Apache Labs ANAN G2

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Created: August 24, 2026

Last Updated: August 24, 2026

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The latest addition 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. Using programs like Thetis, the receiver’s noise reduction—especially when using NR2 or NR4—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.

 

Known Problems and Concerns

Setting Static Ip Address

The G2 normally expects DHCP.  Apache Labs' G2 documentation describes Ethernet as obtaining an IP address automatically. With a normal router, DHCP makes this essentially invisible to the user. If you use a router, the G2 connects fine.

Some hams prefer to connect their SDR network connection directly to the network connection on their PC. This avoids any in-house network traffic and provides a dedicated network path between the SDR and the PC. This was easy to do with the older ANAN radios because it was easy to set a static IP address within the SDR. The IP address was programmed into the FPGA using a small utility program.

For a Direct PC-to-G2 connection there is no DHCP server. Apache's earlier ANAN documentation says that with a direct PC connection, the equipment can fall back to APIPA (169.254.x.x), and that assigning an address can take several minutes. APIPA isn't particularly attractive for Thetis. 

You can end up with the PC and G2 acquiring 169.254.x.x addresses independently. They may eventually communicate, but discovery can be slow or unreliable. This is one reason static addressing is preferable for a permanent direct connection.

The Windows Ethernet adapter becomes part of the problem. The PC must have an address in the same subnet as the G2. If Windows is still configured for DHCP while the G2 has been given a static address, they can be completely unable to communicate.

Windows may have multiple network interfaces. If the PC simultaneously has Wi-Fi and Ethernet, Thetis/network discovery can become confusing because Windows has multiple network paths. Direct-connected equipment is much easier to troubleshoot with the Wi-Fi temporarily disabled.

The G2's Linux networking is another layer. This is particularly relevant to the CM5/Trixie in the G2. You're not configuring a simple Raspberry Pi desktop. The CM5 is running the G2's Linux environment, Saturn software and p2app. The G2 manual says that on the headless version, p2app launches automatically at startup.

Soft Shutdown Required

Computers should not be powered off without performing an orderly shutdown. The Raspberry Pi in the G2 should be commanded to shutdown the OS before the power is removed. In order to perform a soft shutdown you would perform a short press of the power switch. After 20 seconds or so, the power light changes to white which means the OS has shutdown. You can then long press the power switch for a few seconds until the G2 powers down.

I am having a problem with this. When I try to perform a soft shutdown on my system, sometimes it will work properly. Other times it will ignore the first press and not perform an orderly shutdown. The second press will cause a hard shutdown of the running system. I am currently working with Jerry, KD4YAL, to resolve this. It may be related to the upgrade from CM4 to CM5 in production. More to come on this.

 

Linux Skills Desired

Most users would just use the G2 as long as it keeps working. Many users have the attitude, "Don't fix it if it 'aint broke." Many are fearful of breaking configurations and causing failures they do not understand how to resolve. Some are uncomfortable working with Windows so dealing with the Raspbian OS can be scary for them. The more you learn now the more comfortable you will be should a problem arise.

Here's a list of helpful suggestions.

• Learn how to use the standard Raspbian desktop environment which is LXDE. There are many similarities to the Windows desktop.
• Learn the basic Linux directory structure. Here are some of the common directories. 

/etc Configuration files
/boot Boot configuration
/home User files
/usr Installed programs and libraries
/var Logs and changing system data
/tmp Temporary files
/home/pi/github/Saturn/ The G2 Source Tree (files downloaded from GitHub)

• Learn how to bring up a a terminal window.
• Learn how to use SSH to bring up a terminal window on your PC.
• Learn how to bring up the G2 Desktop on your PC using VNC.
• Learn how to make a backup copy of your G2 SD Card.
• Learn some of the basic Linux commands.

cd   - Change Directory
ls   - Directory Listing
mv   - Move
cp   - Copy
rm   - Delete
nano - One of many editors
sudo - Superuser Do (execute with admin priviliges)
sudo raspi-config - The Raspbian Configuration utility

 

G2 Open Collector Output Pinout Different from the Anan 7000/8000

Some hams use the Open Collector outputs on the ANAN radios to control things like automatic band changing on their amplifiers. The DE-9 pin assignments on the G2 are not the same as those on the 7000/8000. You can't simply plug in your cable from your 7000 or 8000 into the G2. You either have to make a new cable or make an adapter to translate the pin assignments. See the following post.

Apache Labs Forum Link - G2 Open Collector Outputs Update

 

Connecting Speakers to the G2

As with all Apache Labs radios, care must be taken when connecting speakers to the radio's rear speaker connections. These speaker jacks are what is called TRS which means Tip-Ring-Sleeve. This means they are three conductor jacks. On the Anan 7000 and others, the jacks are a 1/4 inch TRS jack. On the G2 the jacks are 1/8" TRS jacks. The plugs that fit them look like the ones on stereo headphones or stereo earbuds.

The Anan speakers are connected to Tip and Ring. No speaker should ever be connected to the sleeve. Normally the sleeve is connected to the mounting nut which grounds the sleeve to the cabinet. The Anan audio amplifier speaker outputs are bridged. That means both speaker wires are hot with respect to ground. In other words, both speaker conductors are floating. If you connect either speaker conductor to the sleeve (ground) the speaker may create sound but you run the risk of permanently damaging the audio amplifier IC. I personally would not insert or remove a speaker plug with the Anan power turned on.

If you want to connect powered speakers you can connect them to the headphone jack. This jack is also TRS. The Tip provides the Left Channel audio. The RIng provides the Right Channel audo. The sleeve is the common ground.