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ADS1293 Pacemaker channel

Gustavo Roitman
Prodigy 110 points
Other Parts Discussed in Thread: ADS1293

Hello,

I'm using the ADS1293 Analog Front End for an ECG application. I intend to use the digital pacemaker channel to implement a detection in an MCU.

The issue I'm having is that the level of noise present in the pacemaker channel is similar to the pacemaker pulse that I have to detect. For example, a pacemaker pulse according to the IEC 60601 standard has an amplitude between 2mV and 200mV with durations between 0.1ms and 2ms. Another reference pulse is from an ECG simulator we are using (Dale Technology "DALE 13"), which has a pacemaker pulse with an amplitude around 4mV. The level of noise that I can measure in the pacemaker channel is around 0,65mV rms, which is also consistent with the datasheet that claims around 0,6mV rms. Naturally, measured peak noises are around 2mV~3mV, and when implementing a detection based in first order derivative, the noise is doubled.

Is this noise level normal for this part?

Is there any known way to detect these standard pulses with the digital pacemaker channel having such level of noise?

I'm using the ADS1293 with the following configuration:

External crystal: 4.000MHz

Sigma Delta Modulator frequency: 200kHz

Low resolution mode

Stage 1 decimation filter: R1 = 4 (Standard pace data rate)

Stage 2 decimation filter: R2 = 5

Stage 3 decimation filter: R3 = 8

So my ECG channel ODR is 1250sps, and my PACE channel ODR is 10000sps.

I can attach some ECG captures showing this issue in case you ask me to.

Thanks,

Gustavo

  • 0
    TI__Expert 3350 points

    The digital pacemaker feature is implemented in the digital filters stages of the sigma-delta converter and because of wide bandwidth of the channels, it is probably not  suitable for detecting pacemaker pulses with the amplitude you have mentioned in the posting. You may want to try the analog pacer channel for this reason. I will take a close look at the test data archive and  let you know if I find out  otherwise.