Thanks, Craig

 

Good clarification on the data format from the ships. However, you now infer that CSPs will perhaps be asked to format messages from ships – but not all CSPs have signed up to do this (I know of only one). It is the understanding of many CSPs that the manipulation of the “raw” data from ships starts at the ASP level. Also, the LRIT coordinator has said in the past that coordination (“oversight”) starts at the ASP level. The CSP has largely been seen (until now) as purely the comms pipe that provides the LRIT data from ships to the ASP and to start involving CSPs in manipulating LRIT data would extend the oversight role.

 

Writing in specifications for all CSPs would therefore appear to be premature!

 

Kind regards

 

Hi All,

 

I'm please to see a good discussion has developed around this topic. Hopefully, more discussion on other topics in the documents will be initiated over the coming week before we meet in Hamburg.

 

Given the e-mails on this topic, the text (including wording in the table) should be altered to eliminate any confusion.

 

I agree that the specific data elements (latititude, longitude, year, month, day, hour, minute, unique equipment identifier) that the shipborne equipment transmits is the important information. The "format" of how those elements are displayed is accomplished by land based software (not shipborne equipment software). Essentially, an application piece of software will take those data elements, process them and display them in a given "format". It has been decided that SOAP messages (using XML format) will be the back bone of the LRIT communication system. Thus, the various data elements contained in a given LRIT message will have to be "formatted" as such. The question of whether application software residing at the CSP or ASP (not software on the shipborne equipment) begins to format the data elements into an LRIT message (SOAP using XML) as defined in the communications document is another issue. Currently, the document is written such that the CSP (for the International Data Centre case) begins to build SOAP messages and pass them to the ASP. We have to define an interface between the ASP and the CSP for the International Data Centre case. If we allowed CSPs to transmit information to the ASP using different formats, protocols, etc than it wouldn't be fair to the ASP. This would add an extra cost burden on the ASPs given that they would have to support multiple formats, protocols, etc. Please note that national data centers and regional data centers are free to define and allow different formats, protocols, etc from the CSP to the ASP.

 

The intention of the LRIT communications document shall be to specify the data elements transmitted by the shipborne equipment as stated in Brian's previous e-mail:

 

Shipborne Data Elements:

 

Latitude -> degrees, minutes and decimal minutes to two decimal places  N / S

Longitude ->degrees, minutes and decimal minutes to two decimal places  E / W

 

Unique equipment ID -> number

 

Year -> 4 digit year number

Month -> 2 digit month number

Day ->  2 digit day number

Hour -> 2 digit hour number

Minute -> 2 digit minute number

 

 

 

 

Regards,

 

Craig Hayley

 

From: Brian Mullan [mailto:Brian_Mullan@inmarsat.com]
Sent: Friday, June 01, 2007 6:18 AM
To: Hayley, Craig
Cc: ccglrit-gcclrit@lists.ncf.ca
Subject: RE: [Ccglrit-gcclrit] June 12-14 meeting of the Ad hoc Working Group onEngineering Aspects of LRIT, Hamburg Germany

Hi, Hayley

 

Many thanks for your email. I can agree that the text of the document is clear; but that the wording in the table is not consistent and appears even to contradict the text you quote. My copy of the document shows wording for 1.1.1.1 that is different:

“The intent of this document is to outline the technical specifications for communication within the international Long-Range Identification and Tracking (LRIT) system as stated in the terms of reference of resolution MSC.211(81).”

 

Your reference is new text in 2.2.2.4 in the copy that I received (15-02-2007 LRIT ad hoc WG)

 

In Table 2, the heading indicates “Parameter provided by LRIT Shipborne Equipment” and then describes the various elements, including specifying the format. It is clear to me and others that this method of presenting the information in the table means that the information transmitted by the shipborne equipment *must* follow the format written in the table. This is where the difficulty lies – the wording is over-prescriptive and does not accord with the wording in 2.2.2.4. My original email showed how, in Inmarsat C position reporting at least, the way the information is transmitted. Other shipborne systems probably will have their own format for presenting data to the ASP.

 

May I suggest, please, that we stick to requiring that the specific data elements (unique identifier, latitude/longitude and date/time of the position) are transmitted from the ship and then only start to prescribe the format for onward transmission from the ASP? In other words, as long as the shipborne equipment transmits, as a minimum, the required elements, any format is acceptable. This allows for all approved shipborne LRIT systems to be offered, no matter in which order or format the data is presented. This approach will also allow the table to be in accord with the new wording in 2.2.2.4

 

I hope that this is clear. Your hard work is very much appreciated and it is clearly understood that the document remains a “work in progress”. Please don’t take my input as criticism – it is not! All I seek is clarity of the wording for all.

 

With best wishes

 

Hi Brian,

 

Thanks for the e-mail. I hope more people will take the time to read the documents and provide comments. I assume you are referring to the LRIT communication document.

 

Please note the following text in the LRIT communications document: 

1.1.1.1          The parameters added by the LRIT shipborne equipment include the latitude, longitude, Time Stamp when the position was generated, and the shipborne equipment identifier. The “Format” of these parameters as outlined in table 2 indicates how the parameters shall be formatted while the information is contained within the LRIT message and does not specify the format of how the shipborne equipment transmits the information.

 

Regarding your concerns with the format of the date/time... The only difference that I can detect between the date/time you state and what is in Table 2 of the LRIT communications document is the separators ("-" versus ":") for the year, month, day, hour and minute. The separator used to separate the year, month, etc in the date stated in table 2 is not important and in no way linked to the format coming out of the shipborne equipment. The format is with respect to SOAP messages communicated along the various LRIT communication segments. CSPs for the IDC shall have to "build" SOAP messages complying with table 2 in the communications document using the format from the ship borne equipment. The important thing with the time stamp is that seconds are not transmitted.

 

Regarding your concerns with the format for latitude... We had a discussion on your e-mail and the intention was to implement your recommendation. I can't recall why the "seconds" component of the latitude didn't change to decimal minutes with a precision of 2 decimal places. The most likely reason is that I forgot to incorporate this change in the document due to the numerous requests. My apologies on this topic. I will make the change for latitude to decimal minutes unless someone raises a compelling reason not to change. Any body from the Communications group recall if there was a specific reason why we didn't make the change (Jilian, Guy, etc.)???

 

I would like to high light to everyone that these documents are in constant flux as a result of many requests from different inputs at the Ad Hoc meeting. Thus, it is important to fully read the documents that come out of each meeting to ensure that any particular topic of interest is addressed in a satisfactory manner.

 

Thanks,

 

Craig Hayley

System Engineer

Canadian Coast Guard

709-772-7740

 

From: ccglrit-gcclrit-bounces@lists.ncf.ca [mailto:ccglrit-gcclrit-bounces@lists.ncf.ca] On Behalf Of Brian Mullan
Sent: Thursday, May 31, 2007 12:35 PM
To: ccglrit-gcclrit@lists.ncf.ca
Subject: Re: [Ccglrit-gcclrit] June 12-14 meeting of the Ad hoc Working Group onEngineering Aspects of LRIT, Hamburg Germany

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