#21 Inconsistencies between the msb-s

[Anonymous]

There are Inconsistencies between the msb-s.

For example let's see the cat 7 1.8 xml file:

SAC/SIC

<dataitem id="I007/010" frn="1" format="fixed" **length="2"**>
      <name>Data Source Identifier</name>
      <definition>Identification of the radar station from which the data is received.</definition>
      <field octed="1" msb="16" lsb="9">
        <name>SAC</name>
        <desc>System Area Code fixed to zero</desc>
      </field>
     ** <field octed="1" msb="8" lsb="1">**
        <name>SIC</name>
        <desc>System Identification Code</desc>
      </field>
      <desc><b>NOTE</b><br/>
      The up-to-date list of SACs is published on the Eurocontrol Web Site (http://www.eurocontrol.int/asterix).<br/>
    </desc>
    </dataitem>

Here the SIC field is in octet 1, msb 8. I guess it means the 2nd byte, since length the of the dataitem is 2.

Let's see the frn 18 from the same file:

<dataitem id="I007/210" frn="18" format="fixed" **length="4"**>
  <name>Track Quality</name>
  <definition>Track quality in the form of a vector of standard deviations.</definition>
  **<field octed="1" msb="8" lsb="1">**
    <format>uint</format>
    <name>Sigma (X)</name>
    <desc>Standard Deviation on the horizontal axis of the local grid system (LSB) = 1/128 NM<br/>
    <b>NOTE</b> - The standard deviation is per definition a positive value, hence the
    range covered is : 0 ≤ Sigma(X) &lt; 2 NM</desc>
    <unit>nmi</unit>
    <scale>1/128</scale>
  </field>
  <field octed="2" msb="8" lsb="1">
    <format>uint</format>
    <name>Sigma (Y)</name>
    <desc>Standard Deviation on the vertical axis of the local grid system (LSB) = 1/128 NM<br/>
  <b>NOTE</b> - The standard deviation is per definition a positive value, hence the
    range covered is : 0 ≤ Sigma (Y) &lt; 2 NM</desc>
    <unit>nmi</unit>
    <scale>1/128</scale>
  </field>

Here the sigma x is also octet 1, msb 8. The length of the dataitem is 4, so I'd guess that it is the 4. byte... but it should be the 1st byte.

How to now this from the xml, since the octet, msb and length are the same?

[Gabor Zavarko]

This is my ticket, just want to subscrive to the email notification:)

[Gabor Zavarko]

I think the msb should be 32 (and lsb should be 25) for sigma x. And octet should be 1 for all the 4 fields.
Sigma y and v should be also modified similar (24-17 and 16-9)

But I undestand that it is also inconsistenet in the original asteix sspecification.
See the attached images.

[Gabor Zavarko]

Or the dataitem's length should be 1.