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I think the discussion here is missing something. The issue isn't "shielding" the radio. Modern power electronics, including Hybrid/EV drivetrains and modern el
by quailfarmer 4y ago
I think the discussion here is missing something. The issue isn't "shielding" the radio. Modern power electronics, including Hybrid/EV drivetrains and modern electronic transmissions, produce in-band interference for broadcast AM. If you shield the radio, you're blocking the _signal_, as well as the noise. The only solution is to shield the power system (including the drive motor). This can add significant cost in both engineering and production, and interfere with thermal management (gaps let out hot air and RF!). Of course, with enough effort, anything can be shielded, but most EMI emissions masks I work with only go down to 30Mhz! Single MHz is below the range of "RF" and within the range of "Power Electronics" in the minds of modern engineers.
The real issue here is that while FM made the switch to hybrid Analog+Digital, AM is still living in the past. The technology has not changed in literally a century. The FCC has authorized hybrid AM operation, but there hasn't been any real adoption. We have 100 years of signal processing magic, and it would be so much cheaper for car manufacturers to include a single chip than to properly shield drivetrains just for AM radio backwards compatibility.
We should have spread-spectrum orthogonal-multiplexed radio beamed to the entire country from space. 100 geo-coded channels, and your car automatically plays the one for the region you're in. Adapt or die, but the high power future isn't going to wait up for AM.
- serf 4y agoICE engines have been try to pollute AM bands since forever with their ignitions and other high voltage discharge systems -- that's why they're usually fairly shielded. HID headlights created huge interference problems on the earliest cars to equip them -- now they're shielded. The early Prius model owners could famously tell when the ICE engine was about to begin operating due to the ICE ignition system beginning charge and causing AM interference, which then became much more pronounced upon activation and ignition discharge. I guess my point is that these were all tremendously noisy sources that got remediated -- I worry for the RF noise floor across the board when companies are no longer incentivized to chase such gremlins.
- News-Dog 4y agoOne of the many sources of generated noise that interferes with AM reception. Broadband over Power Lines (BPL) : https://en.wikipedia.org/wiki/Broadband_over_power_lines https://en.wikipedia.org/wiki/Broadband_over_power_lines >On August 3, 2006, FCC adopted a memorandum opinion and an order on broadband over power lines, giving the go-ahead to promote broadband service to all Americans. The order rejected calls from aviation, business, commercial, amateur radio and other sectors of spectrum users, to limit or prohibit deployment until further study was completed. FCC chief Kevin Martin said that BPL. "holds great promise as a ubiquitous broadband solution that would offer a viable alternative, to cable, digital subscriber line, fiber, and wireless broadband solutions".
- whoopdedo 4y agoWhat good would digital AM do here? Instead of an analog channel filled with engine noise you'd have a bitstream with a high error rate. Neither one is letting your signal through. And 100 channels? There are 4484 AM licenses in the US, 6686 FM commercial, and 4207 FM non-commercial. (https://www.fcc.gov/media/broadcast-station-totals https://www.fcc.gov/media/broadcast-station-totals) That would completely eliminate the last struggling bit of local media ownership.