Comment by jttnr | Hacker News Reader

Comment by jttnr | Hacker News Reader

Parent Full thread

My first car, a Hyundai i10 I bought back in 2010, was very basic and had few features. It only had a simple radio with an FM/AM tuner and a CD player, no navigation system.

What surprised me most was that the clock adjusted itself automatically whenever daylight saving time started or ended.

There was no calendar or date setting, so I assume it must have received the time either via RDS (I don't know whether RDS supports this) or through a built-in DCF77 receiver.

All my subsequent cars had far more features, yet none of them had this one.

I also wonder why cars with built-in GPS navigation don't synchronize their clocks using the time from the GPS signal. Heck, the car could even determine your time zone from your GPS coordinates, so there'd be no need to configure anything manually.

Must be RDS.

Checking wikipedia, there is optional support for transmitting time and date in RDS, with an explicit usecase of updating the clock in cars.

> I also wonder why cars with built-in GPS navigation don't synchronize their clocks using the time from the GPS signal.

GPS doesn't transmit timezone information, nor does it transmit leap seconds. It transmits a very, very accurate UTC minus 18 seconds, but without access to the internet for timezone database updates or (until recently) leap seconds, it's a bit useless for updating a clock.

Since it also provides fine grained location info, with a TZ database it is going to be dramatically better than what is going on.

Then just let the user override TZ offsets or the like if they want.

I think now that leap-seconds are gone, the built-in TZ database approach (with user override) becomes a lot more viable.

I'm not sure if you guys read the article, but OP's car does use GPS for the time, applying a user-settable offset (or in OP's unfortunate situation, a fixed offset).

GPS doesn't but Galileo, GLONASS, and BeiDou all do (no idea about Michibiki). Are car receivers still GPS only these days?

It did in the 1999 Mercedes-Benz S-Class I purchased after 15 years of insane depreciation.

I thought I broke the clock with a DIY repair because it too couldn’t be manually set (aside from enabling a +30 min offset). Luckily it fixed itself after driving out of the garage when it found a GPS signal.

Reply on news.ycombinator.com