Can someone explain how I send packets using a TNC?

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Alligator24

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I have two Kenwood TH-D72A HTs that I'd like to try using with packet data. I understand I can plug them into a computer (both computers will be running Windows 8.1) using the supplied USB cable, but I don't know how to send data between them. I'm hoping someone here can give me the basics.

In the manual, there are a lot of commands I can use, but I'm guessing someone has simplified these into some software. Is there some sort of specialized software that does this automatically?

What can I send from one computer to another? Just text, or can I send simple images too?

I'm completely new to TNCs, but I'd like to learn. Thanks!
 

n0nhp

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Basic would be use a communications application (Google "windows communications software") and send text messages. Again Google is your friend "packet radio software" will find you many programs that will send text and images. Beware 1200 baud packet is slow, I think the only time I played with sending an image it took almost all night to get through.
Have fun
Bruce
 

W9BU

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You need what is known as terminal emulation program. Windows used to come with HyperTerminal, but Microsoft stopped bundling it with Windows at Win7, I believe. You can still find HyperTerminal on the web. There are others that you might want to try. I use one called TeraTerm.

Assuming that you have your D72 connected to your computer and assuming that the D72 serial port driver has been loaded, you'll need to look at the Windows Device Manager to see what COM port the driver is using. Once you know the COM port number, you can configure your terminal emulation program to use that COM port at 9600 baud 8-N-1.

Put your D72 into packet mode (not APRS mode). Hit the Enter key on your computer keyboard a couple of times to see if you get any response from the D72. If you do, type "DISP" and hit Enter. Your D72 should respond with the current status of all the packet commands and settings.

Once you've established that you have communications between your computer and the D72's TNC, you can try connecting the TNC's over the air. Let's assume that your callsign is N9ABC. You will need to set the MYCALL parameter in both D72's. Note that this is different from the APRS callsign. At the TNC's command prompt on your computer, type "MYCALL N9ABC-1" and hit enter. The TNC should acknowledge that command. Now, do the same thing with the other D72 only use N9ABC-2.

OK, with the MYCALL set on both D72s and both D72s connected to computers and both D72s set to the same frequency (try 145.010 to start), you can communicate using packet. On the D72 that's configured as N9ABC-1, use your computer to send the command "C N9ABC-2" and hit Enter. The N9ABC-1 D72 should send a packet that the other D72 hears and responds to. They'll do a little packet negotiating and then connect. From that point, you can type messages keyboard to keyboard between the two D72s. To get out of keyboard to keyboard mode, use your computer to send a Control-C to one of the TNCs. That will get you a command prompt so you can send "D" to disconnect.
 

LtDoc

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Oh boy! That's a 'broad' question.
Can you use a TNC and your two radios to exchange data? Yes, you can. Is it a -simple- thingy? Uh... yes and no. Mainly yes, but there are some 'catches' to that. How to specifically set them up, I ain't even going to try to tell you! But it can certainly be done. YOU have to decide if it's worth the effort. That depends on what you want to do, what information/data you want to exchange. How'zat for a non-answer?
- 'Doc
 

kcwgrunt

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Further help with D72A packet mode?

I'm in the same boat.

I have been successful in talking to the D72A via serial port (USB) with a basic python script. :

['\x00,,\xaa5\x81loaded with defaults\x07\r\r\r\rKenwood Radio Modem\rAX.25 Level 2 Version 2.0\rRelease 16/Nov/2010 2Chip Version 1.00\rChecksum $7772\rA 180611055737\r\n', 'cmd:MY KM6TIG-10\r\n', 'MYCALL was NOCALL\r\n', 'cmd:\xdd\xfekiss on\r\n', '?EH\r\n', 'cmd:']
['restart\r\n', '\r\n', '\r\n', '\r\n', 'Kenwood Radio Modem\r\n', 'AX.25 Level 2 Version 2.0\r\n', 'Release 16/Nov/2010 2Chip Version 1.00\r\n', 'Checksum $7772\r\n', 'cmd:']

But how do I attach the device to my raspberry Pi via an ip address?

I want to send IP packets through the TNC gateway and my assumption is i need a destination IP address for all TCP/IP.

Previously, I setup AX.25 with a AX launch and axports. BUT, this caused conflicts with the ttyUSB0 port. So, running the AX.25 attaches a ax0 port with a ip address (setup in the ax25 scripts)

However, I cannot then talk to the D72A to set it into KISS Mode.

So, I killed the AX.25 scripts and ran the python script. I was received a positive response. But, then what?
How can I send TCP/IP over the radio?

It's so funny that I cannot recall how this is done. I vaguely remember the process during the Compuserve days. It is similar., but that is not helping me at all.

Do you have any suggestions?


You need what is known as terminal emulation program. Windows used to come with HyperTerminal, but Microsoft stopped bundling it with Windows at Win7, I believe. You can still find HyperTerminal on the web. There are others that you might want to try. I use one called TeraTerm.

Assuming that you have your D72 connected to your computer and assuming that the D72 serial port driver has been loaded, you'll need to look at the Windows Device Manager to see what COM port the driver is using. Once you know the COM port number, you can configure your terminal emulation program to use that COM port at 9600 baud 8-N-1.

Put your D72 into packet mode (not APRS mode). Hit the Enter key on your computer keyboard a couple of times to see if you get any response from the D72. If you do, type "DISP" and hit Enter. Your D72 should respond with the current status of all the packet commands and settings.

Once you've established that you have communications between your computer and the D72's TNC, you can try connecting the TNC's over the air. Let's assume that your callsign is N9ABC. You will need to set the MYCALL parameter in both D72's. Note that this is different from the APRS callsign. At the TNC's command prompt on your computer, type "MYCALL N9ABC-1" and hit enter. The TNC should acknowledge that command. Now, do the same thing with the other D72 only use N9ABC-2.

OK, with the MYCALL set on both D72s and both D72s connected to computers and both D72s set to the same frequency (try 145.010 to start), you can communicate using packet. On the D72 that's configured as N9ABC-1, use your computer to send the command "C N9ABC-2" and hit Enter. The N9ABC-1 D72 should send a packet that the other D72 hears and responds to. They'll do a little packet negotiating and then connect. From that point, you can type messages keyboard to keyboard between the two D72s. To get out of keyboard to keyboard mode, use your computer to send a Control-C to one of the TNCs. That will get you a command prompt so you can send "D" to disconnect.
 
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