SBAU171D May   2010  – January 2016 ADS1198 , ADS1298

 

  1.   ADS1298ECG-FE/ADS1198ECG-FE
    1.     Trademarks
    2. 1 ADS1298ECG-FE/ADS1198ECG-FE Overview
      1. 1.1 Important Disclaimer Information
      2. 1.2 Introduction
      3. 1.3 Supported Features
      4. 1.4 Features Not Supported in Current Version
      5. 1.5 ADS1x98ECG-FE Hardware
      6. 1.6 Minimum System Requirements for ADS1x98ECG-FE Evaluation Software
    3. 2 Quick Start
      1. 2.1 Default Jumper/Switch Configuration
      2. 2.2 ADS1x98ECG-FE Operation
    4. 3 Using the ADS1298ECG-FE Software
      1. 3.1 Application User Menu
      2. 3.2 Top-Level Application Controls
      3. 3.3 About Tab
      4. 3.4 ADC Register Tab
        1. 3.4.1 Standby and Reset Controls
        2. 3.4.2 Channel Registers Tab (ADC Register)
          1. 3.4.2.1 Global Channel Registers
          2. 3.4.2.2 Channel Control Registers
        3. 3.4.3 LOFF and RLD Tab (ADC Register)
          1. 3.4.3.1 Lead-Off Detection and Current Direction Control Registers
          2. 3.4.3.2 Right Leg Drive Derivation Control Registers
        4. 3.4.4 GPIO and OTHER Registers Tab (ADC Register)
          1. 3.4.4.1 Wilson Central and Augmented Lead Registers
        5. 3.4.5 Register Map (ADC Register)
      5. 3.5 Analysis Tab
        1. 3.5.1 Scope Tab (Anaysis)
          1. 3.5.1.1 Zoom Tool
        2. 3.5.2 Histogram Tab (Analysis)
        3. 3.5.3 FFT Tab
        4. 3.5.4 ECG Tab (Analysis)
      6. 3.6 Save Tab
    5. 4 ADS1x98ECG-FE Input Signals
      1. 4.1 Input Short Testing
      2. 4.2 Internal Test Signals Input
      3. 4.3 Temperature Sensor
      4. 4.4 Normal Electrode Input
        1. 4.4.1 Capturing 12-Lead ECG Signals
      5. 4.5 MVDD Input, RLD Measurement, RLD Positive Electrode Driver, and RLD Negative Electrode Driver
      6. 4.6 Lead Derivation
      7. 4.7 Wilson Center Terminal (WCT)
      8. 4.8 Right Leg Drive
        1. 4.8.1 RLD Common Mode Voltage
        2. 4.8.2 Driving the RLD Cable Shield
      9. 4.9 PACE Detection
    6. 5 ADS1298ECG-FE/ADS1198ECG-FE Hardware Details
      1. 5.1 Jumper Description
      2. 5.2 Power Supply
      3. 5.3 Clock
      4. 5.4 Reference
      5. 5.5 Analog Output Signals
      6. 5.6 Digital Signals
      7. 5.7 Analog Input Signals
        1. 5.7.1 Patient Simulator Input
        2. 5.7.2 Arbitrary Input Signals
  2. ASchematics, BOM, Layout, and ECG Cable Details
    1. A.1 Overview
    2. A.2 ADS1x98ECG-FE Front-End Board Schematics
    3. A.3 Bill of Materials
      1. Table 13. Bill of Materials: ADS1x98ECG-FE
    4. A.4 Printed Circuit Board Layout
    5. A.5 ECG Cable Details
  3. BExternal Optional Hardware
    1. B.1 Optional External Hardware (Not Included)
    2. B.2 ADS1x98ECG-FE Power-Supply Recommendations
  4. CSoftware Installation
    1. C.1 Minimum Requirements
    2. C.2 Installing the Software

3.5.3 FFT Tab

The FFT tool allows the user to examine the channel-specific spectrum as well as typical figures of merit such as SNR, THD, ENOB, and CMRR. Each feature is numbered below and described in detail in the following subsections. Figure 22 illustrates an FFT plot for a normal electrode configuration.

evm_sw_analysis_normal_config_bau171.pngFigure 22. FFT Graph of Normal Electrode Configuration

1 - Coherent Frequency Calculator

Coherent sampling in an FFT is defined as FAIN/FSAMPLE = NWINDOW/NTOTAL, where:

  • FAIN is the input frequency
  • FSAMPLE is the sampling frequency of the ADS1298
  • NWINDOW is the number of odd integer cycles during a given sampling period
  • NTOTAL is the number of data points (in powers of 2) that is used to create the FFT

If the conditions for coherent sampling can be met, the FFT results for a periodic signal will be optimized. The Ideal AIN Frequency is a value that is calculated based on the sampling rate, such that the coherent sampling criteria can be met.

2 - AC Analysis Parameters

This section of the tool allows the user to dictate the number of harmonics, DC leakage bins, harmonic leakage bins, and fundamental leakage bins that are used in the creation of various histograms. Pressing the Windowing button, illustrated in Figure 23, allows the user to evaluate the FFT graph under a variety of different windows. Note that pressing the Reference button toggles between dBFS (decibels, full-scale) and dBc (decibels to carrier).

evm_sw_windowing_bau171.gifFigure 23. AC Analysis Parameters: Windowing Options

3 - FFT Analysis

Pressing the FFT Analysis button pulls up the FFT Analysis window shown in Figure 24. This window provides calculated parameters obtained from the collected data that may be useful during evaluation. One of the values included in this analysis is the channel-to-channel noise.

evm_sw_analysis_input_short_bau171.gifFigure 24. FFT Analysis: Input Short Condition

4 - User-Defined Dynamic Range

This section enables the user to examine the SNR of a specific channel within a given frequency band defined by Low Frequency and High Frequency. The SNR displayed in this window shows under the Dynamic Range heading as Figure 25 illustrates.

evm_sw_user_define_dyn_range_bau171.gifFigure 25. Changing the User-Defined Dynamic Range for Channel 1

5 - Input Amplitude

This field is a user input that is important for accurately calculating the CMRR of each channel.

6 - Zoom Tool

As with the Analysis, Histogram, and Scope tool, this zoom function allows a closer examination of the FFT at frequencies of interest, as shown in Figure 26.

evm_sw_fft_zoom_bau171.pngFigure 26. FFT Plot Using Zoom Tool