Group 3 EAM/Claude Draft
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This subject of this article has no known official name. This article covers a subject which has not been named and/or discussed in unclassified military documents. Group 3 EAM/Claude Draft is a theoretical or proposed name. |
Group 3 EAMs (also called Group 3 messages) are those EAMs that begin with what HFGCS monitors have designated as Group 3 prefixes. A Group 3 prefix is a two character code identified through characteristic behavioral patterns observed across messages with that prefix: pronounced clustering at specific message lengths (particularly 22, 27, 32, and 37 characters), frequent appearance of embedded repeated character sequences within message bodies, consistent absence of addressee designations, and sporadic appearance patterns with prefixes often active for only brief periods before disappearing for extended intervals. Messages with Group 3 prefixes constitute the least common of the four major EAM categories on the High Frequency Global Communications System (HFGCS), representing approximately 3% of total traffic.
The Group classification system derives from observed message behavior rather than official designation. When examining EAM traffic, monitors note that for certain periods of time, some prefixes will appear on messages clustering at specific shorter lengths with embedded repetitions and no addressees, patterns that distinguish them from Group 2's broader length distribution and Group 1's rigid 30 character format. Those messages can be identified as EAMs with Group 3 prefixes, and therefore categorized as Group 3 EAMs. The concentration at particular character counts distinguishes Group 3 from other groups, while the prevalence of repeated character sequences (appearing in approximately 40% of Group 3 messages) provides additional structural differentiation from Groups 1 and 2.
Defining Characteristics
Group 3 messages are distinguished by several consistent structural features that collectively identify them within the broader EAM taxonomy. The most prominent characteristic is length clustering, where Group 3 messages show strong concentration at specific character counts rather than broad distribution. The most common lengths are 22, 27, 32, and 37 characters, with these four lengths accounting for approximately 60% of all Group 3 traffic. Additional common lengths include 25, 29, 36, 38, and 40 characters, though these appear with notably lower frequency than the primary cluster points.
Another defining feature is the presence of embedded repeated sequences within approximately 40% of Group 3 messages. These repetitions consist of repeated character sequences of three or more characters embedded within the message body, appearing integrated throughout the message structure rather than at fixed positions. This prevalence of internal repetition is nearly identical to Group 4 Messages (38%) and significantly higher than Group 2 Messages (11%) or Group 1 Messages (1%). Examples of Group 3 messages with repeated sequences demonstrate various repetition patterns, including the 32 character message DPZUZGM6IOY2KFCGFRLQPR32RPR32G4K where the sequence "32R" repeats, the 48 character message 72NCECWCDHFIWKPWA65V4WAIHRSS6H33S6H73S6HP3NBHNVQ where "S6H" repeats three times, the 42 character message 72IA225VMX2YRM2EW43F74PAACOHFRCOHFTCOHLVV4 where "COH" repeats three times, the 53 character message OA4WGYNMK7EDIRJQ4NB66WG7K43KVI43KVIKFOB6IZ5BYD4KVZVFX where both "43KVI" and "4KV" repeat, and the 67 character message 64WDQFM7IUKJQLNFEHNFEEOO3RVVCJUEOOKRGSBBBWZCJUEOO3RNTBBUEOOKRV7CIN4 where "JUEOO" repeats three times. The function of these repeated sequences is unknown but may serve as delimiters, error detection codes, formatting markers, or structural indicators similar to those observed in Group 4 Messages.
Group 3 messages consistently lack addressee designations, never including "FOR [CALLSIGN]" specifications that frequently appear in Group 2 Messages. This absence of addressees places Group 3 in the broadcast category alongside Group 1, distinguishing both groups from the directed communication pattern of Group 2. While rare, Group 3 messages can be exactly 30 characters long, with eleven documented instances demonstrating that Group 3 does not avoid the 30 character baseline length that dominates Group 1 and is common in Group 2. However, 30 character Group 3 messages represent less than 4% of Group 3 traffic, making this length uncommon for the category despite not being prohibited. Documented Group 3 messages range from 22 to 78 characters, though the vast majority fall between 22 and 48 characters, with lengths beyond this range representing exceptional cases.
Prevalence
Group 3 messages are rare compared to Groups 1 and 2, with observation of traffic patterns showing sporadic appearance where Group 3 prefixes often appear for only a few days before disappearing for extended periods. This pattern contrasts sharply with the consistent daily presence of Group 1 and Group 2 prefixes, which maintain continuous operational schedules. Group 3 activity shows significant month to month variation, with typical periods seeing Group 3 messages constitute approximately 3% of traffic. However, October and November 2024 showed unusually elevated Group 3 activity at 10% and 11% respectively, suggesting operational factors can significantly affect Group 3 transmission frequency beyond baseline patterns. This variability indicates that Group 3 usage responds to specific operational conditions rather than maintaining steady baseline communication rates.
