Echo PSK31 Testing

Wednesday night I finally had a PSK31 signal to tune in and was able to get Echo configured for better audio in PSK31 mode. The improvement was very noticeable to the ear, and the one and only report I received from that time frame indicated 100% copy on 4 different signals.

Unfortunately, that setup only ran one orbit before Echo was switched into another mode. I think we have something that can be worked with now. We will try another PSK31 session in the future and hopefully see good results as we learn to operate this mode on a satellite.

For the record. We are using the SQRX wide band receiver to receive 10 meter signals on Echo. And the antenna is in fact the VHF whip on the +Z axis of the satellite. There are no changes I can make to the receiver from the ground. I do have control of a few parameters on the transmitter side, in the flight computer (IFC).

If you look at the Echo Block Diagram, which has been published in many different places, you will notice three paths that the signal can take in the IFC to the transmitter. Those are Straight, Resistor, and CTCSS (which includes a resistor).

For FM repeater mode we run either the Resistor or CTCSS path. This provides the best audio in that mode. What I found was using the Straight path, which eliminates the resistor, improved the output signal of the satellite when receiving on 10 meters USB. Also, the Amplitude of the Transmitters signal can be changed from the ground, and that parameter was modified with the straight path to get the best output. I did not have enough time during that one pass to be sure I found the best amplitude setting, but it was close.

Next time we run this mode I feel like you will see a nice improvement in Echo's output.

[ANS thanks Mike, KE4AZN for the above information]

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