My best guess would be that slope detection could be converting the FM signal into AM. This happens in circuits where the response is strongly dependent on frequency (see [1]). A specifically designed filter is typically used, but a resonant circuit like the headphone wires could do something similar. But then you still need to get from AM to audible, and to do that you still need some sort of non-linearity in the system. Some possibility non-linearies could be a poor connection resulting in a whisker-style rectifier junction, or perhaps a magnetic permeability non-linearity in the headphone speakers. I'm sure there are others.

Related, but probably not relevant: Stereo FM broadcast signals in most parts (all parts?) of the world also contain an AM subcarrier. The primary FM carrier has the L+R audio content and is used by both monaural and stereo receivers. Stereo receivers make use of an additional AM modulated sub-carrier (+/- 38 kHz from primary carrier) to obtain L-R audio content. I don't believe this AM carrier is directly rectifiable because it does not manifest as envelope modulation in the full signal.

[1] https://www.electronics-notes.com/articles/radio/modulation/...

https://github.com/opencomputeproject/Time-Appliance-Project...

They do include FPGA bit streams, but it's disingenuous to claim a fully open source release.

The advantage over those IoT picture frame products was that I could use any display I wanted. A cheap 32" TV was perfect. This was key as her vision degraded. The approach also allowed anyone in the family with email to send her photos, no proprietary apps or accounts required.

She passed away mid-Covid and I didn't get to see her in her final 6 months, but she always bragged of her "picture machine." I think she was the envy of many of her fellow nursing home residents!

https://www.xilinx.com/support/documentation/application_not...

If even higher levels of reliability are needed, there are rad-hard-by-design FPGA families (e.g. Xilinx Virtex 5QV). These have a special config SRAM cell that has more charge storage sites than a conventional SRAM cell. It is less area efficient than a conventional SRAM cell, but geometry of the charge storage sites ensures that a single cosmic ray can't flip the state of a majority of them. Essentially the cell can self-correct, no scrubbing required.

People everywhere, regardless of their race, religion, politics, or wealth are generally decent and primarily interested in making a better living for themselves and their family.

Some may see this as an obvious fact about human nature. However, for someone like me who grew up viewing the world through the lens of the US media, I used to think otherwise. Travel fundamentally changed my views in this regard.

My partner, who I had recently started dating at the time, was unhappy with her job and also decided to take the leap. In 2011, we spent 313 days traveling around the world together. Ten years later, we're still together!

As for trip logistics, very little was planned in advance. We both gave up our apartments and put our belongings in storage with friends and family. We started the trip with one-way tickets from the USA to Asuncion, Paraguay. Not a common first destination on a RTW trip, but we had used miles and the cost was the same price to go to a relatively obscure place rather than a more common one. Paraguay is a fun one if you are vegan/vegetarian, but that's another story.

Prior to the trip I had stockpiled a decent amount of frequent flyer miles. The late 2000's were crazy with respect to mile program promotions, but that's a whole different story! Those miles helped offset most of the long-haul travel costs but on the ground we preferred to travel as cheaply as possible with buses, trains, etc. The main thing the miles enabled was access more remote and uncommon destinations. As an example, one of our travel days took us from Mongolia to Palau. I don't think that's a common origin-destination pair.

I will second what others have posted here about moving slow. The places we have the fondest memories of are the ones where we spent the most time. This cuts both ways though. When you are traveling/living this lifestyle it can take some effort to find that magical mix of affordable housing, good food, and interesting activities. When all those factors align, it's easy to "get stuck" and then later have to cut things from the larger itinerary. Burn out from being on the road is another real factor. We felt it strongly at about the 6 month mark, which, conveniently was timing with a detour back home for my brother's wedding. After that we were eager to get back on the road.

Regarding costs, we found the trip to be quite affordable. Our burn rate over the year averaged out to 1000 USD per month per person, however, we had intentionally avoided the more expensive parts of the world (e.g., Europe, OZ/NZ, etc.). Aside from a few splurges, we chose to stay in budget hotels/guesthouses wherever possible. We had also offset much of our long-haul travel costs with airline points/miles.

I would love to take a trip like this again and I'm glad I didn't save this experience for retirement. I can't speak highly enough of doing something like this if you have the means.

If anyone is interested in more details about the trip, I kept a blog here:

http://www.roamingryan.com/

A real world example is GPS, which uses a spreading code to provide about 30 dB of gain. GPS signals aren't directly observable relative to the noise floor in many receivers. It's not until after the signal is "de-spread" that it becomes observable in a spectrogram. This process requires prior knowledge of the signal structure.

In short, if you don't need to send data at high rate there are many ways to hide your signal.

Only the OneWeb sats at LEO can deliver on the latency requirements.

It will be interesting to see what happens as the FCC reviews the "long form" applications.

Given the state of OneWeb, it seems very unlikely they will be able to deliver even across such a tiny geographic area.

No doubt the scummy high frequency traders are already jockeying to get out in front of this change in the telecom industry.