SSC Pacific
Frequently Asked Questions
  Frequently Asked Questions

How do I ...?
  1. Ensure quick order response when ordering NIMA DTED CD-ROM's on the DD 1348 (standard requisition form). This information is provided as a courtesy to our military customers by the Naval Meteorology and Oceanography Command Detachment, Mayport, FL. For addition information, you may contact them directly at DSN 960-6197, 6196, or 6603.

  2. Connect my PC to the Marwin Rawinsonde MW12.

  3. Obtain the latest radiosonde information for the environmental entry to AREPS?

    If you do not have access to your own radiosonde report and are interested in reports from observing stations within the domain of the National Weather Service, you may ...

    1. Start at the NOAA Forecast Systems Laboratory's North American RAOB database homepage.
    2. Fill in the request form, being sure to select the FAA604 (WMO/GTS) format.
    3. When the information is downloaded to your screen, highlight the text and select Edit then Copy from your brower's menu bar.
    4. Start the AREPS program, select Environment then New from the menu bar, and when the window opens, select the paste icon.

    Another good source of real-time radiosonde information is available from the Department of Atmospheric Science at the University of Wyoming. You would use the Custom Column input techniques of AREPS to accept these data. A PowerPoint show may be obtained from your AREPS account homepage showing how to use the Custom Column technique with data from the University of Wyoming.

    Many Naval Meteorology and Oceanography Command centers, facilities, and detachments post their local radiosonde observations on their internet homepages. Once such a homepage is found for your particular area of interest (by using an internet search engine), you may copy the WMO report to the Windows clipboard directly from your browser, and then use the paste feature of AREPS to enter the report into a new environment. For military users, WMO reports are also available from the Fleet Numerical Meteorology and Oceanography Center via the Joint METOC Viewer (JMV) and the Naval Oceanographic Data Distribution System (NODDS).

  4. Obtain my terrain data?

    Our AREPS program utilizes the National Geospatial-Intelligence Agency's (NGA), Digital Terrain Elevation Data (DTED), provided in three resolution level formats, 0, 1 and 2. Level 0 data are available to the general public from NGA's INTERNET homepage. Because some DTED data are limited distribution publications, DTED data are not distributed with AREPS. In addition to DTED formatted data, NIMA provides terrain data in other formats such as raster graphics. AREPS will not accept any of these other formats.

    Notice When DTED level 0 data are downloaded from NGA, they are packed into a TAR format file which must be unpacked with your own unpacking program. One such program for the personal computer is WinZip from Nico Mak Computing, Inc. If you use this program, before you unpack the TAR file, select from the WinZip OPTIONS menu, the CONFIGURATION item. One of the configuration items is named "TAR File Smart CR/LF Converstion." You must uncheck this item. If you do not, WinZip will insert carriage control and line feed symbols into the unpacked data which will cause AREPS to read the data incorrectly.

    For Department of Defense and DoD contractors, you may contact your local NIMA representative for ordering information. The Advanced Refractive Effects Prediction System (AREPS) will import your own terrain data independently from any DTED terrain data.

  5. Read data from a NGA DTED Level 1 CD-ROM?

    Contractors and other government organizations have asked how to read the DTED level 1 terrain data from a NIMA CD-ROM. We have provided two source code routines to demonstrate the technique. To obtain these routines, visit our software page.

  6. The AREPS documentation, TD3101, explains that the "...parabolic equation technique of APM is capable of higher frequencies, we have set a hard upper limit of frequency to 57 GHz." (pg. 59). When I have tried to exercise AREPS at frequencies higher than 20 GHz, the program responds by informing me that AREPS does support analysis above 20 GHz. In that APM is more capable, is there a way of inducing AREPS to predict performance above 20 GHz?

    AREPS contains a number of input fields for which you may override the recommended limits. To do this, type in the frequency, say 35000 MHz, and then hold down the SHIFT key while you press the ENTER key. You will get the error window but the window will have two command buttons, one to accept the entry and one to re-enter. When you accept the entry, you will notice the background color of the input field will turn to yellow. This tells you that the input is beyond the normal recommended limits.

Is something missing?
  1. AREPS does not allow me to enter the mandatory levels of the WMO Radiosonde Code.

    In using radiosondes to measure the vertical profiles of temperature and humidity, the absolute accuracy of the data is not as important for refractivity assessment as accurate measurement of the gradients. These necessary gradients are all found within the significant levels portion of the WMO radiosonde report (IIBB, TTBB, or UUBB). For this reason, the mandatory levels of the radiosonde report (IIAA, TTAA, or UUAA) should not be necessary for refractivity assessment since any mandatory level that is also significant will appear within the significant section of the report. Thus, AREPS does not consider the mandatory sections because these data are not needed.

Software problems ...
  1. When I run AREPS I keep getting errors that say something like "Invalid character [,] [Ascii(44)] at position 3." What is this and how can I resolve it?

    This error is a result of your Windows operating system regional setting. In some regions of the world, the comma character (,) is used for decimal points in numbers and in other regions, the decimal point (.) is used. Because AREPS is a product for the US Navy, it is designed to execute under the English (United States) regional setting. The only solution for your problem is to change your computer’s regional setting to English (United States). You need to make the change from the Control Panel, using the Regional and Language Options. One note of caution. If you change your regional setting, any program that is expecting to see the comma character representing the decimal point within a number may fail. We have had a number of foreign customers encounter this same issue and they did change the regional setting. They reported success in getting AREPS to run correctly after doing so. After they finished with AREPS, they changed the regional setting back to what it was before they changed it to English (United States).

    In order to have AREPS consider the comma character, we would have to do extensive modifications of the program because there are certain Microsoft mathematical functions that we use that will fail with the comma character. If you would be interested in funding us through a contractual arrangement to make these modifications, we would be happy to provide a work and cost proposal.

  2. I have copied the entire collection of DTED CD-ROM data to my hard disk but the AREPS DTED file manager continues to open and ask me to insert a CD-ROM. Why?

    With large computer hard disk space become more readily available, you may choose to copy the entire contents of all the DTED CD-ROMs onto your hard drive. However, not all CD-ROMs contain every file necessary to cover it's particular latitude and longitude region. This is particularly true for over water areas. When AREPS reads a DTED CD-ROM, it will identify these missing files and create on you hard drive, an empty file. The next time AREPS tries to read data from your hard drive, it will recognize this empty file and will not ask you to put in the CD-ROM. Of course, when you copy the CD-ROM files to your hard drive, you are not creating empty files and thus, there are "gaps" in your DTED coverage. Unless AREPS scans each CD-ROM, there is no way for AREPS to create empty files to fill in these gaps. Thus, the DTED file manager may open and ask you to insert a particular CD-ROM. This is frustrating as you "know" you have all the available DTED data on your hard drive. The only way to resolve this problem is to insert a CD-ROM when asked for. AREPS will then create the empty file and the DTED file manager will not ask again for that particular location. Alternatively, you may choose to have AREPS not ask you for missing CD-ROMs. However, this will result in gaps in the terrain data for your project.

  3. I would like to use the FalconView project. I have the FalconLite program installed but AREPS will not recognize it.

    The FalconLite intallation does not include some of the dynamic link libraries that AREPS uses to interface to FalconView. Thus AREPS does not support the use of FalconLite. You must obtain and install the full FalconView program. FalconView is a component of the Portable Flight Planning Software (PFPS). When you execute the installation of PFPS, you have an option install certain components of PFPS and not install other components. For the purposes of AREPS, you need only install the FalconView component.

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Updated: 4/27/2011 2:57 PM EST   Published