The Missile Knows Where It Is...

The Missile Knows Where It Is... — Jeff7181

Jeff7181

AI-assisted summary of The Missile Knows Where It Is... — original source. Check the original for full context.

Source published:

Key ideas

  • The missile continuously establishes its real-time location via negative elimination by subtracting where it is from where it isn't, or vice versa, to obtain a deviation. (0:02)
  • The guidance subsystem translates calculated deviations into corrective commands, systematically driving the missile toward the position where it isn't. (0:02)
  • When transit discrepancies occur, the system identifies a variation between where the missile is and where it wasn't, which can be compensated for by the Guidance Electronic Assembly (GEA). (0:43)
  • To resolve positional ambiguity, the system integrates historical telemetry and calculates overall error by differentiating spatial discrepancies with the algebraic sum of where it shouldn't be and where it was. (0:43)

Detailed notes

## Background Published on YouTube by channel Jeff7181 on August 11, 2012, this video has amassed millions of views without any provided description or show notes. It presents a vintage technical voiceover explaining the navigation logic of an airborne missile guidance system.

## TL;DR The video breaks down the paradoxical, circular logic of missile navigation: the missile knows where it is by continuously knowing where it isn't. By calculating the mathematical difference between its current position and non-current coordinates, the guidance subsystem derives a deviation to steer the weapon toward where it wasn't. When deviations lead to unintended locations, the system registers a variation handled by the Guidance Electronic Assembly (GEA). To rectify corrupted telemetry, the onboard computer factors in historical coordinates of where it was alongside where it shouldn't be, differentiating these values to calculate a unified corrective metric known as error.

## Atmosphere & style The audio delivers an intensely dry, authoritative mid-century military training cadence that treats absurdly circular, ontological phrasing with utmost scientific seriousness. Listening to it feels hypnotic and deadpan, as technical jargon rapidly twists into a dizzying semantic labyrinth of 'where it is' and 'where it isn't.' The relentless, unblinking delivery creates a uniquely surreal and humorous contrast between rigorous military precision and utter linguistic bewilderment.

## Bulletin - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) The missile continuously establishes its real-time location via negative elimination by subtracting where it is from where it isn't, or vice versa, to obtain a deviation. - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) The guidance subsystem translates calculated deviations into corrective commands, systematically driving the missile toward the position where it isn't. - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) When transit discrepancies occur, the system identifies a variation between where the missile is and where it wasn't, which can be compensated for by the Guidance Electronic Assembly (GEA). - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) To resolve positional ambiguity, the system integrates historical telemetry and calculates overall error by differentiating spatial discrepancies with the algebraic sum of where it shouldn't be and where it was.

## Key takeaways - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) The core premise of the guidance logic is that the missile knows where it is at all times because it knows where it isn't. - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) Positional discrepancies, designated as deviations or differences, are calculated by subtracting where the missile is from where it isn't (or vice versa, depending on which value is greater). - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) The guidance subsystem utilizes derived deviations to formulate corrective flight commands. - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) Corrective maneuvers guide the missile from its present position to a target coordinate space that it does not currently occupy. - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) Arrival at a new position triggers a continuous state transition: the position where it wasn't becomes where it is, and where it was becomes where it isn't. - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) A variation is defined as the mathematical difference between where the missile currently is and where it wasn't supposed to be. - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) Significant variations acting as flight factors are compensated for and corrected by the Guidance Electronic Assembly (GEA). - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) Accurate navigation requires telemetry of historical positions, establishing that the missile must also know where it was. - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) When variations obscure exact coordinates, the missile falls back on knowing where it was and, within reason, where it isn't. - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) The unified metric known as error is derived by differentiating the difference of where it should be and where it wasn't from the algebraic sum of where it shouldn't be and where it was.

## Detailed walkthrough ### [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) The Logic of Deviations and Corrective Guidance

The operational logic of the guidance subsystem hinges on an exhaustive, circular deduction of positional states. The narrator explains with dry, authoritative military cadence that the missile maintains continuous awareness of its location through a process of negative elimination: “The missile knows where it is at all times it knows this because it knows where it isn't.” By performing mathematical operations on its current and non-current states—specifically subtracting where it is from where it isn't, or where it isn't from where it is, depending on which value is greater—the system calculates an absolute numerical discrepancy designated as a difference or deviation.

```mermaid flowchart TD accTitle: Missile Guidance Deviation Loop accDescr: Logic flow of guidance subsystem subtracting positions to derive deviation and generate corrective commands. subgraph PosCalc ["Position Calculation"] A["Where it is"] B["Where it isn't"] A ---|"Subtract whichever is greater"| B B --> C["Deviation / Difference"] end subgraph Guidance ["Corrective Maneuver"] C --> D["Guidance Subsystem"] D --> E["Generate Corrective Commands"] E --> F["Drive missile to position where it isn't"] F --> G["Position where it wasn't is now where it is"] end ```

Once this deviation is derived, the guidance subsystem translates the error value into actionable steering commands. These corrective commands steer the missile out of its current physical location and drive it toward a target coordinates space that it currently does not inhabit. This traversal causes a continuous ontological shift: once the missile arrives at the target position where it previously was not, that location immediately ceases to be where it wasn't and becomes where it is. Consequently, the previous coordinates where the missile used to be automatically transform into the position where it isn't.

- Primary calculation: subtracting where the missile is from where it isn't (or vice versa, selecting whichever value is greater). - Operational objective: generating corrective steering commands to relocate the missile from where it is to where it isn't. - Dynamic state update: upon arrival, the position where it wasn't becomes where it is, and where it was becomes where it isn't.

---

[00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) Managing Variations, Past Positions, and Error Calculation

The calculation becomes increasingly complex when spatial discrepancies arise during transit. Should the missile arrive at coordinates that fail to match the intended position where it wasn't, the guidance unit registers an anomaly classified as a variation. The narrator defines this variation as the precise mathematical gap between where the missile currently resides and where it wasn't supposed to be. If this variation grows large enough to be deemed a significant flight factor, it can be compensated for and corrected by the GEA (Guidance Electronic Assembly).

To resolve this ambiguity, the onboard computer must integrate historical telemetry, operating under the principle that the system cannot solely rely on present and absent states: “However the missile must also know where it was.” When an uncorrected variation corrupts the telemetry data, leaving the missile unsure of its exact coordinates, it falls back on reliable parameters: it knows where it was in the past, and within reason, it remains certain of where it isn't. The guidance computer then executes an advanced algebraic reconciliation: it subtracts where it should be from where it wasn't (or vice versa) and differentiates that result from the algebraic sum of where it shouldn't be and where it was. Through this differentiation, the system isolates both the deviation and its associated variation, yielding the unified flight metric known simply as error.

- Definition of variation: the recorded difference between where the missile is and where it wasn't. - Corrective authority: the GEA handles significant variations to stabilize trajectory. - Fallback telemetry: when variation clouds positional certainty, the missile relies on knowing where it was and where it isn't within reason. - Error formula: differentiating the difference between where it should be and where it wasn't from the algebraic sum of where it shouldn't be and where it was.

## Notable quotes > [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) The missile knows where it is at all times it knows this because it knows where it isn't. — Narrator

## Mentioned GEA (Guidance Electronic Assembly)

[Source](https://www.youtube.com/watch?v=bZe5J8SVCYQ)

中文简报

导弹知道自己在哪里…… 该视频解析了导弹导航看似矛盾且循环往复的逻辑：导弹通过不断明确自己“不在哪里”，从而获知自己“在哪里”。制导子系统通过计算当前位置与非当前坐标之间的数学差异得出偏差，以此引导武器飞向其此前不在的位置。当偏差导致导弹偏离预定航线时，系统会记录下这种变异，并由制导电子组件（GEA）进行处理。为纠正受损的遥测数据，机载计算机结合了导弹过去所在位置的历史坐标与其不应处于的位置，并对这些数值进行微分计算，从而得出一个被称为误差的统一修正指标。 导弹通过逆向排除法不断确定自身实时位置，即通过将其所在位置与不在的位置相减（反之亦然）来获取偏差。 (0:02) 制导子系统将计算出的偏差转化为修正指令，系统性地驱使导弹飞向其目前不在的位置。 (0:02) 当飞行途中出现位置差异时，系统会识别出导弹所在位置与其过去不在的位置之间的变异，该变异可由制导电子组件（GEA）进行补偿。 (0:43) 为解决位置模糊问题，系统综合了历史遥测数据，并通过将空间差异与“不应处于的位置”及“过去所在位置”的代数和进行微分，从而计算出总误差。 (0:43)

Reading summary

According to the narrator, missile guidance operates through a continuous circular deduction of negative elimination, calculating trajectory and steering commands by assessing the mathematical discrepancies between where the missile is and where it isn't. Calculating Deviations Through Positional Elimination (0:02) The operational framework of the guidance subsystem relies on the premise that the missile knows its position solely by knowing where it is not. The system calculates an absolute numerical value—designated as a difference or deviation—by subtracting where the missile is from where it isn't, or where it isn't from where it is, depending on which value is greater. The guidance subsystem immediately translates this deviation into corrective steering commands. These commands maneuver the missile out of its current physical location and direct it toward coordinates it does not currently occupy. This movement triggers a continuous state update: as soon as the missile reaches the coordinates where it previously was not, that location becomes where it is, while its former position simultaneously becomes where it isn't. Integrating Historical Telemetry to Resolve Flight Error (0:43) When spatial discrepancies emerge during flight and the missile arrives at unintended coordinates, the guidance unit records a variation, defined as the mathematical gap between where the missile is and where it wasn't supposed to be. If this variation represents a significant flight factor, it is compensated for and corrected by the Guidance Electronic Assembly (GEA). To resolve data corruption or positional uncertainty caused by uncorrected variations, the system must also track where it was. When coordinates become ambiguous, the guidance computer falls back on historical parameters and what it knows of where it isn't within reason. It then executes an algebraic reconciliation: subtracting where it should be from where it wasn't (or vice versa) and differentiating that result from the algebraic sum of where it shouldn't be and where it was. This differentiation isolates both the deviation and variation, producing the final flight metric known as error. By continually balancing present, absent, past, and intended coordinates, the guidance logic reduces physical navigation to an ongoing algebraic reconciliation of deviation and variation.

