Legal status of spectrum analyzers in the United Kingdom
<p>What is the legal status of <a href="https://en.wikipedia.org/wiki/Spectrum_analyzer" rel="nofollow noreferrer">spectrum analyzers</a> in United Kingdom? Is it considered 'interception', despite only analyzing the magnitude of a frequency?</p>

<p>Presumably this refers to the <a href="https://www.legislation.gov.uk/ukpga/2000/23/contents" rel="nofollow noreferrer">Regulation of Investigatory Powers Act 2000</a>, and the <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/401866/Draft_Interception_of_Communications_Code_of_Practice.pdf" rel="nofollow noreferrer">government's advice</a> regarding interception of communications, where</p>

<blockquote>
  <p>Section 1(1) of RIPA makes it a criminal offence for a person
  intentionally, and without lawful authority, to intercept in the United
  Kingdom (UK) any communication in the course of its transmission if
  that communication is sent via a public postal service or a public
  telecommunication system.</p>
</blockquote>

<p>The act apparently does not define what constitutes "interception".</p>

<p>A spectrum analyzer performs a kind of mathematical analysis on a physical signal which (very roughly put) says "here, the higher frequencies are loud and the mid-range frequencies are soft". You could subject a phone conversation to this analysis and get some information about an individual saying "Let's kill him" (information about "what that utterance sounds like"). In theory you might be able to figure out that a person said "Let's kill him" using that output, but that's close to the realm of science fiction than doable practice. But it's not clear whether that matters for the law. That is, the law isn't stated in terms of methods of extracting usable and possibly damning evidence from some transmitted signal, it simply prohibits "interception".</p>

<p>A frequency analyzer might be mostly hardware or mostly software, and points in between. The machinery itself is legal, and can be used legally or illegally (mostly legally), just as a tape recorder can be used legally or illegally. It would be illegal to record a phone conversation (recording is a form of interception, one that preserves most of the information in the signal). It would, technically, be illegal to spectrum-analyze a phone conversation (another form of interception, one that doesn't preserve enough of the information to be of use for prosecution). There isn't anything in the act that says "but interception is legal if the product is not practically usable in a prosecution".</p>

united-kingdom radio