STANAG 4415
Overview
STANAG 4415 defines the technical interoperability characteristics for communications over severely degraded HF radio links. The STANAG 4415 data waveform is also referred to as the NATO Robust Modem, providing a coded data rate of 75 bps in a 3 kHz bandwidth with an autobaud capability for interleaver identification.
Status
Edition 1 of the STANAG 4415 – “Characteristics of a Robust Non-Hopping, Serial Tine Modulator/Demodulator for Severely Degraded HF Radio Links” was released in June 1999.
Key Features
- STANAG 4415 is a NATO standard for robust, non-hopping digital data communication, used on severely degraded HF channels with poor signal-to-noise ratios, large Doppler and multipath spreads.
- The on-air waveform specified in the STANAG 4415 is equivalent to the 75 bps variant of the MIL-STD-188-110 serial mode. However, the STANAG 4415 modems are required to meet more challenging multipath delay and Doppler spread performance targets.
Relevance
- The STANAG 4415 75 bps modem waveform is typically used to send ACKs and NACKs in Automatic Repeat Request (ARQ) systems (e.g. STANAG 5066) because of its robustness.
“NATO Robust” 75 bps Serial Tone Modem 75:
The table below presents the STANAG 4415 waveform suite. Included in the table are the modulation, code rate and interleaver settings for the supported data rate.
| Waveform | Data Rate (bps) | Modulation Constellation | FEC Coding | Interleaver Settings | Tone Excision Capability |
|---|---|---|---|---|---|
| S 4415 | 75 | Walsh | Convolutional Rate-1/2 | Z, S, L (same as 110A Interleaver definition) | YES |
Table 1: STANAG 4415 – Waveform Suite
The STANAG 4415 waveform includes TEX capability. This waveform is also included as the 75 bps rate of STANAG 4539, MIL-STD-188-110B and MIL-STD-188-110A.
The STANAG 4415 waveform can counter the effects of extreme multi-path delay (≤10 ms) and Doppler spread (≤50Hz). The 75 bps waveform receiver includes tone excision, enabling the suppression of up to 4 tones.
The following tables give modem performance results (HF Channel Simulator).
| STANAG 4415 / MIL-STD-188-110B, 75 bps (NATO Robust) | |||||||
|---|---|---|---|---|---|---|---|
| STANAG 4203 Filters excluded | |||||||
| Data Rate [bps] | IB | STANAG 4415 Mandatory HF Channel Conditions | STANAG 4415 Mandatory Performance | RM Modem SNR Measured [dB] | |||
| Doppler Spread [Hz] | Amplitude Path 2 [dB] | Multi-Path Spread [ms] | BER | SNR [dB] | |||
| 75 | L | 0.5 | 0 | 10 | <10-4 | 0 | -2.0 |
| 75 | L | 1 | 0 | 10 | <10-4 | -1 | -4.0 |
| 75 | L | 2 | 0 | 10 | <10-4 | -1 | -5.5 |
| 75 | L | 5 | 0 | 10 | <10-4 | -1 | -3.8 |
| 75 | L | 10 | 0 | 10 | <10-4 | -1 | -4.2 |
| 75 | L | 20 | 0 | 10 | <10-4 | -1 | -4.6 |
| 75 | L | 30 | 0 | 10 | <10-4 | -1 | -4.9 |
| 75 | L | 40 | 0 | 10 | <10-4 | -0.5 | -3.1 |
| 75 | L | 50 | 0 | 10 | <10-4 | 0 | -3.6 |
| 75 | L | 0 | N/A | N/A | <10-3 | -9 | -11.6 |
| 75 | L | 1 | 0 | 2 | <10-3 | -9 | -5.8 |
| 75 | L | 0.5 | 0 | 5 | <10-3 | -9 | -4.6 |
| 75 | L | 5 | 0 | 5 | <10-3 | -9 | -6.6 |
Table 2: Performance: STANAG 4415 / MIL-STD-188-110B, 75 bps (NATO Robust)
| STANAG 4415 / MIL-STD-188-110B, 75 bps (NATO Robust) | |||||||
|---|---|---|---|---|---|---|---|
| Data Rate [bps] | IB | STANAG 4415 Mandatory Interference Conditions | Mandatory Performance | RM Modem SNR Measured [dB] | |||
| BER | SIR [dB] | ||||||
| 75 | L | Self interference (S 4415 waveform with independent data sequence) | <10-4 | -6 | -9.3 | ||
| 75 | L | Swept CW, 0 – 3000 150 Hz/s | <10-4 | -40 | -59.7 | ||
| 75 | L | NATO standard voice test tape | <10-4 | -25 | Not tested | ||
| 75 | L | FSK, 75 bps, Mark: 1575 Hz, Space: 2425 Hz | <10-4 | -40 | -51.2 | ||
Table 2: Performance: STANAG 4415 / MIL-STD-188-110B, 75 bps (NATO Robust)
The figure below illustrates the Bit Error Rate (BER) performances of the STANAG 4415 waveform suite as measured for AWGN, ITU-R poor and good Channels. The RapidM RS8 HF & V/UHF Channel Simulator was used to simulate the HF channel conditions.
Figure 1: Bit Error Rate (BER) Performance of STANAG 4415 (NATO Robust) modems for AWGN and ITU-R CCIR poor and CCIR good Channels