Compare two same fields with time difference in Views, using node revisions
This is a bit of a hackish solution. 

What you need to do it create a field which would be unique per node on all the revisions. You could use the Computed Field instead of the normal field to crate this field and use the code below to computed the field 

if (!$entity-&gt;nid) 
{
 node_save($entity);
}

$entity_field[0]['value'] = $entity-&gt;nid;


This would set the value of the computed field to the nid of the node so that you dont have to bother about setting a unique value. 

Now in the views create a view of the type content revision. (This would be done by selecting content revision from the dropdown near Show  

Add the fields for which you want the revision data. Use the one which says  (historical data) at the end of it.

Now add the contextual filter with the computed field we created earlier. make sure the select the one with (historical data) at the end of it. 

In the filters you can choose Content revision: Updated date and select the date range you want. you can also provide relative values such as -7 days to get the all the values before 7 days. 

The computed field was used because I was not able to get the nid of the revisions. If any one has a work around on that please do make the required changes.