Low power test signal generator for medical equipment

1. A cardiac signal generator, comprising:

a portable housing;

a memory storing programming instructions, said programming instructions including instructions defining a plurality of mathematical relationships;

a processing device configured to execute said programming instructions to:

generate a sequence of output values at least in part by calculating each of a set of the output values using at least one of the plurality of mathematic relationships as a function of time, wherein said sequence of output values defines a sampled waveform output simulating an ECG signal and having linear portions and at least one curved portion, and

provide the sequence of output values at an output;

a digital to analog converter operably coupled to receive the sequence of output values from the output, the digital to analog converter configured to generate an electrical signal having a waveform corresponding to the sampled waveform output;

at least one or more analog outputs operably coupled to the digital to analog converter.

2. The cardiac signal generator of claim 1 , wherein the processing device is further configured to generate the sequence of values to include, in sequence, a first curved portion, a positive-slope linear portion, and a negative-slope linear portion.

3. The cardiac signal generator of claim 2 , wherein the processing device is further configured to generate the sequence of values to include a first flat portion between the first curved portion and the positive-slope linear portion.

4. The cardiac signal generator of claim 3 , wherein the processing device is further configured to generate the sequence of values to include another negative-slope linear portion between the first flat portion and the positive-slope linear portion.

5. The cardiac signal generator claim 1 , wherein the processing device is further configured to generate the sequence of values to include, in sequence, a first curved portion, a first flat portion, a first negative-slope linear portion, a first positive-slope linear portion, a second negative-slope linear portion, and a second positive-slope linear portion.

6. The cardiac signal generator of claim 5 , wherein the processing device is further configured to:

generate the first curved portion of sequence of values using a first relationship as function of a counter value;

generate the first flat portion of the sequence of values using a second relationship;

generate the first negative-slope linear portion of the sequence of values using a third relationship as a function of the counter value; and

generate the first positive-slope linear portion of the sequence of values using a fourth relationship as a function of the counter value.

7. The cardiac signal generator of claim 1 , further comprising a digitally-controlled potentiometer operably coupled to the analog output, and wherein the processing device is further configured to provide digital control signals corresponding to a simulated respiration pattern to the digitally-controlled potentiometer.

8. The cardiac signal generator of claim 1 , wherein the first sequence of output values defines a sampled waveform output simulating a repeating ECG waveform, the ECG waveform including an S-wave, an R-wave and a T-wave.

9. The cardiac signal generator of claim 8 , wherein the processing device is configured to execute said programming instructions to:

generate output values simulating the S-wave using a first of the plurality of mathematic relationships as a function of time, and generate output values simulating the R-wave using at least a second of the plurality of mathematical relationships as a function of time.

10. The cardiac signal generator of claim 9 , wherein the first of the plurality of mathematical relationships defines a curve.

11. A cardiac signal generator, comprising:

a memory storing programming instructions, said programming instructions including instructions defining a plurality of mathematical relationships;

a processing device configured to execute said programming instructions to:

generate a first sequence of output values defining a sampled waveform output simulating an ECG signal and having linear portions and at least one curved portion, and

provide the first sequence of output values at a first output;

generate a second sequence of output values defining a sampled waveform output simulating a respiration signal;

provide the second sequence of output values at a second output;

a digital to analog converter operably coupled to receive the first sequence of output values from the output, the digital to analog converter configured to generate an electrical signal having a waveform corresponding to the sampled waveform output;

a potentiometer operably coupled to receive the second sequence of output values, the potentiometer configured to provide a variable resistance based on the second sequence of output values;

at least one or more analog outputs operably coupled to the digital to analog converter and the potentiometer.

12. The cardiac signal generator of claim 11 , wherein the analog outputs are configured to provide an output signal comprising the simulated respiration signal superimposed on the simulated ECG signal.

13. The cardiac signal generator of claim 11 , wherein the analog outputs include a resistive network operably coupled to the variable resistance of the potentiometer.

14. The cardiac signal generator of claim 11 , wherein the processing device is configured to execute said programming instructions to generate the first sequence of output values using a plurality of mathematic relationships as a function of time.

15. The cardiac signal generator of claim 11 , wherein the first sequence of output values defines a sampled waveform output simulating a repeating ECG waveform, the ECG waveform including an S-wave, an R-wave and a T-wave.

16. The cardiac signal generator of claim 11 further comprising a portable housing and a battery, wherein the battery is operably coupled to provide operating power to the processing device, the digital to analog converter, and the potentiometer.

17. The cardiac signal generator of claim 11 , wherein the processing device is further configured to generate the first sequence of values to include, in sequence, a first curved portion, a positive-slope linear portion, and a negative-slope linear portion.

18. The cardiac signal generator of claim 17 , wherein the sampled waveform output simulating the respiration signal comprises a sampled trapezoid-shaped waveform.

19. The cardiac signal generator of claim 11 , wherein the sampled waveform output simulating the respiration signal comprises a sampled trapezoid-shaped waveform.

20. The cardiac signal generator of claim 1 , wherein

the memory stores at least a first slope value; and

the processing device is configured to execute said programming instructions to calculate each of the set of output values using a value representative of time multiplied by the first slope value.

21. The cardiac signal generator of claim 20 , wherein

the memory stores at least a second slope value; and

the processing device is configured to execute said programming instructions to calculate each of another set of the output values using the value representative of time multiplied by the second slope value.