W1700K SDR: a router as a test bench for investigating industrial wireless networks

In short

For those developing products with ESP32 or investigating communication failures in the field, our assessment is that the W1700K SDR deserves attention as an experimental bench tool. The project turns a compatible router into a receiver capable of sending radio samples to a computer. Those keeping equipment running normally do not need to change its firmware because of this. For hobbyists, the appeal lies in studying signals using a repurposed platform.

What it is

SDR stands for software-defined radio: some of the signal processing is handled by software instead of remaining limited to the fixed functions of the communication circuitry. The open-source w1700k-sdr project, by h0m3us3r, uses the Gemtek W1700K router for this purpose. According to CNX Software, it receives signals in the 2.4, 5 and 6 GHz bands, with sampling rates of up to 320 million samples per second, and sends the data over 10-gigabit-per-second Ethernet to a Linux computer. Installation replaces the original firmware, the software that controls the equipment. Source on the W1700K SDR.

The context is the exploration of commercial radio circuitry to access signals before packets are interpreted. Coverage of ESP-SDR had already described this access on ESP32 devices. The W1700K SDR is a separate project, based on a different platform; here, the editorial interest lies in the path from data capture through transport to analysis. Context on radio access on the ESP32.

These receivers work with I/Q samples, two numerical components that represent the amplitude and phase of the received signal. They allow a spectrum to be calculated, showing how energy is distributed across frequencies. Another common visualization is the waterfall: each row represents a point in time, and the colors show signal intensity. This makes it easier to spot short transmissions, persistent activity and changes over time.

What it is for

The benefit of observing the radio is seeing a layer that application logs do not show. An ESP32 may report that it lost its connection or failed to deliver a message. That log entry describes the effect perceived by the software. Observing the spectrum adds information about the electromagnetic activity present at that location and time.

Consider a typical investigation: sensors send temperature readings over MQTT, a messaging protocol in which devices publish information to an intermediary server called a broker. The supervisor notices gaps in updates. Possible causes include the sensor's power supply, a software fault, network congestion, broker unavailability and radio interference. Recording failure times and comparing them with spectrum activity helps organize the hypotheses.

This comparison requires a method. First, normal operation is recorded. Then, the operation that coincides with the failure is repeated, keeping the antenna position and receiver settings unchanged. An emission appearing at the same instant becomes a lead for further tests. To establish the cause, one condition must be changed at a time to check whether the behavior follows the change.

Where it is used

Spectrum observation is a laboratory practice used in wireless equipment development, investigations of coexistence between transmitters and installation assessments. In a factory, access points, mobile terminals and sensors may compete for the same communication medium. In the field, antenna position, the presence of metal structures and the movement of people or machines also affect propagation.

One example of an industrial architecture combines instruments connected over RS-485, a differential electrical interface used for serial communication, with a concentrator that sends the data over Wi-Fi. Modbus, a protocol that organizes reads and writes of equipment data, can operate over the serial link. Separating these segments during diagnosis avoids looking for a cabling fault in the radio or attributing a wireless network interruption to the instrument.

In this scenario, radio analysis belongs to the wireless segment. On the RS-485 segment, the investigation involves termination, biasing, electrical reference and signal integrity. In the SCADA system, supervisory control and data acquisition software, it is also relevant to check the time of the last valid reading and the quality of the information. This division turns a general communication complaint into specific tests for each layer.

Relevance for industry

Editorial view: the W1700K SDR is primarily of interest to teams that already need to investigate radio problems and can maintain an experimental test bench. Its potential value lies in expanding observation during testing, especially when device logs show interruptions without explaining what happened in the wireless medium. For maintenance of a stable installation, we see no reason to change the architecture solely because of the announcement.

A useful procedure starts before any capture: define the question to be answered. Does the signal disappear when a metal door closes? Does the failure happen only during a particular operation? Are all sensors affected at once? Questions like these determine where to place the receiver and which events to record. Without this preparation, a screen full of signals may generate more curiosity than diagnostic insight.

The application also needs to be observed. In an industrial sensor network, known as IIoT, data needs to arrive with identity, time and an indication of validity. An old value left on the screen may look like a current measurement. That is why connection monitoring, stale data detection and defined behavior during unavailability remain essential, regardless of the tool used to investigate the radio.

Impact on embedded systems

Editorial view: this project's main contribution for embedded developers is to highlight that signal capture is only one part of the system. The entire chain needs to sustain the flow: memory, transfer, processing and storage. This reasoning also applies to an ESP32 collecting audio, images or sensor signals, even when the amount of data is much smaller.

The sampling rate indicates how many measurements are produced per second. The size of each sample determines how much space they occupy. Multiplying these factors gives the initial data load, to which transport overhead is added. A memory buffer absorbs temporary delays, but it does not solve an output that is permanently slower than the input. When it fills up, the system needs to discard data, stop acquisition or reduce production.

For product firmware, this translates into concrete decisions: separate acquisition from transmission, limit queues, count losses and log resets. Firmware is the embedded program that controls the device. PlatformIO, a development environment that organizes builds and dependencies, helps reproduce the tested version of that program. Keeping the same build during comparisons avoids mixing software changes with changes in the radio environment.

On the hardware side, measurement needs to account for the antenna, power supply and physical position. An antenna near metal can change the observed behavior; power supply noise can affect the circuitry itself; strong signals can saturate the receiver input. Saturation occurs when the circuit stops correctly representing the received signal. Under these conditions, increasing the gain can make observation worse instead of revealing weaker signals.

Limits and what is still missing

The report consulted does not establish certified metrological performance, validated industrial use or equivalence to a calibrated spectrum analyzer. Nor does it provide a basis for promising that the project will identify a specific ESP32 failure. Among the candidates provided, there is no primary source specific to the W1700K SDR; official notes for other projects do not substantiate its characteristics.

The maximum sampling rate alone does not determine the quality of the analysis. The observed band, filter response, gain, noise and sample loss during transport all matter. A spectrum image also does not automatically reveal packet contents or identify the transmitting equipment with certainty. To reach a diagnosis, it needs to be combined with network logs and controlled tests.

Since the approach involves replacing the router's software, our recommendation is to set aside a laboratory unit and confirm compatibility and recovery before installation. What is worth following is the project's documentation on capture stability, known limitations and reproducible measurement procedures.

What to do now:

- Choose a specific failure and record the times when it occurs. - Confirm the equipment model and restoration procedure before modifying it. - Compare captures while keeping the antenna, position and gain constant. - Cross-reference radio observations with ESP32, network and application logs. - Validate the hypothesis with a controlled test before changing equipment in the field.