{"id":12274,"date":"2026-03-19T08:00:06","date_gmt":"2026-03-19T07:00:06","guid":{"rendered":"https:\/\/medtech-ingenieur.de\/?p=12274"},"modified":"2026-03-16T17:11:48","modified_gmt":"2026-03-16T16:11:48","slug":"ble-synchronisation-sensorik","status":"publish","type":"post","link":"https:\/\/medtech-ingenieur.de\/en\/ble-synchronisation-sensorik\/","title":{"rendered":"BLE synchronization for medical sensors \u2013 precise down to 50 \u00b5s"},"content":{"rendered":"

In wireless distributed systems, each node runs its own hardware clock. Even identical embedded systems start with different time values, tick at slightly different frequencies, and experience variable delays when sending, receiving, and processing data. Without synchronization, a system with a \u00b120 ppm quartz crystal can drift apart by several milliseconds in just a few minutes, which is problematic for many medical applications.<\/p>\n

\"Ganganalyse<\/span><\/p>\n

Why synchronicity is crucial<\/h2>\n

In medical technology, for example in gait analysis or the control of orthoses, multiple sensors must work in precise sync. Our solution at MEDtech Ingenieur enables the synchronization of BLE devices with an accuracy below [insert value here]. 50 microseconds <\/strong>with simultaneous data transmission. This allows movement data from foot sensors and body modules to be precisely combined wirelessly.<\/p>\n

Synchronization in action<\/h2>\n

In the video, we show how two sensors initially drift apart. Then our synchronization logic kicks in: Within a very short time, both signals are perfectly aligned again.<\/p>\n

The technical challenges<\/h2>\n

The causes for time discrepancies are manifold:<\/p>\n

    \n
  • Quartz tolerances<\/strong> (\u00b120 ppm, temperature and voltage dependent)<\/li>\n
  • Aging and drift<\/strong><\/li>\n
  • Fixed radio delays<\/strong> (e.g. radio frontend + PPI chain)<\/li>\n
  • Jitter<\/strong> through interrupt latency, CPU scheduling, ring buffer<\/li>\n
  • Package Losses<\/strong>, which lead to cumulative errors\n<\/li>\n<\/ul>\n

    Our solution: The bsync module<\/h2>\n

    We rely on a beacon-based synchronization protocol for nRF52 devices, which combines the following components:<\/p>\n

      \n
    • Hardware timestamp<\/strong> via PPI + TIMER<\/li>\n
    • Offset and drift estimation<\/strong> with lightweight logic<\/li>\n
    • Periodic triggers<\/strong> about the Event Generation Unit (EGU)<\/li>\n
    • Timeslot Management<\/strong> through the Multiprotocol Service Layer (MPSL)\n<\/li>\n<\/ul>\n

      Master-slave roles<\/h2>\n
        \n
      • Master:<\/strong> It captures its 1 MHz timer timestamp and transmits it via radio.<\/li>\n
      • Slave:<\/strong> It receives the packet, records its own timestamp, and calculates offset and drift.<\/li>\n<\/ul>\n

        Since both processes execute their routines within MPSL timeslots, their interval becomes the effective synchronization period. In practice, however, timeslots are never perfectly timed. Therefore, our solution is robust against jitter in the microsecond to millisecond range.<\/p>\n

        Applications beyond gait analysis<\/h2>\n

        Time-synchronized data is required for many applications. Examples include:<\/p>\n

          \n
        • Synchronized vital data recording<\/strong> (e.g. ECG + exercise)<\/li>\n
        • Multi-sensor tracking<\/strong> in telemedicine<\/li>\n
        • Neurotechnology<\/strong> with closed-loop systems<\/li>\n
        • Robotics and prosthetics<\/strong> with real-time sensors<\/li>\n<\/ul>\n

          Reliable and fast methods are needed to synchronize the various nodes. Our BLE synchronization technology provides the foundation for new, networked medical devices \u2013 precise, robust, and wireless. If you have applications where timing is critical, please contact us. We'll show you how to synchronize sensors down to the microsecond level.<\/p>","protected":false},"excerpt":{"rendered":"

          In drahtlosen verteilten Systemen l\u00e4uft auf jedem Knoten eine eigene Hardware-Uhr. Selbst identische Embedded-Systeme starten mit unterschiedlichen Zeitwerten, ticken mit leicht abweichender Frequenz und erleben variable Verz\u00f6gerungen beim Senden, Empfangen und Verarbeiten von Daten. Ohne Synchronisation driftet ein System mit \u00b120\u202fppm Quarz \u00fcber wenige Minuten bereits um mehrere Millisekunden auseinander und das ist f\u00fcr viele […]<\/p>\n","protected":false},"author":1,"featured_media":10896,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","tve_updated_post":"

          In drahtlosen verteilten Systemen l\u00e4uft auf jedem Knoten eine eigene Hardware-Uhr. Selbst identische Embedded-Systeme starten mit unterschiedlichen Zeitwerten, ticken mit leicht abweichender Frequenz und erleben variable Verz\u00f6gerungen beim Senden, Empfangen und Verarbeiten von Daten. Ohne Synchronisation driftet ein System mit \u00b120\u202fppm Quarz \u00fcber wenige Minuten bereits um mehrere Millisekunden auseinander und das ist f\u00fcr viele medizinische Anwendungen ein Problem.<\/p><\/div>

          \"Ganganalyse<\/span><\/div>

          Warum Synchronit\u00e4t entscheidend ist<\/h2>

          In der Medizintechnik, etwa bei der Ganganalyse oder der Steuerung von Orthesen, m\u00fcssen mehrere Sensoren exakt im Takt arbeiten. Unsere L\u00f6sung bei MEDtech Ingenieur erm\u00f6glicht die Synchronisation von BLE-Ger\u00e4ten mit einer Genauigkeit unter 50\u202fMikrosekunden <\/strong>bei gleichzeitiger Daten\u00fcbertragung. Damit lassen sich Bewegungsdaten von Fu\u00dfsensoren und K\u00f6rpermodulen pr\u00e4zise zusammenf\u00fchren und das kabellos.

          <\/p>

          Synchronisation in Aktion<\/h2>

          Im Video zeigen wir, wie zwei Sensoren zun\u00e4chst auseinanderdriften. Dann startet unsere Synchronisationslogik: Innerhalb k\u00fcrzester Zeit sind beide Signale wieder perfekt aufeinander abgestimmt.<\/p><\/div>

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