Where does jamming collide?

Jamming is the deliberate transmission of interfering energy to disrupt a communication or radar link, degrading or denying the target signal at its receiver. Scholtz's 1982 The origins of spread-spectrum communications traced how the need to resist jamming drove the development of spread-spectrum radio, and Basar's 1983 The Gaussian test channel with an intelligent jammer modelled the jammer as a strategic adversary that spends power to force the largest possible error on the receiver. The practice is much older than these papers, reaching back to early twentieth-century radio, but the referent here is engineered adversarial interference in a channel, scaled by power and error rate, and it has nothing to do with grains locking into a rigid solid or activists reworking an advertisement.[1][2]

Unit

A jamming transmission, described by its power, bandwidth, and jamming-to-signal ratio

Recovery means

Not applicable

Measured by

Quantified by the jamming-to-signal power ratio and the resulting bit error rate at the receiver

Culture jamming is the subversive reworking of mass media and advertising so that their own images and slogans are turned against them, a tactic of media activism. Dery's 1993 pamphlet Culture Jamming: Hacking, Slashing, and Sniping in the Empire of Signs gave the practice its first extended treatment, borrowing a term the band Negativland had used in 1984, and Harold's 2004 Pranking rhetoric analysed it as a rhetorical strategy that parodies and redirects commercial messages rather than simply opposing them. The referent is a cultural and political practice of appropriation, judged by its rhetorical effect on audiences, and it is unrelated to interference aimed at a radio receiver or to particles that pack into a rigid solid.[3][4]

Unit

A single act of media appropriation, such as an altered advertisement or spoof campaign

Recovery means

Not applicable

Measured by

Assessed qualitatively by rhetorical and cultural analysis of the reworked message and how audiences receive it

In soft-matter and condensed-matter physics, jamming is the transition by which a disordered collection of grains, bubbles, droplets, or particles stops flowing and rigidifies into a solid-like state as its density rises, its temperature falls, or the stress on it drops. Liu and Nagel's 1998 Jamming is not just cool any more proposed that these varied systems share a single jamming transition and sketched a phase diagram organised by density, stress, and temperature. The referent is a physical change of state in a many-particle system, tracked through packing fraction and the onset of rigidity, and it is distinct from interference broadcast at a signal or from the cultural reworking of advertising.[5]

Unit

A many-particle system at or near the density where it becomes rigid

Recovery means

The packing can unjam and flow again if density falls or the applied stress rises past a threshold

Measured by

Characterised by packing fraction, average contact number, and the emergence of a finite shear modulus