Unfortunately FMCW lidar is sweeping the lasers across the same band. You don’t need the exact frequency just a beat frequency that’s within your detection Bw.
Also balanced detectors have something called common mode rejection. This is not infinite. In high volume applications it’s difficult for this to be >25dB but you can buy some devices >35dB.
Given that Lidar dynamic range is ~100dB you will definitely see the DC. I’ve not thought about this too much but it seems like an issue for the AGC as your demodulator won’t be bothered by it.
Unfortunately the gain falls as function of temperature so you also get a lot less light and you have to pump harder (more current). So while it’s possible to somewhat compensate somewhat with the mirrors the device still has this behavior at high temperatures as the device self heats. This behavior is widely documented in the literature.
VCSELs have a smaller current aperture and the current density is higher than in an edge emitting laser. As the reliability is a function of the junction temperature and the current density, VCSELs operating at high temperatures have significantly reduced lifetime compared to an edge emitting device due to the high current density.
See for example slide 5 which shows how lifetime scales as a function of temperature and current density. For high reliability your devices need to have low current density.
If the device is reliable then you should quote a FIT number. A very good VCSEL based transceiver in an indoor environment has a FIT of about 100 at Tj~65C and a CI of 60%. If we assume your FIT rate is similar (it won’t be because your operating conditions are more difficult) and have 128 of these devices your FIT rate ~12800 (assuming independent failures). This puts your MTBF at around 8.9years.
Some transceivers have a FIT rate of ~300FIT so if that’s the case your rel will only be 3 years.
The issue will not be at cold but at high temperature. VCSELs have very poor efficiency at high temperature and it’s possible to operate them where increasing current reduces light output. In a vehicle application the temperatures are very high and humidity can also be very high and condensing.
Imagine every car has a FMCW LIDAR. The chance of interference is very high. Additionally if those receivers are using SE PDs, then these sensors will also be “blinded” (TIAs and or PDs will saturate) when a nearby Lidar system shines its laser into the detector.
Used to be a Microcenter in Santa Clara. It was a good store and huge. But it closed a few years back. At the time it seemed like it suffered from the same problem as Fry’s. Sounds like maybe they regrouped and are doing better now.
The future of these interconnects is to make them optical. Once the interconnects are optical lots of problems get solved. Chips don’t have to be in same enclosure, simplifying cooking etc.
Having worked in a large company that is famous for its feedback culture, I think the type of feedback culture you refer to is hard to scale. While I think it helps people improve, I’ve mostly seen how feedback is used to hurt people.
It’s funny how these modern companies are rediscovering the old rules for behavior. When I was young it was a given that you didn’t discuss politics, religion, etc...
I’ve always read that binary systems seem to be the norm and stars like our Sun the exception. Is it possible stars like our Sun form from binary protostars that form too close together and collide to form a single star? Or do we have plentiful examples of single protostars?
The implicit assumption here is that you can always change jobs. That’s not true if the economy is bad. We now have a generation of people in the workforce that have not seen a downturn. Back in 2001-2003, I was locked into a startup that cut our already below market pay by 20% due to the poor job market at the time. There are simply times when it is difficult to move companies due to macroeconomic trends.
Yet another reason not to have so much concentration in a single person. If we had smaller or more distributed social networks it would be impossible to control the spread of E2E encryption.
Sorry but I don’t agree this is a bug. You need to decode your bytes to properly write a string. Otherwise you get the unexpected result you are showing because it has no way of knowing how your bytes are encoded.
This is a cool article. It raises all kinds of interesting questions.
I’ve often wondered if it’s possible to have consciousness as we experience it without language. When I think, I do so in words so I can’t imagine how I would do that without words. I also wonder if you lack language; say you were raised by wolves; would you create one in your mind.
Most people get paid electronically. A lot of things people don’t realize is that at 330M+ people, the US has a lot of legacy systems due to the sheer size of the population.
I am as American as they come but wealth as reported by this article is a false metric. The Swiss have an amazingly high quality of life and standard of living. For most Americans, I don’t think our quality of life is anywhere near what it is in Switzerland.
The cost of installation is why I don’t have solar. While I agree 25 year life is a limitation on adopting better panel technology, it’s hard to justify the installation costs at shorter intervals.
Maybe if you had the money to grow up with a computer and had people around to help you. I didn’t program until 1991 in Turbo Pascal. It was a terrible experience and somehow it was something you were supposed to already know. On the Vax or Unix machines in the lab, literally nobody was helpful. If you asked a question people would bark “read the man page.”
I had my first major career failure this year and lost a very good job. I was able to land another good job quickly but I’ve been full of doubt and am seriously lacking in confidence ever since. I can’t sleep and have anxiety. The new job has significantly more responsibility and in many ways the pressure that the author describes in rewriting Slack is very similar to what I’m going through. Every time I have a setback at work I am afraid of losing my job. I finally recognized this as burnout and am trying to come back from it but it’s a slow process. I’m trying to exercise more and get enough sleep but the sleep part is still not working all that well.
I think so. I grew up surrounded by WW2 vets that had seen lots of combat and lived through the Great Depression. They were good men but they were pretty hardened people.
I don’t think the GP was implying that everyone gets severance. Generally employers are often in legal grey areas when they are letting people go; particularly in cases where there is no legal or policy violation. In these cases they often try to bully you into giving up your rights. Severance is payment for agreeing to waive your right to sue for wrongful termination.
I am into motorcycles and so there are plenty of forums for that. In the Bay Area we have 2 active forums. A problem is that Facebook has eroded it a bit. I also mountain bike and there are also forums for that. One of my favorites is a garage forum for people who deck out their garages. Cool to see concepts people come up with for garage workshops. All those sites seem supported through ads related to the specific topic.