Posts by DH2VA

For the PLL phase detector, it is most important to determine the phase as accurate as possible. This is best done if the slew rate of the signal into the phase detector is highest or to put it in other terms, if the edges are as steep as possible. So square wave is preferred over sine wave.

I assume you took the different polarization into account?

Wie gesagt, es geht auch einfacher/günstiger als ICD4. Aber es ist nicht nur das Debug Protokoll ist wichtig sondern auch gewisse Hardware Funktionen im ICD4, hab schon eine Weile nichts mehr damit gemacht aber der Performance Gewinn beim Debuggen war mir den höheren Preis wert. Und ich wäre nicht überrascht, wenn es schon funktionierende ICD4 Clones gibt (gab es beim ICD 3 auch).

Hallo Ulrich, ich war am Downconverter Design nicht beteiligt, aber ich kenne besagtes Programmierkabel gut, ich benutze das im qrl sehr gerne. Es gibt den auch direkt als no-leg Variante, den ich selber bevorzuge und der hält auch ganz gut ohne die Riegel (die Stahlstifte klemmen ganz gut, auch fürs Debugging), keine Notwendigkeit irgendwas zu verstümmeln.

https://www.tag-connect.com/pr…-microchip-icd-10-version

Der benötigte ICD4 kostet über 200 USD, insofern finde ich 40 USD für einen qualitativ hochwertigen Adapter in Ordnung. Sicher geht es einfacher (auch was Programmierer angeht), aber so schlimm find ich das Setting nicht.

73s Achim

can you check the Pluto output in real-time with another receiver (a second pluto maybe)?

David G0MRF will there be a technical analysis of the mishaps? I have tons of questions but for these to be answered a more detailed breakdown of the sequence of events and the lessons learned would be helpful.

Thanks for supporting this education project, as always!

The case of Arecibo is a sad but classic case of negligence and budget cuts. The hurricanes did not killed it, they just gave it the final blow. Working with them in 2014 for the ISEE-3 recovery, they were already struggling then for basic maintenance.

exactly Andreas, and that is why you normally optimize receive antennas for G/T or Gain over (system) noise temperature. Because this will end up in Signal-to-noise ratio.

Having a huge G with crappy T might be worse than decent G with low T. So depending on your setup, a slightly underilluminating feed will produce better results as it won't pick up as much noise from behind the main reflector (as for me, being close to the wall).

oh2uds it seems you have a severe ground loop problem and as USB is not galvanically isolated, this will lead to future defects unless fixed. You have to break the loop somewhere, either by inserting a capacitor in the SMA GND input or using an OTG USB-Ethernet adapter (Ethernet is galvanically isolated).

The Pluto is rather power hungry so you have to be super certain about the PSU for the Pi4 (which itself requires a bit of power). Have you tried a USB power monitor dongle to measure the voltage? You can also use a separate USB line to power the Pluto via its second USB socket (from a 5V /1A charger, NOT from another Pi4 port).

@SA2BFO wenn du das Phaenomen messtechnisch aufbereiten koenntest (Beobachtungen bei gutem/schlechtem Wetter) gaebe das einen ausgezeichneten Journal Artikel! Deine geringe Elevation (mehr atmosphaerische Strecke) und das schlechte Wetter sollte da hilfreich sein.

Hallo Andreas,

auf 10 GHz ist das nicht Aurora sondern dann wohl Regenscatter.. mein alter Herr Dieter DL3NQ hat auf 10 GHz viel Regenscatter-Verbindungen an Gewitterwolken gemacht und das klingt vom Sound her genau so. Das Signal wird an den vielen Reflektionszentren (Schneeflocken oder Wassertropfen) gestreut und da die alle verschiedene Geschwindigkeiten und Richtungen haben ist das vergleichbar zu einem 'schlechten' LO.

Ausschliessen laesst sich das indem Du eine lokale 10 GHz Signalquelle anhoerst. Die sollte sauber klingen. Vom Satelliten kommt es sicher nicht.

DD4YR is correct.. the any bad matching on the PA output will not (or only at a tiny degree) backpropagate on the PA input.. This is actually related to the S12 S-parameter and can be n the order of 20 dB. So even with a full short on the output, your input return loss is still -20dB and therefore close to perfect.

wobei man -1 Grad trotzdem mal testen sollte.. atmosphaerische Refraktion? Braucht evtl. mehr Antenne..

Quote from OM3BD

I did have a high SWR issue in the past but the bag cured it, at least until today.

That sound already very odd and should be the first thing to be checked. It could be a faulty cable.. if this is not 50 Ohms all the way (including connectors) it can transform even a perfect 50 Ohm match into anything else triggering the SWR warning of the PA.

Any news about the REALTEK8812BU driver in the Pluto firmware from F5OEO?

you should not look on the Es'hail-2 footprints on the WWW as they only list the spot beams for the TV programmes. The AMSAT payload (QO100) has dedicated global beams which are not listed in the usual places but here:

https://amsat-dl.org/p4-a-nb-t…and-operating-guidelines/

Be aware, that actually two transponders are used for hamradio: one for TV and one for narrowband (SSB, CW, digimodes), check out the amsat-dl.org website for more information (frequencies, polarisation). Don't bother looking for the TV programmes of the main satellite.

Use SDR-Console with it's integrated RX offset/drift correction (locking onto the beacons). This should take care of the LNB drift (if it is a PLL LNB) and the RX drift of the Pluto. When transmitting, your signal will eventually start drifting which is the remaining unless you start modifying the Pluto's reference frequency.

A very interesting thought but it likely needs dedicated firmware on the PLUTO FPGA. I don't think a software solution where the data first goes via USB to the host and then adjusts the TX frequency in real time would give satisfactory results.

That said, a non-SMD component solution is to scrape the REF_FREQ line between the XO and the ADC and feed your external 10 MHz reference there. This has been documented widely and only does require /some/ soldering skills, nothing too fancy.

I assume you know this diagram from the datasheet, it gives an IM3 of -30dBc for Pout=27W. I would think that more would be possible with less output power?