DIGITAL HF PREDICTION TOOL DISPLAY FUNCTION: Prediction of the reliability for digital HF radio transmission or reception. The reliability of a radio system is defined as the probability of achieving a specified system performance (e.g., minimum required signal-to-noise ratio) under a specified set of conditions (e.g., time, date, solar activity level, transmitter power, etc.). Reliability can be expressed as one of four types, depending on the number of frequencies involved and whether multimode interference is considered: 1) Basic Circuit Reliability (BCR): only single-frequency transmission is used and the possibility of multimode interference is ignored. 2) Basic Reception Reliability (BRR): multi-frequency transmission is used and the possibility of multimode interference is ignored. 3) Overall Circuit Reliability (OCR): only single-frequency transmission is used and the possibility of multimode interference is included. 4) Overall Reception Reliability (ORR): multi-frequency transmission is used and the possibility of multimode interference is included. The white/black areas on the map represent the day/night sectors of the Earth's ionosphere, at a height of 200km. HF circuits that cross the day sector are more likely to be disrupted by shortwave fadeouts, associated with solar flare activity. The horizontal gray bars on the map represent the approximate locations of the day/night terminators, at an ionospheric height of 200km. HF circuits that cross a day/night terminator can be difficult to use at certain times. The large red dot on the map represents the approximate location on the Earth where the Sun is directly overhead at the current (computer) time on the specified date of the prediction. Note: If the Sun appears to be in the wrong place, the applet probably has the wrong time. You can check what universal time the applet thinks it is by looking in the Java Console (if enabled on your browser). Look under Tools->Sun Java Console. The date and time are loaded on applet start, so if you want to update the solar position you will need to reload the applet. You can select a small or large map (centered either at 0 or 180 degree) from the drop-down list at the left of the first row of panel buttons. If you move the map's scroll bars, the white/gray/black areas of the map might not be refreshed properly until you move the mouse cursor back onto the map. INPUT REQUIREMENTS: Type of prediction (base-to-area or base-to-base); Base name, location and type; Communication area (if base-to-area) or Second base name and location (if base-to-base); Transmitter power; Receiver bandwidth; Environmental noise on 3MHz at the receiver site; Required signal-to-noise ratio (SNR) for the specified bandwidth; Minimum probability of ionospheric support; Minimum antenna elevation angle [NB: only isotropic antennas allowed at present]; Limits for multimode interference to occur: - maximum signal-to-interference ratio (SNR margin); - minimum relative delay time window; and - minimum frequency shift window; Date; Solar activity level as measured by the IPS T index; and Frequency set. The type of prediction must be selected first. The default is base-to-area. If a single circuit base-to-base prediction is desired, press the drop-down menu at the end of the fourth row of buttons/data items, next to "Pred. Type", and select "base-to-base". The base name(s) and location(s) can be entered in either of two ways: 1) If you know the geographical name of the base station location, press the "Base Locator" button and, in the new locator window that opens up, left-click inside the box next to "Name" and enter the first three or four characters of the name (case insensitive). Press the "Search" button to reveal the full name and geographic coordinates. If the name and coordinates are incorrect, press the "Clear" button and try again with a less abbreviated name. When the correct name and coordinates show up, left-click the "Load Base" button to enter that place as the base for the prediction and to close the locator window. (Note: The locator window can be dismissed also by either left-clicking the "X" button at the top right of the Base Locator window; or by right-clicking at the top of the Base Locator window and selecting "X Close"; or by pressing the "Base Locator" button again.) If the name does not show up at all, because it is not in the terminal database, use the following second method for entering the base details. 2) Alternatively, left-click anywhere on the map image and the corresponding latitude and longitude at the mouse location will be entered as the base name and coordinates for the prediction. Note that, as the mouse cursor is moved over the map area, the geographic coordinates of its location are displayed just above the top of the map. You can then manually change the name for the base in the "Base Station" box or leave the name as co-ordinates. The base type can be either a transmitting ("Tx") or a receiving ("Rx") station. This is specified by pressing the drop-down menu to the right of the base name and selecting either "Tx" or Rx". The second base station will be set automatically to the opposite type. Also, the shorter great-circle path between the two base stations will be displayed by a green curve. For a base-to-area prediction, the communication area of coverage is specified by drawing a green box on the map image. This is done by left-clicking and dragging the area box on the map image in any direction. Note that the coordinates of the end corner of the box are displayed just above the top of the map. Also, as you are dragging the mouse, the colour of the box is initially pink if you are in the day sector, but becomes all green when the mouse is released. The transmitter power is specified by manually entering the value in units of kW (0.001 to 1000 kW). The receiver bandwidth is specified by manually entering the value in units of kHz (0.001 to 1000 kHz). The receiver site noise can be specified from the drop-down menu in the middle of the second row of buttons/data items. Select either one of the four standard noise categories ("City", "Residential", Rural", "Remote"), or select "User" and manually enter a value in the adjacent box for the site noise, measured in units of dBW/Hz at 3MHz (-204 to 0 dBW/Hz). Alternatively, the receiver site noise can be ignored altogether by selecting "Ignore", which effectively sets the noise floor at -204 dBW/Hz. The required SNR is specified by manually entering the value in units of dB for the specified receiver bandwidth (-99.9 to 99.9 dB). The minimum probability of ionospheric support is specified by manually entering the value as a percentage probability (0.1 to 99.0%). The minimum antenna elevation angle is specified by manually entering the value in units of degrees above the horizontal (0 to 90 degrees). The limits for multipath interference to occur are specified by manually entering the values for SNR margin [in units of dB (0.1 to 100 dB)], relative