Secure communications is critical in battleplace as well as in public-safety and other government-agency applications. Frequency-hopping spread-spectrum techniques can ensure voice and data security over long-range communications links, and such technology is now with-in range of most radio system manufacturers with the introduction of the model 3400 SMR board-level spread-spectrum radios from FreeWave Technologies (Boulder, CO). Designed for use from 3.3 to 3.5 GHz, the 3400 SMR radio (see figure) features advanced data encryption techniques for security. The radio's proprietary spread-spectrum technology prevents detection and unauthorized access to sensitive communications.
Military services and government agencies depend on the security and reliability of spread-spectrum communications system, whether based on frequency-hopping algorithms or direct-sequence techniques. The 3400SMR radios employ the former flavor of spread-spectrum technology. Single-channel hopping patterns can be used for 25 to 200 MHz of the available (200-MHz) bandwidth using 25-MHz steps and as many as 112 hopping frequencies. As many as six user-selectable hopping bandwidths are available to avoid interception of signals or interference from other spread-spectrum radios in the vicinity.
The spread-spectrum radio's receiver features sensitivity of –102 dBm for a bit-error rate (BER) of 1 X 10–6 and –104 dBm for BER of 1 X 10–4. Because it is a frequency-hopped spread-spectrum radio, it only occupies 350 kHz of the full 200-MHz bandwidth at any one time. The receiver selectivity is 20 dB at ?350 kHz of the center frequency while receiver system gain is 132 dB. The frequency-agile transmitter runs with output power levels from 5 to 750 mW using two-level Gaussian frequency-shift-keying (GFSK) modulation for a line-of-sight communications range of 20 miles and standard data rate of 115.2 kb/s.
The 3400 SMR military radio employs 32-b cyclic-redundancy-code (CRC) error correction to ensure reliable operation even under adverse environmental conditions. It features Substitution and Dynamic Key forms of data encryption for security above and beyond the proprietary spread-spectrum radio technology, and 128-b Advanced Encryption Standard (AES) data encryption is also available.
The radio consumes less than 80 mA at +12 VDC in receive mode and less than 325 mA at +12 VDC in transmit mode. Each radio can function as a slave or repeater for extended-distance applications. The 3400 SMR radio measures 127 X 61 X 15 mm and is designed for operating temperatures from –40 to +75°C. It operates at voltages from +9.5 to +30 VDC and works with RS-232/RS-485/RS-422 interfaces as well as with the TTL (IM510) protocol.
The 3400 SMR is ideal for original-equipment manufacturers (OEMs) involved with the design and development of full spread-spectrum radio systems for tactical military and Public Safety applications. It can be supplied with or without SMA RF connectors. It is available in board-level and enclosed-housing formats.