From: Dana Swift [swift@runt.ocean.washington.edu]
Sent: Thursday, August 31, 2006 1:13 PM
To: keweebead@verizon.net
Cc: emmanuel.boss@maine.edu
Subject: RE[2]: Ocean Optics 2006 paper on Float 0005

> Internal boards average data over a pre-set sampling period of several 
> seconds (Dana?)

Not quite right.  The internal averaging period is less than one second and is factory determined...not user-specified.  

The sampling interval is user-specified and I happened to use 4 seconds.  This is irrelevant to a deployed float though because the sensor is powered up only long enough to produce a single sample before being powered back down.  Hence, the sensor is powered up for only about 1 second for each sample transmitted in argos data.


> and output the data as a serial stream and in scientific units.

Not in scientific units.  The data are transmitted as 12-bit integers from the FLSS sensor to the float controller via a serial stream.  A calibration equation is used to convert the 12-bit (analogue-to-digital) output into scientific units.

> In order not to significantly affect the physical oceanography 
> mission, the bio-optical data were compressed to less than 30% of the physical
> data volume, which required (Dana?)   

I'm not quite sure how I'm supposed to finish that sentence.  I'll take a stab and you can tell me if this is what you're looking for. The FLSS data require 8 bytes per sample and the remaining hydrographic data (P,S,T,O) also require 8 bytes per sample.  So the bio-optical data are 100% the volume of the (non-bio) physics parameters.  The bio-optical data volume is 50% of the total data volume for each sample.

The following excerpt is taken from the format specification:  

The FLSS surface measurement is transmitted in bytes 2-11 of message #2.  A new FLSS surface measurement is made each time a new message block is transmitted.  The surface FLSS measurement consists of P (2 bytes), BlueRef (2 bytes), BlueSig (2 bytes), LssRef (2 bytes), LssSig (2 bytes).

Next, the hydrographic data are transmitted in messages 2-N in the order that they were collected.  The sample taken at the end of the park phase will be transmitted first (in message 2) followed by the samples collected during the profile phase.  Each sample consists of 8 bytes of hydrographic data in order of T (2 bytes), S (2 bytes), P (2 bytes), O (2 bytes) followed by 8 bytes of optical data in order of BlueRef (2 bytes), BlueSig (2 bytes), LssRef (2 bytes), LssSig (2 bytes).