# Communications Systems Questions

Joined Mar 10, 2014
4
Hey guys have a small exam comming up, and I've got few questions I am not too sure of could someone take a look and guide me in the right direction.

1. An accelerometer in a fall sensor system is band limited to 5Hz. If the system is operated at 5 times oversampling, what sample rate will be used?

I assume thats 5Hz * 2 (the nyquit rate) * 5 ?

2. The same sensor incorporates a three axis accelerometer and three single axis gyroscopes. If the sample rate is now 100Hz and the samples are 16 bit per measurement channel, calculate the required bit rate.

Is someone could explain how to go about getting the answers to those I would be very happy, thank you in advance.

#### WBahn

Joined Mar 31, 2012
29,883
How many data values do you get our of the sensor per sample? How big is each data value, in bits? How much data do you get, in bits, every second?

Joined Mar 10, 2014
4
I am only looking for the sample rate and the bit rate. And its to be calculated from the information I am given in the question

#### WBahn

Joined Mar 31, 2012
29,883
So, given the information you are given in the question, in the second problem how many data values do you get out of the sensor per sampling period? How big is each data value (in bits)? How much data do you therefore get, in bits, every second? What does that mean as far as your bit rate?

#### Veracohr

Joined Jan 3, 2011
772
You're correct on the first question, although one could argue that the sample rate doesn't HAVE to be exactly twice the bandwidth, it could be even greater. So the question is worded in a way that can be confusing or lead to mistaken assumptions for some people.