Greg Ordy
S Meter Lite is a no-cost program that displays your receiver's S Meter signal strength in a window. The next picture is an S Meter Lite screen capture. The S Meter data was obtained from my ICOM IC-756PRO radio.
The large black bar below the typical S Meter scale is the S Meter reading, in this example, slightly more than S7 and a half. This bar is updated 20 times per second, and follows the S Meter on the radio. This window is shown at its actual size.
The green bar above the S Meter scale displays additional S Meter data. It shows the minimum, maximum, and average S Meter values computed over a small period of time. In this example, it is the last one-half second. The left edge of the green bar is the minimum, and the right edge is the maximum reading. The black line within the green bar is the average S Meter reading computed from the last half second of accumulated data. The minimum S Meter reading is approximately S6.7, the maximum is S7.7, and the average is slightly more than S7.
S Meters are often used as a basis for signal comparison. Perhaps the comparison is between multiple stations or antennas. In order to make this comparison easier, it would be desirable to be able to save recent S Meter readings so that we could refer to them and see the difference. By clicking the Restore button on the above window, the window expands, revealing the full S Meter Lite window, shown in the following screen capture.
The simple S Meter shown in the first picture has been augmented with several additional controls, and a large graph that shows the recent history of S Meter data. Again, the same green bar data interpretation is used. Each vertical green bar with a black dot represents the minimum, maximum, and average S Meter readings computed over a sample period - in this case, one half second. Since we are obtaining 20 S Meter samples per second from the radio, each sample or update period reflects the minimum, maximum, and average of 10 readings. The graph moves from left to right, adding a green bar every half second.
The previous example was captured while listening to 20 meter SSB. The samples on the left, near S9, represent a transmission I encountered as I was tuning across the band. The drop-outs are the pauses between words. Shortly after the first (left-most) red line, I tuned away from the station. The S Meter value dropped to near S0, the background noise level of the band. The red lines are created by pressing the Mark button. This is nothing more than a visual clue to help separate events. I soon came across another station, with a signal level similar to the first. The right pair of red lines mark their transmission.
In this mode of operation, the radio S Meter is captured both as a real-time bargraph, and a time-varying data graph. The readings exactly follow the meter on the radio. In some cases, we would like to make more accurate measurements of differences between signals.
S Meters are usually not accurately calibrated - both in the S Unit and dB portions of the scale. S Meter Lite has a second mode of operation where the typical meter scale is replaced with a dB-only scale that is centered around S9 (S9 equals 0 dB). In this mode, S Meter Lite can be calibrated to follow decibel changes accurately. This mode is entered by pressing the dB button. Here is a screen capture from that mode.
The typical S Meter scale has been replaced with a scale that ranges from -18 dB, through S9, to +12 dB. Since the data points have been set with the help of an RF generator, and a step attenuator, they are much more accurate than the usual S Meter markings. This example shows a local AM broadcast station transmission. The red lines separate the use of two different antennas. The signal strength difference appears to be about 17 dB.
Detailed information on the S Meter Lite features and operation can be found in the program documentation, which is available on-line. While there is always strong temptation to just download the software and jump in, you may want to read the next few sections of this page, and see if S Meter Lite will work with your radio. Unfortunately, only a handful of radios support external access to S Meter data. If you believe that your radio does allow external S Meter access, and it is not on my supported list, please feel free to contact me, and let's see if we can get it to work.
While creating this program, I stopped to look at S Meters, in general. Those comments are on another page. I would like to recognize and thank Ekki, DF4OR, who has a web site that includes an excellent summary of the ICOM radio/computer communications protocol.
Version 2.0 of S Meter Lite introduced an antenna pattern plotting capability. In order to use this capability, your test antenna must be mounted on a rotator that can turn the antenna at a constant rate. In addition, you will need a stable test signal. While the constant test signal is being generated, the test antenna is rotated, and S Meter Lite captures all of the data samples. After a complete rotation, the data can be displayed in a resizable dialog box that contains the common antenna pattern plot. Here's a picture of the plot derived from data captured from my 6 meter Yagi. While one side of the antenna seems to have a reasonable response, it's clear that something is upsetting the pattern on the other side. The antenna pattern plotting capability of S Meter Lite provides this sort of diagnostic information for real-world antennas.
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| W8GB's 6 Meter Antenna Pattern Plot |
Four different plotting scales are provided. These include the popular modified scale which is tied to a logarithmic response, a scale with a polynomial response, and two linear response scales.
