According to our team “The frequency offset is ~18025 Hz on Spectravue, so it looks likely. He’s tuned to XB, so just seeing the very tip of the PM carrier.”
http://spacecollege.org/isee3/detecting-isee-3-with-a-8-foot-dish.html
“I calculate a C/N0 of -2.5 dB-Hz for you, depending on mod index. Seem right? That’s weak!”
Dear Iban,
Thank you for the timestamp, qth etc, and the info about the Spectravue
header format.
I examined the file anyway and worked out that a “stereo” signal was I and Q,
16-bits each, LSB first.
I confirm the signal as you found. I averaged small and large numbers of
FFTs. This showed that the signal strength varied, between approximately
11 to 16 dB-Hz. The spacecraft is spinning at about 3 rpm, so this may be
the reason.
Attached is a typical plot from my my own software. This is not the strongest
signal display; the largest I found was a signal = -45.7 dB over the
noisefloor = -53.8 dB, or SNR = 8.1 dB.
With a bin bandwidth of 0.124 Hz, this equates to a CNR of 16.4 dB-Hz.
Congratulations!
73 de James G3RUH
ISEE-3 signal processed by G3RUH
Finally after four days of attempts I detected the ISEE-3 / ICE space probe 🙂
I used the LHCP channel that is at 2217.5MHz becuse I have a lot of noise in the RHCP channel. I used a can feddhorn and a plexiglas depolarizer.
The signal is very weak and impossible to see without time integration. The offset reported by the Arecibo guys of 7202Hz has been very important to locate the probe. In my case I’m getting the probe with a carrier offset of 6035Hz from 2217.5MHz.
Here the first detection:
ISEE-3 / ICE Dection
After the detction, to confirm that I moved the dish 18deg, and the signal disappears:
ISEE-3 / ICE off center
To confirm again the signal I stoped the doppler compensation:
ISEE-3 / ICE no signal without the doppler compensation
Finally I started to compensate the doppler again and the signal is acquired again:
ISEE-3 / ICE with doppler corrected
To finally confirm at 100% a offline signal process without doppler compensation to see doppler signature. I used the amazing baudline autodrift option, it is a great feature to see signals with doppler:
ISEE-3 / ICE baudline autodrift
Here the IQ recording from Spectravue without the doppler compensation used in the baudline analysis. The sample rate is 8138 samples/sec:
www.eb3frn.net/files/Record1_20140607_151047_nodoppler.wav
73!