The ASCII code, which is internationally adapted as the CCITT ITA-5 alphabet, is used in all kinds of data transfer of information between computers or computer based equipment. Only the 7-bit values 0 – 127 are internationally defined and standardized. For asynchronous transmissions, the code consists of a start bit, 7 or 8 data bits, one parity bit (optional) and 1 or 2 stop bits.
|
Parameter |
Value |
|
Frequency range |
HF |
|
Operation modes |
Asynchronous |
|
Modulation |
FSK |
|
Symbol rate |
50, 75, 100, 110, 150, 180, 200, 300 and 600 Bd, variable 50-1200 Bd |
|
Receiver settings |
DATA, CW, LSB or USB |
|
Input format(s) |
AF, IF |
|
Additional Info |
ITA-5 |
For ASCII mode standard baud rates from 110 to 300 Baud are available. Non-standard baud rates may be selected using the Baudrate menu item.
The parity bit allows error detection. The number of "1"s is counted. If an odd number is found and parity has been defined as ODD, then the parity bit should be "1", otherwise an error has occurred. If parity has been defined as EVEN and an even number of "1"s is found, then the parity bit should also be "1".
The ASCII code does not distinguish between a "Letters" or "Figures" case as does Baudot because 7 or 8 data bit ASCII has 128 or 256 possible bit combinations. This covers most symbol requirements.
ASCII based transmissions are finding their way into radio data communications because of the compatibility with computer communications thus avoiding time and resource consuming code conversions.
From Options/Frame length and Parity the various code word lengths and parity options may be selected.
Mark parity means that the parity bit is always set to the mark signal condition, and likewise, space parity always sends the parity bit in the space signal condition. Since these two parity options serve no useful purpose whatsoever, they are almost never used.