Apache Labs ANAN G2
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The latest acquisition to my Ham Radio station is the Apache Labs G2 Software Defined Radio. This is a new posting so I will be updating this frequently.
Apache Labs provides two versions of the ANAN-G2. The G2 is shown above with no front panel display or controls. This is often called G2 Headless or G2 Blank Face. The other model is the G2 Ultra which has the front panel display and controls.
The ANAN G2 is an impressive high-performance SDR for operators who prefer controlling the radio entirely from a computer. With no front-panel display or controls, it is particularly well suited to shack, remote, and multi-computer operation. Its combination of powerful FPGA processing, excellent receiver performance, and Thetis software provides exceptional flexibility. The receiver’s noise reduction—especially NR2—is outstanding, while features such as Diversity Reception, PureSignal, sophisticated filtering, and extensive DSP controls give experienced operators tremendous capability. Independent owners consistently praise its receiver and signal-processing performance.
The downside is complexity. Thetis has a substantial learning curve, and the G2’s Linux/Raspberry Pi subsystem requires proper shutdown procedures. The headless version also sacrifices the convenience of immediately available physical controls.
Overall, the G2 headless is a superb choice for the serious SDR operator who values performance and flexibility over simplicity. It is powerful, exceptionally capable, and highly configurable—but best suited to someone comfortable with computers and SDR technology.
The ANAN-G2 rear panel provides an unusually comprehensive set of connections for a high-end SDR. On the RF side are three independent ANT 1–3 connectors for transmit and RX1, plus RX2, an RF Bypass input for PureSignal feedback, EXT1 for an RX path bypassing the T/R switch, XVTR In/Out for transverter operation, and a 10 MHz reference input. A ground stud provides the RF earth connection.
Power is supplied through a Powerpole 13.8 V DC input rated for 30 A. The built-in Raspberry Pi provides Gigabit Ethernet, two USB 2.0 ports, Wi-Fi antenna connectivity, and two full-function HDMI outputs. These connections are especially important on the headless version because Ethernet provides the primary connection to Thetis, while HDMI and USB allow a monitor, keyboard, and mouse to be attached when needed.
The auxiliary section includes seven programmable open-collector outputs, digital inputs, line-level TX audio, PTT in/out, speaker outputs, balanced XLR microphone input, and rear-panel CW, headphone, and microphone connections.
The ANAN-G2 block diagram illustrates how the radio moves signals between its antennas, RF hardware, SATURN FPGA, Raspberry Pi, and external equipment. On receive, signals entering ANT1–3 or the RX2 input are routed through the appropriate switching and band-pass filtering before reaching the high-performance ADCs. The SATURN FPGA then performs the initial digital signal processing, separating the received spectrum into selectable bandwidths and sending the resulting data to the Raspberry Pi and, through Ethernet, to software such as Thetis. The G2 has two independent receive paths, allowing advanced functions such as diversity reception.
On transmit, digitally generated signals travel in the opposite direction: software processing feeds the FPGA, which drives the RF transmit chain through frequency conversion, amplification, filtering, and the antenna switching network. The diagram also shows the dedicated transverter path, RX bypass connections, and PureSignal feedback path used for amplifier linearization. Together, these blocks explain why the G2 combines sophisticated SDR processing with conventional RF filtering and amplification.
This is the inside top view of the ANAN G2. This unit has no front panel display or controls. You can see the Main Board, a simple rear header board for some rear panel jacks, and the balanced mic preamp board. These components are mounted on a thick heatsink. Under the heatsink is the RF power amplifier and filters.
Here is a closeup view of the main board identifying the Raspberry 5 Compute Modukle (CM5), the FPGA (Field Programmable Gate Array) and the SD Card slot.
The Raspberry Pi 5 and Compute Module 5 (CM5) are essentially the same computer internally. Both use the BCM2712 quad-core Cortex-A76 processor running at 2.4 GHz. The major difference is physical design and intended use.
The Pi 5 is a complete single-board computer, with built-in USB, Ethernet, HDMI, microSD, GPIO, and other connectors. It is designed to be used as a standalone computer.
The CM5 is the Pi 5's computing core packaged as a small module. It has no normal external connectors; instead, it plugs into a custom carrier board that provides whatever connections the manufacturer needs. CM5 is also available with optional onboard eMMC storage.
For the ANAN-G2: the CM5 is particularly appropriate because Apache Labs designed the G2's motherboard as the carrier board. In other words, the G2 effectively provides the CM5 with its own specialized computer motherboard and connections.
The CM5 runs a Rasperry Pi OS (a version of Raspbian). It handles the ethernet network connection between a host computer and access to the internet. In the case of a front panel display and controls, the CM5 can run the G2 in stand-alone mode where applications like piHPSDR or Zeus can run on the front panel with no external PC attached.
This is a photo of the G2 Ultra showing the Raspberry Pi Desktop. From here you can launch a stand-alone radio application or launch p2app which allows the radio to interface with radio applications on your PC such as Thetis. If you have a G2 without the front display you can bring up the desktop on your PC using VNC. You could also attach a monitor, keyboard and mouse directly to the G2 and do the same thing.
This is a photo of the G2 Ultra running the radio application piHPSDR.
This is a photo of the G2 Ultra running the radio application Zeus. Zeus can also be run on a PC.
About the Field Programmable Gate Array (FPGA) Chip
The FPGA in the ANAN-G2 is essentially the high-speed digital engine of the radio. It is needed because an SDR has to process enormous amounts of digital RF data in real time, far faster and more predictably than a general-purpose CPU alone can handle.
In the G2, the FPGA sits between the high-speed ADC/DAC hardware and the CM5/Raspberry Pi. On receive, it handles tasks such as digital down-conversion, filtering, spectrum processing, and routing multiple receiver data streams. On transmit, it performs the corresponding high-speed digital processing before the signal reaches the RF hardware.
An FPGA is particularly well suited because it can perform many operations in parallel. Instead of a CPU processing samples sequentially, thousands of FPGA logic elements can work simultaneously on the incoming data stream.
The CM5 then handles the higher-level computing—network communications, operating-system functions, and running the G2's p2app—while software such as Thetis provides the user interface and advanced control.
In simple terms:
Antenna → ADC → FPGA → CM5/Ethernet → Radio Application Software such as Thetis
The FPGA provides the real-time horsepower, while the CM5 provides the computer intelligence.
The FPGA requires programming. It is lind of like firmware, often called gateware. Gateware is the programming that defines what the FPGA actually does. Unlike normal software running on a CPU, gateware configures the FPGA's internal logic so that it becomes a specialized digital signal-processing machine. Several brilliant members of our Ham Radio community have written the gateware code to load into the FPGA. CM5's Linux software tells the FPGA what to do, while the gateware determines how the FPGA performs those operations in hardware. Loading new gateware can add new features to the radio without replacing the physical FPGA chip.