High Performance Digital Mode Interfaces for Ham Radio
Accurate PC Clock Sync for Digital Modes Guide
Windows NTP Configuration for FT8, JS8Call, and Related Applications
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Why Precise Time Matters
Digital modes like FT8, JS8Call, and WSPR rely on tightly synchronized time slots. If your PC clock drifts by more than a couple of seconds, you may miss decodes, introduce logging errors, or fail to transmit within the expected window. Maintaining accurate UTC alignment is essential for reliable operation.
Windows includes a built-in time synchronization service (W32Time) that can use NTP servers to keep your system clock aligned. However, its default configuration only checks the time once per week — insufficient for digital mode use. This guide shows how to configure Windows to sync hourly using standard NTP sources, without installing third-party software.​
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Step-by-Step: Configure Hourly NTP Sync on Windows
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Step 1: Enable Internet Time Sync
This guide applies to both Windows 10 and Windows 11. Layouts may vary slightly, but the settings and PowerShell commands are identical.
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Open Settings > Time & Language > Date & Time
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Enable:
- Set time automatically
- Set time zone automatically -
Scroll to Synchronize your clock and click Sync now
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To switch to a more reliable NTP server (e.g., pool.ntp.org):
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Press Windows + R, and in the "open" dialogue type "control, and press Enter
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Navigate to Clock and Region > Date and Time
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Select the Internet Time tab > Change settings…
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Enter pool.ntp.org and click Update now
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Step 2: Set Hourly Sync Interval via PowerShell
By default, Windows syncs time every 7 days, which isn’t precise enough for digital mode operation. Your PCs clock will wander a long way in a week. To improve accuracy, we’ll configure the system to sync once per hour using Windows PowerShell. Don't worry if you are not familiar with it as its really simple to use.
Open PowerShell as Administrator
Press Windows + X and select Windows PowerShell (Admin). You will need to accept a User Account Control pop-up acceptance to allow it to run. A window similar to the one below will open.
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1. To set the NTP polling to every hour and enter it into the Windows Registry, copy the entire text in red below and paste it into the Powershell Window and hit "ENTER"
​Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient" -Name "SpecialPollInterval" -Value 3600
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2. To set the NTP as the time source into the Windows Registry, copy the entire text in red below and paste it into the Powershell Window and hit "ENTER"
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\W32Time\Parameters" -Name "Type" -Value "NTP"
3. To set pool.ntp.org as the default time servers into the Windows Registry, copy the entire text in red below and paste it into the Powershell Window and hit "ENTER"
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\W32Time\Parameters" -Name "NtpServer" -Value "pool.ntp.org,0x1"
4. We now need to Restart the time service so it takes the updated setting. Copy the entire text in red below and paste it into the Powershell Window and hit "ENTER"
Restart-Service w32time
5. To Force NTP to Resync, copy the entire text in red below and paste it into the Powershell Window and hit "ENTER"
w32tm /resync
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6. And to confirm the NTP Sync Status, enter text in red below and paste it into the Powershell Window and hit "ENTER"
w32tm /query /status
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In Powershell, you should now see something like this:
Summary
This configuration ensures your PC maintains accurate time alignment for digital mode operation. By using Windows’ built-in NTP client and adjusting the polling interval, you can avoid missed decodes and maintain consistent logging without relying on external software.