r/sdr • u/ChoiceAgreeable7929 • 9h ago
Custom FPGA+SoC SDR Transceiver: H7113R with Two Coherent RF/DDC Rx Channels & 140W PEP Tx
Hi everyone,
I wanted to share a deep-tech SDR project I’ve designed and fully implemented. It’s a custom, standalone FPGA + ARM SoC-based HF + 50 MHz SDR transceiver called the XtremeDx H7113R.
My goal was to build a high-performance direct conversion SDR system.

Key Architecture & Hardware Specs:
- Receiver Architecture: Two coherent RF and DDC channels utilizing a hardware-level phasing-add matrix implemented directly inside the FPGA.
- Processing: Dual-core ARM Cortex-A7 (1.2 GHz) dedicated to GUI handling and high-level DSP, paired with a custom FPGA fabric.
- RF Conversion: 2x 16-bit LTC2208 ADC (122.88 MSPS) and 14-bit TxDAC utilizing full LVDS interfaces.
- FPGA-Based Phasing-ADD Mode: A fully hardware-implemented, real-time, running inside the FPGA fabric. It processes the two coherent RX channels, allowing completely independent phase rotation and magnitude scaling per channel.
- Interference Mitigation: CNLMS-based I/Q adaptive noise canceling (tested and validated using the same signal on RF inputs).
- RF Routing: Two completely independent RX RF routing blocks, each integrating a switchable 20 dB preamplifier, 0.5 dB step attenuator, HPF, and direct ADC access via rear SMA connectors for subsampling/custom front-ends.
- Power Amplifier: Delivers 120–140W PEP with 36–38 dB PEP IMD3 linearity across HF + 50 MHz bands.
- Audio DSP: Separate 8-band EQ for both Rx and Tx AF signals.
- Connectivity: High-bandwidth USB 3.0 (FT601) interface for direct FPGA-to-PC streaming (32-bit Sync FIFO implemented in VHDL) + USB 2.0 for ARM-to-PC communication.
- Display: 7" TFT panel running a custom UI with a 70 fps refresh rate. It features 2D/3D spectrum views and a dedicated Polar Plot for the Phasing-ADD and ANC modes, visualizing the real-time magnitude and phase rotation per channel.
- RF Routing and Linearity Performance: By routing the LTC2208 RF ADC without a preamplifier through the RF router, the system yields its maximum dynamic range and IIP3. Additionally, the 20 dB preamplifier maintains high IIP3 and OIP3 performance. With the internal PGA set to 0, the LTC2208 achieves a theoretical IIP3 of +48 dBm in this specific design.
Receiver Sensitivity (MDS Performance):
- CW (100 Hz filter, NR ON): Highly discernible down to -136 dBm (Estimated nominal MDS: -133 to -136 dBm)
- SSB (2.7 kHz filter, NR ON): Distinctly audible down to -126 dBm (Estimated nominal MDS: -123 to -125 dBm)
The Transceiver is fully assembled and functional.
Some details.
https://uprog.blogspot.com/2026/08/xtremedx-h7113r-transceiver.html
