Frequently Asked Questions Trouble Shooting a GMSK Node Adapter-based System

1. Will the board work with my radio?

2. What's all this callsign registration stuff?  Why do it?

3. What is Callsign Routing?  What do I need to do to use it?

4. I'm trying out my Hotspot for the 1st time, and I can't get the receive test (e.g. RF Read) to work.  What should I do?

5. I'm trying out my Hotspot for the 1st time, and I can't get the transmit test (e.g. Echo Test) to work.  What should I do?

6. I can connect my Hotspot to a repeater and hear them, but they can't hear me.  Why?

7. When my Hotspot transmits, the audio is a little garbled/R2D2.  What is causing this?

Will the board work with my radio?

The short answer is -- if your radio provides access to the receiver's discriminator without filtering, and access to the transmitter's modulator without filtering, then yes, your radio will probably work.  By far the easiest way to ensure the above is to use a radio that supports 9600 Data, typically for Packet.  Many of these radios provide a standard 6-pin Mini DIN connector on the back, but some radios use a DSub9 or other connector. 

If thinking about buying a particular radio for your Hotspot, find that radio's manual on the internet and check the back panel documentation for a Data connector.

You can also check the Radio Files section of the gmsk_dv_node Yahoo Group to see if anyone has already documented that radio for use with a Hotspot.

Note: if you are adept at reading schematics and can add a small modification to a radio, you usually can find the tap points for discriminator and modulator and convert radios lacking the 9600 Data port.

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What's all this callsign registration stuff?  Why do it?

Most people want their Hotspot to be able to issue DPlus Link requests so they can connect to DPlus-enabled repeaters and connectors, so this answer will focus on that need.  However, if you instead plan to use WinDV's DExtra linking exclusively, this answer does not apply to you.

DPlus is an application that repeater administrator add to their gateways, and most reflector owners choose to utilize the DPlus Reflector application.  DPlus, in an attempt to ensure only authentic callsigns are allowed to connect and transmit over remote repeaters, checks to make sure the callsigns involved are already properly registered terminals on a US Trust-connected repeater.  See Step 1 at http://www.k6jm.com/hs-setup.htm. 

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What is Callsign Routing?  What do I need to do to use it?

Callsign Routing is an excellent feature of the D-Star specification, but it is a little harder to use that first time, so many (most?) people get started using only DPlus linking.  But as they get more knowledgeable, many people also learn to use Callsign Routing.  There are two major reasons:

• You can Callsign Route to a friend who is mobile or travels, and you don't necessarily know what repeater or reflector he's hanging out on right now.  Callsign Routing allows you to ask the D-Star network to find the most recent repeater where he's been heard, and route your transmission there.  This is neat stuff.

• You can use the STARnet Digital system of creating or joining various groups, so that you can easily contact hams in a group without having to know where in the D-Star world they are right now.  Click here to join the STARnet Digital Yahoo Group.

Your Hotspot can be configured to do callsign routing and accept incoming callsign routing transmissions.  DVAR software does not support this, but the DUTCH*Star WinDV does, since it supports ircDDB (learn more).  In addition to WinDV, people also use Jonathan Naylor G4KLX's Repeater Controller with his ircDDB Gateway software, but for simplicity, this FAQ will focus on WinDV. The following assumes you want to be able to do both Callsign Routing and Dplus Linking.

ircDDB requires that your Hotspot or full duplex repeater must have a different callsign from your own personal MyCall callsign.  This is your "gateway callsign."  These callsigns are obtained in different ways in various countries.  For example, in the US, this is gotten by forming a club and requesting a club callsign (http://www.k6jm.com/usasetupclub.htm).

Summary:

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I'm trying out my Hotspot for the 1st time, and I can't get the receive test to work.  What should I do?

• Start out with RX trimpot in the middle
• Using your receive test tool (e.g. NAWinTOOLS RF Read) transmit with your D-Star radio, typically an HT, but it doesn't have to be. 
  • You want to see the callsign headers decoded at the top of the window, and for NAWinTools, you want to see the received data scroll in the RF Data section of the window.  And, you want to see on the right, the first line of each data block highlighted in green.
  • If you don't like what you see, or you don't get anything, then go into your firmware config program (e.g. NAWinCFG) and toggle the RX Invert setting, then go back to your RF Read test and try again.
  • Once it kind of works, you can tweak the RX trimpot if you think it needs it.  In my experience, the RX trimpot in the middle works with most radios.

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I'm trying out my Hotspot for the 1st time, and I can't get the transmit test to work.  What should I do?

• Once the receive test (e.g. RF Read) works, move on to the transmit test (e.g. Echo Test). 
  • When you transmit, the window should say it is recording
  • When you let up on PTT, it should have your Hotspot radio go into Transmit mode, and hopefully your D-Star radio can decode it. 
  • If it doesn't work, first thing is to go into the firmware program (e.g. NAWinCFG) and toggle TX Invert, then go back to Echo Test and try again
  • Once it kind of works, tweak the TX trimpot for best decoding.  Kenwood radios almost always give garbled or R2D2 audio when the TX trimpot is centered, and you have to turn it up almost to max.  Other radios need to be backed off, and still others have a very narrow sweet spot.  Setting the TX trimpot is more critical than the RX trimpot, but only worry about it once you get TX Invert right.
  • If you use DUTCH*Star firmware, I recommend you uncheck AutoPolarity and manually test until you find the correct RX and TX Invert settings for your radio.

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I can connect my Hotspot to a repeater and hear them, but they can't hear me.  Why?

You are failing DPlus authentication.  Remember that the MyCall in your D-Star radio must be a registered terminal, but also your Node Callsign and your Auth Callsign must also be registered terminals. Note: when Hotspots were starting up, the Node Callsign did not have to be registered, but DPlus was changed to now require this.

The easiest way to comply is to use your callsign with a blank suffix for all three of the above.  But many people prefer a different convention and end up setting up three terminals with different suffixes.  See the callsign registration question above.

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When my Hotspot transmits, the audio is a little garbled/R2D2.  What is causing this?

• Hotspot's transmitter is running too much power and overloads the D-Star radio's receiver.
• Hotspot's transmitted signal is disrupted between antenna and D-Star radio -- for example, if the Hotspot has an outside antenna placed fairly far away from the shack, and metal objects or even a metal roof disrupt the path of the signal, resulting either in a weakened signal or multipath -- note that mutlipath is probably the biggest enemy of a GMSK modulated signal.
• TX trimpot not quite adjusted to the sweetspot. Sometimes a bit of one of the above is combined with this problem.
• A variation of the above, rare but it does happen -- the radio's required TX audio level is outside the range of the TX trimpot. In that case, people have placed an appropriate resistor in the TX audio path to further reduce the audio level, or in extreme cases have had to change a resistor on the board to allow more drive to the transmitter. Again, this is rare.
• Analog radio's VFO is not quite on the exact same frequency as that of the D-Star radio. Some older analog fm radios have been measured and been off enough to cause this. In one case (my own Hotspot), instead of setting the hotspot's radio correctly, then locking the controls, I left lock off and accidentally banged the VFO knob and was transmitting slightly off frequency without realizing it.

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Revised: March 30, 2012.

D-Star® is a registered trademark used for communication equipment (repeaters and transceivers) for amateur radio communications, and owned by Icom Incorporated.