Length Distribution
Group 3 messages show distinctive length clustering that serves as a key identifier for the category, with concentration at specific character counts providing one of the most reliable means of recognizing Group 3 patterns. The most common length is 27 characters, accounting for 19% of Group 3 traffic, closely followed by 22 characters at 18% of traffic. Together these two lengths account for over one third of all Group 3 messages and are rarely observed in other groups, making them particularly diagnostic of Group 3 classification. The 32 character length represents 10% of Group 3 traffic, while 37 characters accounts for 6%, with these four primary lengths collectively representing approximately 60% of all Group 3 messages.
Secondary common lengths appear with lower but still notable frequency, including 25 characters at 7% of Group 3 traffic, 29 characters at 2%, and the lengths 36, 38, and 40 characters each appearing in 3 to 4% of Group 3 traffic. The strong concentration at 22 and 27 characters is particularly distinctive, as this clustering pattern suggests Group 3 messages follow predetermined message templates or formatting structures with specific length requirements. The preference for these particular lengths, combined with the general absence of these lengths in Groups 1 and 2, provides monitors with a length based signature that aids in Group 3 identification even when other characteristics remain ambiguous.
Identification Methodology
Group 3 messages present unique identification challenges due to their rarity and structural overlap with other groups, requiring monitors to employ multiple analytical approaches to achieve confident classification. Length based identification provides the most straightforward initial approach, as messages of exactly 22 or 27 characters with no addressee are highly likely to be Group 3 given these lengths are uncommon in other groups. However, definitive identification still requires observing prefix behavior over time, as isolated messages at these lengths could theoretically represent unusual Group 2 transmissions or prefix reassignments.
The presence of embedded repeated character sequences provides additional identification evidence, particularly when combined with other Group 3 characteristics. Repeated sequences of three or more characters in messages without addressees suggests Group 3 or Group 4, with the length range then providing differentiation between these structurally similar groups. The shorter length range typical of Group 3 (22 to 78 characters, with most messages falling between 22 and 48 characters) distinguishes it from Group 4's consistently longer message lengths (36 to 292 characters). When a message contains repeated sequences, lacks an addressee, and falls within the typical Group 3 length range, the probability of Group 3 classification increases substantially.
Prefix consistency over multiple observations provides the most reliable identification method, allowing monitors to establish definitive Group 3 classification through behavioral pattern recognition. A prefix can be identified as Group 3 if it is consistently used for messages clustered at characteristic Group 3 lengths (particularly 22, 27, 32, and 37 characters) and never appears with addressee specifications. This consistency check requires monitoring over time periods ranging from days to weeks depending on message frequency. An elimination process also assists identification, particularly for ambiguous cases such as 30 character messages without addressees. If such a message uses a prefix that is neither the current Group 1 prefix nor the current Group 2 prefix, and that prefix is observed with other messages at distinctive Group 3 lengths, classification as Group 3 becomes likely.
The sporadic appearance pattern of Group 3 prefixes complicates identification efforts, as prefixes may appear for only a few days or even a single day before disappearing for extended periods. This ephemeral pattern means that multi day observation windows may not always be possible, forcing monitors to make provisional classifications based on incomplete behavioral data. The rarity of Group 3 messages means that even experienced monitors may go days or weeks without observing any Group 3 traffic, limiting opportunities to refine classification criteria through repeated observation. These identification challenges reflect the specialized and intermittent nature of Group 3 communications within the broader HFGCS message architecture.
Prefix Patterns
Group 3 prefix behavior differs significantly from Groups 1 and 2, with patterns suggesting fundamentally different operational usage rather than simply a variant rotation schedule. Rather than showing regular rotation schedules with prefixes remaining active for weeks or months as observed in Groups 1 and 2, Group 3 prefixes appear sporadically and often for very short durations. Many Group 3 prefixes appear for only one to four days, with continuous monitoring from June 2023 through February 2024 documenting cases such as prefixes W5, QL, and NR each appearing for a single day, while the prefix 64 appeared for four days across August and September 2023.
