SIL v Heriberto on phone data

In a recent post “Madeleine – Heriberto on phones”, I raised a technical glitch with the detailed co-ordinates provided by Heriberto. To be brief, when I used them I was getting totally the wrong location.

I flagged this as a minor problem, given that Herberto’s map was showing masts in two locations where I know there are/were masts in Aug 2013, the date of Heriberto’s data.

An overnight sleep was enough to resolve the glitch, but I wanted to use yesterday to clarify the error I had made re the death of Diane Thomas in this year’s Luz triathlon. In the scale of things, this correction was much more important than talking about a minor technical glitch.

Now it is time to return to the glitch, and as expected, the solution is ridiculously easy. Heriberto is using a pure decimal form for his co-ordinates, whereas to date I have used degrees, minutes and seconds. I simply got caught out with a format that I was not familiar with.

Let’s take the example of the Luz water tower to illustrate this.

Heriberto reported 37.090395N -8.742667. The minus makes this a west co-ordinate, rather than an east co-ordinate. Heriberto appears to be getting this from a data set, then using it to plot his map. I would call this going forward.

I was using 37° 05′ 25.73”N, 8° 44′ 35.16”W. I have been getting my locations by finding the mast in Google streetview and/or Google Earth, then using Google Earth to work out the location co-ordinates. I would call this going in reverse.

Heriberto’s coordinates can be plugged straight into Google maps. This shows the co-ordinates correspond to 37° 05′ 25.4”N, 8° 44′ 33.6”W.

There is now a very minor difference. This difference can be explained by a number of factors, so there is no point in being pedantic about this. The difference makes a negligible alteration in any phone maps.

The bottom line is that Heriberto’s co-ordinates check out, as expected.

I have a further stage to go on Heriberto’s data. He pointed out that he might need a refinement as his data set is from Aug 2013. Google streetview can be used to show that one of the masts did not exist in Aug 2009. I need to see if the remaining two (not the water tower) had been deployed in Madeleine McCann’s day.

As I said in my previous post re Heriberto’s phone data, this represents a big step forward in analysing phone traffic.

One would assume that Scotland Yard is sufficiently clued up to have full and accurate phone mast maps, complete with the propagation information that Heriberto has shown is available. Unfortunately, the Luz 2014 dig suggests that there are basics that Scotland Yard is not clued up on, so it looks like another email to Operation Grange is required to cover that possibility.


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