# Unit conversion mm/sqrt(Hz)/degree to m^2/Hz/rad

1. Aug 15, 2012

### robbie.

Hello,

I have two datasets containing power spectral density data to be compared. One of these datasets is presented in units mm/sqrt (Hz)/degree, and I would like to do some transformation so that data is comparable with the other set, which has units m^2/Hz/rad.

Any help on how to do this would be massively appreciated, as this kind of thing is not my strong point!

Many thanks,

Robbie

2. Aug 15, 2012

### Simon Bridge

They look like they've each measured something different - they have different dimensions.

The first units look like
$$\left ( \frac{mm^2}{Hz} \right )^{1/2}\text{deg}^{-1}$$

So this is the square-root of the other one scaled for degrees.
I would reverse the per-degree part of the calculation and square it to get the same thing, then bother with converting the units.

3. Aug 15, 2012

### robbie.

Thank you for your reply, however I am struggling to understand what you mean when you say 'reverse' the per degree part?

4. Aug 16, 2012

### Simon Bridge

The numbers had to be calculated somehow that ended up with the units being "per degree" ... whatever they did, do the opposite. eg. if they divided by 360, then multiply by 360.

Put another way:
If there are X (mm2/Hz)1/2 in one degree ... then how many mm2/Hz are there in 1 degree?