However, Group 3 does not exclusively follow the brief appearance pattern, with certain operational periods showing sustained prefix activity more similar to Groups 1 and 2. The October and November 2024 period showed unusual Group 3 consistency, with the DX prefix remaining active across two months and the FJ prefix showing extended usage in October 2024. This sustained activity contrasts with the typical pattern of brief, scattered appearances and suggests operational factors can affect Group 3 usage patterns, potentially activating more continuous Group 3 operations during specific mission phases or exercise periods. July 2025 provided another example of sustained Group 3 activity, with the DP prefix active throughout the month and brief concurrent appearance of the GV prefix, demonstrating that Group 3 prefixes can show sustained activity similar to Groups 1 and 2 under certain conditions.
Whether Group 3 operates on a rotation schedule similar to Groups 1 and 2 but with longer intervals between active periods, or represents a fundamentally different usage pattern triggered by specific operational conditions, remains unclear from available monitoring data. The variability in appearance patterns suggests Group 3 usage may be tied to specific operational conditions or requirements rather than following a predetermined rotation schedule independent of operational needs. The occasional emergence of sustained Group 3 activity during specific time periods, contrasting with typical sporadic usage, supports this operational trigger hypothesis rather than a simple rotation model.
Relationship to Other Groups
Group 3 exists within a four group EAM taxonomy and shows particularly strong structural similarities to Group 4, suggesting possible operational or encoding relationships between these two rare message categories. Both Group 3 (40%) and Group 4 (38%) show nearly identical rates of embedded repeated character sequences, a shared characteristic that distinguishes both groups from the lower repetition rates observed in Groups 1 and 2. This structural similarity suggests both groups may serve related operational purposes or employ similar encoding and formatting schemes, with the primary distinction between them being message length rather than fundamental structural design. Group 3 messages cluster at shorter lengths with typical messages ranging from 22 to 48 characters, while Group 4 Messages are consistently longer with documented lengths ranging from 36 to 292 characters.
Group 3 contrasts sharply with Groups 1 and 2 in multiple structural characteristics. Group 1 Messages are invariably 30 characters long, never include addressee designations, constitute approximately 66% of all EAM traffic, and rarely contain repeated sequences (appearing in only 1% of Group 1 messages). Group 2 Messages exhibit variable lengths ranging from 30 to 163 characters, frequently include "FOR [CALLSIGN]" addressee specifications, constitute approximately 26% of traffic, and show moderate repetition rates at 11%. The pronounced length clustering, high repetition rate, and sporadic appearance pattern of Group 3 distinguish it from both of these higher volume groups.
All four groups operate independently with separate prefix systems, with no observed cases of prefixes being shared across groups. The strong structural similarity between Groups 3 and 4, combined with their comparable rarity (each representing approximately 3% of total traffic), suggests these groups may represent specialized communication categories distinct from the baseline Group 1 traffic that provides continuous routine communications and the directed Group 2 communications that address specific recipients. The parallel structure and similar rarity of Groups 3 and 4 raise questions about whether these categories serve complementary functions, with Group 3 handling shorter format specialized messages while Group 4 handles longer format specialized messages requiring the same encoding or formatting approach.
Operational Context
The distinctive characteristics of Group 3 messages, including specific length clustering, embedded repeated sequences, absence of addressees, and sporadic appearance patterns, suggest this group serves a specialized operational purpose within the HFGCS architecture rather than representing routine baseline communications. The strong preference for 22 and 27 character messages indicates constrained message formats, possibly corresponding to specific types of commands, status updates, or coordination messages with predetermined structures where message length corresponds to message type or content category. The prevalence of repeated character sequences appearing in 40% of messages mirrors Group 4's pattern and suggests both groups may employ similar formatting or encoding schemes for specific operational purposes, potentially indicating shared design principles or common operational requirements driving both message categories.
The sporadic appearance pattern contrasts with the continuous presence of Groups 1 and 2, suggesting Group 3 usage is tied to specific operational conditions, exercises, or mission requirements rather than continuous baseline communication needs. The occasional periods of elevated activity, such as the October and November 2024 period where Group 3 messages rose to 10% and 11% of traffic respectively, demonstrate that operational factors can trigger sustained Group 3 transmission periods. These elevated activity windows may correspond to specific exercises, operational phases, or mission conditions requiring the specialized communication capabilities Group 3 provides. The ability of Group 3 to shift from sporadic minimal presence to sustained elevated activity suggests flexible activation based on operational necessity rather than fixed rotation schedules.
However, without access to message content or operational documentation, the specific purpose of Group 3 messages remains speculative. The observable patterns provide evidence of specialized function and operational triggering, but the precise nature of what distinguishes Group 3 communications from other EAM categories, what operational conditions trigger elevated Group 3 usage, and how the length clustering and repeated sequences relate to message content all remain unknown to external monitors working solely from transmission characteristics.