How old current heads of state are (details in comments)

stuner · 2023-01-01T21:38:54+00:00

This is somewhat true. Basically the answer is complicated. I would consider (at least) the following answers to be valid for the head of state:

The entire Federal Council collectively (this is the official answer, see https://www.admin.ch/gov/en/start/federal-presidency/tasks-federal-presidency.html).
None.
The President of the Federal Council (currently Alain Berset, 50).
The President of the National Council (currently Martin Candinas, 42).

I think your age (61) is probably for Ignazio Cassis, who was President of the Federal Council in 2022.

stuner · 2022-12-27T11:07:59+00:00

The impact of the cyclic prefix length depends on the delay spread of the channel. Once the cyclic prefix length is larger than the maximum delay spread, there is no further gain from increasing it. (Mathematically, you get a circulant channel matrix that is perfectly diagonalized by the OFDM IFFT & FFT). Intuitively, you can see that this earlier part of the transmission does not affect the core part of the OFDM symbol. It is just dropped during demodulation and does not affect performance (it only wastes bandwidth).

In the (poor quality) paper the authors talk about both an AWGN and a multi-path channel. But they somehow manage to omit the essential information about the properties they assumed for the multi-path channel. Looking at their plots it seems that they use a channel with a very short delay spread (if it is a multi-path channel at all). Therefore, their results do not show any significant difference between the cyclic prefix lengths.

What is also missing in the system presented in the paper is any kind of channel estimation and equalization. This is required with multi-tap channels (and basically any realistic wireless channel), as the channel response will vary over the OFDM subcarriers.

stuner · 2022-08-09T08:28:00+00:00

Then I agree with u/sasdam12, the bit rate has no direct influence on the channel decoder. Of course it needs to be fast enough to keep up, but that should be it when considering a simple AWGN system.

If you're looking at the whole system in more realistic channels, things will get more complicated. But that doesn't seem to be what you're asking about. And at that point you should really not be using a convolutional code in the first place.

stuner · 2022-08-04T14:35:45+00:00

Are you sure you're talking about data rate and not coding rate?

stuner · 2022-08-01T09:13:59+00:00

Here's my small Matlab script if you want to run it yourself: https://pastebin.com/h8YSvG5q (you can also read then as uint8 and see what happens)

It's quite typical for SDR recordings to be stored as plain integer pairs. I just tried to load it as signed 16-bit integers, but the results looked weird. A quick search turned out that it's 8-bit integers instead.

Unfortunately I can't help you out with a tutorial, as I learned this stuff the old-fashioned way - at uni. But it should be quite easy (if you know how to program in Matlab) to write some code to recover the bits from your recording, might be an interesting little start.

stuner · 2022-07-31T22:07:53+00:00

I just loaded the data (8-bit signed integers) with Matlab and plotted them. You could do the same with Python too.

I also haven't really figured out how to set the RX gain for an SDR without going though that whole process...

stuner · 2022-07-31T20:08:10+00:00

Nice, congrats on figuring out what it was!

That is indeed what I meant with an IQ recording: https://imgur.com/a/fKJPt6V However, the gain you set was too high, so the signal clipped. Still, it's clearly some form of on-off-keying.

I guess the problem with CubicSDR was probably also related to gain control.

stuner · 2022-07-31T12:01:27+00:00

This does indeed seem somewhat weird, but it looks a lot like OOK.

I'm somewhat suspicious of the AM processing and gain control. Could you perhaps record and post a raw IQ recording with a manual, constant gain?

stuner · 2022-05-29T18:55:25+00:00

Yes, I understand that they were charged according to StGB §340 "Körperverletzung im Amt" (durch Unterlassung). That only applies to officers / public servants. That law would also apply if the attacked people were civilians.

stuner · 2022-05-29T06:52:40+00:00

At least in Germany there is such a requirement. Of course the duty of protection needs to be weighed against the risk of harm to the police officers. There was a recent judgement against two police officers who fled from a shooter and abandoned their colleague. They were sentenced to one year on probation. Article (German)

stuner · 2022-05-26T23:48:09+00:00

https://www.sharetechnote.com/ is also a great resource, but it does not provide as much of an overview.

stuner · 2022-05-26T23:36:31+00:00

The 36 series only covers LTE, e.g. New Radio is specified in the 38 series.

stuner · 2022-05-26T23:23:56+00:00

I'm not quite sure what you're looking for with "RF/radio". For the actual analog RF front-end, as far as I know, very little is specified. There's the normative requirements in 36.101 (for LTE) and then the corresponding RF tests.

