OZ7SAT by AMSAT OZ

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The AMSAT OZ team used to operate a legendary ground station, OZ7SAT, offering unique telemetry reception for cubesat and amateur radio satellite operators:

It was an “old school” setup using a wide variety of shell scripts and tools, such as predict, to do automatic scheduling and reception. Decoded telemetry was stored in a mysql database and made available on the website using CGI scripts (yes, we are that old).

Unfortunately, political circumstances forced us to leave this very nice location in 2016, and we have spent 2017 trying to establish ourselves at a new location. We ended up as a group in the OZ7AMG radio club located in the southern part of Copenhagen, where we are now doing a comeback as part of the SatNOGS network :slight_smile:

The antennas are a pair of X-Quads from Wimo with polarization switch, pre-amplifier and bandpass filter for VHF and UHF. The rotator is a Yaesu GS-5600 with G6LVB interface to PC. Receiver is an Airspy R0 SDR connected to an old PC with quad core AMD processor.

Is it still very much a work in progress (forever?) but we can already now receive satellites and we can receive them well :smiley:

Despite a lot of terrestrial noise, in particular on VHF, we have very good SNR from most satellites.

Here, the FUNCUBE-1 BPSK beacon is so strong that we can even see the sode lobes:
https://network.satnogs.org/observations/106675/

A low elevation (10 deg) pass of KKS-1, received almost from AOS to LOS:
https://network.satnogs.org/observations/106164/

More photos from the past and present can be seen in my photo album on Flickr.

Alex

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We were a bit worried about what would happen when the others fire up the HF station. The satellite antenna is located just below the multi-band HF beam, and OZ7AMG is known to be a bad ass kilowatt contest station…

In this pass the satellite antenna points at ~ 20 deg elevation. I think the horizontal lines on the waterfall come from the HF transmitter being active:
https://network.satnogs.org/observations/106237/

And here, at around 310 second it looks like we are actually pointing the antenna up into the HF beam while they are transmitting:
https://network.satnogs.org/observations/106679/

Everything survived…

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Our current setup.

OZ7SAT
OZ7SAT1280×840 24 KB

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Hello Alexandru,

Your setup is very interesting, thanks you for sharing. How about the diplexer ? did you use commercial (if so which one ?) one or is it homebrew ? And same for the pre-amp :slight_smile:

For the diplexer i was thinking about this one : https://wimo.com/diplexer_e.html First on the list for type N connectors.

Best regards,

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Hi Julien,

Our diplexer looks a lot like the MX-72 Diplexer VHF/UHF from the Wimo page. The preamps are some old, filtered preamps from ssb.de

The high pass filter is home built and was added because there is a HFcontest station right next to the satellite antenna :smile:

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Hello Alexandru,

Thanks a lot for your answer. Yes indeed the presence of the high pass filter seems to be mandatory ^^

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Hello.

I am currently mounting an antenna similar to yours (yagi crossed uhf + yagi crossed vhf + preamp mvv70cm and mvv2m + airspy + diplexer)

I saw that you have add filters before the preamps. What are the models of your filters?

Thank you

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The filters are integral parts of the ow noise amplifiers, so no dedicated model for them.

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ok I see. But I see 4 box at the top of your dice, what are they for?

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maybe the polarization switches (2) and the filtered preamps (2)?

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ok thanks ( my ground station for information : https://network.satnogs.org/stations/888/ )

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Yes, that is correct :slight_smile: