Optimized Digital Message Entry Device (DMED)
Abstract
The Optimized Digital Message Entry Device Program was an exploratory development program which resulted in the design and fabrication of two exploratory development models of a portable, two-way Digital Message Entry Device (DMED). The DMED has been designed almost exclusively with complementary-metal-oxide-semiconductor (CMOS) MSI logic permitting five-day operation without changing or recharging the self-contained batteries. The device has two selectable bit rates, 150 and 600 bps; two symbol sets, alphanumeric (ASCII code) and hexidecimal (4-bit binary code); and two types of error control coding, a block (iterated) error detecting code for use with the alphanumeric symbol set and a Hamming 8,4 error correcting/detecting code which is used in conjunction with the hexidecimal symbol set. An internal adaptive audio FSK modem (which permits the DMED to interface with the audio circuits of voiceband radios) is a novel design implemented exclusively with CMOS logic and micropower FET amplifiers.
- Publication:
-
Final Report Electronic Communications
- Pub Date:
- November 1974
- Bibcode:
- 1974eci..rept.....S
- Keywords:
-
- Data Processing;
- Digital Systems;
- Input/Output Routines;
- Messages;
- Communication Equipment;
- Portable Equipment;
- Pulse Communication;
- Communications and Radar