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Author Topic: How do I get a Kenwood D7A(G), a GPS *and* PC APRS  (Read 3422 times)

Posts: 35

« on: April 09, 2003, 02:04:10 PM »

Hello all!  I am considering getting a Kenwood D7A(G) HT that has both a TNC built-in and internal APRS software.  It would fit most of my needs, except I've had a question about how the TNC works, and that will affect the scenario I want to use.

Basically, I want to be able to use the HT in conjuction with a PC or Palm WinAPRS, UIView, pocketaprs (for the palm), etc.

However, the HT's TNC has two (2) modes to it.  TNC and TNC-Packet.  This is a very important distinction.  To my understanding, TNC mode is used for the radio's internal APRS.  A GPS can be plugged into the GPS port and the HT is able to use it to send a beacon, and the radio can display APRS messages.  TNC-Packet mode is used to send packets to and from the computer, and the computer is now the controlling APRS unit, not the HT.

But, the scenario I'd like to use is the following:

A PC *or* palm connected to the TNC of the Kenwood HT.  A GPS connected to the Kenwood HT's GPS port.  I will be running WinAPRS (or similar) on the computer end.  

Now, here's the issue...  Remember those two TNC modes for the HT?  Well, to get the HT to act as the TNC mode for connection to the PC, the Kenwood needs to be in TNC-Packet mode, right?  Now I can run APRS software on the PC (or palm), and can see all the stations start popping up.  *However*, I want to *also* send out my beacon based on my GPS data.  

Here's the problem:  So, the HT is in TNC-Packet mode talking to the computer, but the GPS is connected to the HT (GPS port)... How do I get the GPS data from the GPS *through* the HT to its TNC port (which is in *packet mode*) to get to the controlling APRS software on the PC?

In other words, can the Kenwood pass the GPS data (GPS connected to the Kenwood) over to the computer (also connected to the Kenwood) via the Kenwood's TNC (in packet mode which is needed to talk with the computer)?  If so, then the PC can take the GPS data and prepare a message for sending back to the TNC of the radio for transmit.

But, I haven't read anything about the GPS connected to the HT being able to pass it's data *through* the HT's TNC that is connected via packet mode to a PC.  The only thing I was able to get from the docs is that you can use the GPS in plain old TNC mode on the HT for HT APRS, and use the TNC-packet mode for connection to a PC for controlling software there, but no mention of whether the GPS connected to the HT can pass its data along through the TNC (packet mode) port to the PC.

Does anyone know for sure either way?

You may ask, why not connect the GPS directly to the computer (bypassing the HT) along with the TNC of the radio connected to the computer.  My laptop a) has only one serial port, and b) I may use a Palm instead which only has the one serial port.

So, I need to have the Kenwood HT acting as the conduit for the GPS-to-PC connection, so that my PC's APRS software can send out a beacon based on the GPS data.

Of course, I could make life easy and get a Kantronics KPC 3+ (it's got 2-serial port capability) and a seperate 2m rig, but I lose the portability of the Kenwood HT (if I use the HT in the car, I'd have a 2m amp to go along with it, and an external antenna.)

I know it was somewhat wordy above, but I wanted to make sure I explained the exact scenario (which, I assume, is a common scenario).

Thanks, and 73!


Posts: 1

« Reply #1 on: April 21, 2003, 08:09:39 AM »

I have the Kenwood THD-7E (the same as the one you're considering but for the European market). I've had the radio for over three years and have used it extensively as a talking tool, packet radio (to local BBS's), APRS and SSTV. It has proved to be one of the most resiliant transceivers I've ever owned and would happily purchase again!
The TNC implementation is such that you can use it as a 'standard' TNC for connection with a terminal emulator to talk with BBS's or other packet stations (this means you can also use WinAPRS, UI-View and the PocketPC APRS programs whilst having data from a connected GPS automatically forwarded THROUGH the PC port on the Kenwood). You can also use the 'built-in' APRS functionality where you don't bother with a PC connection, rather the radio itself uses it's own APRS facility rather than an external TNC APRS program. It is also possible to allow received APRS stations to load as waypoints automatically onto the GPS! Feel free to drop me a note to my other ham radio callsign:-
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