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Summary of Contents for WHALETEQ CMRR 2.0
- Page 1 Common Mode Rejection Ratio Tester | User Manual WHALETEQ Common Mode Rejection Ratio Tester (CMRR 2.0) User Manual (Revision 2020-09-03)
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Page 2: Table Of Contents
Common Mode Rejection Ratio Tester | User Manual Contents Introduction ......................... 2 Description ........................... 3 CMRR Box .............................. 3 ECG Breakout Boxes ..........................4 Set up ........................... 5 Environment, noise reduction ....................... 5 Calibration ........................... 6 Principle of the CMRR test ....................9 Common mode rejection ratio explained ..................... -
Page 3: Introduction
Common Mode Rejection Ratio Tester | User Manual Introduction WhaleTeq’s main focus is on tests in ECG standards is the Single Channel and Multichannel ECG test systems. However, these systems do not cover common mode rejection ratio due to the nature of test (double box construction, noise free environment). To meet this need, WhaleTeq has developed a CMRR test box. -
Page 4: Description
Common Mode Rejection Ratio Tester | User Manual Description 2.1 CMRR Box The CMRR box internal construction as below, the only features not shown is the internal screen (internal box), which is provided around the circuit floating at 10Vrms as shown by the blue shading below: For connecting the CMRR Box to test the ECG device, use the “ECG breakout box”... -
Page 5: Ecg Breakout Boxes
Common Mode Rejection Ratio Tester | User Manual 2.2 ECG Breakout Boxes The WhaleTeq CMRR 2.0 is supplied with two breakout box to suit different standards. IEC 60601-2-25: 2011 (formerly IEC 60601-2- 51), IEC 60601-2-47: 2012 and IEC 60601-2-27 requires 9 leads (RA/RL/LL/V1 to V6) to be... -
Page 6: Set Up
A noise free environment is necessary for testing ECG equipment. This can be achieved relatively easily by using a metal bench or metal sheet underneath the ECG device under test, the WhaleTeq CMRR test unit, and also connecting together the ground as shown: ECG Device... -
Page 7: Calibration
In general traceability for capacitance is not easy to obtain. An alternate method involves using the 27kΩ capacitance resistor also used for verifying the WhaleTeq Single channel system. With the 27kΩ connected between RA and ground, the voltage should drop to: At 20Vrms, 50Hz: 16.97mVrms±10%... - Page 8 Common Mode Rejection Ratio Tester | User Manual Nominal Parameter Tolerance Method value 10Vrms ±15% Shield This can be measured indirectly using the internal 50MΩ:50kΩ divider. A measured voltage of 10mVrms voltage between the “Monitor” and “GND” terminals is equivalent to 10Vrms. To eliminate noise, a battery operated meter with short leads, located on the GND shield should be used.
- Page 9 Common Mode Rejection Ratio Tester | User Manual Nominal Parameter Tolerance Method value Impedance 47nF ±5% This can be measured between Imbalance (with DC) imbalance, terminal and any other lead (with DC offset set to off). Measurement of capacitance in circuit can be done provided that the meter’s measurement frequency is 1kHz or higher, to minimize the influence of the 51kΩ...
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Page 10: Principle Of The Cmrr Test
Common Mode Rejection Ratio Tester | User Manual Principle of the CMRR test 5.1 Common mode rejection ratio explained A perfect device measuring a differential voltage should not respond to the level of common mode voltage which appears at both inputs. For example, a multimeter where the plus terminal is +100.017V and the minus terminal is +100.001V should theoretically indicate measured voltage of 16mV. -
Page 11: Test Equipment
A function generator is usually limited to 7.1Vrms (20Vpp). To assist with this, WhaleTeq’s equipment has a small transformer built into the equipment which allows the voltage to be stepped up to 20Vrms. The applied voltage can then verified at the “Input” and “GND”... - Page 12 Common Mode Rejection Ratio Tester | User Manual suspected reason is that the right leg drive is unable to respond correctly if there is other higher frequency noise around.
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Page 13: Operation
Common Mode Rejection Ratio Tester | User Manual Operation Operation will typically follow these steps: Step Procedure Diagrams Set up noise free environment as described in Section 3. Connect a function generator to the BNC Function terminal. Generator (FG) Alternate: if bypassing the transformer, a test supply (e.g. - Page 14 Common Mode Rejection Ratio Tester | User Manual Step Procedure Diagrams Turn on the supply. Using the “adjustment capacitor” adjust to 10mVrms (equivalent to FG: On, ~3V as in Step 3 10Vrms) without the ECG device under test connected. The “adjustment capacitor” can be adjusted using a small screw driver.
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Page 15: Warnings/Cautions/Notes
Common Mode Rejection Ratio Tester | User Manual Warnings/Cautions/Notes P lease consider the following warnings / cautions with this equipment: 1. Input other than function generator [WARNING] If the 20Vrms input is sourced directly (bypass the function generator input/transformer), take appropriate precautions. In particular: a. -
Page 16: Specifications
The 50MΩ divider may be affected by high humidity in excess of 85%. * Assured by selection of components or adjustment. Contact details WHALETEQ Co., LTD service@whaleteq.com | (O)+886 2 2596 0701 9F, No.27, Minquan W. Rd., Taipei City 10452, Taiwan...
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