Where to go from here? beginner questions Observation 8554547: JAISAT-1 (44419)

Regarding Observation 8554547

hi everyone.

I just started my satnogs journey and am still a bit lost with my waterfall images. could anyone kindly explain the drift in the data? i understand, that it is probably due to the frequency shift of my rtl-sdr but I just don’t quite understand how to read the waterfall image yet. do i need to fix the frequency shift (probably)? what do the parallel lines even mean? and is this actually useful data i received? how would I go on from here?

is there a wiki or anything that explains how to read/understand your received artifacts?

although i am a bit lost i am super happy that i received something, though!

thank you for your help

Hi @lilylepique and welcome in the community!

For how to vet waterfalls take a look in this wiki page.

Unfortunately it seems that you haven’t received JAISAT-1 in this observation, for this satellite its reception look like this.

I did a quick pass on your station’s observations and none of them had any signal from a satellite. An explanation could be the low or none gain (SATNOGS_RF_GAIN ) set in your client setup, this can be seen in the metadata of the observations. A good starting value if you don’t have an lna in your setup, is 32.8.

If you have more questions, post here or more directly ask in the satnogs matrix channel.

oh well. that is a pity but good to know! will try to put a higher gain.

what would be a good starting value if i use a basic lna with 5V?

thank you

I would try something around 26-28.

Hi lilylepique,

The suggestions you have been given so far are good - but it is a case of trial and error. The gain you will need will depend on the antenna you are using and the losses in the cable between the antenna and your RTL-SDR. If you wanted to tell us what you are using then I could offer you more insight based on what I had to do to get my station working.
If you havent already got one, then you might find a filter is necessary to remove the FM broadcast band stations getting to the RTL. Put this after the antenna and before the LNA and it will help a lot if you are close to any commercial FM stations.
Good luck and keep asking questions!

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Welcome lilylepique,

Can you give some details on the LNA used and maybe also further information on the RF chain.

I had a look at the meta data from your observation that you shared and my first thought was, the gain value is a bit low, and how is the LNA powered, but that is without any details on your setup.

One of my stations has a Nooelec LNA and the SatNOGS client rtlsdr gain setting is 28.

Have a look at this link to get an idea of the systems that I am running and testing.

Good luck with tuning your system.

Jan - PE0SAT

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hi everyone thanks for the tipps.

I just ordered the basic set for the first trial run from rtl-sdr
This is what my setup looks like

and this is the LNA I use

i know this is all rather weak and not the best setup especially since i am running it from an office with much devices around but I thought for the first tests…

my goal is to verify this beauty that we built and to receive some data with this uhf antenna.

Just thought I should become familiar with the whole satnogs setup first.


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hi everyone I tested the yagi antenna as seen in the picture.

I did some satnogs tests and unfortunately I think I am still not receiving any satellite data yet. however I did receive an interesting waterfall image
Observation 8626245

could anyone explain what we see here? is this still just local noise? and why is it so strong and a straight line? thank youuu

It looks like the classic strong signal I see on a lot of sdr’s, not sure of the origin of it as I see it on different hardware. it is at pretty much 400MHz bang on, the doppler curve tells that it is terrestial or internal to the system itself.
Squinting a bit I can see what looks like a signal at ~175s, but may be noise as well.

Looking at the last few obs there is a clear lack of signals. I would assume there is something wrong in the rx chain. Running it with interactive sdr programs like gqrx, sdr++, sdr# etc is recommended in the beginning. Easier to test gain and with(out) lna etc and see the results directly.

Test with a battery of known good sats and high passes, like CUTE-1, LUSAT, SEEDS II, MAX VALIER SAT in the cw mode.
Use Sign In with Auth0 and select one satellite at a time and deselect all stations and select only your 3300 and 1 day forward, calculate, select the ones with a decent high elevation and press schedule.

Hi Lily,

I found a reasonably simple way to test your SatNOGS RPi/RTL-SDR hardware setup was to use the PiSDR image by Luigi Cruz. Luigi has built this for a RPi with heaps of useful ham radio software already installed. PiSDR has a Desktop GUI and you can run GQRX which is a fairly simple SDR program. It does need a display, keyboard and mouse – just temporarily.

Here is the link….GitHub - luigifcruz/pisdr-image: 🥧 A SDR Linux Distro for the Raspberry Pi and other SBC. Compatible out of the box with multiple SDR.. Just download the ‘2022-01-07-PiSDR-vanilla.img.xz’ iso and burn it to another SD card. Pull out the SatNOGS SD card and pop in the PiSDR card and power it up. You will have to configure the usual language, timezone & keyboard stuff but that is quick.

Once you have done that, fire up GQRX and just Scan for Devices……Then select the RTL device and set the Device String to ‘rtl=0’ or ‘rtl=0,biast=1’ to turn on the bias-tee if you have one.

I use that method when setting up SatNOGS stations (mainly to find the optimum gain) but it tests out your hardware fairly easily without upsetting your SatNOGS SD card.
You should be able to listen to terrestial repeaters, fm stations and strong satellites like the ISS or AO-73 when they come over. Your system looks like it is sort-of-working, but it is a bit easier to play around with GQRX than schedulig SatNOGS passes. When you are happy with the hardware config then you can adjust the gain value for optiminal reception and use that in the satnogs-setup when you put the SatNOGS SD card back in.

Hope this helps.

John - VK4JBE