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WHEN Series WiFi Clock: Professional-grade NTP Synchronization Software Released (Beta Users Wanted)

2025-09-06

This update focuses on optimizing NTP time synchronization performance, redesigning the NTP client program in combination with processor characteristics, reducing jitter from over 40ms to within 2ms. The new client program accounts for most NTP protocol features and provides practical configuration options for users.

After upgrading to the new software version, the cost-performance ratio of the WHEN series WiFi clocks has significantly improved. At the price of a standard network clock, it delivers NTP time synchronization performance comparable to professional-grade equipment. For scenarios requiring high-precision time, there are very few digital display devices on the market offering equivalent high-precision network time synchronization, making the WHEN series WiFi clock an ideal choice.

Sources of Network Time Synchronization Errors

Most devices use NTP (Network Time Protocol) for time synchronization, which is currently the most common network time synchronization method, with numerous free public NTP servers available on the internet. We won’t delve into the detailed principles of the NTP protocol (abundant resources are available online) but focus on the three main sources of errors:

  1. Device Design:
    The hardware performance and software optimization of the device directly affect time synchronization accuracy.
  2. NTP Server Time Errors:
    The accuracy of the server’s own time affects the synchronization results.
  3. Network Latency:
    When both the device and server are reliable, network latency is the primary source of errors.
    The NTP protocol measures round-trip time (RTT) through multiple timestamp exchanges, assuming equal uplink and downlink delays, and uses half of the RTT as the one-way transmission time to correct the time. However, in real-world network environments, uplink and downlink delays are often asymmetric, leading to calculation deviations.
    Therefore, higher network latency may result in larger time synchronization errors.

New Software Settings

The new software version provides users with more flexible configuration options for network time synchronization, optimizing NTP performance to meet diverse needs. Below are the new features:

1. Primary and Backup Server Logic

Users can set a primary server and a backup server. The system prioritizes the primary server and automatically switches to the backup server if the primary server fails multiple times, ensuring time synchronization stability.

Primary and Backup Server Settings Diagram
Primary and Backup Server Settings Diagram
2. Advanced Settings

Provides fine-tuned control for advanced users, improving time synchronization accuracy and compatibility:

  • Time Acquisition Compensation:
    Allows fine-tuning of system time to compensate for known server time deviations or clock display delays, suitable for scenarios requiring extremely high precision.
  • Latency Limit:
    Allows setting a network latency threshold; time data exceeding this threshold will be discarded, effectively filtering high-error data caused by network fluctuations.
  • Burst Mode:
    An NTP high-precision time synchronization mode, recommended for use with private servers to significantly improve accuracy.
    Note: Disable this mode when using public servers to avoid being blacklisted.
  • Fault-Tolerance Mode:
    Strictly validates the reliability and standardization of data sent by the server. When enabled, non-standard parameters are ignored, improving compatibility with private servers, suitable for users with non-standard NTP servers.
Advanced Settings Diagram
Advanced Settings Diagram

Accuracy Test Data

It should be emphasized that NTP time synchronization accuracy is highly dependent on network latency.

Test 1:
Local NTP Server, Burst Mode Enabled, Synchronization Interval 1 Minute
Test 1 Chart
In nearly 2 hours of test data, network latency remained stable at around 3ms, with time deviation maintained near 0ms and a maximum deviation not exceeding ±2ms.
Test 2:
Public NTP Server, Burst Mode Disabled, Synchronization Interval 1 Minute (Wired Broadband)
Test 2 Chart
In approximately 30 minutes of test data, network latency stabilized at around 38ms, with time deviation controlled within ±3ms (ignoring initial synchronization data with larger system deviations). The wired broadband network had highly symmetric uplink and downlink, resulting in minimal time deviation.
Test 3:
Public NTP Server, Burst Mode Disabled, Synchronization Interval 1 Minute (Mobile Network)
Test 3 Chart
In approximately 40 minutes of test data, network latency averaged above 100ms, with occasional significant spikes. The chart shows that time deviation spikes synchronously with network latency spikes, indicating that network quality has a critical impact on synchronization accuracy. In practice, enabling the latency limit function with a threshold of 150ms in this environment can effectively filter out high-latency outlier data.
Test 4:
The first three tests were conducted internally, recording the deviation between system time and server time. Test 4 was conducted by other professional users in a local network environment, using a GNSS standard time source to compare standard time with the actual display time on the screen, with results as follows:
Test 4 Chart
The report shows a 2-4ms delay from system time refresh to screen display. To meet different needs, the following is recommended:
  • Time Announcement/Alarm Scenarios: Prioritize the accuracy of time announcements or alarms, set “Time Acquisition Compensation” to 0.
  • Display Accuracy Scenarios: Set “Time Acquisition Compensation” to 2~4ms to compensate for display delay.

Beta Testing Notes

To ensure a smooth beta testing process, please refer to the following notes.

Software Stability

The new software version has undergone extensive testing but may still have unknown issues. If any abnormalities are found, please provide feedback promptly, and we will optimize quickly.

Target Users

· Recommended Users: Users familiar with network knowledge and pursuing high-precision time.
· The current version’s accuracy already surpasses most similar clocks on the market. Regular users can continue using the current version and wait for the official release after beta testing (free upgrade).

Accuracy Verification Methods

  • Do not use mobile phones or computer time as a reference (insufficient accuracy). Professional equipment (e.g., GNSS time source) is recommended.
  • Quickly press the red button 4 times to enable the screen pulse flashing test mode, facilitating millisecond-level accuracy verification.

Multi-Device Testing

Millisecond-level display deviations can be tested across multiple clocks, but users should understand the sources of NTP synchronization errors (see “Sources of Network Time Synchronization Errors” section), particularly the impact of network latency.

Network Latency Display

Zone 3 can be set to display the network latency of each synchronization, allowing users to assess the current network environment.

Recommended Settings

  • Public NTP Servers: Enable “Latency Limit,” disable “Burst Mode” (to avoid being blacklisted), and set the synchronization interval to 5 minutes.
  • Private NTP Servers: Enable “Latency Limit,” enable “Burst Mode,” and set the synchronization interval to 1 minute.
Important Note: When using public NTP servers, be sure to disable “Burst Mode” (to enhance accuracy) to avoid affecting normal server operation.

Parameter Initialization

The new software version modifies NTP and display-related parameters, which will be initialized to default values after the upgrade, requiring reconfiguration.

Beta Version and Participation

Version: WHEN: 2.1.x   |   WHEN-Voice: 1.4.x
Beta Participation: Please send the clock’s serial number to us via email, and we will provide the beta firmware and upgrade guide.
Email: junhui.gong@outlook.com.
Welcome to join the beta test, experience high-precision NTP time synchronization and new features, and your feedback will help us create a more perfect network clock!

Statement on Accuracy

We often encounter users requesting precise error data, expecting 24/7 “zero error” with standard time, or asking us to guarantee “no deviation whatsoever.”

We solemnly declare:
Our clocks are designed with scientific and objective principles, pursuing high precision but not being a sci-fi product.
We cannot promise “absolute precision,” “zero error,” or “no deviation whatsoever,” nor do we promote such claims.
The test data above are based on specific conditions, and NTP time synchronization accuracy is affected by factors such as network latency and server quality, which cannot be eliminated by a single terminal device.

Acknowledgments

We sincerely thank havitem for their strong support and professional guidance in this software update!

As a senior scholar in the field of time and synchronization, havitem’s in-depth research provided critical assistance for this update. We encourage everyone to explore their published articles on time synchronization to learn more about the intricacies of time synchronization. Thank you again!