|
Winter 2004 Issue |
|
The Frontlines:
HSMM |
|
In the previous issue of CQ VHF we discussed the basics of HSMM radio and how to get started. What is a ham to do with all this high-speed data capability? Let us now examine a few of the exciting new applications for HSMM radio in more detail.
If you read the Fall 2003 issue of CQ VHF, you
already know that HSMM stands for High Speed Multi-Media radio networking.
That is a mouthful, but nonetheless, it is not a specific operating mode,
but rather a radio networking direction within amateur radio. Commercial
folks often call this sort of radio mobile computing. The current
developmental emphasis is on adapting to amateur radio use. The
inexpensive, easy-to-use, commercial, off-the-shelf (COTS) microwave
spread-spectrum digital packet-radio gear is readily available from most
office and computer supply stores. This equipment is known in the
commercial market as wireless local area network (WLAN) or WiFi gear. In a
nutshell, HSMM amateurs throw away the little indoor rubber-ducky antennas
that come with the gear and replace them with outdoor antennas. They set
the gear for operations on the provided channels 2 through 5 and operate
in the amateur radio 2.4-GHz band. Amateur radio research into spread spectrum was started in 1981 by the Amateur Radio Research and Development Corporation (AMRAD) and continues to this day by organizations such as the Tucson Area Packet Radio (TAPR) group and the ARRL HSMM Working Group (http://www.arrl.org/hsmm/). The initial project was described in the May 1989 issue of QST and was reprinted in The ARRL Spread Spectrum Sourcebook. Current amateur research into spread spectrum can be found in the AMRAD and TAPR newsletters. Also, it is on the HSMM webpage noted above. A thorough explanation regarding how spread spectrum works can be found in the current edition of The ARRL Handbook. Because of the considerable research progress being made in this area by radio amateurs, the spread-spectrum portion of future editions of The ARRL Handbook will be revised considerably.
HSMM radio, although digital, is not primarily
a keyboard radio communication medium, as in conventional HF and VHF
packet radio. The throughput data rates in HSMM are significantly higher,
typically 700–900 kbps or better, depending on the signal-to-noise ratio.
These data rates are equal to 12 to 16 times faster than typical internet
dial-up speeds (<56 kbps). At these high data speeds hams can operate
two-way full-motion streaming video and audio called amateur digital video
(ADV). ADV is about half the resolution or quality of a VHS tape, but it
is still of sufficient quality for many image communication purposes. Click here to return to this month's highlights _________________ © Copyright 2004, CQ Communications, Inc. All rights reserved. This material may not be reproduced or republished, including posting to a website, in part or in whole, by any means, without the express written permission of the publisher, CQ Communications, Inc. Hyperlinks to this page are permitted. |