3 ms·

The "fancy" sound driver on my companys HP ZBook does use 500MB Ram but a few bytes for a correct date are still to expensive ...

tialaramex 7y ago
The data stream doesn't move very many bits per second, and it needs to keep saying the week number, so every extra bit you decide you want for that week number means that for pure GPS units (which don't have the Internet to go get the GPS metadata from, an Internet which also knows perfectly well which week this is) the time from power on to first fix is proportionally slowed as they wade through all those extra bits you just felt sure they needed. "On the downside this will take 40 minutes to tell us where we are, on the upside trampeltier feels better about it" Also your driver probably doesn't use 500MB of RAM, more likely it wants 500MB of address space, and address space is basically free on 64-bit systems anyway so who cares?
- est31 7y ago
  There's plenty of reserved bits in the old protocol to give more bits that the 10 the WN (week number) already has: https://i.imgur.com/QuJDwmb.png https://i.imgur.com/QuJDwmb.png Source: Figure 20-1 in https://www.gps.gov/technical/icwg/IS-GPS-200K.pdf https://www.gps.gov/technical/icwg/IS-GPS-200K.pdf Your argument that the space is sparse is true though in the new protocol which has still a message of 300 bytes but no reserved space any more: https://i.imgur.com/xyxCxIi.png https://i.imgur.com/xyxCxIi.png Source: https://www.gps.gov/technical/icwg/IS-GPS-705F.pdf https://www.gps.gov/technical/icwg/IS-GPS-705F.pdf It gives 13 bit to the message at least, making the counters roll over every 157 years instead of every 20. It's still a bit too little IMO. Date counters should either be so short that engineers must design rollovers into the devices (e.g. 1 year) or longer than human lifespans by several orders of magnitude (e.g. 1000 years).

tialaramex 7y ago

The data stream doesn't move very many bits per second, and it needs to keep saying the week number, so every extra bit you decide you want for that week number means that for pure GPS units (which don't have the Internet to go get the GPS metadata from, an Internet which also knows perfectly well which week this is) the time from power on to first fix is proportionally slowed as they wade through all those extra bits you just felt sure they needed. "On the downside this will take 40 minutes to tell us where we are, on the upside trampeltier feels better about it" Also your driver probably doesn't use 500MB of RAM, more likely it wants 500MB of address space, and address space is basically free on 64-bit systems anyway so who cares?

est31 7y ago
There's plenty of reserved bits in the old protocol to give more bits that the 10 the WN (week number) already has: https://i.imgur.com/QuJDwmb.png https://i.imgur.com/QuJDwmb.png Source: Figure 20-1 in https://www.gps.gov/technical/icwg/IS-GPS-200K.pdf https://www.gps.gov/technical/icwg/IS-GPS-200K.pdf Your argument that the space is sparse is true though in the new protocol which has still a message of 300 bytes but no reserved space any more: https://i.imgur.com/xyxCxIi.png https://i.imgur.com/xyxCxIi.png Source: https://www.gps.gov/technical/icwg/IS-GPS-705F.pdf https://www.gps.gov/technical/icwg/IS-GPS-705F.pdf It gives 13 bit to the message at least, making the counters roll over every 157 years instead of every 20. It's still a bit too little IMO. Date counters should either be so short that engineers must design rollovers into the devices (e.g. 1 year) or longer than human lifespans by several orders of magnitude (e.g. 1000 years).