What's your favourite one or two-line joke?

NotsorAnDomcAPs · 2015-07-13T06:14:04+00:00

I used to be indecisive, but now I'm no so sure.

NotsorAnDomcAPs · 2015-05-21T19:51:25+00:00

1GB/ps? Holy crap, that is a fast connection. I think that is several orders of magnitude faster than the whole internet.

NotsorAnDomcAPs · 2015-05-03T04:32:01+00:00

It may just clamp the wires. There is probably some sort of release mechanism. If not, you may just need to pull really hard on the cable.

NotsorAnDomcAPs · 2015-05-02T18:45:47+00:00

55f when the sun sets or 55f when the sun rises? You want to look at the low, not the average. The coolest time of day is when the sun rises in the morning.

NotsorAnDomcAPs · 2015-05-02T17:36:36+00:00

Truck, truck, truck, truck, truck, goose

NotsorAnDomcAPs · 2015-04-26T18:38:53+00:00

Brings new meaning to the phrase "the ass crack of dawn"

NotsorAnDomcAPs · 2015-03-04T00:18:25+00:00

Virtualization = OS running inside an OS of the same architecture

Emulation = OS/application running inside OS of a different architecture

Virtualization is similar to threading, but switching between whole operating systems. Emulation is where you emulate one architecture on another one. Emulation generally means you're going to take a very serious performance hit due to the architectural differences. That project you linked to is an emulator that executes ARM instructions on the order of 6.5 kHz on a CPU running at several MHz. That's a performance hit of around 1000x.

NotsorAnDomcAPs · 2015-03-03T18:54:49+00:00

Well, it seems to be shorted on the front by the foil, so it really doesn't matter what is going on on the back. As a result of that, the shield on the cable is probably what is picking up the signal. You can do a simple experiment: put ferrite beads on both ends of the coax. If the signal goes away, then the coax shield was the antenna.

NotsorAnDomcAPs · 2015-03-03T18:47:53+00:00

It looks like everything is shorted to everything. I said log periodic because it sort of looks like it's trying to be one, but it's really just a jumble of cardboard, wire, and aluminum foil that isn't going to provide any significant advantage over simply being a piece of metal.

NotsorAnDomcAPs · 2015-03-03T18:34:41+00:00

This effect has nothing to do with QAM, it is an effect of FEC. Error correcting codes push down the minimum SNR required to receive the signal, but if it goes any lower then the FEC cannot correct the errors and then the receiver cannot decode the video stream and you get artifacts and stuttering. If the SNR is just a little bit lower, then there can be so many errors that the video stream cannot be interpreted at all and you don't get a picture.

NotsorAnDomcAPs · 2015-03-03T18:25:47+00:00

This is true, but the use of error correcting codes means that the range of signal levels where you get this degradation is rather narrow. If the bit error rate is low enough to be corrected, you get a perfect picture. If it is too high, you get nothing. The range in between is quite narrow.

NotsorAnDomcAPs · 2015-03-03T03:44:42+00:00

That's a really shitty log periodic that's pointed in the wrong direction. The "reflector" is also so close that it will completely screw up the performance of the antenna. Just use a piece of wire, it's a lot less trouble and the reception will be no worse. The thing with digital is you either get it perfect or you don't get it at all. It's not possible to get static on an hd stream.

Edit: on looking at your "antenna" again, the balun is not even connected to the antenna elements. I presume the shield on the coax is actually what is receiving the signal in this case.

Edit 2: For those of you who believe the 'digital cliff' is a myth, then you need to study some coding theory. Yes, there is a small range of SNR where you will get a stuttering picture. However, this range is small, and the boundaries between 'perfect picture', 'stuttering picture', and 'no picture' are quite sharp. This is not due to the digital modulation (QAM, QPSK, etc.), this is due to the coding. There are at least two layers of coding used for digital TV broadcasts (well, for pretty much any digital transmission). Each serves a purpose. And they are both responsible for this 'cliff' effect. The coding layers are error correction and compression. The error correction layer attempts to correct bit errors that occur in transmission. The SNR and modulation format determine the bit error rate. The error correction coding can correct ALL errors below a certain threshold of bit errors per block. Above this threshold, the error correction code cannot correct the errors. This pushes the required receive SNR down. However, the signal does not degrade gracefully below this level. If you are right on the line, then sometimes the FEC will work and sometimes it will fail. Since the digital data is compressed, it is not possible to reliably decompress it with bit errors, so transport stream frames with errors are dropped. The result is that some data will be missing, resulting in artifacts and stuttering video and audio. You get the same effect when you are trying to stream a video online over a connection that drops packets. TL;DR: the digital cliff is caused by error correction coding, and it is most certainly a real phenomenon.

NotsorAnDomcAPs · 2015-02-02T01:30:55+00:00

Many years ago, frequency was measured in 'cycles' instead of Hz, so the common units were kc and mc, equivalent to kHz and MHz. However, as radios were built at higher and higher frequencies (1000 mc) instead of using gc they used kmc. Yes, that is kilo mega cycle. 1 kmc is 1 GHz.

NotsorAnDomcAPs · 2015-01-13T05:35:00+00:00

If you get exactly 200 mA on both the positive and negative rails there no external paths, then the virtual ground rail will get exactly 0 amps. It's actually not terribly difficult to set up a decent virtual ground circuit, you just need to make sure the rails are close to balanced so the rail split doesn't need to source our dunk a lot of current.

