05 Kenwood APRS Solutions

APRS Article 5

March-April 2000

Kenwood’s APRS Solutions

By Jeff Robbins

VE3JTR (Voice Call)

VA3JTR (APRS Call)

Welcome back APRS hams! Perhaps you have noticed a new look to the column. When I initially set out, I intended only to write a half-dozen or so articles to try to increase interest in APRS. I have since been approached to make APRS a regular column. So I guess I am here to stay! I believe you also get to see a mug shot here as well! I would also like to express my appreciation to everyone who has contacted me with comments and support. I enjoy hearing about how hams are utilizing APRS in their lives and community activities. I will continue to share those stories with you as they come in. Now then, on with the show:

Kenwood has taken a leadership role in getting complete APRS solutions to market. Their first offering, the D7 handheld has been well received by the amateur community. Kenwood broke all of the rules by building an AX.25 compatible TNC with minimal APRS resources right into the radio, no PC or external TNC required! Just plug in an optional GPS receiver and you are on the air with APRS. While the radio is limited in what you can do with APRS, it still goes way beyond any other handheld radio to date. Let’s not forget that this is a dual band radio, so simultaneous voice operation on the unused band is also possible.

It is important to remind everyone that hooking up a GPS is not necessary to enjoy APRS, only if you want to dynamically update your position information over the air is a GPS necessary. You are free to manually enter your position and leave it static in the radio’s memory. All other receiving and messaging functions will work just fine.

So lets dig into the D7 and discover what it is capable of doing for us. In addition to reporting position information (Lat and Lon), the D7 is also able to transmit and receive a variety of station icons, speed and direction, message and status text strings. The D7 is also capable of receiving APRS format weather reports. The D7 has enough memory to store 40 received APRS Position Reports along with any accompanying APRS data.

Now the D7, obviously, does not have maps on board and cannot display position information graphically like the traditional APRS software packages. However, Kenwood has compensated for this by doing some quick mathematics before presenting the location. The D7 compares the Lat/Lon of the received station against its own Lat/Lon position currently in memory, and presents you with the distance and bearing to the received station, the station’s icon, and the Grid Square location. The distance is presented to you in your choice of kilometers or miles, and the bearing is shown as one of eight compass points. In the case of mobile stations, the speed and direction of the station is also available. Power, antenna height, directivity and gain are all available for fixed stations.

In mobile situations, connectivity with a GPS has many advantages. Let’s face it, we bought this radio because it is portable, and we want to move around. Continuously updating your position in the menu is certainly possible, but not realistic. By connecting your GPS, the D7 will be continuously updated with your current location. The GPS requirements are similar to a standalone tracker we talked about a few months ago. Nothing new there, but wait, here is the slick part. The D7 can also take received station data, format it to meet the $GPWPL NMEA format, and send it to the GPS as new waypoints. If your GPS can store and display maps, well all of the sudden, here is our graphic representation of stations we were missing earlier. I haven’t done this yet, as my GPS doesn’t support incoming waypoint data, but someday I will give it a try with a new GPS.

The D7 can also store 16 messages in memory. It is important to note that this memory is shared by incoming and outgoing messages. Bulletins and messages that are not addressed to your station are not saved in memory. Sending messages using the keypad of the radio is awkward, but receiving short messages is quite slick, resembling an alphanumeric pager’s capability. Hmmm, using the D7 as an APRS pager, now there is an idea.

Also available is the PC connectivity cable and a CD containing an In-Depth Instruction Manual, the PC programming software, and an entertaining 22 minute television commercial in RealPlayer format. The movie is a little silly, but does demonstrate the radio’s capabilities and features. Bob Bruninga, WB4APR makes a guest appearance in the movie as well! The In-Depth manual contains information on APRS and the D7, packet operation with the D7, SSTV with Kenwood’s VC-H1, and the new Sky Command system. If you are really keen, and handy writing software, there is also a listing of PC commands you can use to remotely control the D7 from a PC.

I have also found some excellent resources on the web for D7 owners. A great repository of information on the D7 is available at http://www.radiohound.com. Including a page on getting your GPS working with the D7. I have to admit that I haven’t had any success in getting my Lowrance 212 working with the D7 yet.

Now for the downfalls I have observed:

The reason I haven’t been on the air lately as VA3JTR-7 is because I managed to drop the radio on it’s head, and broke the SMA antenna connector! Word to the wise, it is quite fragile. Avoid dropping this radio! I ordered a couple of replacement SMA connectors, I want to have a spare, and it is not an off the shelf item. If you should need it, the Kenwood Part # is E04-0407-05, and the price is $15 each. Wow! Like I said, avoid damaging the antenna connector at all costs!

In February 1999, Kenwood issued a product bulletin announcing that new firmware is available for the D7. The new firmware solves some problems with coordinate resolution and GPS interfacing. Unfortunately, when I purchased my radio new in September, from our friendly dealer in Toronto, I was quite disappointed to find that my new radio still had the old firmware installed. Any radio with a serial number starting with 010 (zero-one-zero) has the old firmware, and should be returned to Kenwood if you desire the bugs fixed resulting from the old firmware. Now I will have to ship my radio to California to have the new firmware installed, so I will lose my use of the radio for several weeks for this. If you are going out to buy a D7, check the serial number before you lay down the cash! Serial numbers with 011 (zero-one-one) or higher will have the new firmware already installed.

Kenwood just recently took the next logical step and created a mobile version of the D7. The D700 appears to be built on the Kenwood V7 frame, with the detachable faceplate and other features enjoyed by V7 owners. The TNC and APRS functions are similar to the D7. Again, setting up as a tracker is as simple as hooking an optional GPS receiver directly into the D700 and you are off and running.

As of this writing, the mobile D700 radios are starting to hit the shelves, and comments are appearing on the internet about peoples reactions. Details about the D700 are still sketchy, but it would appear that the APRS capabilities have been at least duplicated in the mobile version, perhaps extended, so operation should be similar.

So what is my impression of the D700? Well it sure is a great looking radio. It has hit the shelves, and with a healthy price tag I might add, as you probably could have predicted. So, I expect I won’t be buying one anytime soon. However, if anyone out there does manage to save up your pennies, and wants to contact me about it, I will be happy to print your comments about the new mobile D700.

Until next time, I’ll be seeing you on APRS!