Negative ambiguity
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This sounds like it should be a technical term in one discipline or another. I did a Google search for "negative ambiguity" and received 42,800 hits, a negligible number of them false because of punctuation issues. They occur in contexts that fall under psychology, economics, sociology, language and linguistics (grammar, syntax, scope, attachment, translation, etc.), sexuality, business and administration (leadership), investment, finance, tourism, education, biology, military science, politics, race studies (identity), etc.
One of the most prolific sources for the use of "negative ambiguity" is in this low key but still extraordinary paper by WANG Bo1, XIE Junwei1, ZHANG Jing2, and SUN Bosen3 in Journal of Beijing University of Aeronautics and Astronautics ›› 2020, Vol. 46 ›› Issue (1): 122-132. doi: 10.13700/j.bh.1001-5965.2019.0133, "Negative ambiguity function characteristics simulation of FDA", where it occurs frequently.
1. Air and Missile Defense College, Air Force Engineering University, Xi'an 710051, China
2. Shaanxi College of Communication Technology, Xi'an 710018, China
3. School of Information, Xi'an University of Finance and Economics, Xi'an 710100, China
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Received:2019-03-27Published:2020-01-21Supported by:National Natural Science Foundation of China (61503408)
Here's the abstract:
Considering that the existing extensive research on frequency diverse array (FDA) is mainly working on the assumption that single-carrier frequency signals are transmitted under narrow-band conditions. And there is a lack of relevant research on the issue whether linear frequency modulation signals are suitable for FDAs. Considering that ambiguity function based optimization is an important means of radar's waveform design, based on the establishment of FDA data model, this paper establishes FDA negative ambiguity function under linear array transmission and single-antenna reception model and analyzes its main characteristics systematically. On this basis, the characteristics of FDA negative ambiguity function based on rectangular pulse, linear frequency modulation (LFM) signal and different nonlinear frequency offset are simulated and compared. The performance of target range-angle two-dimensional joint estimation of FDA using different nonlinear frequency control functions is compared. The simulation results verify that the FDA ambiguity function is correct, and the performance of FDA with sinusoidal frequency offset is the best. This lays an important foundation for the complex signal FDA waveform design based on ambiguity function and the transmission waveform design based on FDA beampatten [recte beam pattern] decoupling technology.
Most Language Log readers will undoubtedly recognize that "frequency modulation" is where our abbreviation FM (radio transmission) derives from, but it has other applications:
Frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. The technology is used in telecommunications, radio broadcasting, signal processing, and computing.
(source)
The reason I thought about "negative ambiguity" at all is because, under that heading, Stephen Hart sent me the following note:
This quote appears in numerous publications:
"Why aren't people in general not talking more about the pot psychosis-violent behavior connection?"
— Fox News host Laura Ingraham
Ingraham's quotation even made it into Doonesbury several days ago.
As I set about trying to parse what she said, I wondered whether “are” and “aren’t” might (not [!]) have been confused when transcribing from audio. But the transcriptions throughout the media are essentially identical in writing "aren't". Was Ingraham misnegating?
Selected readings
- "Ambiguous triple negative" (8/11/21)
- "Nothing that wasn't something one might not hear" (2/25/10)
- "Double lie toe tease" (3/14/12)
- "Nondisunnegativity" (12/11/12)
- "Evidential 'ain't' on the hustings" (11/1/08)
Gregory Kusnick said,
June 4, 2022 @ 10:17 am
Looks like misnegation to me, if the transcript is accurate.
In the radar abstract, note that "negative ambiguity" doesn't appear without "function", but "ambiguity function" does appear without the "negative" modifier. So I surmise that they're not talking about a function that calculates "negative ambiguity", but rather an ambiguity function whose output is used in a negative sense, e.g. in a negative feedback loop.
Victor Mair said,
June 4, 2022 @ 10:24 am
Excellent point, Gregory!
Victor Mair said,
June 4, 2022 @ 8:34 pm
From Mark Metcalf:
As a recovering electrical engineer who has translated many technical papers over the years, I found the thread on negative ambiguity functions quite interesting.
My first stop was the Institute of Electrical and Electronics Engineers (IEEE) Xplore database to see if the term "negative ambiguity function" appeared in any journals or conference proceedings – it didn't.
So I looked for alternative translations and the one that seemed to make the most sense was "to bear" or "to rely on" – as in "relying on ambiguity functions". That would change BUAA's translation of "频率分集阵列负型模糊函数特性仿真" to something closer to "Simulation of FDA relying on ambiguity function characteristics." Since I don't have access to the complete article, I can't see how the title/abstract corresponds to the actual text. But given the challenges of translating Chinese technical documents, I thought that I'd throw this out there. I'm almost to the point that I'd argue that if you want to reliably translate Chinese technical documents, you also need to be conversant in the details of the technology that you're translating.
FWIW, due primarily to the extensive use of transliteration, Russian technical documents are significantly easier to translate. ICYMI – a decades old IEEE article on technical Chinese translation is attached. [VHM: omitted here; available upon request]
Abstract: Considering that the existing extensive research on frequency diverse array (FDA) is mainly working on the assumption that single-carrier frequency signals are transmitted under narrow-band conditions. And there is a lack of relevant research on the issue whether linear frequency modulation signals are suitable for FDAs. Considering that ambiguity function based optimization is an important means of radar’s waveform design, based on the establishment of FDA data model,this paper establishes FDA relying on ambiguity function under linear array transmission and single-antenna reception model and analyzes its main characteristics systematically. On this basis, the characteristics of FDA relying on ambiguity function based on rectangular pulse,linear frequency modulation (LFM) signal and different nonlinear frequency offset are simulated and compared. The performance of target range-angle two-dimensional joint estimation of FDA using different nonlinear frequency control functions is compared. The simulation results verify that the FDA ambiguity function is correct,and the performance of FDA with sinusoidal frequency offset is the best. This lays an important foundation for the complex signal FDA waveform design based on ambiguity function and the transmission waveform design based on FDA beam patten decoupling technology. (http://open.oriprobe.com/articles/58102941/Negative_ambiguity_function_characteristics_simula.htm)
现有研究主要是关于频率分集阵列(FDA)基于阵元发射窄带条件下单载频信号的假设而展开的,缺乏对线性调频(LFM)信号是否适用于FDA问题的研究。考虑到基于模糊函数的优化是雷达波形设计的重要手段,在建立FDA数据模型的基础上,建立线阵发射、单天线接收模型下的FDA负型模糊函数,系统分析其主要特性。在此基础上,仿真分析了基于矩形脉冲、线性调频信号以及采用不同非线性频控函数的FDA负型模糊函数特性,对比了采用不同非线性频控函数的FDA的目标距离-角度二维联合估计性能。仿真结果在验证FDA模糊函数建立正确性的同时,得出采用正弦频控函数的FDA性能最优的结论。从而为基于模糊函数的复杂信号FDA波形设计以及基于FDA方向图解耦技术的发射波形设计奠定了重要基础。
Victor Mair said,
June 4, 2022 @ 8:44 pm
Mark's long comment corroborates Gregory's surmise.
ktschwarz said,
June 6, 2022 @ 12:25 pm
Mark Metcalf questioned the translation of 负, simplified form of 負; Wiktionary includes "rely on" and "(mathematics, electricity, etc.) negative" among possible translations. I tried googling "负型模糊函数" and "negative ambiguity function" and found several more hits in the field of radar, e.g. a tutorial website and a book Synthetic Impulse and Aperture Radar, which give equations defining both positive (正型) and negative (负型) ambiguity functions. "Positive" and "negative" refer to the sign of the time variable in the integral. So the English version of the paper's title is indeed correct, and their "negative ambiguity function" is a technical term, even though it hasn't been widely used enough to make it into the IEEE database.
The use of "FDA" and "LFM" in the Chinese abstract quoted by Mark is typical of how Chinese can use English acronyms, as discussed often in Language Log.