Talk:ECG Telemetry

Take a look at the MICS band. Here are some presentation slides from Medtronik on how they use the MICS band for their pacemaker telemetry. Notice the channels on slide 4--403.95MHz is one of them. 22:30, 15 September 2015 (GMT)

You know you might be right. Recently I came across an ECG transmission from the Soviet era, when they sent an ECG transmission from cosmonauts in space via voice channel and it looked very similar to this, rising and whatnot. This is where I found it. and another recording. Definitely follow this lead! --Cartoonman (talk) 15:14, 16 September 2015 (NZST)

I've never run into that type of ECG transmission before--fascinating! Reading from the bottom to the top of the waterfall plot, the signal does seem to fit with an ECG--small P-waves before the QRS complex with large T-waves after. It's odd that the waveforms with the large intervals between them lack the T-wave, though. It appears that at least one Medtronik device uses 2-FSKFrequency-Shift Keying. This paper has more details. Could 2-FSKFrequency-Shift Keying manifest itself similar to your plot as well? 209.180.165.155 03:00, 17 September 2015 (NZST)

In this beeper, It does seems like a burst of some data after each tone, possibly pulse modulation, or PSKPhase-Shift Keying. Probably not FSKFrequency-Shift Keying because only two frames seem to exist and two frames with 2-FSKFrequency-Shift Keying wouldn't send much data besides two bits. There does seem to be two primary frequencies however. Each beep, not when it's rising and falling, is spaced exactly 1 second apart. The beep itself is 250ms, and the burst is 50ms. In each burst it looks like two frames are sent, so possibly 40bd. I've attached my SA analysis images on the page.

The continuous wave tone that goes up and down is interesting because this is a method of analog telemetry that uses the frequency the tone is as a measuring metric for whatever receiver sees it, so this is definitely a telemetry of some sort. --Cartoonman (talk) 09:07, 17 September 2015 (NZST)

I agree with you about it not being 2-FSKFrequency-Shift Keying. Perhaps one reason for the beeps is so the receiving equipment can determine heart-rate. Perhaps the long tone is so a PLL can lock on and the short one yields an exact timestamp? i.e. the transition from long to short is where each "heart beat" occurs?. 209.180.165.155 03:56, 19 September 2015 (NZST)

Can you provide any more information about how you got the signal? Were you using a directional antenna? Are you near a hospital / clinic / nursing home? Do you think you could have been in close proximity to medical devices? Did the signal source appear to be moving (i.e. did it fade away)? I'm not experienced with receiving signals from space, but might you be able to tell the type of orbit by the doppler shift if it did come from space?

Here's a link proposal paper from ACMA about medical telemetry. It does mention frequencies around 403MHz. Monash Health holds two licenses in that range (122 Thomas Street DANDENONG VIC 3175 and 823-865 Centre Rd BENTLEIGH EAST VIC 3165. They're both receivers. I'm not sure where the transmitter is. I've looked for some sort of device registration (similar to FCC ID's) but I haven't found one for Australia.

This signal actually wasn't uploaded by me, this was by a user long ago, at least a year ago. I wouldn't know the details on how this was obtained so that's all up to analysis at this point. if 403 is specifically medical telemetry (as in, not ISM or whatever), then we can reliably say it is some sort of medical telemetry device. Determining what medical telemetry device this is from is gonna be the trickiest thing, and will either need someone decoding the data or capturing a sample from a medical telemetry device. --Cartoonman (talk) 17:48, 19 September 2015 (NZST)

Actually, I work in the RFRadio Frequency field at a medical device company. The telemetry output from our radios looks nothing like this. However, I did post the waterfall on my cubicle wall along with a bounty of chocolate for anyone who can identify the device that made it. :) I take it you probably don't have the raw IQQuadrature signals form the basis of complex RF signal modulation and demodulation, both in hardware and in software, as well as in complex signal analysis. data either? I noticed that there's no "ECG" for up to 4.5s. That's a long time for someone to be in asystole. I suppose this could be a respiration monitor. Perhaps there's no data during the 4.5s. 209.180.165.155 12:06, 22 September 2015 (NZST)

Oh wow, thats pretty cool! I also have some interests in medical devices, though I never actually worked with them. Hopefully someone may find it with that chocolate bounty hehe :^). Sadly whatever the article has is all there is. According to the history, a user by the name of Albi uploaded this 09:23, 9 October 2014‎. They would have to have the information regarding this signal. I don't know how I'd contact them however, its dubious they still go on the site. Yea I feel that since the telemetry timing is so exact (at 1 second on the dot), this isn't a realtime representation of a heartbeat but rather some sort of regulated data transmission. It does have some non-consistant timings when it goes into that increased rate with the oscillating continuous wave signal going up and down, so I'm not really sure. --Cartoonman (talk) 14:58, 22 September 2015 (NZST)

Here's one other idea: The weak waveform seems too regular for an ECG to me. If it were an ECG, the T wave seems to be an exact copy of the QRS, but just inverted--I'm no doctor, but I've never seen that before. Could the waveform be the output of a square wave run through an RC-filter? Look at it as the first derivative of a square wave (in red) as I've drawn in the picture.

I'm not sure if this effect also applies in the frequency domain (I know RC-filter would cause these jumps on voltages). I do know that voltage fluctuations can cause frequency drifting, so it might be. The square wave -> RC filter makes sense. --Cartoonman (talk) 12:01, 23 September 2015 (NZST)

That looks like an ECG telemetry from an implanted pacemaker or advanced cardiac rhythm device. It appears that person really does need it - sounds like premature complexes, not enough to cause alarms yet. It's not a respiration monitor. Most pacemakers are programmed at a fallback rate of 60 bpm (that's 1 per second). I know as I am a doctor and had worked in Cardiology for 9 months. Which brand it is - I have no idea. But if you read section 7 of [1] you could know more about such devices. Consider device type as identified. As for why it is audio, I am no expert in Signals but 403.9/4 = FMFrequency Modulation Radio frequency range, and would be easy to make a receiver, would it not? Azhad (talk) 20:06, 7 April 2016 (NZST)