#PDF of the #FCC’s antepenultimate NOUO from March 25. This one is quite a bit spicier than the Jack Gerritsen and Conifer Communications ones: “The Federal Communications Commission (FCC or Commission) received a complaint from Allegheny County Pennsylvania Emergency Services (Allegheny County) concerning interference to its 911 emergency communications channel operating on 470.4375 MHz in Pittsburgh, Pennsylvania. On July 30, 2025, Agents from the Columbia Office of the FCC’s Enforcement Bureau (Agents) conducted an investigation and determined, using direction finding techniques, that the source of the interference to the Allegheny County system was a signal emanating from the residence of David O. Knudtson (Knudtson), licensee of amateur radio station KD3ASC. After the Agents notified Knudtson of the interference issue, he produced a handheld radio (identified as a BTech UV-Pro). An examination of the radio determined that it had been modified to monitor the Allegheny County channel, and its “Audio Relay” feature had been activated. This feature turned Knudtson’s radio into a simplex repeater that was retransmitting the Allegheny County channel. Knudtson surrendered the radio to the Agents. Subsequently, the Agents verified that the interference to the Allegheny County system had ceased.” #communications #RF #radio #law
on 02026-06-02#PDF of the #FCC’s penultimate NOUO (“notice of unlicensed operation”), from April 1, to Conifer Communications: “The San Francisco Office of the Federal Communications Commission’s (Commission’s) Enforcement Bureau has received a complaint of an unlicensed radio station operating on frequency 10.915 GHz located in Moccasin Peak, California. On September 24, 2025, Agents from San Francisco Office confirmed during an on-scene investigation that Conifer Communications was transmitting on 10.915 GHz from Moccasin Peak, California, with a license that had expired on February 12, 2024, and was not renewed.” #communications #RF #radio #law
on 02026-06-02#PDF of one of the three “notices of illegal pirate radio broadcasting” (NIPRBs) the #FCC issued in April. #communications #RF #law #radio
on 02026-06-02Blog of #FCC enforcement actions, including the Jack Gerritsen Notice of Unlicensed Operation, which seems to be the only NOUO they’ve issued since April 1, when they issued another one. Also they issued three NIPRBs in April (“pirate radio” notices, similar to NOUOs), but two of them seem to have been about two #radio stations in Jamaica, New York, on 90.1MHz and 91.9MHz. #communications #RF #law
on 02026-06-02#PDF #FCC “Notice of Unlicensed Operation” on a #ham #radio band, addressed to a Jack Gerritsen, responding to “multiple complaints from licensees in the amateur radio service concerning an unlicensed radio station operating on 146.415 MHz in Los Angeles, #California and causing harmful interference to licensed operators in the amateur radio bands.” I’m curious whether there’s a public list of all of these? #communications #RF
on 02026-06-02public-domain #video from 01944 explaining FM #radio with a simple tank-circuit transmitter (Hartley oscillator?) with a capacitive microphone in parallel with the tuning cap. His example is 40MHz with a ±40kHz max deviation (80kHz swing), which he says is the Army’s maximum deviation, plus a 10kHz guard band on each size. But in reality they used “reactance tubes” and phase modulation rather than capacitive mics for their transmitters. He says the key difference for an FM receiver is amplitude limiting (a “limiter”), plus of course FM demodulation itself, with a “discriminator”. The limiter is a vacuum-tube device that might have a transistor analogue. The discriminator is a tank, a diode, and a (bypassed) load resistor, tuned so that the “rest frequency” is at the steepest part of the tank’s Gaussian response, so basically you’re just turning FM back into AM and demodulating the AM. #electronics #history #radio #RF #communications
on 02025-12-12#video #toread about common-base amplifier design in #electronics #hardware for #RF #communications
on 02025-10-14