FLDIGI Configuration

Configuration Suggestions for FLDIGI

Here are some general guidelines on modes and operating configuration settings for use in FLDIGI which may enhance LINKUp operations.

• FLDIGI should be run in "ARQ" mode. On the "IO" configuration tab, ensure that "Enable ARQ" is checked. If that is done, none of the KISS parameters or any other parameters on that tab need to be changed. Unless you have a real need to run the FLDIGI instance on a different computer than the LINKUp program, please use the defaults for the "XML" line on this configuration tab.
• FLDIGI SQL is not always a good thing -- unless signals are very strong, managing the FLDIGI SQL setting may become critical to copy success (just like when using FLDIGI alone). Consider that since you are using LINKUp, only frames which pass CRC check will be displayed in the receive area. As such, you don't really need to sit and watch the FLDIGI screen and it may be minimized once your configuration is set. LINKUp is meant to be utilized in unattended operations, so setting things properly may be the key to the OTHER guy's success when interacting with your station.
• Since LINKUp is designed to be used in unattended mode, please make note of your operating frequency when in unattended operation, and use the appropriate band segments as defined in FCC Part 97 for automatic operation.
• Use the "Lk" button below the waterfall in FLDIGI to keep your transmit frequency stable. For unattended operation this is critical because you do not wish to wander the pass band. In order to keep your frequency locked at a specific place, it is also wise to set the "Sweet spot" on the "Misc" tab in the FLDIGI configuration to your chosen "center frequency". For example: many rigs have a pass band center of 1500 Hz. On the "Misc" tab, set the "PSK et al" value to 1500. Whenever your modem is changed by TxID, it will re-center at the 1500 Hz mark. So before starting LINKUp, set the waterfall cursor at 1500 and click the "Lk" button. This keeps you consistent even across modem changes.
• Almost always utilize TxID so the other station may, 1. Adjust for any drift at either radio. and 2. You may wish to change the modem in order to have a better connection. This is easily accomplished if you run TxID in FLDIGI. I say "Almost always..." because if you are chatting with another station, and you have a good "connection", it is sensible to turn OFF TxID in order to speed turnaround time for chat sessions. When you then return to listen mode, or unattended operation, turn TxID back on.
• Almost always utilize RxID so you may instantly switch modems upon command from the other station. I say "Almost always..." because, like TxID, RxID is not necessary for chat operations once you and your chat partner have decided what modem to use. While this does not really change things in light of the following bullet, you may wish to turn it off so the detector is not running, and thus not recognizing other nearby TxID signals.
• Incoming TxID signals are displayed and handled in different ways by FLDIGI depending on the settings on it's "IDs" tab. Suggested operating parameters for the "IDs" tab are: Uncheck ALL checkboxes except for "Disable alert dialog" and "Retain tx freq lock". In this manner, your operating frequency will not change if an outside station happens to send a TxID near your operating frequency, you will not be prompted to change frequency by a dialog box and the RxID will search only nearby your current waterfall frequency. Though not a suggestion for LINKUp, you may wish to select only the modes you care about under the Receive modes and Transmit modes buttons. This further limits which modems are processed by the Reed-Solomon ID processes in FLDIGI.

Modem Selection Configurations

• MT63 - reduce "Tone duration (secs)" to 1 or 2 seconds to improve turnaround times, particularly for chat. Uncheck "8-bit extended characters (UTF-8)". All chat and file transfers are done with a 7-bit alphabet and thus the extra overhead is avoided by turning off this feature. Also check the "Allow manual tuning" checkbox. This allows you to keep MT63 at your chosen center frequency instead of it's default settings. This is important for the MT63-500 and MT63-1000 modes.
• Olivia - uncheck "8-bit extended characters (UTF-8)" for the same reasons as MT63.
• THOR - ensure all checkboxes are checked. Leave filter bandwidth at 2.0 to encourage decoding of off frequency signals (a signal up to half of the bandwidth of the THOR signal away from your chosen center frequency can be decoded). CWI needs further research here to make a recommendation. I and other testers have found THOR to be an incredibly reliable and resilient mode, and it is my personal all-around favorite.
• IFKP - while no speed demon, IFKP is quite robust and perfectly suitable for chat especially when conditions are poor. When using IFKP also consider using all lower case in your text chats because the 26 lower case letters all transfer faster than upper case or punctuation and numerals. the LINKUp header still uses upper case, but your content will move along a bit faster nonetheless.
• File Transfers - Modems which appear in testing to work well with file transfer include THOR, MFSK and MT63. They combine robustness with the ability to adjust bandwidth and WPM rates as conditions warrant. Of the three, one must have the best conditions when using MFSK, but when the bands are smiling on you, it can really move along nicely. Evenings on 30 or 40m with MFSK64 when conditions were good have provided some snappy chat sessions.