[OZAPRS] FW: Was Something is wrong, this is a fixed location....Now, we fixed it..

[Gordon Taylor]

More thought on this.

 

If this were coming from a fixed stn, it would have identical data and only
a different time stamp, yet it does not get noted as duplicate data.

 

But in the data below, identical data with a different time stamp is seen as
duplicate data.

 

If the time stamp were embedded in the packet, both packets would be
identical (apart from the path if they went through different digi’s) and it
would clearly be the same packet.  That is the reason for time stamping at
the origin.

 

I think we need to know what the algorithm the servers use to distinguish
identical data.

 

Something is odd, might even be me.....

 

Regards,
Gordo VK4VP

 

From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On
Behalf Of Andrew Rich
Sent: Thursday, 10 March 2011 04:57
To: Australian APRS Users
Subject: Re: [OZAPRS] FW: Was Something is wrong, this is a fixed
location....Now, we fixed it..

 

Why should a time stamp make a difference ?

 

You haven't moved

----- Original Message ----- 

From: Gordon Taylor <mailto:gordon.t at internode.on.net>  

To: 'Australian APRS Users' <mailto:ozaprs at aprs.net.au>  

Sent: Wednesday, March 09, 2011 8:33 PM

Subject: [OZAPRS] FW: Was Something is wrong, this is a fixed
location....Now,we fixed it..

 

The issue of duplicate packets and speeds in excess of 500kmh have been
fixed in my area.

 

Some troubleshooting by Dave VK4UN has shown that whenever my Igate was
running the duplicate packets and excessive speed changes occur.  With my
Igate disconnected from the internet we confirmed all was good as I drove
from Brisbane to Buderim this afternoon.

 

We employed that well known and often used Windows troubleshooting technique
of rebooting the Igate.  This has fixed the problem.  Below are two packets
that demonstrate the issue I had.

 

It is clear that the packet through VK4OG-1 was gated  nearly 6 minutes
before the packet through VK4VP-1.

 

I assume the time stamp is added when the packet is received not when it is
transmitted, which in the telemetry and SCADA world I work in, is just not
on.  Our systems always time stamps event as they occur so that any delays
in the comms network do not compromise the credibility of the data, as has
happened here.  I am not complaining just highlighting that this is an
issue.

 

 

 

2011-03-09 03:49:40 UTC: VK4VP-7
<http://aprs.he.fi/?c=raw&limit=&call=VK4VP-7> >R7R4X6,VK4RBR-3*
<http://aprs.fi/?c=raw&limit=&call=VK4RBR-3> ,WIDE2-2,qAS,VK4OG-1
<http://aprs.fi/?c=raw&limit=&call=VK4OG-1> :`Q]/ }WK\]"3t}=
   type: location
   srccallsign: VK4VP-7
   dstcallsign: R7R4X6
   latitude: -27.41433333333333 °
   longitude: 153.0865 °
   course: 359 °
   speed: 90.74799999999999 km/h
   altitude: 2 m
   symboltable: \
   symbolcode: K
   mbits: 101
   posresolution: 18.52 m
   posambiguity: 0
   comment: ]=

 

 

2011-03-09 03:55:01 UTC: VK4VP-7
<http://aprs.he.fi/?c=raw&limit=&call=VK4VP-7> >R7R4X6,VK4RRC-13*
<http://aprs.fi/?c=raw&limit=&call=VK4RRC-13> ,WIDE2-2,qAS,VK4VP-1
<http://aprs.fi/?c=raw&limit=&call=VK4VP-1> :`Q]/ }WK\]"3t}= [Duplicate
position packet]
   type: location
   srccallsign: VK4VP-7
   dstcallsign: R7R4X6
   latitude: -27.41433333333333 °
   longitude: 153.0865 °
   course: 359 °
   speed: 90.74799999999999 km/h
   altitude: 2 m
   symboltable: \
   symbolcode: K
   mbits: 101
   posresolution: 18.52 m
   posambiguity: 0
   comment: ]=

 

 

Regards,
Gordo VK4VP

 


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