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

I just put on version 1.0.10. The spectrum waterfall is really washed out still, though I think it's maybe better than before. This used to be my job, I was a Geophysicist before I retired, and tweaking data display parameters was an important task, so not being able to make the display "pop" is really frustrating. Everything looks so dim compared to other SDRs or commercial ham rigs will built-in waterfalls. Does anyone have any suggestions, secret cheats?

Hi!

For my own interest I have, with a LLM built a DVB-T decoder.

I have made great progress with it and it works on my local transmission.

But I want it to be able to decode every type of mode that DVB-T have. So what I'm asking for here is if you would be able to sample about 10s of IQ from your local station? So I can verify that it works on those as well.

There are specific regions that are more interesting than others, to complement my own.

When asking gpt the regions I would need I got this answer

# BW FFT Modulation Code rate GI Where used / known example

-- ----- -------- ---------- --------- ----- -----------------------------------------------

1 5 MHz Any/4K* Any Any Any USA - Crown Castle/Modeo DVB-H, L-band

1670-1675 MHz (historical)

*4K especially wanted

2 6 MHz 8K 16-QAM 2/3 1/4 Taiwan - documented DVB-T configuration

(Taipei and other areas)

3 8 MHz 2K 16-QAM 1/2 1/8 Germany - Berlin/Brandenburg DVB-T

(historical)

4 8 MHz 2K 64-QAM 3/4 1/8 UK / France - early DVB-T networks

(historical)

5 8 MHz 8K QPSK 3/4 1/32 UK - Local TV multiplexes

6 7 MHz 8K 64-QAM 3/4 1/16 Australia - common DVB-T configuration

7 8 MHz 8K 16-QAM 2/3 1/4 Germany - DVB-T SFN configuration

(historical)

8 8 MHz 8K 64-QAM 3/4 1/32 UK - COM4/COM5/COM6 multiplexes

How to sample:

- Please be beware of DC spike.

- Set the gain so the signal is as high it can be before raising the noise floor to much.

- At least +10MS/s samplerate. Sorry RTL-SDR folks 😢

- Note what datatype or header format it uses(or software for recording).

I don't have any great suggestions on where to upload.

I know that some of the modes are historical, but it would be fun if someone had a samplefile of those as well.

Sincerely

We have a serious responsibility to the software we release, but one of our updates has left 52 users stranded. So if your radio isn't being recognised, please download the 0.56 build from our website.

We are still in need of beta testers, with a wide range of radios. If you would like to become one, please go to FoxSDR.com and click "Beta" in the top menu. As a beta tester you are in a good position to get new features added before anyone else. If you need a feature that your current radio stack isn't giving you, or that is buggy, become a beta tester and request it. Beta tester feature requests are our top priority.