Overview

The RigExpert Fobos SDR is one of the most capable wideband SDR receivers currently available in the hobbyist‑to‑professional space. It’s a USB‑3.0, 14‑bit, 50 MHz‑bandwidth SDR covering 100 kHz to 6 GHz, with both heterodyne VHF/UHF reception and coherent HF direct‑sampling channels. Below is a complete, structured technical profile synthesizing everything available from RigExpert’s documentation and product pages.


🧩 Core Identity and Architecture

The Fobos SDR is a high‑performance wideband SDR acquisition board designed for SIGINT/COMINT, spectrum survey, radio astronomy, HAM radio, telemetry, and general RF research. It uses:

  • Primary RF path:
    Double‑conversion heterodyne receiver covering 25–6000 MHz (tuning range 50–6000 MHz).
  • Auxiliary HF paths:
    Two coherent direct‑sampling channels (HF1, HF2) covering 0.1–25 MHz.
  • ADC:
    14‑bit, up to 50 MHz IQ sample rate (8–50 MHz selectable).
  • Interface:
    USB 3.0 via Cypress CYUSB3014 controller.


This combination makes it unusual: most SDRs either do HF direct sampling or heterodyne VHF/UHF. Fobos does both simultaneously.


📡 Frequency Coverage & Modes

  • HF (direct sampling): 0.1–25 MHz
  • VHF/UHF (heterodyne): 25–6000 MHz
  • Continuous operating range: 100 kHz–6 GHz (RigExpert marketing spec)

Modes:

  • Primary mode: double‑conversion heterodyne (VHF/UHF)
  • Auxiliary mode: two‑channel coherent HF direct sampling


📈 Performance Characteristics

  • Blocking Dynamic Range:
  • 82 dB (UHF/VHF)
  • 86 dB (HF)
  • Selectivity: −110 dBm combined
  • IQ Image Rejection: 52 dB (software)
  • Frequency Stability: ±0.5 ppm
  • Maximum RF Input: +10 dBm


These numbers place it well above RTL‑SDR class devices and competitive with mid‑range professional SDRs.


🔧 Hardware & Connectivity

  • RF connectors:
  • 1× SMA (primary RF 25–6000 MHz)
  • 2× SMA (HF1, HF2 0.1–25 MHz)
  • 1× SMA clock input (10 MHz)
  • 1× SMA clock output (10 MHz)
  • Clocking:
  • Internal stable clock
  • External 10 MHz input
  • Permanent 10 MHz output
  • Digital I/O: 8 user‑defined low‑speed GPIO lines
  • Power: USB‑powered (3.8–5.5 V)
  • 450 mA idle
  • 670 mA HF direct sampling
  • 850 mA full‑band mode
  • PCB: 6‑layer impedance‑controlled, EMI‑shielded RF section 130 × 60 × 16 mm, 143 g


🖥️ Software Support

As well as SDR Console there is native and plugin support for:

  • μSDR (recommended by RigExpert)
  • SDR++ (native)
  • SDRSharp (official portable packs)
  • HDSDR
  • GNURadio (IQ source block)
  • SoapySDR
  • SDRangel
  • SatDump plugin

Drivers:

  • Windows: libusb/WinUSB
  • Linux: native libusb


🚀 Special Capabilities

14 GHz/s Band Scan

RigExpert advertises a 14 GHz per second scanning speed, making Fobos one of the fastest wideband spectrum scanners available in its class.


Coherent HF channels

HF1 and HF2 share a clock domain, enabling:

  • diversity reception
  • phase‑coherent experiments
  • direction‑finding (with external processing)
  • MIMO‑style research


Full‑rate continuous IQ streaming

No gaps or burst‑mode limitations.


🛠️ Practical Notes from the User Guide

  • HF direct sampling requires 50 MHz sample rate for best performance; lower rates need external LPF.
  • HF channels have fixed gain — external attenuators/amplifiers recommended.
  • USB‑3.0 only — USB‑2.0 not supported.
  • Avoid front‑panel USB ports; use motherboard rear ports for stability.


🧪 Applications

RigExpert lists the following use‑cases:

  • SIGINT / COMINT
  • Wideband spectrum survey
  • Waveform digitizing
  • HAM radio (HF + VHF/UHF)
  • Wireless / cellular / IoT analysis
  • Radio astronomy
  • High‑performance telemetry
  • Test & measurement


🆚 How Fobos SDR compares to other SDRs (quick expert summary)

Strengths:

  • True 14‑bit ADC (better dynamic range than Airspy, RTL‑SDR, HackRF)
  • HF + VHF/UHF in one device
  • Coherent HF channels (rare)
  • Very fast scanning
  • External clocking
  • Excellent software ecosystem

Limitations:

  • No transmit capability (RX‑only)
  • No onboard gain control for HF channels
  • Requires clean USB‑3.0 environment
  • Not as flexible as AD9361‑based SDRs (e.g., PlutoSDR) for custom RF experiments