The antenna plotting dialog also supports a Save capability, which saves the original S Meter data in a comma separated value (.csv) file. This standard file format can be imported by programs such as spreadsheets, for custom analysis and graphing.
Please refer to the on-line documentation for further details.
S Meter Lite supports the following radios:
These radios have been tested with S Meter Lite. The radios marked with a * character will work with S Meter Lite, but do not have a specific default calibration (S Unit, dB, or both). In order to obtain best results, you will need to calibrate the software for your radio according to the information in the program documentation.
It is assumed that the Yaesu FT-1000MP Mark V is so similar to the existing 1000MP that it will also work with S Meter Lite.
In order to use S Meter Lite, your radio, one that is supported by the software, must be connected to your computer. If you are already using other software that communicates with your radio, such as logging software, you are probably ready to go. If not, you will need an available COM port on the computer, a serial interface cable, and potentially a radio interface box, depending upon the brand of your radio. Please consult the on-line documentation Reference section for more information on connecting your radio to your computer.
S Meter Lite has been tested on Windows 95, 98, ME, and NT 4.0. It should also run on Windows 2000. Performance (clock speed) of the CPU is not critical.
The current S Meter Lite self-extracting download file is approximately 600 Kilobytes, which typically requires approximately 2 minutes of transfer time (at 28.8 KBaud). The download program is executed to perform the S Meter Lite installation. Total installed disk space consumed is approximately 500 Kilobytes (half of a megabyte).
S Meter Lite, when running, consumes approximately 2.5 Megabytes of RAM memory.
S Meter Lite help information is viewed through the HTML Help viewer.
Through this section you can download the current version of S Meter Lite.
When you download S Meter Lite, you are actually downloading a self-extracting compressed archive file onto your computer. The downloaded file name is a combination of the program name (SMeterLite) and the program major version number. In order to install S Meter Lite, you must execute the downloaded file. The install program is in the form of the common installation wizard. You will be asked several questions that will customize the installation for your computer.
One of the installed programs is the S Meter Lite uninstall program. You should use this program to remove S Meter Lite from your computer. The uninstaller will remove all S Meter Lite files, and remove S Meter Lite-specific entries from the system registry. The uninstall program will also be available from the Add/Remove Programs applet on the Control Panel.
Although S Meter Lite includes an uninstall program, you are responsible for the downloaded self-extracting installation wizard file. In other words, the uninstall program does not remove the downloaded file (it removes the installed files). After S Meter Lite is installed, the downloaded file may be manually deleted.
Finally, the software. The following table contains the S Meter Lite major releases, in reverse chronological order (most recent is first).
Version |
Release Date |
Description (Size) |
Download File |
Download |
History Information |
2.08 |
September 14, 2002 |
Version 2 (600 KBytes) |
SMeterLite2.exe |
View |
Additional installation and operation information can be found in the on-line documentation (next subsection).
All S Meter Lite documentation, both the help information and user's manual, is written in HTML. HTML, the language of the Internet, is also becoming the preferred language for program support documentation. In fact, Windows 98 is shipped with the HTML Help viewer in addition to the older Winhelp viewer.
If you are not running Windows 98, or a more recent compatible operating system, you may not have the HTML Help viewer. The viewer is available from the Microsoft web site, and it will operate on any version of Windows. The viewer will also be automatically installed if you install Internet Explorer 4.0 or higher numbered version. If you do not have the HTML Help viewer, you will not be able to use the help facilities built into the program, or read the user's manual (through the program). Since the documentation is written in HTML, however, we have placed all of the documentation under this web page. This means that you can access all of the information regardless of your help viewer. You can also read the manual before downloading the software.
If you have problems, questions, or comments (concerning this software), please contact me via email, at ordy@seed-solutions.com.
S Meter Lite was developed by, and is owned by Seed Solutions, Inc. Copyright ©, 2000, 2001, 2002, Seed Solutions, Inc. All rights reserved. No warranty of any kind is made as to performance, or fitness of use in any application. Your use of this software is your agreement with these terms. You agree to hold Seed Solutions, Inc. free from responsibility for any damages that may or may not be associated with the installation or operation of the program.
This software may be redistributed in original form. No fee may be charged for redistribution without the prior and specific written consent of Seed Solutions. Inc. This software is licensed for personal and non-commercial use only, and is subject to the export laws and regulations as defined by the State Department of the United States of America, and other applicable regulatory agencies.
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