delay window [in units of milliseconds (0.1 to 100 ms)] and frequency shift window [in units of Hz (0.1 to 100 Hz)]. For multimode interference to occur at a particular time on a particular circuit, there must be at least two ionospheric propagation modes open for that time and circuit, with the difference in their SNR values (SNR margin) between the dominant mode (mode with the highest SNR) and a sub-dominant mode being less than or equal to the specified SNR margin value and with their arrival times at the receiver being separated by at least the specified delay value and their frequency shift from the receiver's tuned frequency being at least the specified frequency shift limit. The default date is the current date. If you change this, you must select also an appropriate T index for the new date. T indices can be entered either manually in the "T index" box (-100 to 300) or automatically from the pull-down menu ("Tmonth", "Tday", "Taus", "Tnh", "Tsh", "Tnz", "Tant"), the menu choice being dependent on the application (see below). If you select "Amateur" from the pull-down frequency menu near the end of the fourth row of buttons/data items, the amateur frequency set is loaded. If you select "Arbitrary", the default arbitrary frequency set is loaded. Delete or alter any unwanted frequencies and/or add other frequencies (maximum of 10). Select the "Do Prediction" button to perform the prediction. If some input data is missing or any of the input parameters are outside their valid range, the prediction will not proceed and an error message will be displayed in red below the map, indicating the problem or the valid range for the faulty parameter and the current value. Enter a valid value for that parameter and press the "Do Prediction" button again. Select the "Clear" button to clear all the settings. Select the "Reset" button to reset all the settings to the initial default settings. Which T index to use? The T index defines the state of the ionosphere for the prediction. This value depends on a number of factors, including phase of the solar cycle and how disturbed the ionosphere is currently. A choice of T can be selected. The tool starts up with the monthly predicted global T value. No real-time data availability is indicated by a value of 999, in which case, either select Tmonth or manually enter what you consider to be a reasonable value between -100 (deepest possible solar minimum) and 300 (highest possible solar maximum). T index Description Application ____________________________________________________________________________ Tmonth - monthly observed or forecast global T index Past or future date Tday - daily forecast T index (Southern Hemisphere) Daily average Taus - real-time Australian region T index Now Tnh - real-time Northern Hemisphere T index Now Tsh - real-time Southern Hemisphere T index Now Tnz - real-time New Zealand T index Now Tant - real-time Antarctic region T index Now For backwards-looking predictions for past dates, or for longer term (quiet) planning predictions, use the observed or predicted monthly global T index (Tmonth), which follows the long-term solar cycle trends. The daily forecast T index (Tday) is issued each morning (23UT) by the Australian Space Forecast Centre and should be used for the Southern Hemisphere region (particularly during disturbed conditions). Ionospheric conditions are partially determined by seasonal effects, which can result in differences between Northern and Southern Hemisphere T indices. For real-time communications, use the relevant real-time index for your hemisphere or region. If communicating from one hemisphere/region to another during a disturbed period, use the lower of the two indices. OUTPUTS: The prediction output is displayed in either a new browser window or a new tab, depending on your browser settings (Tools->Options->Tabs). The ouptut is preceded by a summary of the input data. 1) For a base-to-base prediction, the output is presented below the input summary in a table that lists the following parameters for each UT hour: BCR or BRR (= basic circuit reliability or basic reception reliability, depending on the number of frequencies specified). OCR or ORR (= overall circuit reliability or overall reception reliability). BCR-OCR or BRR-ORR (= reduction in reliability due to multipath interference). MHz (= frequency in megahertz of dominant mode [column 5] and strongest interfering mode [column 7]). Mode (= dominant mode [column 6] and strongest interferring mode [column 8]). Notes: a) If, at a particular hour, the ionosphere does not support any of the frequencies for the specified circuit, then the symbol ".." is placed in the entries in all the columns for that hour. b) If there is a dominant mode, but no interferring mode falls within the specified multipath tolerances, then the symbol ".." is placed in the entries in just columns 7 and 8. c) The symbol "SS" means "interference by an equatorial scatter mode". 2) For an base-to-area prediction, the output is accessed by left-clicking on the hotlink that appears below the input summary, usually within one minute. The output consists of two sets of charts for each UT hour, displaying either "Reliability" (REL) information or "Frequency and Mode" (FAM) information. The REL information is a set of three, colour-coded, area plots of either BCR, OCR and BCR-OCR or BRR, ORR and BRR-ORR. The FAM information is a set of four, colour-coded, area plots of the frequency and mode of both the dominant mode and the strongest interferring mode (if any). For convenience, both sets of charts also display curves of constant range from the base station. Initially the REL charts for 00UT are displayed. To access the output for another UT hour, left-click on that hour at the top of the display. Alternatively, left-click the "Next" or "Previous" hotlink to display the next or previous hour, respectively. To view the FAM charts, left-click on that hotlink at the top right of the display. To save an individual output display into a file, left-click on "the displayed UT hour as a PNG file" hotlink to download the current display into a PNG-formatted image file, called either PNGs_XXXXX_relZZ.png (for a REL display) or PNGs_XXXXX_domZZ.png (for a FAM display), where "XXXXX" is a random ID number and "ZZ" is the UT hour of the display. To save all the REL or FAM output, left-click on the "all UT hours as a zip archive of 24 PNG files" hotlink to download a zip file called PNGs_XXXXX_rel.zip for the complete set of REL charts or PNGs_XXXXX_dom.zip for the FAM set, where "XXXXX" is a random ID number. REQUEST FOR FEEDBACK: This tool is still under development and is based on theoretical models (particularly section 10 and the Appendix of Rec. ITU-R P.533-10), developed from actual measurements of radiowave propagation modes. We now feel the need for some user feedback to make it more user-friendly, so your comments would be greatly appreciated. Please send an email with your comments to webmaster@ips.gov.au