Seeking: SI derived units with higher base powers.

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Discussion Overview

The discussion revolves around the use of SI derived units in a chemistry setup, specifically focusing on the powers of these units in relation to a data descriptor that utilizes a limited bit range. Participants explore the feasibility of measuring SI derived units with powers exceeding +7 or below -8.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant is seeking SI derived units with powers greater than +7 or less than -8, noting that they have only identified units with powers ranging from -3 to +4.
  • Another participant suggests that using only 4 bits for data descriptors may lead to problems, implying that more bits could be beneficial.
  • A participant emphasizes that sending longer messages is generally not a significant issue compared to the potential problems of insufficient space for data transfer.
  • One contributor mentions that bits are relatively inexpensive and unlikely to pose a problem in most communication scenarios.
  • Another participant proposes using ASCII text for unit abbreviations as a more efficient method for saving bandwidth, highlighting the benefits of human-readable messages for debugging.
  • A later reply dismisses concerns over bit usage, suggesting that modern technology has alleviated such issues.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of limiting bit usage, with some advocating for more bits to avoid potential issues, while others argue that the current approach is sufficient. The search for SI derived units with higher or lower powers remains unresolved, as no consensus is reached on available units.

Contextual Notes

The discussion does not clarify the specific context or limitations of the units being considered, nor does it resolve the mathematical or technical aspects of the proposed bit usage.

Knaapje
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Hey guys,

I'm currently working on a chemistry setup and we're building some protocols. We decided that every communication on the protocol between two devices will be in SI units. However, for a data descriptor I plan to use 4 bits per standard SI unit. This means that units for variables can go from -8 to 7.

Now, I'm wondering if there is any measurable SI derived unit which has a higher power than 7 or lower than -8?. I can only get to -3 or +4, but that's it. Anyone suggestions?

For instance, if you have pressure in hPa, this is kg * s^-2 * m^-1, the lowest is -2, highest is 1. Farad is kg^-1 m^-1 A^2 S^4, highest 4.
 
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Welcome to PF, Knaapje! :smile:

My recommendation: don't use just 4 bits!
It's just not worth all the problems you'll get.
 
I like Serena said:
Welcome to PF, Knaapje! :smile:

My recommendation: don't use just 4 bits!
It's just not worth all the problems you'll get.

In total I'll be using 7 * 4 = 28, or 32 bits because alignment. I'm just curious if there is anything which we can actually measure has more than 7 or less than -8 powers.. Went through Wikipedia as well and just get stuck on 4. Also, it has to be as little as possible to keep everything at reasonable speed. Sending a message that's twice as long just to be sure seems a bit silly.
 
Knaapje said:
In total I'll be using 7 * 4 = 28, or 32 bits because alignment. I'm just curious if there is anything which we can actually measure has more than 7 or less than -8 powers.. Went through Wikipedia as well and just get stuck on 4. Also, it has to be as little as possible to keep everything at reasonable speed. Sending a message that's twice as long just to be sure seems a bit silly.

As I said, it's likely not worth the trouble.
Sending a message that is twice or 4 times as long will (almost) never be a problem.
Handling problems because you have too little space to transfer what you want to transfer really is a problem.
 
Bits are cheap as chips, as they say. Neither processor power nor channel bandwidth are likely to be a serious problem for you unless you are communicating with a submarine of a deep space probe.
 
If you really want to save bandwidth, why not just use the ASCII text for the standard abbreviations of unit names?

"F" for farad is only 8 bits, not 28 :smile:

And when things go wrong, human-readable messages make debugging easierr.
 
Dude! This is the 21st century! Nobody quibbles over bits. That's what they did in like the stone age.
 

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