Acoustic microscopy acoustic microscope (CSAM), and C-mode scanning acoustic microscope (C-SAM). More recently acoustic microscopes based around picosecond ultrasonics systems have demonstrated acoustic imaging in cells using sub-optical wavelengths working with ultrasonic frequencies into the multi-GHz. Since the vast majority of acoustic microscopes in use today are C-SAM type instruments, this discussion will be limited to these instruments. Ultrasound is broadly defined as any sound having a frequency above 20 kHz, which is approximately the highest frequency that can be detected by the human ear. However, the acoustic microscopes emit ultrasound ranging from 5 MHz to beyond 400 MHz so that micrometre
History of broadcasting in Australia there is just a small change in format. 1920s all broadcast services allocated to a few specific frequencies, MF + LF early 1920s Class A Services low end of AM band & longwave, Class B services upper end of band, Amateurs above 1400? kHz mid 1920s AWA-influenced longwave services commenced to be switched off due to difficulties in achieving radiator efficiency late 1920s Australia commences to allocate AM radio services in the range between 1400 kHz and 1500 kHz 1926 AM restack 1930 Captain Eckersley and Radio Research Board give consideration to widespread deployment of longwave services, but eventually it