Raspberry Pi-based WSPR project

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Hello Doug and the list

For comparison and inspiration here are some measurements on a Si5351A on the RFzero platform: http://www.rfzero.net/documentation/rf/

Bo, The Real OZ

Bo

Good info to explore.

A few comparison points :
Raspberry Pi Zero about $Aud20 shipped, 
RFZero about $Aud85 plus shipping - and I'm assuming that an Arduino  board is needed as well at $Aud???
(I don't play Arduino .. and don't plan to.)

... Then you need to add the band filters, power amps etc , cost much the same for either variant.
... Then you have to get familiar enough with the Arduino IDE and C to make it all work. The hardest bit.

My project started off as a low-cost WSPR generator. Sure the complexity and costs have risen with multi-band operation and power amps but those were my choice to undertake.

While I am not anything like a Linux/Raspbian guru, there are enough articles around that basically step-by-step take you through getting a Pi board going on WSPR using the commonly-available code.



The interesting bits (to me) about the RFZero board:

The RFzero board is an Arduino compatible GPS based RF clock generator built around the powerful SAMD21G18, an 48 MHz 32-bit ARM processor from Microchip (Atmel). The RFzero can generate frequencies from 2605 Hz and beyond 200 MHz. At the same time 28 I/O pins are available and eight of those are via an ULN2803A power driver. The programming and configuration is done via the USB port.

The typical use  of the RFzero is as a beacon (IBP, SPB, CW, FT8, JT9, PI4 and WSPR), signal generator, VFO, Qatari Oscar 100 dual LO or a low cost 10 MHz GPSDO. A dozen of example programs (sketches) are integrated into the Arduino IDE.

The RFzero has been tested generating WSPR signals on 200 MHz and receiving the fifth harmonics on 1 GHz with 100% decoding performance. On 1,3 GHz the decoding percentage was reduced to around 80%. However, this may be due to the performance of the receiver that was unlocked. The RFzero has also been tested generating PI4 signals on 108 MHz that were fed into a x96 multiplier resulting in a 100% decoded signal on 10 GHz. These tests were carried out with a foam covered oscillator.

The technical parameters (harmonic levels, phase noise etc) are all looking good - undoubtedly far better than the basic Raspberry Pi but the project complexity has risen many times.

I think I will stick with my basic Pi Zero... plus multi-band filters and PAs. And it's working well based on the signal reports out of EU on 10MHz WSPR of late.

Doug