RM4 HF Data Modem

RM4 HF Modem & ALE Controller

The RM4 is a high data rate HF data modem and ALE controller for standards-based naval and military data communications. The RM4 is suitable for long-distance (up to 10000 km) point-to-point data communications. The unit includes a built-in 2G ALE controller (optional).

The maximum data rate is 9600 bps over a standard 3 kHz (SSB) HF radio channel.

The RM4 is designed to operate in conjunction with an external STANAG 5066 ARQ server such as the RC50 Email Communications Suite. The unit is intended for installation into 19-inch rack systems or to be used as a desktop unit. The front panel (status LEDs) shows the current modem status.

The function of the RM4 is determined by the selection of a built-in modem software pack:

  • M2: HF Modem (SSB, up to 9600 bps)
  • M3: HF Modem (SSB, broadcast, up to 2400)
  • M4: HF Modem (SSB, S4539, up to 9600 bps)

The following software option is available for software packs M2, M3 and M4:

  • 2G ALE Controller Software Option

Features and Benefits

RM4 Modem Platform

  • Up to 9600 bps in 3kHz (SSB Radio)
  • STANAG 5066 Interoperable
  • AC Supply: 110 – 250 VAC, 40 – 440 Hz
  • DC Supply: 6-36 VDC (MIL-STD-1275B)
  • -30°C to +70°C operating
  • Size: ½ of 1U 19-Inch Rack
  • Two Units Will Fit Side-By-Side in a 1U Slot


HF Software Packs (M2-M4)
Software Pack
M2 M3 M4
MIL-STD-188-110B Appendix C (QAM)
MIL-STD-188-100B (QAM)
MIL-STD-188-110B Appendix F (QAM)
MIL-STD-188-110A 5.3 (8-PSK)
STANAG 4415 (WALSH)(NATO robust)
STANAG 4285 (8-PSK)
STANAG 4529 (NB 8-PSK)
FSK Variable

2G ALE Controller Software Option

  • MIL-STD-188-141B App. A
  • FED-STD 1045
  • Occupancy Detection
  • MIL-STD-188-141B App. B
  • FED-STD 1049 Linking Protection
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Product Accessories

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System Architecture Diagrams