Tag Archives: eTrex

APRS in the Toyota Tundra

I’ve played around with APRS in the Toyota Tundra before. Now I’m upgrading the setup a bit. Instead of using the ICOM IC-T81A I switched to the Kenwood TH-D7A(G). To bump up the 5 watt output, I tossed in a Mirage 30 watt amp that I’ve had sitting on the shelf for the last five years. I’m still using my Garmin’s eTrex Vista, but now have the combo data/power cable. No longer do I need to worry about swapping out the 2x AA batteries.

Tomorrow I’m going to try to integrate one of my old Palm Pilots (Palm m125) to run Pocket APRS.

I also have to do some massaging with all the cables.

Go here to track me while mobile.

Bicycle Mobile

My endstate objective is to have a bicycle mobile setup with APRS and packet functionality.

Bicycle Mobile – Test #1

Objective: xmit at least one APRS beacon packet from my bicycle mobile HT to a digipeater capable of ultimately passing the packet to an Igate and enabling anyone to view my location via www.findu.com.

Components used:
(1) Garmin eTrex Vista GPS. I originally got this GPS when I was stationed in Korea back in 2001. While pulling duty in the brigade EOC I overheard radio traffic of a company XO who was making a chow run…. running hot chow out to soldiers in the field. The company XO (a lieutenant) was lost. He didn’t admit it at first, but finally said he didn’t know where he was. Being lost as a lieutenant is pretty bad, but having to admit over the brigade net that you are lost ranks among the most humiliating acts. At that point, I determined I’d purchase a GPS so I’d never be “lost”. I’ve really enjoyed the GPS so far. It worked great in Korea, I also used it in Germany, took it to Kuwait, used it on the convoy into Iraq and Baghdad, used it in and around Baghdad, and also used it on the return trip. It’s very solid and is pretty easy on the batteries. I was previously using the GPS along with my TinyTrack as an APRS beacon (http://www.livejournal.com/users/shedberg/2005/04/21/).
(2) GPS handlebar mount. I received it in the mail yesterday and installed it this morning. Pretty easy to install, the GPS slides on and locks into place.
(3) Kenwood TH-D7A(G). Designed to be used specifically for APRS, I figured the D7A was the radio for the task. I have the stock battery pack (PB-39, 9.6 V, 600mAh). For an antenna, I’m using something similar to the MFJ-1715S. It’s one of those thin, long dual band jobs.
(4) eTrex-Kenwood GPS data cable. I purchased this off of eBay from the GPSGeek store. The cable has the Garmin eTrex proprietary plug on one end and the 2.5mm plug for the radio on the other.

As a preparatory test last night, I attached the D7A to my 2m/70cm vertical installed on the top of my house. I set the packet path to Wide3-3, manually inserted my lat/long location into the D7A, activated the beacon function and was able to transmit the following packets that made it to the www.findu.com database:
KD7PJQ-6>S7PS8P,WIDE3-1,qAo,N9VP:’h/Vl TH-D7A(G)
KD7PJQ-6>S7PS8P,N3XKU-15*,WIDE3,qAo,KA1UDX-1:’h/Vl TH-D7A(G)
KD7PJQ-6>S7PS8P,N4EVA-11,WIDE3*,qAo,N3IJW:’h/Vl TH-D7A(G)
KD7PJQ-6>S7PS8P,N4EVA-11,WIDE3*,qAo,W8JUK-3:’h/Vl TH-D7A(G)
KD7PJQ-6>S7PS8P,K4EME-3*,WIDE3-1,qAo,N4DSL:’h/Vl TH-D7A(G)

This test confirmed for me that the D7A was capable of transmitting APRS data locally, finding it’s way to an Igate, providing anyone the capability to check my location via the internet.

Test #1 Execution:
This morning I clipped my GPS onto my bikes handlebars and rolled the bike onto the driveway. Turning on the GPS, I was quickly able to get satellite lock and a position read out. I connected the data cable between the GPS and the D7A and powered the D7A on. A Band was already set with the APRS freq and TNC on. I pressed the POS button and the D7A successfully pulled my current location from the GPS and displayed it on the D7A. Immediately after that, the D7A’s red xmit light came on, indicating that the HT was xmiting my current position. The radio beeped and I could see other APRS traffic being received. I locked the key pad and placed the D7A into the bag on the front of my bike with the antenna sticking out at a 45 degree angle.

I headed out on my 5.44 mile trek to work.

The GPS was working fine the entire ride. The speedometer on the GPS was showing the same speed as my little Bell cycling computer.

I arrived at work and pulled the radio out of the bag. There were no stations listed on the screen – which indicates to me that no APRS stations were received by the D7A. I hit the BCON button a few times, but didn’t receive any responses.

I’m assuming one of two things happen: (1) my antenna isn’t doing an adequate job. Again, the D7A is located in the bike bag hanging off my handlebars and I’m not using any type of counterpoise with the antenna. Or (2) there was an issue with how the radio was positioned in the bag which either caused the data cable to come loose or accidentally engaged a key on the key pad.

Test assessment:
Overall the test was a failure.

Before I head back home after work, I’m going to take my bike over to a location with good line-of-sight and try sending an APRS beacon to see if I’m getting a response. I’m going to first attempt to send the beacon while I’m holding the radio so I can monitor what is being displayed on the screen. If I’m successful with that, I will carefully place the radio into the bike bag and try this test again on my trip home.

Road Trip Wrap Up: APRS – from California to Virginia

Here’s a snapshot of my APRS track across the US – the track is shown in blue – the gaps indicate areas where my radio dedicated to emitting failed to make contact with another radio acting as an APRS relay.

My APRS setup consisted of the following equipment:

This is a quad band radio (6m, 2m, 440 MHz, and 1.2 GHz), discontinued a due to the absolute hate folks had for that round “Multi” switch located to the bottom left of the LCD window. Admittedly, the radio takes a little to get used to, but overall, I’ve been very satisfied with it’s performance. The primary handicap of using this radio for APRS operation is that like most HTs, at high power it only transmits 5 Watts. I powered the radio with the optional CP-12L cigarette lighter cable with noise filter OPC-245L DC power cable.
IC-T81A manual

Byonic’s TinyTrak3
The heart of the whole operation. It connects with both the GPS and radio. TinyTrak3 takes the position data from the GPS, formats the data for use with APRS, and then passes the data to the radio for transmission. My TinyTrak3 worked flawlessly on the entire trip. It’s powered by a fused cigarette lighter plug connected with a fabricated cable that provides a serial connection to TinyTrak3 and TX/RX to the radio.
Download the configuration software and documentation.

And the final piece of my APRS triad is the GPS:

Garmin’s eTrex Vista
I purchased this GPS in 2001 when I was in Korea after I monitored a fellow lieutenant get humiliated when he got lost near the DMZ while trying to deliver hot chow to some of our soldiers. I vowed never to be “that lieutenant” and have not been lost since (as long as I had my GPS with me). The GPS got me through Korea and my subsequent assignment to Germany, but it really performed in Kuwait and Iraq. With only 2x AA batteries, the eTrex Vista usually operates for 12-14 hours.
Owner’s Manual (Software Version 3.00 and above) Rev. B, Aug, 2004

So with all the above items, I was able to traverse the continent allowing friends and family to “keep an eye” on me.