Multi-Purpose Event Timer
Starting February 1st, 2016 Eventech has been awarded with its first European Space Agency (ESA) contract for on-board multi-purpose event timer (MPET) development for space applications supported by Institute of Electronics and Computer Science (IECS) and Czech Space Research Centre (CSRC).
MPET is intended for applications, which require very accurate time measurements. Traditionally such measurements were performed by using time interval measurement technique. As opposed to that, event timing approach is different and uses the notion of so called time scale. When the event timing is performed the measured value of time (“time-stamp”) is expressed relative to a time scale that is formed in the measurement device and conforms to universal time scale. This way an event timer produces “time-stamps” of input events of an input event stream.
MPET offers an optimum ratio between accuracy and the measurement speed compared to competitive devices for terrestrial applications. Expected parameters for space applications are resolution of less than 10-12ps (in terms of RMS resolution for time intervals), supported by high performance as well.
The developed timer is going to be designed as a universal measurement module, which can be incorporated in various application-specific systems that require the event timing or time interval measurements. In fact, MPET is a time-to-digital converter that produces an accurate time for each input event (for pulses, coming from a sensor, as the European Laser Timing Detector) with respect to its internal time scale, which coincides with some application-specific time scale (for example, in the European Laser Timing system it is the time-scale defined by the Atomic Clock Ensemble in Space). i.e. the MPET converts the input information from a physical sensor to output digital information to be used directly in the application system, while the format of the input data - pulse sequence - and output data format - time-tags - are the most common. In this sense, MPET is self-contained.
The typical application is the laser ranging and its derivative applications like 3D-scan, planetary altimetry, LiDAR, range finding, etc. As soon as MPET has a time scale (on which its measurements are based) the MPET can be used in time synchronization and time transfer tasks.
MPET Main Features
- Two measurement inputs A and B (accordingly marked in time-stamps)
- Dead time for measurements of adjacent events: <80 ns
- Accuracy – <10-12 ps (RMS resolution)
- On-board high quality (low jitter) PLL that derives the system clock (100 MHz) from an external 10 MHz reference source
- Dedicated input for the 1PPS signal
- Autonomous mode for short range timing (without 10 MHz external reference signal)
- On-board FIFO memory
- External power supply: +28V
- Power consumption: ≤4W
- Bi-stable relay, 2 external TTL signals
- Power lines equipped with on-board EMI filter
- Communication interface: RS-422 (full duplex) or Spacewire
- Aluminum case
- Rad-Hard parts and performance in according environmental conditions dependent on mission