garphunkle (u/garphunkle)

garphunkle commented on Live coding interviews measure stress, not coding skills hadid.dev/posts/living-co... · Posted by u/mustaphah

garphunkle · 7 months ago

I thrive in high-stress situations (for short periods of time). Examples include hardware validation before a large production run, putting out literal fires in manufacturing sites, and working in foreign countries to troubleshoot/rework bad hardware. I do fine in live coding interviews, they don't feel much different than being alone at an editor for me.

I was interested by the author's statement: "Working memory is the most reliable proxy (I know of) for fluid intelligence, your ability to reason, solve novel problems, and think abstractly." and the linked study (https://pubmed.ncbi.nlm.nih.gov/21037165/). My working memory is not so great, but it degrades less under stress.

Question worth considering for hiring managers: do you prefer stress-capable employees, or greater working-memory employees? Is my model a false dichotomy?

garphunkle commented on Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More bicyclerollingresistance.... · Posted by u/jacksgt

ActorNightly · 2 years ago

Its totally possible to hit over 40 mph on steep hills on an MTB, especially if you weigh more. I was more referring to slight grades with just pure rolling without pedaling.

Im in Austin so I frequent COTA Bike nights on Tuesdays on the track. Coming down the hill from turn 1 with other riders is a very good test of aero efficiency, because there is a slight uphill after the bend. Couple of my friends ride gravel bikes, one of them is heavier than me, and its pretty clear that that my bike is more efficient.

garphunkle · 2 years ago

Shout-out to Violet Crown, PHENOM, Breakfast Club, UNITED, Night Owls, and all the other great cycling clubs in Austin! Wonderful community that I still miss.

Have you tried swapping bikes with your buddy? Are you two the same height/weight? Who has the more flexible spine? It would be fascinating to measure aerodynamic efficiency for two riders on the same bike. Is the more variation within populations, or between populations?

garphunkle commented on Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More bicyclerollingresistance.... · Posted by u/jacksgt

stephenbez · 2 years ago

What type of difference did you notice? I switched from a stock Bontrager tires to Continental Grand Prix which are supposed to be high end and didn’t really notice too much of a difference.

garphunkle · 2 years ago

Try using the Silca Tire Pressure calculator set to "Gravel Roads". This will give a safe PSI recommendation with a nod to comfort. I would ride 28mm GP4000s around 75 psi on a training ride with lots of chip seal

garphunkle commented on Bicycle Rolling Resistance: Tire Rolling Resistance Tests and More bicyclerollingresistance.... · Posted by u/jacksgt

cogman10 · 2 years ago

To add to this, unless you are actually competitively cycling (you probably aren't) this sort of thing makes pretty much no difference for someone that is using cycling for transport.

It's a bit like obsessing over the lightest frame possible. Yeah, we can get a 1lb frame made of space materials but at the end of the day it's basically something that will reduce a cyclist's average speed by like 0.1mph.

For anyone doing anything other than competitive cycling, comfort is far more important than anything else and fat wheel bikes with steel frames are damn comfortable to ride on.

A relatively heavy bike with giant wheels might take your average speed down .5 or even 1 mph. You almost certainly won't notice it.

garphunkle · 2 years ago

I'm not sure if steel frames make a significant difference in comfort. If we measure comfort as deflection or vibration, then tire choice will have orders of magnitude more importance. When you have two springs in series, the combined spring constant is dominated by the weaker spring.

I race on a carbon frame with 30mm tires, and commute on a steel frame with 38mm tires for what it's worth.

Bike weight is irrelevant on flat roads. We should be obsessing over Watts/gram of drag, not Watts/kg if you're not a climber

garphunkle commented on Bit-Banging Bluetooth Low Energy dmitry.gr/?r=05.Projects&... · Posted by u/userbinator

seanalltogether · 2 years ago

> Can a modern phone contact a BT device without being manually paired (assuming it has cooperating software on the phone)?

