VHS FORMAT (VHS = IEC 774 / VHS-C = IEC 1077)
Introduced soon after Betamax, the Video Home System format has become the dominant consumer standard. For camcorders, the VHS-C concept was introduced, using a smaller cassette which can be used with an adaptor in a full-size machine. The Hi-Fi version buries a longer wavelength FM audio carrier under the short wavelength video in the depth of the tape coating to escape the limitations of longitudinal audio tracks at low tape speeds.
| Signal system | ||
| Analogue, composite, 'Colour under'. | ||
| Scanner | ||
| Geometry | Helical | |
| No. of rotating heads | 2 * | |
| Scanner diameter | 62 | mm |
| Rotation speed | 25 | rev/s |
| Tracks/revolution | 2 | |
| Head-to-tape speed | 4.85 | m/s |
| Video track angle | 5.96 | degree |
| Track width | 58.0 | µm |
| Track pitch | 58.0 | µm |
| Azimuth | ±6.0 | degree |
| Tape Properties | ||
| Coercivity | 650 | Oe |
| Type | Cobalt modified oxide or chromium dioxide | |
| Width | 12.65 | mm |
| Thickness (total) | 21.0 (max) | µm |
| Tape Consumption | ||
| Linear | 23.39 | mm/s |
| Areal | 0.018 | m²/min |
| Shelf volume | 120 (E-240) | cm³/h |
| Electrical Characteristics | ||
| Sync tip carrier frequ. | 3.8 | MHz |
| Peak white | 4.8 | MHz |
| Chroma s/c | 0.627 ** | MHz |
| Shortest wavelength | 0.78 | µm |
* More heads are sometimes provided for improved slow-motion etc.
** Strictly fsc = (44fn + 1,953) Hz.
IEC 774
VHS-C IEC 1077
