findU hit the Internet in March 2000. Since that time I have released dozens of cgis. None has produced more email debate than panel.cgi released in January, 2014. It seems like everyone has an opinion, and few of those opinions agree. The only answer was to add a ton of parameters.

What is a parameter?

Parameters are values passed to a program. In this context they are options that allow you to take control of the function of a findU web page. Almost all of findU cgi's take parameters via the URL, bookmarked or entered into the box at the top of the browser. The advantage of this is that it is easy to customize the pages to fit your needs. Generally you will build the URL you need, then bookmark it. Start with the basic URL for the panel.

This tells your browser how to get the information (http - otherwise know as the web), what computer the information is on (, the directory on the computer the information is located (cgi-bin), and the file name (panel.cgi).

Entering this URL does nothing, because the panel must know which data you want to appear on the panel. You do this by adding a parameter, like

Everthing after the ? is passed to the program. A parameter is a name/value pair, the name is what you want to affect, the value is how you want to affect it. In this case the name is call (a holdover from findU's origins as an amateur radio system, everything is identified by government issued callsigns). If you aren't a ham, you are probably looking at Citizen Weather Observing Program data, with calls like CW0925.

You can add multiple parameters, separated by &

The order of parameters does not matter, but there cannot be more than one parameter with the same name.

Required Parameters

As mentioned above, panel.cgi must have at least one parameter. This can either be a call as in the examples above, or you can specify a position

Position is specified in latitude and longitude, with negative numbers for southern and western hemispheres. With this option the cgi will find the nearest weather station that has reported to the CWOP/APRS networks within the last hour and display it on a page.

This may not seem so useful, until you visit

This will make a smartphone browser figure out its position and insert it into a request to the panel cgi. As you drive, the above page will always find the closest active weather station!


The size of a browser window is a most difficult thing for panel to determine remotely. Some new features in recent browsers make this easier and more accurate, but are not implemented in older browsers. findU has an older mix of browsers than the internet as a the whole, so I need to stick to older features. This allows panel to set its size to fit the horizontal visible extent of the window but not its vertical extent. Since it may be viewed in a widescreen iPhone held vertically or a huge 16:9 horizontally-oriented monitor, one size cannot fit all.

The default is the panel image occupies 90% of the horizontal space of the browser window. You can change this to fit any display with the xsize parameter:

Display mode

This option controls whether the panel is displayed as a simulated LED display. Default is led=1

Hide text

This option keeps the text information normally shown above and below the pnel graphic from displaying.

Hide wind chill

Normally at temperatures 32F and below the dewpoint field becomes wind chill. If you are a wind chill hater you can make that go away and show dewpoint even at those temperature where there is no dew.


The default is english, which gives speeds in miles/hour, temps in degrees F, rain in inches, and pressure in inches Hg. Nautical gives speeds in knots, temps in degrees F, rain in inches, and pressure in inches Hg. Metric gives speeds in kilometers/hour, temps in degrees C, rain in centimeters, and pressure in millibars. You would think, since metric is hailed as a universal standard, that metric was metric, but no. Some countries use km/hr, others use m/s. Some use mm for rain, others use cm. I feel better realizing this since I live in a country that rejected the metric system! I have set the defaults to those used by a majority of countries responding in a recent poll, but some individual options will be added in the future so everyone can be happy (or at least less unhappy).


Color is denoted by three eight bit values in decimal specifying red, green and blue. Each value can range from 0 to 255. Four different colors are used. fcolor is the color for the numbers, acolor is the annotations (or labels), rcolor is ring color, and bgcolor is the background. The example is chosen to show clearly the different places each color is used. You should probably find more pleasing combinations!

Constructive comments welcome!

APRS is a registered trademark of APRS Software LLC and Bob Bruninga, WB4APR.