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TOPIC: Time on CSV and 10Hz data saving

Time on CSV and 10Hz data saving 10 years 2 days ago #7394

  • amcpreto
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Hi Matt.

Is there any possibility to include the time as part of the CSV export ???

On the CSV file the data is registered only in 1Hz (one data/second). As many ecossounders, even the simple ones like Lowrance HDS-7 Gen2 (which I own) can save depth data in the SD card up to 20hz, and the internal GPS with external antenna work in 10 Hz, is there a way that our data can be saved in the CSV file in a high rate as 10 pings per second (10Hz)?? Can it be set anywhere in RM?
With a higher saving rate it is possible to minimize the motion (pitch,roll) error.

Hope to hear good news.
Thanks,
Augusto
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Time on CSV and 10Hz data saving 10 years 2 days ago #7395

  • Matt
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Our experience is that the units won't save more information to the log file, even with a 10Hz GPS connected. We observe 1Hz updates in the logfiles, even for headings supplied at 10Hz, and position is limited to integer metre values on Lowrance devices due to the file format used - which also limits the number of updates.
The only real solution is to log heading and position information entirely separately to the unit, and then synchronise position and sonar logs in post-processing. We have done quite a lot of work on this and should be releasing something towards the end of the year - although of course it will require extra hardware to use the feature.
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Time on CSV and 10Hz data saving 10 years 2 days ago #7396

  • amcpreto
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The logs in sl2 file are in 20hz. When I extract the sl2 in matlab, I have 20 depths values per second. Some times (almost never) it repeats the same position in 2 subsequent points, once the unit GPS system refresh position in 5Hz . When I am logging live with RM I use an external GPS which works in 10 Hz, interpolation and real depth error would be drastically reduced if RM could record the depth and position data in a rate superior than 1Hz. 5 hz would be good, but 10 Hz would be great.
Please!
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Time on CSV and 10Hz data saving 10 years 2 days ago #7397

  • Matt
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Can you send me an example of one of your extracts, along with the original log file? (This email address is being protected from spambots. You need JavaScript enabled to view it. )

Lowrance logs in an integer position format similar to Mercator metres, so a new position 20 times a second (assuming, for a moment, a straight n/s or e/w path) would equate to roughly 20 m/s or 72 kmph. Our investigations have shown that even when fed with a high rate GPS/heading, updates are not recorded with a frequency greater than approx 1Hz - although it's possible that this behaviour has been improved since.
In any case, the logic we use when importing data is to create a new point whenever the position changes, although it is likely that there have been quite a number of individual pings in the interim (and also possible that the depth could vary across those pings, but since they are all recorded at the same position we use only one).
What speed are you logging at?
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