This is the maintenance page for the SML schema.  It contains:

• A description and Introduction to SML
• Information and help Using the File Manager tool
•  The schema itself

SML Introduction:  

The SETI community needs and deserves a modern method of storing and sharing the data it collects.  The data must be stored in a context free environment so that it can be analyzed by others without access to the original tools used to create the data.  The methods used to create the data must be based on an agreed standard so that others may understand its organization and be able to use its content directly from the data itself.  The organization will be based on XML and will be collected into a language specific to SETI.

I have decide to convert the DTD, created a couple of years ago to a XML Schema.  This will be easer to maintain since only one language will need to be learned and I forget SGML a lot faster than I relearn it.

Language Organization:

Each file of SETI data will be composed as described in the following.  It starts with three main sections the Title Block for later identification, the Equipment Setup so that data collected can be analyzed properly and the Data Set itself.  Each element is decomposed under that.  Details are contained in the SML schema on the Schema page.  Please remember that not all the data is required.  For example if you don't have a Band Pass Filter (most don't) you are not required to enter any data for it.  Many elements are required so that the data makes sense.  For example unless we know where on earth you were and which direction your antenna was pointed and what time it was when you heard the first ET contact you will forever be a footnote in SETI history as the one that almost was first.

SML is a mix of automatically generated and manually entered data.  The goal is to be as flexible as possible for your Argus station.  For example the Creation Date in the Title Block could be entered manually or put into the data set automatically by your SETI station.  The Data Set itself my be a part of the file or it might reference a separate file collected outside the system.  It might even be on a different computer altogether.

Title Block - Describes the structure of the file itself.    Elements of the Title Block are:

1. Location Coordinate System - The Argus station must be located for the data to make sense later on.
2. Creation Date - The local Date that the file was created.
3. Creation Time - Local time of creation.
4. Operator Name - Who was at the controls when the file was created.
5. Observer Name - People looking over your shoulder at the time the file was created.
6. SML Version - Shows which version of SML was used when the file was created. 

Equipment Setup - To simplify the process there can only be one equipment setup per file of data.  Elements of that setup are:

1. LNA - The gain in dB of the LNA and its noise factor.
2. L1 Insertion Loss - The loss in signal between the LNA and the Band Pass Filter.  On my system its small because they are co-located but it might be different on your system.  This loss, and the others, are needed for system noise temperature calculations 
3. Band Pass Filter - The upper and lower edge of the filter and its insertion loss.  Lower 3 dB point, Upper 3 dB point.  
4. L2 Insertion Loss - Loss between the  BPF and the RF Amplifier.
5. RF Amp - Characteristics  of this amplifier if present in the system.
6. L3 Insertion Loss - Between the RF amp and the receiver.

1. Analog Filter - If you use an analog filter to flatten the IF response as I do a simple description goes here.
2. A-to-D Converter - Most Argus systems us a Sound Blaster on a PC.  This element allows the entry of the manufacture and model along with the setup such as sampling rate, encoding scheme (8, 16 bit) and the recording mode (Mono or Stereo) and the channel (left/right) in use.
3. Weighting Window - A signal sampled for a limited amount of time may exhibit a distorted Fourier spectrum. In order to minimize this distortion, the signal may be multiplied by a weighting function which reduces the signal towards zero at both ends of the sampling window.  This element simply indicates which if any window was in use.  Window types could be Triangle, Hanning, Gaussian, Hamming, Blackman or other.
4. DSP - Digital Signal Processing in use.  Most Argus systems use a FFT that creates a set number of bins.  This element is used to capture the bin width in Hertz.  It also defines the type of data collected from the FFT which could be Magnitude, the Power Spectrum, the Real Spectrum, the Imaginary Spectrum the Phase Spectrum or the RMS Spectrum.
5. Filter - If digital filters were used they are defined here.
6. Time Keeping - The data collected must be time tagged for future analysis.  This element allows you to define the time of time keeping system in use.  Most Argus stations use the PC clock but it may be synchronized for better accuracy.

The above list is only the outline of the SML data organization.  The SETI Markup Language gives the parser the rules that a well formed SML document must maintain.  The details  of SML are kept in the SML Schema and are subject to continuous update and adjustment as new parameters are added and definition of existing ones change. 

Download instructions:

1. Download by clicking the SML.xsd file.   Your browser may open and display the file.  In that case simply hit File | Save As... to save it on your computer.
2. Use a simple editor, like notepad, to modify the third line of the Test1 file to point to where you put the schema file.  I like to use XML Spy as the schema and XML development tool.  It can be downloaded as a 30 day trial from Altova

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Schema:

The files you create using the File Manager are built to the SML schema.  This insures uniform construction and meaning of the data.  If you would like to help develop the SML schema I would welcome it.  Down load SML Spy or some other tool and build your test files. Insure that the NamespaceSchemaLocation information points to this page. 

Your SML files must point to this page to be verified against the schema.  They should contain the following Name Space information:

 To view the schema itself click here.  This will cause your browser to display the schema (IE 5 and above).  Save it for you local use.  You can also view the schema  graphically by following the Schema link on the left side.

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