How to Synchronise Your Windows PC Clock for FT8, JS8Call and WSPR

Why Precise Time Matters

Digital modes such as FT8, JS8Call, and WSPR rely on tightly synchronized time slots. If your PC’s clock drifts by more than a couple of seconds, you may miss decodes, transmit outside the expected window, or introduce logging errors. Maintaining accurate UTC alignment is essential for reliable weak-signal digital operation.

PC clocks naturally drift over time. While this is rarely noticeable during normal computer use, even a few seconds of clock error can impact digital mode performance. More frequent time synchronization helps ensure accurate decoding, correct transmission timing, and reliable logging.

This is because even modern computers gradually gain or lose time between synchronizations. For everyday computing this is seldom a problem, but for modes such as FT8, JS8Call, and WSPR, a clock error of only a few seconds can reduce decoding performance and cause transmissions to fall outside the expected time slot.

Many amateur radio operators choose to install dedicated time synchronization utilities such as NetTime,
Dimension 4, or Meinberg NTP. These applications work well, but they also add additional software that must be installed, maintained, and usually run in the background or at system startup.

Fortunately, Windows already includes everything needed to maintain accurate time. By adjusting the built-in Windows Time service to check reliable NTP servers more frequently, you can achieve excellent time accuracy for digital mode operation without installing any additional software.

This guide shows how to optimise Windows' built-in time synchronization settings so that your station remains accurately synchronized for FT8, JS8Call, WSPR, and other time-sensitive digital modes.

Step-by-Step: Configure Hourly NTP Sync on Windows

Step 1: Enable Internet Time Sync

This guide applies to both Windows 10 and Windows 11. The layout may vary slightly between versions, but the settings and PowerShell commands are the same.

Open Settings > Time & Language > Date & Time
Ensure the following options are enabled:
- Set time automatically
- Set time zone automatically
Scroll down to Synchronize your clock and click Sync now

This confirms that Windows is actively synchronizing system time and that the Windows Time service (W32Time) is functioning correctly.

By default, standalone Windows systems synchronize time using Microsoft's public NTP service, time.windows.com. In the next step, we will configure additional NTP servers to improve reliability and prepare Windows for more frequent synchronization.

Note: If synchronization fails or Windows reports Local CMOS Clock as the time source, check for third-party time synchronization software such as Meinberg NTP before continuing.

Step 2: Set Regular Sync Interval via PowerShell

By default, standalone Windows systems synchronise time only infrequently, often with many hours or even days between updates. For digital modes such as FT8, JS8Call and WSPR, more frequent synchronisation helps maintain accurate timing and reduces the risk of clock drift affecting operation. To improve accuracy, we'll configure Windows to synchronise time more regularly using its built-in Windows Time service (W32Time). This provides regular, predictable corrections without installing any third-party software.

In the next step, we'll reduce the Windows Time polling interval so that the clock is checked and corrected more frequently.

Don't worry if you're not familiar with PowerShell. This step simply involves opening an Administrator PowerShell window and copying and pasting a command.

Open PowerShell as Administrator

Press Windows + X
Select Windows PowerShell (Admin) or Terminal (Admin)
(The name varies slightly depending on Windows version.)
When prompted, click Yes to accept the User Account Control (UAC) prompt

A blue PowerShell window similar to the one below will open.

Next, we’ll copy and paste six PowerShell commands into the PowerShell window. Each command performs a specific task; they are safe to run and can be entered one at a time.

1. Configure a More Frequent NTP Polling Interval

By default, Windows may leave long periods between time synchronisation updates. For amateur radio digital modes such as FT8, JS8Call and WSPR, more frequent checks can help reduce clock drift and maintain accurate timing during extended operating sessions.

NTP servers approximately every 5 minutes. This is significantly more frequent than the Windows default behaviour and is usually sufficient to maintain accurate timing for FT8, JS8Call and WSPR.

Copy the entire command below, paste it into the PowerShell window, and press Enter:

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient" -Name "SpecialPollInterval" -Value 300

2. Configure which internet time servers Windows uses

This command configures the Network Time Protocol (NTP) servers that Windows will use to synchronise its clock. The 0x8 option ensures Windows operates as an NTP client when communicating with these public time servers.

Multiple servers are specified to improve reliability, allowing Windows to obtain accurate time from alternative sources if one server is temporarily unavailable.