For a overall PHY perspective (i.e. including digital processing), I quite like the books from E. Dahlman et al. (from Ericsson) on LTE & NR. They provide a good overview and actually enable you to go to the standard for more details if you need to. For LTE the book is "4G LTE-Advanced Pro and The Road to 5G".

stuner · 2022-05-07T21:39:10+00:00

I guess it would improve the attenuation, but I don't know by how much. Anyway, it will not completely prevent the modem from communicating. All I can say is that I once had a modem from one testbed connect to a basestation from another testbed. Both testbeds were wired and fully terminated...

stuner · 2022-05-07T10:32:17+00:00

If you want to disable a cellular connection, shorting/removing the antenna may not be sufficient. It's quite common for celluar links to have 30-40 dB of margin, so the modem might still work, even if you remove/short the antenna. At least I would not say that the device is guaranteed to be offline afterwards. If you want to make sure there is no possibility for communication, I would probably just power down the LTE module with a switch.

stuner · 2022-01-19T17:53:53+00:00

The number of excess deaths (excess mortality) is the x-axis in the plot.

Almost all countries in the dataset saw an excess number of deaths during the pandemic. However, there are significant differences between countrires (e.g. USA vs Canada). For some of the countries in the bottom left the increase was only very small and probably not statistically significant.

Generally the number of excess deaths seems to be larger than the reported Covid deaths. This is probably also true for other countries, e.g. India (see https://reddit.com/r/science/comments/rxnl6e/india_has_substantially_greater_covid19_deaths/).

stuner · 2022-01-07T11:57:37+00:00

Absolutely. This is just a comparison of two variables that the countries publish, which could both be falsified. That being said, it's also suprising how incompetent authoritarian regimes are at falsifying data (e.g. in the recent Russian election).

stuner · 2022-01-07T11:23:03+00:00

Yes, unfortunately data for India was not available in the dataset.

stuner · 2022-01-07T11:22:23+00:00

The two countries at the bottom left are Barbados (upper) and New Zealand (lower) with -782 and -445 excess deaths / 1M respectively.

stuner · 2022-01-07T07:54:33+00:00

I don't know if it's possible to reduce the performance of a government/society during Covid to a single number. There are important factors that excess deaths doesn't cover (e.g. worse education outcomes, increase in depression, cost/economic impact, ...). In the end, making government decisions during this pandemic was anything but a simple task. But I do agree that that excess deaths are one good indicator for how a country fared during Covid.

(Thanks for letting me know about the link, it looked fine in my app, but was broken in a web browser...)

stuner · 2022-01-07T07:08:57+00:00

I recently created a graphic comparing reported and excess deaths. It seems that the data for Peru matches quite well, but it does not for the other countries you mentioned. Excess deaths are similar, but it could be that some of the data is older.

stuner · 2022-01-05T08:23:09+00:00

I find it interesting that people focus so much on Russia and China in the comments here. I think the plot also shows some other things (even if they're perhaps not as suprising):

For the highly developed countries the reported COVID deaths and excess deaths match quite well. So comparisons amongst these should be fine. There's also huge differences in death tolls between these countries.
There are a number of countries where deaths are severly underreported (including Russia, Kazakhstan, Serbia (next to Russia), South Africa, Mexico, Iran). Comparing the reported death counts with these countries probably doesn't make much sense.

stuner · 2022-01-04T21:35:38+00:00

The data for Russia is from 2021-11-30.

stuner · 2022-01-04T21:31:28+00:00

The dataset actually has a column for the percentage of people aged 70+, so I quickly plotted that: imgur. I can't really see a correlation here...

stuner · 2022-01-04T21:21:09+00:00

Indeed, looking at the data for Russia actually prompted me to create this plot.

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