开云体育

Great development.

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I think a wonderful rig would have a Pi Pico controller for the SDR processing tied tightly to a Pi for GUI and third party apps. The Pico SDR could have essentially an api for control over USB and perhaps send data back for display over SPI. This would solve the timing response problem the sBITX has for CW and free the Pico from GUI handling and allow a world of apps while still in a compact self contained unit.

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I worked on the HAMSCI GRAPE 2 receiver for ionosphere studies that had strict signal timing requirements that couldn't be met by the Pi in spite of our best efforts. We tied in a Pico for the data collection and pushed the timestamped data back to the Pi over SPI. The Pi was used for GPS, GUI, data buffering and interface to cloud storage.

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Another view of this is that it's like the Hermes Lite 2/Anan/SunSDR2/FLEX that uses a dedicated SDR with a fast Ethernet connected computer for GUI and have some models with both in the same box.

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73
??? Bob? KD8CGH

Hi Jerry

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The part number of the 40MHz crystals is ECS-400-20-46X. I got them from Mouser. I didn't bother with matching. I built a test setup and the measured response was fine into 50 Ohms. The flattest response was with 33p. With lower value capacitors the bandwidth increased but so did the ripple. I wanted to keep things simple so no matching network. Also I needed to keep the bandwidth below 15KHz in order to use the rate of 500Khz with 16x oversampling (31250Hz). There is no filtering before the ADC other than the crystal filter.

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73, Ian

VK7IAN

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