CPAP clock drift enhancement for OSCAR (multiple time-dependent corrections)

[sawinglogz]

@sawinglogz

Glad to hear clock drift enhancements are on the radar. Not sure I would want to enter a new clock drift correction every time I do a flash card dump, though. Just a per-profile set  of voluntary occasional  corrections would work best for me (just as described in OP)
...
I imagine for some machines with wifi, the machine clock can be possibly be queried or otherwise observed during download, and compared with computer network walltime. This would be a more automated approach that could easily be done along with each download. But for those of us that hand-carry the card to a computer for download, not having to enter a correction each time is essential.

You're exactly right. The idea would be to expand the underlying data structures for *allow* for a time correction at each import, but not require it.

When OSCAR can connect to a device and determine the clock skew, it can (eventually) automatically record such a correction. When you bother to write a correction down, OSCAR could (eventually) let you record it for that session, and interpolate (if desired) between this correction and the last correction you entered for all intervening sessions.

And following on what Arie said, we want to make it easy to enter an adjustment during the import as well as afterwards, when looking at the data.

As a fun data point: I had left my SleepU in a drawer for about a month. I used it without syncing to my phone. Then when I imported I discovered its clock had drifted by about 7 minutes! I sure wish I could tell OSCAR to adjust the oximetry timestamp for that one session...

[A KLERK]

Isn't there a way to trigger all machines for synchronization? I try a cough plus movement...
Think of the motion clap board (right name?) used for the same purpose in movie industry...

But even armed with that knowledge, OSCAR doesn't make it easy for you to correct the relative timestamps for that night.

... not yet, I bet!
And, everything should be related to the PC-clock, which is the only accurate reference.

[2SleepBetta]

Isn't there a way to trigger all machines for synchronization? I try a cough plus movement...
Think of the motion clap board (right name?) used for the same purpose in movie industry...

I do use attempts to simultaneously do sharp inhalations as I abruptly do jerks upward with the accelerometer before "wearing" (affixing) it. The sigh and the coincident slight motion is far more accurate.  Startup delays in logging, as well as reaction time variations, come in to play. It occurs to me now to try not starting the oximeter until lying down and ready to sleep. Turn it on as simultaneously as possible with start of a large leak by lifting the mask. There will still be a logging start up lag for SpO2 data, but more nearly constant.

[PjotterHasApn]

I synch the flow graph as follows:

At the beginning of a session I will move my hand in synch with my breath up and down, and then I’ll hold my breath for 5 seconds, and hold my hand still.
Later I can use the timestamp of my IR-camera and the flat flow line in the graph and my hand being still to find out how much the graph needs to be shifted.

I also enter the real (camera) start time of me holding my breath in the note for that day in OSCAR (so I could resync that day when needed). 

I need to resync every few days. It's crazy in this day and age that a device like my Airsense 11 can't keep the correct time.

It would be nice if one wouldn't have to recalculate the shift every time. If one could enter the CPAP time and a source-time, OSCAR could calculate it itself.

I would be really happy if OSCAR would allow for a timeshift per day (forget about the interpolation for now)...


Two questions:

1. If I would let my ensurance company enable Wifi on it, would it keep the correct time?
2. When will OSCAR have this feature to enter a timeshift per night? It is really needed!!

[frolic]

I'd like to suggest the ability to time-shift to align individual waveforms on the daily report page. I noticed my wellue oximeter stats (spo2, pulse, motion) did not align with the Resmed Air 10. Ends up the CPAP time was off, and therefore correcting the CPAP time reduced the misalignment but my older readings are still misaligned.

I can guage the misalignment by visually corrolating oximeter motion detection to gaps in CPAP readings (I got up, turned off the machine, then came back to bed and turned on the machine.)

I would not expect this to be a precise alignment, but aligning within a minute or a few would help.

[Crimson Nape]

https://www.apneaboard.com/wiki/index.ph...with_OSCAR
- Red

[cathyf]

I think I've said this before, but I think ResMed is a canonical example of Idiot Savant Engineering.

There are a huge number of subtly brilliant engineering decisions in a ResMed machine.

...and then there's the bone-headed idiocy.

In order to have that cellular card and to connect to the cell phone network, a clock is required. Which means that every ResMed with a cell modem has TWO clocks to choose from when recording times of data. One of those clocks is part of the modem and it's synched to the world's time servers.

Even if you are going to ignore the correct clock that's right there, there is another way that the machine could get the correct time. Every day the machine "phones home" and uploads data to the main ResMed servers. While it's chatting, it COULD ask the server "hey what time is it?"

But, no, they label the data with the clock that drifts... 

[PjotterHasApn]

Coincidentally, I just added a comment regarding this:

https://www.apneaboard.com/forums/Thread...#pid529398





(@cathyf, it could have also synced time using the myAir App via BlueTooth)..

[frolic]

What I intended to convey is a feature that allows the alignment within the GUI. Ideally, being able to slide wave forms to align them. However, I do understand that making feature requests is much easier than writing code. I am greatly appreciative that this software exists as-is!

I tend to put the oximeter on first, which is registering motion as I get the mask on and other things to prep for sleep. Opposite when I get up. And its not unusual that I may get out of bed in the night, turning off the APAP but leaving the oximeter on. So, it tends to be obvious when the wave forms are out of alignment.

The only other thing I'd like to be able to do is filter out the first X and last Y minutes of the recording from the stats, though I understand the resmed, not Oscar, is doing the calculations.

Thank you for developing this software

[PjotterHasApn]

@frolic
You are absolutely right. It would even be possible to align the CPAPs graphs automatically to the oximeters graphs.
It is certainly possible to find the best fit automatically to the CPAP graphs, and it would be pretty accurate. 

However, if memory serves me right, it is indeed pretty complex to make such changes in Oscar because of the way it is was developed a long time ago. 
I might have a look at it again shortly.