STANDARD:

MIL-STD-188-110C

Overview

MIL-STD-188-110C describes the technical standards and design objectives for narrowband and wideband HF data modems. This version of the standard includes the wideband HF data modems spanning bandwidth from 3 to 24 kHz in 3 kHz steps, as described in Appendix D.

Status

The third revision of the MIL-STD-188-110 “Military Standard Interoperability and Performance Standards for Data Modems” was released in April 2000. The updated MIL-STD-188-110C Appendix D WBHF waveform standard was ratified in 2011. It has since been superseded by later revisions, the current one being MIL-STD-188-110D (December 2017).

Key Features

Autobaud capable Single Sideband (SSB) Narrowband STM waveforms including the Legacy MIL-STD-188-110A and the high data rates waveform modes of MIL-STD-188-110B Appendix C, providing data rates above from 75 bps to 9600 bps in 3 kHz.
Autobaud capable Single Sideband (SSB) Wideband STM waveforms described in Appendix D of the MIL-STD 188-110C standard, specifies wideband HF Data Modem Waveforms for bandwidths from 3 kHz to 24 kHz in 3 kHz steps. In 24 kHz, the data rates range from 600 bps to 120 000 bps.

Relevance

The 3 kHz bandwidth waveforms, as specified in MIL-STD 188-110C Appendix D, provides a better performance compared to the 75 bps to 2400 bps waveforms of the MS110A/MS110B specifications.
The motivation for extending the HF bandwidths is to provide user bit rates up to 120 kbps, and allow users the option of selecting the bandwidth and modulation so as to optimize modem and ARQ (e.g. STANAG 5066 WB) performance.
HF communication has generally been limited to narrower bandwidths and lower data rates compared to satellite communication. The availability of high data rate beyond line-of-sight (BLOS) communications without the use of satellites or radio-relay is important to provide satellite-like data services over HF.
The higher data rates supported by the Appendix D waveforms are sufficient to support services not previously practical over HF radio, such as real-time video transmission.

Serial Tone Mode (STM) – Single Sideband

The table below summarises the complete MIL-STD 188-110C Appendix D STM waveform suite. Included in the table is the data rate as a function of bandwidth, waveform number and modulation.

	Data Rate [bps]
Bandwidth	Waveform Number & Modulation
	13	12	11		10	9	8	7	6	5	4	3	2	1	0
	Q-PSK	256-QAM	64-QAM		64-QAM	32-QAM	16-QAM	8-PSK	Q-PSK	B-PSK	B-PSK	B-PSK	B-PSK	B-PSK	WALSH
24 kHz		120000	96000		76800	64000	51200	38400	25600	12800	9600	4800	2400	1200	600
21 kHz		115200	76800		57600	48000	38400	28800	19200	9600	4800	2400	1200	600	300
18 kHz		90000	72000		57600	48000	38400	28800	19200	9600	–	4800	2400	1200	600
15 kHz		76800	57600		48000	40000	32000	24000	16000	8000	4800	2400	1200	600	300
12 kHz		64000	48000		38400	32000	25600	19200	12800	6400	4800	2400	1200	600	300
9 kHz		48000	36000		28800	24000	19200	14400	9600	4800	–	2400	1200	600	300
6 kHz		32000	24000		19200	16000	12800	9600	6400	3200	2400	1200	600	300	150
3 kHz	2400	16000	12000		9600	8000	6400	4800	3200	1600	1200	600	300	150	75

	Ground Wave			Sky Wave

Table 1: MIL-STD-188-110C Appendix D – STM Waveform Suite