QHY GPSBOX SYNC TIMER

The QHY GPSBOX provides high-precision GPS hardware time scales allowing QHYCCD cameras equipped with 6-pin GPS sockets to obtain accurate exposure time information.  

This information is returned to the camera internally and added to the image data after the start of one frame of the image. GPS timing information and image information are therefore completely consistent.  No confusion is created due to transmission, buffering or other reasons. 

The QHY-GPSBOX has a built-in GNSS module and can currently provide both pure GPS operation and GPS/Beidou dual-mode operation. The GPSBOX also contains a local 10MHz voltage controlled crystal oscillator (VCXO) that provides an internal 0.1us resolution timing clock. At the same time, the timing clock is reset by the PPS model of the GNSS module. Therefore, the clock and the GNSS system’s second start time are strictly aligned, and the error is within a range of 20ns to 100ns.

Note: when choosing a QHY camera, you must specify the special version with the 6-pin GPS socket. 

When the camera is working, an electronic shutter measurement waveform is generated every frame. The waveform is output to the GPSBOX. After the GPSBOX performs high-precision time measurement, it outputs a serial header data and sends it back to the camera. The camera records these data after the frame header of each frame (replacing some pixel values in the first few lines).

The QHY GPSBOX has a perfect fault tolerance mechanism. For example, if the PPS signal is lost, after 50.0us an internal second step will be recorded. For timing information without a PPS signal, a cumulative timing error of 50us per second will be generated. When the PPS signal is restored, the PPS signal will be used again to reset the internal timer. Therefore, it has GPS timing accuracy after recovery and will not accumulate previous errors.

The QHYGPS will also output a GPS measurement value of an internal 10MHz clock every second, which can be used to accurately calibrate the frequency of the internal 10MHz crystal oscillator later in software to avoid an internal 10MHz crystal oscillator error and temperature drift.

Currently ONLY the following models have 6-pin aviation plug which supports GPSBOX (without further modification):

• QHY600 Pro
• QHY268Pro
• QHY4040
• QHY4040Pro
• QHY6060
• QHY42Pro
• QHY411
• QHY461

Other models don’t natively have a 6-pin plug but can be modified to be compatible with the QHY-GPSBOX. Please contact us for more info.