1 Echocardiography (echo) is a painless test that uses sound waves to create pictures of your heart.  This test gives your doctor information about the size and shape of your heart and how well your heart's chambers and valves are working.
USB was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power.
USB (Universal Serial Bus) is a serial bus standard to connect devices to your computer. As you may already know the USB specification limits the length of a cable between high speed devices to 5 meters (about 16 feet) and for low speed devices the limit is 3 meters (about 9 feet).