I want to interface radio to PC plz note in mind i want to measure the electromagnetic field strengths of different FM, AM, TV stations can any body help me , or else is there any device that can be used to do it ,or any software
You can use either a spectrum analyzer or a (EMC) measurement receiver for this purpose. You also need an antenna with a known antenna factor. Logper antennas (or LPDAs) are widely used for this purpose. They have even gain over several octaves.
In some newer spectrum analyzers (since early to mid-1990ties) you can store the antenna factors so the device can calculate the field strength and directly display it in V/m or dBuV/m. These devices are available as used devices on the surplus market for low prices (a few thousand Dollar).
What radio are you trying to interface? i.e. Icom HF receiver.
The reason I ask is because some of the more modern receivers have serial outputs that can be used for control and signal strength functions.