Asset Management/Capturing help. Open problem

Hi,
I am trying to solve this problem @ work and am wondering if anyone has any experience in this area?

Scenario:
There are sites located within an area (eg. New York) called BTS sites or Base station sites. These sites are the first point of contact for your mobile phones when you switch on/place a call. You might have seen them when driving
http://en.wikipedia.org/wiki/Base_transceiver_station

Assume company A needs to capture all the information on a particular site. The captured information should be visual (eg. in block and termination diagrams). For example, we need to know the brands of the equipment, how they are connected, what the lengths of the cables are etc etc.

I have attached a few simple examples. Both these diagrams are of the same site (call it Site ABC). Each block and cable contains information. When they are clicked, detailed information will be displayed related to that component. So now, instead of going on site and seeing what is actually out there, we now have a way to see what is on site from our office.
http://i41.tinypic.com/k39kr7.png
http://i41.tinypic.com/2rm4601.png

Questions
1. Has anyone implemented such a system at their own work place?
2. What is the most efficient way of capturing this information? My solution is to go on site, draw what you see on a lightweight Block Diagagram program (SmartDraw). Send the .pdf file back to HQ and fill in the rest of the details later (on a more comprehensive program called DAD [Dynamic Asset Documentation]).

Just trying to start a discussion on this so that I may get an idea on what some problems may be and some solutions to these problems..