Hello All ,
doing some experimental decoding from stratosat tk-1 on 435.870
received this image and also telemetry on 9.29 utc (10.29 CET)
setup ::: antenna omnidirectional ATA turnstyle (dereksgc assymetric turnstyle) 436 MHz
coax 20 m ecoflex , NO LNA used in setup
rtlsdr 2832u , sdrsharp , vb cable , decoder stratosat.
image seems to be also in Antartica i think
GREAT setup !
Hello everyone,
could someone help me by sending me an audio (wav ) of StratoSat TK-1 satellite?
Merci A+
Image 12 is identical to image 10.
I also built an ATA today to see if the signal improves, the signals have been quite weak for me to decode an image.
Image 13
The new ATA antenna seems to be working better than my previous antenna, but I still couldnāt decode neither telemetry nor an image. Can you take a look at my IQ file to see if itāsthereās something else wrong on my end?
04/012024 Last night StratoSat 7.25pm another pass 9.35pm two distant passes, no telemetry signal from me, I donāt know if there is a problem, I only received the signal I did not receive telemetry
Could you please save the two parts with transmissions fm demodulated as wav and provide a downloadlink?
ciao Tony, your signal is too weak for decoding, could you add an LNA? bella la turnstile ma devi tirare su il segnale
Hi, Bombolo, yes the signal is all at maximum LNA and 1.920, the position coming from the east is very far away and the same when it comes from the west I have some weak reception as in the photo, when it passes over it is fine!! I havenāt received anything since yesterday, I donāt understand!!! and the same Turnstyle BOā¦
Tony,
If I am looking at your screen dump correctly and I am seeing a noise floor of around -30dBm then I would say you really need to go through the exercise of setting your gains correctly.
Basically you want to start off with the the gain settings set to lowest valueā¦ā¦If you are using a RTL-SDR Dongle without a LNA I would expect it to be about -75 to -90dBmā¦.Other, better SDRs could be much lower. If you slowly increase the gain while watching the noise floor (not the signal!) you should see no change at first then at some point the noise floor should start to rise. That is generally speaking your optimal gain.
If you raise the gain higher you are simply increasing the noise floor along with the signal gain and the SNR wonāt improve.
The SatNOGS Wiki > Build > Omnidirectional HowTo has a good image showing this.
They comment as followsā¦ā¦āWe can see that between 0 db and 20 dB of gain there is essentially no change in the noise floor - this indicates the receive system is limited by the noise figure of the RTLSDR. As the gain increases through 30 dB, the noise floor starts to lift, indicating that we are now most likely limited by either the noise figure of the preamplifier, or the local noise environment. Any increase in gain past this point just results in reduction of the available receiver dynamic range.āā¦ā¦I would typically set the gain to about 25dB in this case.
Do the same thing for your system and then try to decode some signals.
That said, I must confess I always use a LNA with my RTL-SDR dongles because their Noise Figure is not that good. That means the RTL-SDR gain setting is generally on the lowish sideā¦The pre-amp improves the noise figure of the overall system and adds gainā¦ā¦but it depends on the total LNA Gain/Noise Figure, Coax length, Filter Losses, etc of your system setup.
Depending on the signal modulation type, data speed, etc I find I need a SNR of 15-20dB to decode signals reliably. Sometimes just getting a sync lock on a signal is difficult and once you start decoding things can go lower.
Hope this helps.
Regards,
John - VK4JBE
One detail here regarding that connection to the SDR.
Thereās two gain modes available, āsettings fieldā is pretty much what you see in that dialog, except the names are often much shorter.
Then the āoverallā is a one value setting that soapy takes and derives the individual setting you see here above. I mostly recommend the overall mode with a few exceptions.
When using different sdr software you can either see the direct controls or both, also depending on the device profile. For example gqrx can connect directly to a rtlsdr and also via soapysdr. As satnogs uses soapysdr it will be more meaningful to test with this so the values can be used as-is.
Do note that maxing the gain values and connecting antennas with strong out of band signals will definitely degrade the performance.
It is like using a microphone and turning up the gain to max and trying to whisper in to it while standing in the middle of a rock concert 
square wave comes to mindā¦
It is also worth reminding that all the signal that is lost in the cable simply cannot be recovered with a LNA at the receiving end, it must be placed close to the antenna for this to work in a meaningful way.
Will there be any transmissions for the upcoming days?
Hi @geoscan !
Iām interested in developing a decoder for the high-resolution imagery. How is it transmitted? Via S-Band?
73,
VE3SVF
Thanks John - VK4JBE, for your suggestion, when I try to do what you asked me, from tonight when I have the satellite I will have another satellite I will try to find a good audio and have an excellent signal, I have no words I am satisfied with yours information thanks Johnā¦
73 Tony ik1hgi.
UHF 435.870 MHz
Edit: Never mind didnāt read the high resolution imagery.
11/01/2024 20.36 UTC excellent signal tonight now I understand that he drove me crazy for 10 days with his 100mw Stratosat, if I have clouds the signal doesnāt pass even if it rains today it was 8 degrees higher than the past 3 days 2 degrees with my mini Turnstyle antenna Iām glad it works well, Iāve only received telemetry success
73 ik1hgi Tony
