Delfi-n3Xt Update November 22

Delfi-n3Xt Satellite

Delfi-n3Xt Satellite

Delfi Nanosatellite Program Manager, Jasper Bouwmeester PC4JB, provides this update on the Delfi-n3Xt satellite which was launched November 21 and carries a 435/145 MHz linear transponder.

Dear radio amateurs,

We had a fantastic launch and early reception of Delfi-n3Xt! The good news is that Delfi-n3Xt is transmitting when in the Sun and is off in eclipse to save battery power; just as we want it to be. The signal strength is also good.

VHF Reception

We have noticed however that the DUDe telemetry client does not properly indicate the frequency offset and it is very difficult to get a lock on the signal.

Also our ICOM910 receivers have too limited bandwidth to receive a 2400 bit/s BPSK signal properly (although we had a few packets decoded with this, so it is just on the edge of what is possible). We now use only AR5000 in combination with an SDR to record a wide spectrum in IQ files. This way we can replay the files and retune the signal again and have been able to decode more packets than before. This morning at our second pass we were lucky to have a real time lock on the signal and retrieve many packets, so it is possible to have it right at once. But of course we would like to get the ‘luck-factor’ out of it.

A few people will look into the Costas PLL inside DUDe to see if we can improve its performance.  Meanwhile, you can regard Delfi-n3Xt as a real challenging game to decode packets…

S-band reception

With respect to the S-band, we have not been able to test this as all our efforts go into VHF reception. The beacon is however on (also in eclipse), transmitting packets in a duty cycle of 5%, 1 Hz at 50 kbit/s MSK. The satellite is however still tumbling, so the antenna might be pointing in arbitrary direction. Next to this, a lot of gain is needed to be able to even see something above the noise floor (we have an 38dB dish). I believe that dish antenna below 25 dB will not be able to receive the beacon (let alone decode it). If someone however has the right equipment and good see the 1 Hz beacon, e.g. in a waterfall plot, please let us know and sent us a picture!


These are the latest TLEs we have received:
1 00371U 00371A   13325.30974640  .00000000  00000-0  10000-4 0     7
2 00371  97.7888  38.2587 0131876 190.4863 345.6615 14.61864099    08


Jasper PC4JB

Telemetry reception


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