Q: I'm evaluating the ADAS1000 and I don't have a patient simulator, how else might I evaluate the device? can I use a signal/function generator
A: As the EVAL-ADAS1000SDZ was designed for evaluation purposes and as such was not designed to be connected to a human or animal, the best methods for evaluation are to use either a patient simulator or a signal/function generator.Patient simulators are very convenient when evaluating the ADAS1000 as they have a myriad of features applicable for this application, some have respiration features and include pace maker artifacts. The Patient simulator we use during our demonstrations is generally the Fluke PS420. If you don't have a patient simulator, there are some things that you can do with a signal/function generator.
Here, we'll step through how you'd go about using the ADAS1000 evaluation board setup with the SDP board for USB-PC interface and a function generator.
- Power up the board using the +5V wall adaptor (provided as part of the EVAL-ADAS1000SDZ kit)
- The LK links on the evaluation board should be in the default condition per UG-426
- Connect the SDP board and USB cable
- Connect the signal generator +ve terminal to one or more of the electrode inputs (RA/LA/LL/V1/V2)
- Connect the signal generator to the RLD (or ground - this may depend on the generator)
- Configure the signal generator for low frequency, small magnitude signals, ECG signals tend to be in region of a couple of mV and the frequency of interest will be low Hz.
- launch the ADAS1000 evaluation board software from the Analog Devices folder
- Starting at the main panel, click on the "default settings" button, this writes a few commands to power the device up into a particular mode. This mode is perfect when using a patient simulator, but some changes are necessary when using a function generator to ensure user can see the signals clearly.
- The following changes should be made:
- Clicking on the "Program all RW Reg", select the CMREFCTL tab. Here you need to re-configure the settings of the Common mode amplifier. The default software setting is (RA+LA+LL)/3 (Wilson Central Terminal) which is fine for normal operation and typically used in the V1 and V2 calculation However, if you are using a function generator with the same signal applied to all of the electrodes, then this won't be so useful and may confuse things. Therefore, change the LA/LL/RA to "No", this means the common mode is set to the internally generated 1.3V (VCM_REF) on chip.
- Going back to the main panel now and select the "Stream ECG" button
- Within the "ECG Update" tab, select "Electrode" Data Format. The signal below shows a 1Hz, 500mV signal from the signal generator
- You may also need to change the "offset" within the "Graph Control" tab here
- Changing the frequency of the signal generator to 10Hz, gives the following on all channels. Within the labview tools, it's possible to Right-Click and export the captured data straight out to excel for offline processing/analysis.