RF Receiver and VB

First you need some kind of hardware that will interface the receiver to the PC (USB, serial, PCI, etc.). Then you will need software drivers to allow communication between the hardware and the PC operating system - if Windows, API files. Then you may be able to use VB to access the API functions.

It depends on what type of interface you want (, text, video, voice, etc.) and what type of signals (data or control codes) you plan on on transferring and the directional mode (send, receive, simplex bi-directional, or duplex bi-directional).

Although you mentioned an RF receiver, which one would normal expect to "receive" a signal from, you might also "send" control codes to the receiver to change its operating parameters. i.e. frequency, filtering, RF gain, line levels, etc. For many shortwave receivers and VHF/UHF monitors there is command software available that will allow programming memories or active PC-based control through the PC serial or USB ports. A simple hardware cable is usually require that includes a built-in interface for the particular radio. ICOM, Yaesu, Kenwood, and many other use their own proprietary interface.

If you mean to transfer data from the receiver to the PC, things are even simpler. You can use an audio interface that plugs into the the Receivers speaker or audio out jack and into the PC sound card microphone or "audio in" jack. The audio interface takes care of RF isolation and impedance matching. Depending on what you want to decode, there is lots of free or very-low-priced software available, much of it shareware. Radioteletype (RTTY) is a common mode that people want to "listen in" on. Amateur Radio Operators ("Hams") now use several digital modes for text and digital voice that can be decoded with a PC/Sound Card combination. Even the old Morse Code (CW), still used by Hams and some foreign or clandestine stations, can be decode and displayed on a PC screen without "knowing the Code", if you have the right software. Packet Radio data is also decoded, using either a modem (serial input)or Sound Card.