PolySync Temperature/Speed of Sound Measurement

Hello,

I'm using PolySync version 1.0.17. It's configured with two probes, with the checkboxes to measure both temperature and speed of sound checked. However, after converting the .vno file the .tem.txt file is empty (column headers only) and I've looked in the .vno file and the configuration XML reads:

<TEMPERATURE measured="1">0</TEMPERATURE><SALINITY>0</SALINITY><SOUND_SPEED measured="1">1402.4</SOUND_SPEED>

Obviously the temperature and salinity are not being stored, and the speed of sound seems to be the default setting.

Using Vectrino Plus, the speed of sound is shown as 14833 on the Header tab (presumably this is an unscaled value - similarly the temperature reads 2033 rather than 20.33).

I assume that that the values measured by the probe are being used correctly for the velocity calculations. However, I will need the temperature measurements for future data processing. Is this stored anywhere by PolySync? Is there anyway of getting the measured values written to the vno file?

Thanks,

Mike

Hi Mike,

I haven't used PolySync before but the standard Vectrino (and + version) software only reports the temperature value at the start of data collection. This has to do with the manner in which data is transmitted from the instrument and the lack of a field for temperature measurements to be stored. The Vectrino will be reading the temperature continuously while collecting data, but will not report this nor the speed of sound used. So, if your test facility water temperature increased during an experiment, the Vectrino would know this, and as long as it was not using a fixed speed of sound would adjust its measurements accordingly.

I will see if I can get an answer for you on what data should be in the PolySync file you mentioned.

P.J.

Hi Peter,

Thanks for that. It sounds like I'll just have to make a note of the water temperature measured at various points during the day. Back to pen and paper!

I have another question regarding the PolySync software. I'm trying to write a tool to read from the .vno files output by PolySync. I've looked at the System Integrator Guide for ParaDopp products and it includes a table describing the format of the Vectrino velocity data (page 43). This appears to be very similar in format to the PolySync .vno files and working from that I have been able to extract the velocity, amplitude and correlation data from the list of measurements held in the file.

However, as I'm using two probes I need to be able to tell which measurement is from which probe. I'm probably missing something obvious, but I can't see how to do this. The file has an xml header containing the probe configuration data, but as far as I can tell from looking at the .vel.txt file produced by PolySync's own data conversion tool, the first measurement in the file is not necessarily from the first probe in the config list. Sometimes the first measurement is from probe 1 and sometimes it's for probe 0.

Is there a similar document describing the format of the PolySync .vno files? Or could you just tell me how I can distinguish between measurements from the two probes?

Thanks,

Mike

Hi Mike,

I ran into the same problem regarding temperature measurements with one of my experiments. There are quite a few low cost logging temperature sensors that you could put in your tank if you need a continuous record.

I haven't done much data conversion of the *.vno files unfortunately so I can't help you there. I will ask if there's a document containing the PolySync binary format or about how PolySync identifies the two probes in its binary data files. I think a lot of NortekAS is on holiday so it might be a couple of days before I get a response.

P.J.

Hi Peter,

Thanks again. I'll check in a couple of days to see if there's any news.

Mike

Hi Mike,

The person at NortekAS who can answer this question is on vacation for another week and a half.

P.J.

The PolySync file format description can be downloaded here.

Best regards,
Oistein