The other day I was still trying to figure out something from the burst signals discussed here and here and on that occasion I was using Harris's RF-5710A HF modem. Turning between the various operating modes provided I came across what at first glance seemed a strange waveform: i.e. 5066-G. As far as I know, STANAG-5066 is a protocol standard that does not define waveforms, so I went into detail to see what the hell it is.
Quoting Edition 3 #G.3.0 Implementation Guidance for STANAG 5066 Operation at Higher Rates: "It is clear that higher throughput will be available for the HF long-haul channel in near future (i.e, post 2000). What is not clear is the final form of the waveform standard or standards that will provide these data rates". Notice that the Edition 3 was promulgated on 30 march 2015 and the Annex G is still "information only", ie it is still not mandatory for the purposes of the communication minimum requirements.
Now look at the words "...in near future (i.e, post 2000)": clearly, Annex G has remained unchanged from the first editions of STANAG-5066 (dated before year 2000). Most likely the NATO groups responsible for the standardization preferred a separate STANAG to define the new waveforms since 5066 is a protocol standard, so Annex G is "frozen" and stands like a kind of ancestor to MIL 188-110B and STANAG-4539 (3200 to 12800 bps): these new waveforms used constellations and much of the waveform structure developed for Annex G and added further enhancements.
Harris developed its implementation of 5066-G, you may find it among the operational modes of their RF-5710A HF modem:
The STANAG-5066 Annex G waveforms provide the highest possible data rates over conventional 3KHz HF channels. A single 1800 Hz sub-carrier is modulated at a constant rate of 2400 symbols per second. the type of modulation varies from QAM-64 to PSK-4 according to the data rate selected. Known data symbols are periodically inserted in the transmitted signal to allow fro adaptive channel equalization at the receiver. Convolutional coding FEC and Viterbi decoding are combine with interleaving to enhance the performance of the receive modem on fading HF channels. Data rates from 3200 bps to 9600 bps are supported together with long, double long, short, and zero interleaving options. An additional 12800 bps uncoded waveform is supported for line-of-sight applications. Automatic detection of the data rate and interleaver setting are provided in the receive mode.
Back to the burst signals (here and here), I tried to demdulate them with 5066-G, despite it is an obsolete mode. Surprisingly, the modem is responsive and distinguishes four different waveforms: 4800L (PSK-8), 8000L bps (QAM-32), 9600L and 12800 bps uncoded (QAM-64), the last two are detected less frequently (Fig. 1). It should be noted that when the same transmission is demodulated using 4539 or 110B you always get the same waveform 12800U.
I believe neither of the twos (4539/110B and 5066-G) is the appropriate mode to demodulate these burst signals, but in my opinion this attempt is a further clue in favor of a modified 4539 waveform.
Quoting Edition 3 #G.3.0 Implementation Guidance for STANAG 5066 Operation at Higher Rates: "It is clear that higher throughput will be available for the HF long-haul channel in near future (i.e, post 2000). What is not clear is the final form of the waveform standard or standards that will provide these data rates". Notice that the Edition 3 was promulgated on 30 march 2015 and the Annex G is still "information only", ie it is still not mandatory for the purposes of the communication minimum requirements.
Now look at the words "...in near future (i.e, post 2000)": clearly, Annex G has remained unchanged from the first editions of STANAG-5066 (dated before year 2000). Most likely the NATO groups responsible for the standardization preferred a separate STANAG to define the new waveforms since 5066 is a protocol standard, so Annex G is "frozen" and stands like a kind of ancestor to MIL 188-110B and STANAG-4539 (3200 to 12800 bps): these new waveforms used constellations and much of the waveform structure developed for Annex G and added further enhancements.
Harris developed its implementation of 5066-G, you may find it among the operational modes of their RF-5710A HF modem:
The STANAG-5066 Annex G waveforms provide the highest possible data rates over conventional 3KHz HF channels. A single 1800 Hz sub-carrier is modulated at a constant rate of 2400 symbols per second. the type of modulation varies from QAM-64 to PSK-4 according to the data rate selected. Known data symbols are periodically inserted in the transmitted signal to allow fro adaptive channel equalization at the receiver. Convolutional coding FEC and Viterbi decoding are combine with interleaving to enhance the performance of the receive modem on fading HF channels. Data rates from 3200 bps to 9600 bps are supported together with long, double long, short, and zero interleaving options. An additional 12800 bps uncoded waveform is supported for line-of-sight applications. Automatic detection of the data rate and interleaver setting are provided in the receive mode.
Back to the burst signals (here and here), I tried to demdulate them with 5066-G, despite it is an obsolete mode. Surprisingly, the modem is responsive and distinguishes four different waveforms: 4800L (PSK-8), 8000L bps (QAM-32), 9600L and 12800 bps uncoded (QAM-64), the last two are detected less frequently (Fig. 1). It should be noted that when the same transmission is demodulated using 4539 or 110B you always get the same waveform 12800U.
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| Fig. 1 |
I believe neither of the twos (4539/110B and 5066-G) is the appropriate mode to demodulate these burst signals, but in my opinion this attempt is a further clue in favor of a modified 4539 waveform.
