The “Bosun's Pipe - Navy-Marine Corps MARS

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Available software ApplicationsIZ8BLY MT63 Terminal – This application is a freeware application available fordownload from the internet. It is a single purpose application. It works very well and is easy toconfigure. If using with an interface the user must have a com port (COM1, COM2, COM3, orCOM4) available for keying port.MultiPSK - This application is a multi-mode software package and is also available in botha freeware version and a shareware version. It is also available for download from the internet.Since it is a multi-mode application, it is more difficult to configure. It also works well and offersthe member other sound card modes to evaluate (Note: the difference between the sharewareversion and the freeware version is that there are added features for the user; i.e. an audiospectrum oscilloscope, etc., none of which affect the use of the different modes.}MIXW – This application is also a multimode application. It is shareware but there is trialversion download for the user (time period limited). This software also requires more carefulconfiguration. Although this application requires the shareware license for continued use, it isnominal and the application has the advantage of adding additional modes, Olivia, as they becomeavailable. The application may also be configured to be used as the terminal program tobe used with a TNC without affecting the sound card modes. It also works well for our use andwhen setup properly will send AMFEC readable by a TNC.Setup:Without InterfaceReceivingInstall the software of your choice. Configure the software to key VOX so that it is not lookingfor a port. Insert the computer microphone into the MIC IN jack on the computer. Place themicrophone near the transceiver speaker. Using MIXW or MultiPSK select the mode MT63.When you hear (a low growl) you should a broad signal in the waterfall and the applicationshould decode the signal and print on your screen. You can now copy the signals. (Note: thiswill work with all three applications)TransmittingFor testing purposes, with the transceiver off or in receive USB and VOX off, place the softwarein TX using the function in the program. From the computer speakers you should hear theMT63 audio. Type some words into the “transmit data box” (usually the lower box of the dividedwindow) and observe the words echoed in the receive area. To transmit live, you willhave to key the microphone and place it in front of the computer speaker and key the software.The XCVR microphone will pickup the audio and modulate the XCVR sending the signal to thenet. This is awkward as the microphone must be keyed during the entire transmission of thedata. Using a desk mike w/ a key lock makes it easier although a rubber bank that can be easilyslid up on a handheld mike works also. (Note: check w/ NNN0IBM as she has used this techniqueon the 4C1B net on THURS)After experiment in this manner, it is recommended that you either build a simple interfaceor purchase a kit and build on or purchase a commercial interface.With InterfaceAn interface is placed between the computer and the transceiver. An interface relieves theoperator of the task of manipulating two microphones and the awkwardness of remembering
several steps in the RX/TX process. It also isolates the computer and transceiver reducing thepossibility of computer generated noise getting into the transmitted data. It also provides thekeying function through a serial port. The Alabama NAVMARCOR MARS web site is a goodreference for sound card application information. The WM2U site (www.qsl.net/wm2u) is alsoan excellent reference site for information on sound card modes. The software mentioned earliercan be downloaded through these sites.The selection of an interface that a person uses in his/her station should be compatible with thetype of operations in which the member participates; i.e. normal net operations, traffic rep duties,and equipment that the member has in his station. A quick search on the internet for“sound card interface” produced nearly 20000 hits. The query produced a number of circuitdiagrams of simple devices, a large number of kits for the user to build and customize his owninterface, and the full range of commercially constructed units ranging from a few tens of dollarsto those with many bells and whistles costing several hundred dollars. The question “Is anyone particular device best for MARS and/or Amateur operations?” is difficult to answer. Thewriter is a firm believer of the KISS principle. Perhaps the best way to illustrate this is to outlinethe thinking process that was used in selecting the interface that is in current use in thewriter’s station. The primary station is made up of a 100 watt transceiver, antenna tuner, TNC,sound card interface, key/ paddle, CAT interface, and computer. This equipment array is usedboth for MARS operations and amateur operations. During MARS operations I may use up tofour computer applications simultaneously during a single net. While at other times when pollingthe WL2K mailbox as traffic rep only a single application may be used. Therefore thesound card interface and its operation must not interfere with the other operations. In generalthe sound card application prefers unprocessed analog data for its input and the data from thesound card should not be processed prior to modulating the RF signal in the transceiver. Havingthis information it is necessary to get out the manuals and determine where to get the necessarysignals and where the necessary inputs will be going to accomplish our requirements. Afterreading carefully the writer found that unprocessed audio at a constant level is available atthe accessory port on both the Kenwood and ICOM transceivers. It was decided that this portwould be used for the sound card interface and that a mike/TNC switch would be used for TNCoperations allowing some audio processing for both voice operations and TNC mailbox duties.Therefore the writer is using a simple interface consisting of two 1:1 audio xfmrs for isolation,two 5 kohm potentiometers to adjust audio level to and from the sound card, two NPN switchingtransistors for keying the transceiver from the serial port. If I were replacing this interface Iwould use two optical isolators in place of the NPN xstrs. This interface is also available as akit and as commercially built unit. This interface has worked satisfactorily for all sound cardmodes including MARS-ALE. (The circuit for this interface was published in an earlier newsletter)The above section is not designed to detract from any of the available interfaces. The memberneeds to make the selection to match his/her station operations. I personally set up andtested sever of the units that are on the market for amateur radio friends and have found themall satisfactory when setup and operated within their design parameters. Most problems thatarise in setting up the sound card/ interface and the application are usually resolved with appropriateadjustment of the input and output volumes of both the computer and the interface. Keyingproblems are usually related to port settings and/or the pins selected in the application forthat function. Other than this general advice each problem needs to be assessed individually.
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Page 11: 210 / 3.750 (band center) = 56 (unk

The “Bosun's Pipe - Navy-Marine Corps MARS

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