精炼阅读摘要

叙述者阐述了导弹制导子系统基于反向排除与状态比对的定位逻辑，即通过持续计算导弹“所在之处”与“未在之处”的数值差异来生成修正指令。 差值逻辑与动态状态转移 (0:02) 导弹制导子系统的运行基于严密的状态推演。叙述者指出，导弹能够时刻明确自身方位，是因为其清楚知晓自己“不在何处”。系统通过将导弹“所在之处”与“不在之处”进行相减运算（取两者中较大值减去较小值），解算出被称为“偏离”或“差值”（deviation）的绝对数值偏差。随后，制导子系统将该偏差转化为控制指令，驱动导弹脱离当前坐标并前往其目前尚未处于的目标空间。伴随位置转移，空间状态发生连续更替：导弹一旦抵达原先未处于的目标位置，该坐标便即刻转变为“所在之处”，而其先前占据的物理位置则自动归入“不在之处”。 变异管理与综合误差代数解算 (0:43) 飞行过程中若实际坐标未能与预期的“未在之处”吻合，制导单元将记录两者的数学间距并将其定义为“变异”（variation）。若变异幅度足以构成显著的飞行影响因素，则由制导电子组件（GEA）介入补偿。在未修正变异导致遥测数据不确定时，导弹必须调取历史遥测数据以确认自身“曾经所在”的位置。计算机会将“应当所在之处”与“未在之处”的差值，同“不应在之处”与“曾经所在之处”的代数和进行微分，从而离析出偏离与伴生变异，最终得出被称为“误差”（error）的统一度量标准。 该制导逻辑完全建立在当前、历史与排除坐标的代数微分之上，当变异扰乱定位精度时，系统运行严格依赖于导弹对历史轨迹及合理非驻留空间的判定能力。

Detailed notes — zh

## Background 该视频由创作者 Jeff7181 于 2012 年 8 月 11 日发布在 YouTube 平台。视频时长为 1 分 40 秒，原页面未提供任何简介或说明文本。 ## TL;DR 视频以严谨的工程解说口吻，阐释了导弹制导计算机独特的定位与纠偏逻辑。其核心论点在于导弹能明确自身位置是因为它清楚自己“不在哪里”，并通过相减求出“所在位置”与“不在位置”之间的偏差，以驱动系统修正轨迹。当导弹出现未对齐的偏差时，系统会生成“变异量”，并通过将“应在位置与不在位置之差”与“不应在位置与曾在位置之代数和”进行微分，最终解算出用于制导修正的闭环综合“误差”。 ## Atmosphere & style 解说员操着一口极其冷静、专业且富有年代感的技术播音腔，通篇呈现出冷战时期军工科教片典型的严肃氛围。然而，解说词由大量高密度的套话悖论与递归式绕口令构成，在极度严肃的说教形式与荒诞反逻辑的语言游戏之间产生了强烈的反差喜剧效果。整个过程听起来既像是一场严肃的控制工程推导，又像是一段荒唐却无法反驳的逻辑催眠，充满离奇而一本正经的幽默感。 ## Bulletin - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) 导弹制导的核心逻辑建立在其对自身“不在何处”的认知之上，通过计算“所在位置”与“不在位置”的差值推导出控制偏差。 - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) 制导子系统依据计算得出的偏差生成修正指令，驱动导弹移动至原本不在的目标位置，并在到达后完成状态逻辑的递推更新。 - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) 当实际位置与目标非所处位置存在出入时，系统会生成变异量（variation），并在必要时交由作动机构进行动态校正。 - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) 在信息受扰无法确知当前确切位置的情况下，制导计算机结合过去位置与否定逻辑，通过代数和微分计算出闭环总误差（error）。 ## Key takeaways - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) 导弹始终掌握自身位置的前提，在于它在任何时刻都明确知道自己“不在哪里”。 - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) 系统通过将“所在位置”与“不在位置”相互相减（较大值减较小值），得出被称为偏差（deviation）的关键差值。 - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) 制导子系统利用位置偏差生成驱动指令，引导导弹向原本不在的位置移动。 - [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) 当导弹抵达目标位置后，该位置转变为“现在所在位置”，原先的位置随之更新为“现在不在位置”。 - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) 若当前所在位置与预期的非所处位置未能精准对齐，系统将产生表征两端差距的变异量（variation）。 - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) 当变异量被判定为关键影响因素时，制导作动系统可介入并对飞行轨迹实施动态纠偏。 - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) 即便部分信息被变异量修改导致无法确认确切所处位置，导弹依然能够笃定自身不在何处以及过去曾在何处。 - [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) 制导计算机将“应在位置与不在位置之差”与“不应在位置与曾在位置的代数和”进行微分求导，解算出系统总误差（error）。 ## Detailed walkthrough ### [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) 导弹位置认知与偏差纠正机制 解说开门见山地阐述了导弹制导的核心逻辑，指出导弹在任何时刻都清楚自己所处的位置。它之所以能够做到这一点，是因为它明确知道自己“不在哪里”。导弹通过计算“它所在的位置”与“它不在的位置”之间的差值（即二者相互相减，以数值较大者减去较小者），从而获得一个差值或称为“偏差”（deviation）。 随后，制导子系统（guidance subsystem）会利用这些偏差数据生成修正指令。这些指令驱动导弹从“它所在的位置”移动到“它不在的位置”。当导弹成功抵达那个“曾经不在的位置”时，该位置便成为了它“现在所在的位置”。依照此逻辑递推，原本“它所在的位置”现在就变成了“它不在的位置”；同理，它“过去曾经在的位置”，自然也就成了它“现在不在的位置”。