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This is a 3 part protocol, and is designed for all 3 to be run in order in the Desktop App.

The MultispeQ measures ambient PAR (Photosynthetically Active Radiation, which is light in the 400nm (deep visible blue) to 700nm (deep visible red) range. While the MultispeQ uses some optical filtration, it is still necessary to calibrate each device against a known PAR sensor to ensure comparability and consistency across devices. We choose to use the LiCOR 190R Quantum Sensor to calibrate against as a long term and well respected PAR sensor.

A light box with 5 LEDs (red, green, blue, orange, and 940nm) is set up with a location to place the MultispeQ or LiCOR PAR sensor. The MultispeQ is then connected to the light box via the USB-C port. This protocol can initiate the light box sequence by sending a digital HIGH/LOW/HIGH signal over USB-C. Once initiated, the light box and the MultispeQ progress through 6 different light regimes (even light, full sun, cloudy day, fluorescent lighting, under a dense canopy, and white LED). While these regimes are not exactly like their namesake (there's no full sun in the box :) ) the combination of LEDs attempts to mimic the spectra of each of these conditions. So - for each light regime, 4 different intensities are measured, resulting in 24 separate measurements (6 regimes x 4 intensities).

Once the LiCOR and MultispeQ data have been collected for the 24 light conditions, they are fed into a model (multiple linear regression) which produces coefficients for predicting the LiCOR PAR value from the MultispeQ white, red, green, and blue raw data. These coefficients are then saved to the device and applied when PAR data is requested from the device.


  1. Place the LiCOR in the light calibration box and run through the 24 light conditions, writing down the LiCOR value in each condition. This should only be performed once or twice per day if multiple MultispeQs are being calibrated.
  2. Place the MultispeQ in the light calibration box and plug in the USB-C cable. Run through the 24 light conditions. At the beginning of the protocol, you should be prompted to enter the 24 values from the LiCOR PAR sensor collected earlier, all separated by commas.
  3. Once complete, press the "save to device" button to save the outputs to the MultispeQ device. If it is running as part of a Calibration Project (as during factory calibration), then press "keep" to save the values to the photosynq.org website.

As with any values saved to the MultispeQ, you can see the saved calibration values by opening the Desktop App, going to "Settings" --> "console", and entering print_memory+ . The coefficients for ambient PAR calibration are saved as "light_slope_all","light_slope_r","light_slope_g","light_slope_b","light_slope_yint".

    "pulses": [
    "pulse_distance": [
    "pulse_length": [
    "pulsed_lights": [
    "pulsed_lights_brightness": [
    "message": [
      "alert,1 Place MultispeQ LiCOR 1 in the light chamber make sure its correctly seated",
012409 pbi 160 low low res headshot
Created by

Greg Austic



Compatible Instruments

MultispeQ v1.0

Latest Update

Dec 2017