In my continuing education about APRS, I was reading up on the differences between Items and Objects. Based on what I have read, the major difference is that Objects have a timestamp because they can move whereas Items do not have a timestamp because they are stationary.
When setting an Object in YAAC, the program has a check-box to make the object Permanent, without a timestamp -- in other words creating an Item.
In the APRS packet, an Object is denoted by a leading character of a semi-colon ; and an Item is denoted by a leading close-parenthesis ) .
However, when I play around with the Permanent check-box, the leading character seems to always be a semi-colon ; indicating it is an Object regardless of if the box is checked or not.
Likewise, an Item is indicated as Live by the use of the exclamation symbol ! while a live Object uses the asterisk *. Again, playing around, I only ever see the asterisk * for an Object used regardless of the setting in the Permanent check-box.
The Kill packet indication for both Objects and Items is the same, an underscore _ .
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Originally, YAAC implemented permanent objects as Items. However, I was informed by Bob Bruninga that Items are mostly obsolete because most software only does Objects. Permanent Objects are sent with a special reserved timestamp of 111111z; not sure why that was picked, as it is a legal time value, but the assumption is that the likelihood of landing exactly on that timestamp with a moving Object is low, and a future Object report for the same Object would update the timestamp anyway.
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In my continuing education about APRS, I was reading up on the differences between Items and Objects. Based on what I have read, the major difference is that Objects have a timestamp because they can move whereas Items do not have a timestamp because they are stationary.
When setting an Object in YAAC, the program has a check-box to make the object Permanent, without a timestamp -- in other words creating an Item.
In the APRS packet, an Object is denoted by a leading character of a semi-colon ; and an Item is denoted by a leading close-parenthesis ) .
However, when I play around with the Permanent check-box, the leading character seems to always be a semi-colon ; indicating it is an Object regardless of if the box is checked or not.
Likewise, an Item is indicated as Live by the use of the exclamation symbol ! while a live Object uses the asterisk *. Again, playing around, I only ever see the asterisk * for an Object used regardless of the setting in the Permanent check-box.
The Kill packet indication for both Objects and Items is the same, an underscore _ .
Originally, YAAC implemented permanent objects as Items. However, I was informed by Bob Bruninga that Items are mostly obsolete because most software only does Objects. Permanent Objects are sent with a special reserved timestamp of 111111z; not sure why that was picked, as it is a legal time value, but the assumption is that the likelihood of landing exactly on that timestamp with a moving Object is low, and a future Object report for the same Object would update the timestamp anyway.
OK. Was just wondering if there was something behind this. Thanks!