旁白一本正经地宣称：“The missile knows where it is at all times. It knows this because it knows where it isn't.” ```mermaid flowchart TD accTitle: 导弹位置偏差修正机制 accDescr: 展示导弹如何通过对比所在位置与不在位置来生成修正指令并更新状态 subgraph Logic ["位置对比与偏差计算"] A["所在位置 (Where it is)"] B["不在位置 (Where it isn't)"] A --- B B -->|"相减求差"| C["偏差 / 差值 (Deviation)"] end subgraph Guidance ["制导子系统执行"] C --> D["制导子系统 (Guidance Subsystem)"] D -->|"生成纠正指令"| E["驱动移动至目标位置"] end subgraph StateUpdate ["状态转换更新"] E --> F["抵达原先不在的位置 (Now is)"] F --> G["原所在位置变为不在位置 (Now isn't)"] end ``` ### [00:43](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=43s) 变异量修正与导弹制导计算机的误差推导 然而，实际飞行中并非总是完全吻合。在导弹“当前所在的位置”并非“它原先不在的位置”的情况下，系统就会获取到一个“变异量”（variation）。所谓变异量，即导弹当前实际所在之处与原本不在之处二者之间的差距。如果系统判定该变异量是一个显著且关键的因素，它便可以交由制导作动系统（GEA/GAA）进行校正。 但与此同时，导弹还必须清楚自己“过去曾在哪里”。导弹制导计算机的具体运作机制随即展开：由于变异量篡改并修正了导弹所获取的部分信息，导致导弹无法百分之百确信自己确切在何处；但在合理范围内，它非常笃定自己“不在何处”，并且清楚自己“过去曾在何处”。解说详细说明了后续的代数逻辑：“It now subtracts where it should be from where it wasn't, or vice versa, and by differentiating this from the algebraic sum of where it shouldn't be and where it was, it is able to obtain the deviation and its variation, which is called error.” 导弹将“它应该在的位置”与“它不在的位置”进行相减（或反向相减），并将得到的结果与“它不应该在的位置”及“它过去所在位置”的代数和进行微分求导，由此最终得出其偏差以及变异量——这一最终结果在制导工程中即被称为“误差”（error）。 - 系统在位置未精准对齐时生成“变异量”（Variation），即当前实际位置与预期非所处位置之差。 - 变异量过大时，可由制导机构介入实施动态纠正。 - 制导计算机在信息受扰、当前位置不确定的情况下，依据“合理范围内不在此处”和“过去曾在此处”两个已知量重新计算。 - 通过“应在位置与不在位置之差”与“不应在位置与曾在位置之代数和”之间的微分运算，闭环解算出总误差（Error）。 ## Notable quotes > [00:02](https://www.youtube.com/watch?v=bZe5J8SVCYQ&t=2s) The missile knows where it is at all times. It knows this because it knows where it isn't. ## Mentioned The Missile Knows Where It Is..., 制导子系统, 导弹制导计算机 [Source](https://www.youtube.com/watch?v=bZe5J8SVCYQ)

Source quotes

[0:02] The missile knows where it is at all times. It knows this because it knows where it isn't.

Source quotes

[0:02] Narrator: The missile knows where it is at all times it knows this because it knows where it isn't.

Original transcript

[0:02] the missile knows where it is at all [0:04] times it knows this because it knows [0:07] where it isn't by subtracting where it [0:10] is from where it isn't or where it isn't [0:12] from where it is whichever is greater it [0:15] obtains a difference or [0:17] deviation the guidance subsystem uses [0:20] deviations to generate corrective [0:22] commands to drive the missile from a [0:24] position where it is to a position where [0:27] it isn't and arriving at a position [0:29] where it wasn't n it now is consequently [0:32] the position where it is is now the [0:35] position that it wasn't and it follows [0:37] that the position that it was is now the [0:39] position that it [0:43] isn't in the event that the position [0:45] that it is in is not the position that [0:47] it wasn't the system has acquired A [0:50] variation the variation being the [0:53] difference between where the missile is [0:55] and where it wasn't if variation is [0:58] considered to be a significant factor [1:00] it too may be corrected by the GAA [1:03] however the missile must also know where [1:06] it was the missile guidance computer [1:09] scenario works as follows because A [1:12] variation has modified some of the [1:14] information the missile has obtained it [1:16] is not sure just where it is however it [1:20] is sure where it isn't within reason and [1:22] it knows where it was it now subtracts [1:25] where it should be from where it wasn't [1:27] or vice versa and by different [1:29] differentiating this from the algebraic [1:32] sum of where it shouldn't be and where [1:34] it was it is able to obtain the [1:36] deviation and its variation which is [1:38] called error