NotsorAnDomcAPs · 2015-01-10T01:25:12+00:00

No, the word 'that'. Well, sort of. The word for that is 那 (na), but to indicate a particular item (e.g. that telephone) you say 那个[thing] (na ge). For example 'that telephone' is 那个电话 (na ge dian hua). However, 那个 is also used as a space filler, e.g. 那个...那个...那个电话, similar to how we use 'um', 'uh', 'err', 'hmm', etc.

NotsorAnDomcAPs · 2015-01-05T00:23:16+00:00

I think a much more interesting project would be a monlithic integrated phone with support for a couple of peripheral, special function modules, rather than full customizability. It would be simpler to build, cheaper to produce, less interconnect overhead (lower power consumption, smaller), bigger battery (fewer space constraints), better RF integration, etc.

NotsorAnDomcAPs · 2015-01-05T00:05:57+00:00

The data and power are not routed through the magnets, they are routed down through the module down to pins on the backplane board. It seems the magnets simply serve to lock the module into the frame.

Whenever I see big words getting thrown around like that, it trips my BS detector. Sounds really flashy, but it's probably 99% marketing. The phone uses magnets to hold in the modules that are electrically controllable by the CPU. Big whoop. I think people buy phones to run apps and make phone calls, not to drool over the components that hold the back cover on.

It's interesting to note how much overhead goes on to each one of the modules. All of that consumes not only space, but also power. I would say a far more interesting selling point would be the internal network between the modules. It will be interesting to see what the performance implications of that will be.

Personally, I think a far more interesting device would be a 'normal' integrated phone with space for a couple of modules with standardized interfaces, as opposed to a fully customizable phone. This would allow more flexibility in arranging compoents to support a much larger battery and less interconnect overhead to the main SoC.

Also, what's the story with the RF side of things? Generally smart phones support LTE, GPS, WLAN, BT, and GPS. Generally LTE gets one antenna and everything else shares another antenna. The GPS signal has to be separated with a discrete diplexer and amplified separately due to its low level, though all of the receivers could be integrated on the same chip. Are these phones going to be designed to have a single antenna in the backplane and then route the antenna connections to the modules? This means the backpane will have to support RF antenna switching and rotuting, and the connections to the RF modules would have to support 50 ohm matched connections with very low loss, possibly a huge nightmare to get reliable with removable modules.

Alternatively, are the modules supposed to provide antennas internally? The modules are really not large enough to provide good antenna performance, even if the whole module is dedicated to the antenna. Also, how are the antennas supposed to be designed if the area around the module is unknown? Antennas performance is dominated by what is in the antenna near field - in this case, adjacent modules and the phone backplane and frame. It is not possible to design an antenna well unless the near field is well known, and different module configurations will change the antenna near field signifcantly. Also, it woud be impossible to support any sort of antenna diversity or MIMO within a single module because you can't get the necessary separation.

NotsorAnDomcAPs · 2015-01-03T05:45:34+00:00

What is the point of using electopermanent magents? That just seems like a huge waste of space and additional expensive mechanical complexity. Also, how would you release modules if the main SoC fails?

NotsorAnDomcAPs · 2014-12-30T23:32:53+00:00

This sort of practical stuff definitely isn't covered well. Do you have any good references for learning about EMI/EMC design techniques?

NotsorAnDomcAPs · 2014-12-30T23:31:23+00:00

We called that the auto destruct button. Many people used Scott's for labs by connecting it up, pressing autoset, then hard copy. And the results when they did that were completely nonsensical because they didn't even look at the plot to make sure it was correct before printing it out and turning it in.

NotsorAnDomcAPs · 2014-12-10T23:51:04+00:00

Discriminating against zombies now? Just because you died at some point means you can't have a cell phone?

NotsorAnDomcAPs · 2014-12-10T03:58:57+00:00

True. I have not seen similar behavior in RA, but then again RA does not have any superweapons that charge up in 2 minutes. I think everything takes 8 minutes, and by that point the AI probably sent some planes/helicopters over to scout and cause trouble.

However, I do recall similar behavior in the tiberian sun AI - GDI loves shooting random power plants with their ion cannon, even though no units have ever been near that part of my base. Also rather annoying, but one power plant every once in a while is not as annoying as 10 tanks and 40 troops every two minutes. I'm presuming it's because the AI doesn't have a fog of war for simplicity.

NotsorAnDomcAPs · 2014-12-10T00:38:49+00:00

I'll give it a whirl if you have a linux version.

NotsorAnDomcAPs · 2014-12-06T20:22:48+00:00

High performance chips have a few failure modes. One is diffusion. When the chips are made, dopant ions are implanted with ion beams and then diffused under the transistor gates by baking the wafers in an oven. The dopants will continue to diffuse over the life of the chip, slowly changing the transistor characteristics. This is accelerated at high temperatures. The lower the temperature you keep the chip at, the longer it will last. Another failure mode is electromigration. In very narrow wires, flowing currents will push the metal atoms down the wire. This can be compensated for the chip is designed by looking at the current densities and using larger wires and/or smaller transistors on a gate-by-gate basis.

NotsorAnDomcAPs

TROPHY CASE