The DQMH is a free toolkit based on the National Instruments Queued Message Handler Project Template (NI QMH). The DQMH expands on the NI QMH by providing safe, event-based message handling and scripting tools to make development easy, encourage same style between different developers in the same project and improve efficiency. The DQMH is ideal for applications where multiple modules must run in parallel, possibly at different rates, while communicating with each other. The DQMH can also be used for applications that have a single module, where the developer would benefit from having a Tester with the capability of eavesdropping on the different DQMH events and messages. The built-in productivity tools make it very easy to add modules to existing projects without having to start from the project template. In addition, there are tools to add and remove events by selecting the desired action from the Tools>Delacor>DQMH menu. The DQMH easily integrates with TestStand since all development and troubleshooting can take place under LabVIEW, while calling the public API VIs as individual steps in the Teststand sequence. The tester can eavesdrop during the execution of the TestStand sequence. This is especially useful when the LabVIEW code is written during the research and development or prototyping phase, because the same code can be easily called by TestStand in production or manufacturing sequences without any changes. The DQMH uses LVOOP for some internal functions, but developers need not be familiar with LVOOP to use or understand this architecture.
DQMH is available for LabVIEW 2014 or later.
This application uses the myRIO-1900 to implement a lock-in amplifier in the FPGA. The application measures a modulated signal and a reference signal, which can also be generated with myRIO. The lock-in amplifier can measure very low level input signals, even if they are buried in noise or are smaller than myRIO’s 12-bit resolution. The lock-in amplifier includes a selectable high-pass filter to remove any input DC offset, and also includes a programmable output low pass filter that removes any noise beyond the frequencies of interest. The application is geared towards education and understanding the principles of a lock-in amplifier. It includes extensive documentation and instructions for building a circuit to measure heart rate by using an LED and photodiode amplifier to measure the amount of light absorbed through the blood vessels in a finger.
Lock-in Amplifier Accessory for myRIO
This accessory is the fastest way to get started with the Lock-In Amplifier for myRIO add-on. The board includes a red LED to generate modulated light, and a photodiode and signal conditioning circuitry to measure the received signal. This accessory can be used for a variety of measurements, such as determining your heart rate. If you place your finger between the LED and photodiode, the Lock-In Amplifier will pick up the small difference in absorbed light as blood pumps in and out of the capillaries in your fingertip. The add-on uses this information to calculate heart rate. You can order the board with the configuration that best suits your measurements:
- LED and photodiode soldered on the board as shown in the image
- Loose LED and photodiode so you can attach them to your own fixture
- SMA Connectors for the reference output and 5V input signal.
If you would like a board with SMA connectors configured for current input, or for orders outside the US, please contact us at firstname.lastname@example.org.