Rutgers University
  • Velocity Plots from the boat experiments

    Posted on July 19th, 2010 admin No comments

    This is the plot of Velocity VS. Time from Savitsky’s GPS boat path on July 13, 2010. The velocity match very well with the radio velocity computed by the MATLAB code using the doppler shift. This is because the boat was moving towards and away from the antenna and the velocity of the boat should be the same of the radial velocity.

    This is the boat path related to this data.

  • The effect of the buildings

    Posted on June 29th, 2010 admin No comments

    The above image shows the range of our riversonde. The system not only covers the entire width of the river but some range cells spread across the land on the other side(NYC). We know that the stationary buildings contribute to zero doppler shift. This is the reason y we see good smear in the range cells from about 25 to 32 at  0 hz. The fact becomes clear from the spectrogram below.

  • Aliasing

    Posted on June 29th, 2010 admin No comments

    With 16 Hz and 512 Doppler Bins, the above image formed.  Even though this graph indicates that a boat is traveling away from the Riversonde, it was actually traveling towards it.  This is an example of aliasing, which is when the velocity of a boat is beyond the limits of the graph.

  • A bunch of discoveries: June 16 to 22

    Posted on June 23rd, 2010 admin No comments

    Hello all-

    Here’s the u and v velocity plot from the first six days:

    Here are the functions associated with this plot.  I apologize that these files are NOT .m, but are in Microsoft Word documents.  However, simply copy and paste these into Matlab and you should be good to go 🙂

    Use these in the following order

    variablesorter.doc : This will create variables from the RiverSonde data.

    dataconverter.doc : This will converter time from a cell array to datenum format (i.e.:Matlab friendly)

    plotcreator.doc : This will plot time and two other variables.

    ——————————————-

    Another plot we wanted to focus on was the number of vectors collected by the RiverSonde.  If less vectors were collected, the river surface was rough enough to collect adequate data.  A rough surface indicates the presence of wind.   Therefore, we decided to compare the number of vectors collected by the RiverSonde and the NYHOPS wind speed measurements:

    For the most part, the wind speed and the number of vectors mirror each other: when the wind speed increases, the number of vectors decreases.

  • Codar optimizes Riversonde

    Posted on June 22nd, 2010 admin No comments

    email from Don Barrick

    Hugh —

    It didn’t take us long to get into the RiverSonde and optimize the settings after you sent the connection info to us.  Lo and behold, we are getting all the way across the Hudson!  We did this partly by reducing the sweep bandwidth to 2.5 MHz, which gives us a 60-m range cell.  However, we still have 20 range cells to span the river.  The bigger the range cell, the more SNR we get because of the larger scatter-patch echo.  We can also try smaller range cells, for higher resolution studies for a while.
    Pass this along to your staff and the Stevens people.  We shouldn’t get too optimistic from a couple hours data, maybe wind/roughness conditions were just right.  We’d still like to put it on top of the Admin building at some point.  And we’d like to plan for a boat antenna pattern run.  The latter will need to be done with an active transmitter on the boat, so when Pete returns, we’ll plan for how to do this.

  • River Sonde data

    Posted on June 22nd, 2010 admin No comments

    ExportedData(2) –works for macs

    DHS.exporteddata.xls –SHOULD work for others (Microsoft Excel format)

    This is the filtered extracted data from the web interface.

  • RiverSonde Geometry

    Posted on June 21st, 2010 admin No comments

    Here is an image that shows the geometry of the RiverSonde.  The blue lines indicate the range rings, every 10 meters.  The red lines indicate the angular bins, every 5 degrees.

    I set the maximum range to 600 meters or 60 range cells.  This only gets us half way across the river.

  • RiverSonde Computer Info

    Posted on June 21st, 2010 admin No comments

    The ports on the back of the mac mini are from left to right:

    The connector for the monitor that is there is for VGA

    I can bring an adapter on wednesday or if someone can find one on stevens so much the better.

  • Ships are on the spectra map!

    Posted on June 18th, 2010 admin No comments

    These are pictures of the spectra readings from this afternoon as ships passed by each other at the same time. We have video and additional pictures of this happening but you can clearly see the boats cross past each other in the spectra. One was at about 400 m and the other at 500 m

    

  • River Sonde Update: Friday, June 18

    Posted on June 18th, 2010 admin No comments

    Below are general time series and radial plots over the last 24 hours.  Positive along-shore velocities reflect water moving south towards the Hudson Estuary; positive cross-shore velocities reflect water traveling across towards NYC:

    Even though we are pleased with the radial profile, we are skeptical about the along-shore and cross-shore measurements taken by the River Sonde.  We were hoping for more clarity in our data (less standard deviation), but knowing how rapidly the physical properties of the Hudson change, the River Sonde might be giving accurate measures.  According to the River Sonde manuel, a typical time series plot looks like:

    The above plot is over five days, so we manipulated parameters on our own time series plot to (hopefully) look more like the above.  Over 48 hours, the average along-shore and cross-shore velocities look as such:

    Time series over 48 hours

    Along-shore average velocities over the last 48 hours

    Cross-Shore average surface velocities over the last 48 hours

    There are similarities between our measurements and ideal measurements, but there is still ambiguity in the data.

    For more comparison, we are including the NYHOPS river model from the last 12 hours, and a prediction for the next 48 hours:

    Assuming that the NYHOPS model are showing magnitudes of the velocity measurements, the River Sonde and NYHOPS model are comparable, and there are few discrepancies between them.  Thus, we feel more confident in the River Sonde and its accuracy.

    -The Radar Team