# Multichannel sampling with aliasing

if i have 2 sensors, sensor1 and sensor2, that sample a signal on complementary points so that sensor2 samples always between sensor1s sampling points. can I achieve the doubled sampling rate with the combination of both ? so with merging both samples, although they are aliased individually.

Yes; what you describe doesn't mathematically look any different than a single sampler at twice the rate. But they sensors need to sense the same, band-limited thing!

Actually, that's how some very high-speed ADCs work.

If you're not actually doing GS/s, getting a faster ADC would probably be easier than staggering multiple ADCs.

• could you pls make a little bit more clear what you mean with band-limited thing? If my signal is bandlimited with a low-pass-filter to 4khz nyquist, and I sample the signal with two sensors with sampling rate 2khz but complementary sample points, i can merge them right? and what is GS/s?
– Khan
May 13, 2020 at 19:59
• another question, if i have a rotating machine, where i measure vibration on two axis with accelerometer sensor. I measure a phase lag in x , y axis. Do you think, combining the signals from different axis is comparable to a merge like i have decribed in my question? so merging two axis with phase lag, (if measured with aliasing) could increase the resolution, if the sampling points are known
– Khan
May 13, 2020 at 20:19
• If my signal is bandlimited with a low-pass-filter to 4khz nyquist, and I sample the signal with two sensors with sampling rate 2khz but complementary sample points, i can merge them right? no, if your Nyquist rate is 4 kHz, you need 8 kS/s sampling rate in total. But two 4 kS/s sensors would work. GS/s = gigasamples per second. May 13, 2020 at 21:19
• I measure a phase lag in x , y axis. Do you think, combining the signals from different axis is comparable to a merge like i have decribed in my question? No, that doesn't work. that's what I meant with "the same thing": these two sensors are observing different things. May 13, 2020 at 21:20
• ok, I understand, that the two sensors measure a different thing, but if the underlying rotation is constant, it can be considered the "same" signal and therefore lead to a higher resolution right? But I understand what you mean by that, I need the same signal to be sampled simultaneously. in the same axis
– Khan
May 13, 2020 at 23:10