Aquadopp Profiler power consumption
| Quote |
Why is it that when I increase the number of cells in a profile that the battery consumption (according to both aquapro 1.21,1.27) decreases, which is the opposite of what I had expected. This only occurs when wave mode is enabled. As the two modes operate separately I would have thought the wave mode would have made no difference to the result. An example follows for a 20 day deployment: Waves: 2Hz, 2048 pts, 3600 s interval, 0.5 m bin with Profile... A. 180 s average every 1200 s, blank = 1m, compass 1200 s, cell size 0.5, number of bins = 20; gives 56% battery B. 180 s average every 1200 s, blank = 1m, compass 1200 s, cell size 0.5, number of bins = 4; gives 71% battery |
I agree, this is counterintuitive
" />
'> The reason for this comes down to a point you made in the presentation of your question. That is that the "two modes operate separately". This is not wholely true. It turns out that there is an internal ping rate that is initially determined by the current profile configuration.The user can configure the Aquadopp Profiler to average current profile data over a specified interval as well as write data to the recorder at a specified profile interval. However there is one layer that many are not aware of and that is the internal pinging rate. The internal pinging rate specifies how many pings are sent out per second.
The internal pinging rate is limitted by the range (or number of cells). The shorter the configured range, the more pings that can be squeezed into each second. Each ping is limitted by the travel time from the instrument to the furthest cell and back to the instrument. This is all fine an well but how does this effect the power consumption?
It turns out that by default we use the same iinternal pinging for the wave burst that we use for the current profile. So if there are only a small number of cells used then there will be higher internal pinging for current profiles and wave burst sampling; as a result this leads to a lot of power consumption. A large number of cells will have fewer pings per sample and this will be a less power consuming wave burst.
So if the profiling range is short then there will be higher number of pings internally for wave burst sampling; as a result this leads to higher power consumption. A large profiling range will cause fewer pings per wave sample and this will be a less power consuming wave burst.
-Torstein
Dear Torstein
I am trying to get current data from an AWAC 600KHz from the surface to the bottom using the following configuration:
Profile interval: 60s
Average interval: 20 s
Number of cells: 40
Cell size: 1m
The problem is that when I download the data, in the *.hdr file (attached), it appears that the number of "pings per burst" is only 4. I would like to have at least 20 pings per burst so I can have more data to average in one minute, but in the software there is nothing related to this variable. I haven’t been able to configure the number of "pings per burst" from the AWAC’s configuration software.
Do you know how can I change this value?
I really appreciate your help.
---
Juan David Osorio Cano, C.E, M.Sc
Universidad Nacional de Colombia, Medellín
I am not sure there is much we can do to help. The AWAC multiplexes (i.e. pings only at one beam at a time) and we are limited by the speed of sound. So one way to think about this is that have a total of 750 m (sound both has to go out and come back) in a second.
40*1 m cells is 40*1/cos(25) along the beam. Since you have three beams that each ping at 4 Hz, we get:
3*4*40/cos(25) = 530 meters.
It is possible that we could have squeezed in one more ping per second but the software seems to suggest that the overhead that is involved is too long for that to be possible.
Best regards, Atle Lohrmann
Forgot your password?
New user?
