Sunday, April 22, 2007

HSMM with the 900 MHz Aerocomm modem

High Speed Multi Media (HSMM) is often referred to as being the Hinternet (Ham Internet), as it is primarily used under FCC Rules & Regulations Part 97. Under Part 97 commercial off-the-shelf equipment can be used at higher power and higher gain than the more common Part 15 802.11a/b/g operations.

The primary purpose for HSMM and Hinternet is to augment emergency communications via long range high speed wireless data networks that can handle voice, data and video communications. HSMM can also be used in the day-to-day aspects of Amateur Radio Communications.

The AeroComm CL4490, is a 1 watt 900 MHz, frequency hopping spread spectrum (FHSS) serial modem that can yield 20-25 kbps of throughput. They are about $100, which is really quite reasonable considering the price of a conventional TNC and radio.

The actual RF module itself (AC4490) can be bought for $62. The complete AeroComm CL4490 transceiver includes the AC4490 module housed in a nice aluminum case with an internal switching power supply and the necessary RS-232 to TTL conversion circuit.

We have experienced solid mobile non line of site coverage for 3 miles, with mobile coverage extending to 6 miles depending on terrain. This is with a measly 6 dB base station at 35 feet. Distances over 20 miles line of site are theoretically possible with these.

For more information on the Aerocomm, and to obtain specifics on the network configuration see:

HSMM Information Resources: