN Gateway, and goodness knows what else that could be causing RF Interference!

My plan is to move it out of the garage, put a proper antenna on it, and (eventually) work my way up to the rotator model, but it’s good to know that the unit itself is working.

I’ll feed back with more once I’ve got a proper antenna on it :slight_smile: