D-Star Technical Specification

The following table compares D-STAR capabilities with those of VHF packet for both low-speed and high-speed systems. High-speed D-STAR links provide approximately 10 times the performance of high-speed packet at less than three times the price.

	D-STAR	PACKET
VOICE CODEC	3600 bps AMBE®	None
DATA SPEED	DV: 1200 bps (net 950 bps) DD: 128k bps (net 90k bps)	LS: 1200 bps HS: 9600 bps
BANDWIDTH	DV: 6kHz DD: 150kHz	20 kHz
FREQUENCY	DV: Any VHF/UHF band DD: 1.2 GHz	Any VHF/UHF band

Software and system developers want to know the detailed technical specifications and the following table illustrates the main points of the D-STAR system.

DV: Digital Voice + Data DD: High Speed Data LS: Low Speed Data HS: High Speed Data

	D-STAR	PACKET
DATA INTERFACE	DV: RS-232 or USB 1.0 DD: Ethernet	RS-232
DATA FORMAT	Same as Ethernet	7-bit ASCII text
AIR LINK	D-STAR packet format and 0.5GMSK modulation	LS: AX.25 using Bell 202 modulation HS: AX.25 using K9NG Bell 212A
NETWORK & TRANSPORT	DV: Transparent point-to-point DD: TCP/IP	AX.25 of TCP/IP

Data Interface

For low-speed DV D-STAR* links (1200 bps), the data interface to your laptop or terminal is a familiar RS-232, three-wire connection (Rx data, Tx data, and signal ground) or a USB 1.0 interface, depending on the radio. For high-speed D-STAR* (128k bps), the data interface is an Ethernet connection with the customary RJ-45 jack.

Air link

Over the air, packet signals use FSK protocols originally designed for land-line applications and adapted to amateur radio. D-STAR* uses the up-to-date modulation method of 0.5GMSK--Gaussian Minimum Shift Keying. GMSK provides improved performance over packet because it is designed for wireless links. Data is sent using the D-STAR* packet format, which includes FEC (Forward Error Correction) and routing information. The data itself is encapsulated within the D-STAR* packet as an Ethernet packet.

Network and transport

Low-speed DV D-STAR* data is a "keyboard-to-keyboard" mode. The D-STAR* system provides reliable, transparent transport from user to user by using CRC error detection. High-speed DD D-STAR* data appears at the data interface as an Ethernet packet suitable for encapsulation by the TCP/IP protocol stack. The Ethernet connection is a bridged, point-to-point connection between static IP addresses so that standard Internet application software can be used to transfer data across the D-STAR* system.