What are the *technical* reasons preventing connection to 4G? How can I diagnose myself? I have an EVO Shift, and often see an icon similar to 4G! (see enclosed picture with red arrow) in my android status bar.  I have consulted with my carrier ad-nauseum, read the manual, rebooted, updated firmware, updated profile, updated PRL... all to no avail.

The HTC manual says that this icon means that 4G is available, but I am not connected.

This problem can happen at any time; in fact, sometimes it is literally ten or twenty feet from an area where I had max 4G signal strength.  In fact, the last time I took the phone into the carrier's store, the tech saw the 4G! icon, clicked to "scan for 4G service" and the phone suddenly came up with maximum 4G signal strength.  This screen capture is after walking less than 30 seconds outside the door to the carrier's store, where again the phone cannot connect to 4G service.

I am an engineer and love to understand the details of how things work.  So my questions...


I hope to hear from people who understand the intimate details of Sprint's 4G technology and/or the innards of the HTC Shift, and can elaborate on why these erratic 4G connections could be happening (other than low signal strength).
I already know I can use the iproute2 family of commands from a non-root terminal shell; but this is only giving me ip address and link up/down info.  Can I get signal strength measurements in dB?  What about signal-to-noise ratio, logging, or a list of available 4G tower ids?  
What apps or Android native APIs I can hook into for better diagnostic information?




This map shows exactly where I had the problem, and Sprint's own coverage map indicates that I should get maximum connectivity here:
While I'm not intimately familiar with Sprint's 4G or your phone (sorry) I have found in my own CDMA troubleshooting that the built in HTC diagnostic tools can be very useful. I found this guide over at XDA as one of the better lists of Sprint CDMA diag codes (even though it's not for your phone specifically). I recommend trying ##33284# or ##3282#, one of these should bring up a utility that lists very specific information about your cellular network connection.