Yes. I manage IOT apps for android and iOS that do exactly this. You can write/read data to any bluetooth device around you that is advertising as connectable and has a GATT characteristic that supports it.

garphunkle · 2 years ago

Someday vendors will provide L2CAP support and we can all stop using GATT for bi-directional data transfer

garphunkle commented on Bit-Banging Bluetooth Low Energy dmitry.gr/?r=05.Projects&... · Posted by u/userbinator

anonacct37 · 2 years ago

Android has a BLE scanner app that can passively read info. I don't know enough about the protocol to know if that is the same thing you are referring to.

garphunkle · 2 years ago

Android allows you to initiate scanning and receive advertisements without user interaction (assuming the app has the permissions to run in the background and use Bluetooth). Advertisements are "broadcasts" or "beacons"

garphunkle commented on Bit-Banging Bluetooth Low Energy dmitry.gr/?r=05.Projects&... · Posted by u/userbinator

whartung · 2 years ago

In the movie Blackhat, the Bad Guy communicated "anonymously" with his cronies by setting up (I think) a Bluetooth hot spot in an open mall.

They all virtually crossed paths at some specific spot, where there was a radio and computer hidden in a bush.

The premise is these folks have never met, and assuming that the cronies aren't familiar with the tech and told to "go to this bench, do this workflow, enter in these codes". Rather they were told to download an app to their phone, go to this area and "start chatting", or maybe they connected to the bush server, and exchanged messages without ever having to be in the same place at the same time.

Can a modern phone contact a BT device without being manually paired (assuming it has cooperating software on the phone)? A non-hacked phone? Could they have been using just raw BLE for this?

What kind of range does BT and BLE have?

garphunkle · 2 years ago

"Pairing" in BLE-speak is a key exchange procedure so devices can establish a secure connection without performing authentication again.

BLE communication can happen inside of a "connection", or outside of a connection.

A typical device "advertises" it's presence with beacons which are broadcast on 3 channels. These beacons are user-defined, so you can use them like UDP packets. Sensor wakes up and broadcasts the current temperature.

Your smartphone can receive advertisements while scanning. Check out the insane number of beacons present in an American apartment complex.

Note: BLE connections may be encrypted, or not. That's up to you. You do not need to "pair" (exchange keys) to communicate with a connection. There are 4 "modes" to authenticate. Without an out-of-band communication mode, all are vulnerable to MITM.

The latest BLE standard improves range with a half-data rate PHY. Range is determined by transmit power and attenuation. Most BLE radios are designed for short-range communication. I've never seen one consuming more than mW, but that does not mean you couldn't make an amplifier that transmits BLE much further

garphunkle commented on Matter, set to fix smart home standards in 2023, stumbled in the real market arstechnica.com/gadgets/2... · Posted by u/Bender

simbolit · 2 years ago

The sub-headline says everything you need to know: "Gadget makers, unsurprisingly, are hesitant to compete purely on device quality."

garphunkle · 2 years ago

Lutron Electronics is a good counter example

garphunkle commented on To save money on insurance, drivers agree to intrusive monitoring technology money.com/usage-based-car... · Posted by u/mcone

garphunkle · 3 years ago

I like to joke that as usage based insurance goes to infinity, we all become uninsured drivers...

Each insurance company uses the telematics differently. While the pricing model is regulated, it is not public. There is a substantial difference company-to-company

I think this is an instance of HN-confirmation bias. We all hate monitoring, so a study or article that says UBI and behavioral modification is harmful appeals to us.

garphunkle commented on Matter Raspberry Pi GPIO Commander – Turn Your Pi into a Matter Lighting Device github.com/canonical/matt... · Posted by u/sowbug

detaro · 3 years ago

Matter is a recent-ish "smart home" protocol: https://en.wikipedia.org/wiki/Matter_(standard)

This apparently allows to have an RPi act like a lamp-type device in that protocol, with control over the GPIOs

garphunkle · 3 years ago

Matter came around after I left, but I believe it is the same as CHIP: * IEEE 802.15.4 (2.4 GHz PHY/MAC) * 6LowPAN (IPv6 for constrained devies) * Thread (Mesh network layer) * UDP or CoAP (CoAP is like http for connectionless networks)

You need a bridge to connect CHIP to the internet (e.g. Apple Home). It was cool to route IP packets directly to lightbulbs from aws, but we don't bridge the networks in practice and all incoming/outgoing traffic goes through the bridge application.