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[aprssig] New APRS Device, The YagTracker!

Jason Rausch jason at ke4nyv.com
Wed Aug 17 19:23:04 UTC 2011

Stephen, all good questions...

> So the YagTracker is functionally
> equivalent to the Kenwood RCD-710 (control-head of the
> TM-D710 sold separately)?

Yes, in fact I feel that the YagTracker is far superior in function.  Hopefully my answers to your questions below will help me to convince you of that.

The only draw back is the lack of 9600 baud operation, but I have yet to hear anyone really balk at that.

>      I.e. all-in-one APRS
> modem/terminal minus the GPS that you connect to the TX
> audio/RX audio/PTT of an existing radio.  

Yes, the GPS is external.  There is full two way coms with the GPS.  NMEA in for GPS datum, as well as $GPWPL output for waypoint plotting to a compatable mapping GPS.  Just about any serial Garmin, Maggelan and so on will work.  My personal testing is with a Garmin Map176c and eTrex legend.  These are older units, but still valuable for testing these features.

I have talked with Remi about the possibility of adding support for the Garmin binary protocol (ie. Nuvi 350 support) and also the Kenwood proprietary protocol.  This would cover the extra features in the AvMap units, but the AvMaps also understand the $GPWPL strings, so those users can at least utilize that function until the Kenwood support is added to the firmware.

> (But hopefully minus the screwball 8 VDC power requirement of the
> Kenwood head!)

Wide voltage input range.  9-24VDC  This means standard 12-13.8VDC in a car will power it just fine.

> Will TX tone levels be high enough (i.e. capable of line
> level output) to drive a 6-pin mini-DIN data port, rather
> than just millivolt mic jack level?

Yes!  In fact ALL of my test units are wired up this way, through a mini-din packet port and so far the results have been excellent.  Even when I have a longer run, such as 10' from radio to YagTracker, the decode rate is very good.  The built in audio pre-amp is fully user settable and the on-screen scope allows you to see your audio coming in and where the peak is at full packet audio vs. white noise levels.  I'll be posting some pictures of this on the website tonight.

> Since the YagTracker would probably be used on top of the
> dash as a sort of "heads-up" display with a clear view of
> the sky (but does NOT include an internal GPS receiver), it
> would be a natural for the Green Light Labs compact GPS
> add-on for the D710 head.
>      Could suitable connector
> position/pinout be provided to make adding the Green Light
> GPS a plug-and-play proposition; i.e. provide an RJ-45 jack
> with same pinout as Kenwood mic jack to provide power for
> the GPS?

An internal GPS was on the list of considered options.  In the long run I determined it was not worth it:

1. This tied up the serial lines and would have to have some kind of isolation circuit for when you wanted to load firmware, access other options through the port, ect.

2. An internal GPS is only good for GPS datum, that's it.  What if I wanted to connect up a nice, new Garmin Colorado (with the serial port option) with a color screen for displaying waypoints?  It would would become a pain to either disable the GPS through firmware or hardware.

3. The cost of adding the internal GPS, antenna and pre-amp really blew the price point up on the whole unit.  Right now, at $195 the Yag is priced at just under half of a RC-D710 head.  Grant it, the price margin slips when the RC-D710 goes on sale.  I think most people already have a GPS they would be fine with using and just raising the cost to include a limited one doesn't make much sense to me.  I learned that with the RTrak.  Just because the GPS is built in, doesn't mean people want it more.  That would probaly explain why Byonics sells 10+ MicroTraks to my every 1 RTrak.  It's a matter of dollars and sense.

So getting back to the subject of Green Light Labs, no I have not considered a proprietary connection to suit a single type of GPS.  The serial interface already available is as universal as it gets.  Just about any serial GPS with NMEA output will do.

Along with the radio/GPS interface, we included two switchable voltage outputs.  +5VDC and source switched DC.  The +5VDC links back to the days of the HamHUD II allowing you to power a +5VDC GPS off of the port.  Most people are also familiar with this same function on every OpenTracker and TinyTrak out there.  They all have this function.  Makes for a very nice, clean and seamless interface to the GPS.  Of course, if you GPS can handle more voltage, like my Garmin GPS III+, I can use the switch source voltage pin to power it.  The advantage to this is when you turn on the Yag, the voltage is turned on to the GPS and you have full power control of both units.

Take it one step further.  With the new breakout board we'll have available, there will be an on-board 5VDC relay good for up to 10A of current.  This relay will be controlled by the switch +5VDC output and can be used to power up the APRS radio connected, remotely.  With the single flick of the YagTracker's power switch, you can power up the radio and GPS all at the same time.  Just hide everything under the seat, armrest, truck, wherever and no need to get to it every time you go anywhere!
Jason Rausch

> You mention the following bullet-list features:
> - Map plot screen plots all in station list
> - Map plot has "show callsign" feature to see who is who
> - Map plot can be oriented "North Up" or auto-rotate in
> direction of travel
> Does this mean the device has some sort of internal mapping
> capability, or does this mean when used with an external
> display GPS with GPWPL capability?

Yes and no.  Go back and think of the old Garmin days before they had mapping, but plotted waypoints on a blank screen!  This is exactly what we are doing with the map plot screen on the Yag.  You are always centered on the map and the stations around you are plotted on the map.  You can instantly see what traffic you have around you.  The rotary encoder allows you to zoom in and out quickly to change the range of view.

Enabling the view callsign feature in the pop-up menu will now show you the callsign of each station, one at a time and also shows you their current distance from you.  When in the callsign view, it starts with the station closest to you and as you turn the encoder clockwise, it moves out to the next farthest and so on.

Hope that answers your questions!

Jason Rausch - KE4NYV
RPC Electronics, LLC

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