Variation in temperature measurement

Jay Buggy

Other Parts Discussed in Thread: LM92

Hello,

I have observed that with sensortag hardware, the temperature reported by the IR temperature sensor varies by a couple of degrees F (sometimes as much as 4 degrees). I am measuring the temperature of my skin in this case. The app reports a measurement which keeps changing every second. Questions I have are :

1. Is this expected behaviour?

2. Is this variation for every reading expected with other sensors (e.g. high accuracy LM92 sensor)?

3. Would any one suggest or has any one used a algorithm to normalize the reading?

Thank you very much

Jay.

over 9 years ago

0 Abhishek Muppiri over 9 years ago

TI__Expert 7945 points

Hello Jay,

Please understand that Sensor tag has built in TMP0006 to showcase the non-contact feature of the device. The purpose is to just sense temperature and is not built for achieving higher accuracies. To answer your questions:

1. Is this expected behaviour?

This could be an expected behavior of the device since it depends on stability of the physical setup, distance from your skin, external noise effects such as air flow. etc

2. Is this variation for every reading expected with other sensors (e.g. high accuracy LM92 sensor)?

No. Silicon temperature sensors such as LM92 work on a completely different principle of operation. They deliver higher accuracies compared to our IR based temperature sensors.

3. Would any one suggest or has any one used a algorithm to normalize the reading?

You can implement Transient correction, for which I can provide you C code if you are interested.. What accuracy are you targeting for Skin temperature measurements?

Best Regards,

Abhi

0 Jay Buggy over 9 years ago in reply to Abhishek Muppiri

Prodigy 125 points

Hello Abhi,

Thank you for your reply. I have the following additional questions -

1. Does the top surface or bottom surface (that goes towards the PCB) of LM92 measure the correct temperature? Would like to confirm for LM92 sensor positioning on our product.

2. Yes, please do send me the Transient correction code when you get a chance.

3. Would you also have a LM92 driver code that would work with IAR software? I had downloaded it earlier, but I can't seem to find it now.

Thank you very much.

Jay.