[aprssig] Parameter Names and Labels for Digital Telemetry Information

Steve Noskowicz noskosteve at yahoo.com
Thu Oct 18 20:03:03 EDT 2012


 
 
I think I see your point. First, these are individual single line indicators, not a single 8-bit quantity.
 
  I may be wrong, but it appears to me that these are free field text values that you can use any way you want. 
 
 I think the intention is to define the 'polarity' of the bits. The example has on's and the like. 
Sun ON, Shutter OPEN, 10M ON. Is "1" open or closed for a door.

   Some binary functions may not be obvious, or your particular hardware may provide a non intuitive indication - like a zero may occur when some function is ON rather than OFF.   This seems like more than is needed because if you have some custom setup you know what you have and can make your receiving software give you the indication you want regardless of the over-the-air bit polarity.
 
EH?

73, Steve, K9DCI USN (Vet) MOT (Ret) Ham (Yet)
--- On Thu, 10/18/12, Charles Bland <root at blandranch.net> wrote:



The names for digital channels makes sense to me already..... Door1, Pump, etc. But there are also 8 labels, but just 8. There aren't separate labels for the bit states.


So, if I already have the names, what do the labeles, sent in a different message, accomplish?


Chuck


On Thu, Oct 18, 2012 at 3:48 PM, Steve Noskowicz <noskosteve at yahoo.com> wrote:






 
Thinking more...
 
Say you have four door switches on your trailer and four window switches.  The labels could be this for your trailer telemetry:
  
UNIT,...bla,bla,bla...Door1,Door2,Door3,Door4,Win1,Win2,Win3,Win4
 
Since you can put anything you want it could also be:
 
UNIT,...bla,bla,bla...Open1,Open2,Open3,Open4,Front,Rear,Back,Roof
 
If you don't want anyone to know which is which, I suppose you could have :
 
UNIT,...bla,bla,bla...Open,Open,Open,Open,Open,Open,Open,Open
 

73, Steve, 









 
I just looked into this.
 
Units should be obvious for the analog quantities. This specifies the units of measure - the units of these quantities.  Things like volts, Degrees F,  Degrees C, or Degrees K -- seconds, or minutes, or days.  If it was money, it could be dollars, pounds, or Yen.  These can also be scaled by making the units volts/100 for large values or volts*100, or perhaps mv (milivolts) for small values.
 
Now we get to "What's in a name..." for the digital bits.
  Call it a name or a lable, but it must tell what the digital bit represents in your situation. 
The digital labels will indicate the function of each bit.  What is it representing.  These will be only 1 or zero but the labels tell you what they indicate. They  are for things like a door open or closed; a switch open or closed; a shutter button pushed down or notl; a motor running or not. 
 
Does that help?
 

73, Steve, K9DCI USN (Vet) MOT (Ret) Ham (Yet)

--- On Thu, 10/18/12, Charles Bland <root at blandranch.net> wrote:
Chapter 13 of the APRS spec goes into the detail of the parameter names.




The PARM. message contains the analog and digital channels.


The UNIT. message contains units for the analog channels and "labels" for the digital channels. This isn't clear to me.


Regarding the digital channels, what is the difference between a "name" and a "label"? I see the message examples in the spec, but I really don't see an application for the labels.


Can anyone provide for clarity on this?


Chuck Bland
na6br




 
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