Ucs2 And Gsm Data Coding And Conversion For Sms Text Mode - Multi-Tech MultiModem EDGE Reference Manual

1.5.2 UCS2 and GSM Data Coding and Conversion for SMS Text Mode

This section provides basic information on how to handle input and output character conversion for SMS text mode
and Remote-SAT if the internal (TA) and external (TE) character representation differ; e.g., if the Data Coding
Scheme and the TE character use different coding.
1.5.2.1 Implementing Output of SIM Data to Terminal (Direction TA to TE)
Used Character
Set
GSM
UCS2
The ratio of SIM bytes to output bytes is given in parentheses.
Note:
Case 1
Every GSM character is sent to TE as it is (8-bit value with highest bit set to zero).
Example: 47'H, 53'H, 4D'H
Case 2
Every data byte will is sent to TE as 2 IRA characters each representing a half byte.
Example: B8'H (184 decimal)
Case 3
Every 16-bit UCS2 value is sent to TE as 4 IRA characters.
Example: C4xA7'H (50343 decimal)
Problem: An odd number of bytes leads to an error because there are always two bytes needed for each USC2
character.
Case 4
Every GSM character is sent to TE as 4 IRA characters to show UCS2 in text mode.
Example: 41'H ("A")
Case 5
Every data byte is sent to TE as IRA representation of UCS2 (similar to case 4).
Example: B2'H 30'H, 30'H, 42'H, 32'H, displayed as "00B2".
Case 6
Every 16-bit value is sent to TE as IRA representation of it. It is assumed that number of bytes is even.
Example: C3x46'H 43'H, 33'H, 34'H, 36'H, displayed as "C346".
Multi-Tech Systems, Inc. AT Commands for EDGE Modems (S000371G)
DCS = 7 bit DCS = 8 bit
GSM Data
Case 1 Case 2
GSM (1:1) 8 bit to IRA (1:2)
Case 4 Case 5
GSM to IRA (1:4) 8 bit to IRA (1:4)
47'H, 53'H, 4D'H, displayed as "GSM".
42'H, 38'H, displayed as "B8".
43'H, 34'H, 41'H, 37'H, displayed as "C4A7".
30'H, 30'H, 34'H, 31'H, displayed as "0041".
Chapter 1 – Introduction
DCS = 16 bit
UCS2
Case 3
UCS2 to IRA (2:4)
Case 6
UCS2 to IRA (2:4)
13