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Receiving SGARN HF Multicasts:

Charles Brabham (N5PVL) on March 30, 2014
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The Second Generation Amateur Radio Network (SGARN) transmits bulletins of interest to amateur radio operators, daily. These bulletin transmissions are sent via AMP, Amateur Multicast Protocol, which allows an unlimited number of Client (receiving) stations to receive bulletins from a single multicast server at the same time, with 100% accurate copy.

This is very similar to what the ARRL's W1AW station does, the difference being that SGARN's AMP transmissions allow for errors in reception to be corrected for 100% accurate copy.

Software:

SGARN has adopted W1HKJ's programs FLDIGI and FLAMP as the best possible software for our use on HF. To receive the SGARN multicasts, you will need the current version of FLDIGI and FLAMP from the W1HKJ website.

w1hkj.com

At the top of the page there is a DOWNLOAD link. Go there and download FLDIGI and FLAMP for your operating system. There are versions available for Windows, Linux and OSx.

Software Setup:

To operate a Client (receiving) station, you must run FLDIGI, then FLAMP so that they run together. Consequently, the SGARN-specific setup for FLDIGI will be described first, then the setup for FLAMP, then a few notes about running them together to receive the SGARN multicasts.

FLDIGI:

You may already be using FLDIGI, as it is the most popular digital multimode program for amateurs at this writing. Many new users of FLDIGI can get started by placing their computer's microphone close to the radio speaker in order to decode the digital transmissions, but best performance is obtained by using a ham radio soundcard interface which connects your computer and radio together so that they may hear each other directly.

Any of the popular soundcard interfaces will do... Pick your favorite, what somebody you trust uses, what is cheapest, or what works best with your equipment. Mine is a home-brew haywired Frankenstein's monster, but it works and that's the main thing.

When you first start a new installation of FLDIGI, there is a setup routine that all must go through, where you enter your callsign and choose your preferences. It is recommended that you set up and use FLDIGI normally in order to familiarize yourself with its use before going on to utilize it for receiving SGARN transmissions. It is a great program that will do a lot.

Use it to read the mail on PSK31 QSOs on 14.070 USB as a good way to test your setup. Or better yet, use FLDIGI for a few PSK31 QSOs of your own.

--- SGARN-specific setup recommendations for FLDIGI:

Be sure the RxID button in the upper right corner of the FLDIGI window is check marked, and its green light is glowing.

Click on Configure, then click IDs. In the resulting window, change the "Allow errors" box to 'Low', check only the "Disable freq change" box, then click Save and close.

Disabling the automatic frequency change will prevent a new signal on the waterfall from pulling you off-frequency in the middle of receiving a file. It also means that you must click onto the SGARN hamcast manually, but mode changes will still be automatic.

These settings help to ensure that the proper mode will be selected automatically for your receiving station.

FLAMP:

Setup of FLAMP for receiving SGARN transmissions is more involved than setting up FLDIGI - but not by much. It is still fairly simple.

In FLAMP, click the "Configure" tab for the Configure menu. Here you enter your callsign and if you like, some brief info about your station. Below, there are a number of check-boxes, only one of which should be checked: Check the box that says "Auto sync flamp to fldigi mode selector"

This will cause FLAMP to automatically follow FLDIGI's advice as to which mode to utilize, so that both programs work smoothly in concert.

No other box should be checked.

Now, just click the "Receive" tab at the top of the FLAMP window - and assuming you already have FLDIGI running too, you are now ready to receive the SGARN transmissions.

SGARN Multicast Reception:

From here, it is assumed that you have a basic working knowledge of FLDIGI, have the RxID activated, have FLAMP running and set up as indicated above, and are tuned in to an ongoing SGARN multicast transmission.

Times and frequencies for SGARN transmissions are listed here: SGARN Servers and Schedules

They are also listed periodically on the NBEMS, fldigi-windows, and linuxham Yahoo! e-groups.

When you first tune into an ongoing SGARN transmission, nothing much will happen until the current file has been sent, and the next file to be sent comes up to be transmitted. - At this time, a TxID will be sent that FLDIGI will respond to by changing to that mode. The mode in both FLDIGI and FLAMP will change to the proper mode, if they are not already there. As the file information is received at your station, your FLAMP "Recieve" tab screen will show the blanks being filled in for the new file.

At this writing, the mode being used is MT63-500L. Note that MT63-500L mode does not start to decode data for about ten seconds, but when it does start decoding, it will be quite robust.

File, Date/Time, etc. will be filled in and as the first DATA statement is received, you will see a block indicated in the FLAMP Recieve "Blocks" pane. - You will also see data in the "DATA" pane as the file is received.

After all of the blocks for a particular file are received, it will be created on your system 100% accurate, and will show in the "Receive Queue" pane.

When you click a file in the "Receive Queue" pane, you can choose whether to SAVE or REMOVE it.

For SGARN use, ignore the "To TxQ" and "Report" buttons. SGARN does not take or respond to reports, instead re-transmitting the files in a continuous loop so that an unlimited number of stations can access and use the data stream at any time. - If you miss a block on a particular file, just leave it as it is and the next time that file is transmitted, the block will most likely be filled.

The best system is to tune into a SGARN data stream and let it go until all of the files are intact on your system, then save the files and you are done for the day. Since the present SGARN multicast starts at 0200 UTC and continues until 0600 UTC, it may be best to just let your system listen overnight, and see what you have in the morning.

At present the current ARRL bulletins, categories X,P,K,D,S and B are being sent, along with brief SGARN bulletins in Text and HTML format. As new ARRL bulletins are released, the SGARN files are updated so that by receiving the SGARN transmissions, you will always have the latest from ARRL HQ. In the future, other content will be added.

The PART97 restriction upon what may be transmitted via multicast is that it be information "of interest to amateurs". SGARN will be interpreting "of interest to amateurs" as being information released by recognized amateur radio news and information sources - not what somebody might want to get up on a soap-box and rant about.

Signal reports are requested, and greatly appreciated. If you receive a SGARN transmission, let us know about it by sending an eMail using the address given in the SGARN bulletins.

For more information about the Second Generation Amateur Radio Network (SGARN) visit: http://sgarn.org

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