I have documented 3 other FPGA projects involving Software Defined Radio:
- Direct Fourier Conversion Software Defined Radio using Cuda Processing
- Direct Fourier Conversion Software Defined Transceiver
- Software Defined Transceiver Redux
This blog will document a complete system for transfer of ADC samples from multiple remote sites to a central computer via fiber.
This is really a continuation of the earlier work, tempered by the realities of moving massive amounts of data without loosing anything!
Each time I start s new version I end up upgrading the FPGA cards used. This time I have updated to an Alinx AXKU3:
This card is used to connect to 1 thru 4 ADC sample cards via 8GB fiber.
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I am refitting the previously used Alinx XC7K325 to simulate 4 separate DC cards, each with an ADC running at 60.44MHZ/122.88MHz
The real system will have 3-4 cards, each with 1 ADC.
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The sample transfer math (sample rate x 2 bytes per sample x 8 bits per byte x 4 ADCs)
4 2217s sampled at 61.440MHz (DC thru 10 meters) gives us: 61,440,000 × 2 × 8 × 4 = 3,932,160,000 bits per second
4 2208s sampled at 122.880MHz (DC thru 6 meters) gives us: 122,880,000 × 2 × 8 × 4 = 7,864,320,000 bits per second.
To achieve this xfer speed, without loosing any data I had to:
- Go to a faster CPU (threadripper)
- enable Ubuntu low latency features
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More to come tomorrow....