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DVB-ASI Characteristics
The following tables list some of the physical and logical characteristics
of DVB-ASI.
| Parameter |
Value |
Comments |
| Connection medium |
Coaxial cable |
75-Ohm, low loss, double shielded |
| Connector type |
BNC |
75-Ohm version |
| Cable length |
300 meters |
Depending on cable type used |
| Bit rate on link |
270 M bit/s |
27 MHz byte clock multiplied by 10 |
| Link character length |
10 bit |
Input octets sent as 10-bit link characters |
| Byte rate on link |
27 M bytes/s |
8 user bits encoded as 10 line bits |
| Voltage levels |
800 mV p-p |
Nominal into 75-Ohm termination |
Table 1: Selected Physical Characteristics of DVB-ASI
| Data format |
MPEG-2 Transport Packet |
1 start byte, 187 MPEG-2 data bytes |
| Data packet length |
188 bytes or 204 bytes |
User can select via software |
| Data in bytes 189-204 |
Dummy bytes for modulator |
Input devices ignore them |
| Maximum MPEG-2 bit rate |
213 M bits/s (approximate) |
Theoretical peak payload capacity |
| Useful data rate |
0.1 M bits/s to 100 M bit/s |
As implemented by DiviCom |
| Packet spacing (See Figure 1) |
2 ticks to 65536 ticks |
1 tick = 37.037 ns (1/ 27 Mhz) (as implemented by DiviCom) |
| Data byte spacing (See Figure 2) |
0 ticks to 255 ticks |
1 tick = 37.037 ns (1/ 27 Mhz) (as implemented by DiviCom) |
Table 2: Selected Logical Characteristics of DVB-ASI
The following figures provide examples of packet and data byte
spacing using DVB-ASI.
Figure 1: Example of Inter-Packet Spacing
Set to a Value of Four
Figure 2: Example of Data Byte Spacing Set
to a Value of Two
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