Railfan Technology > Railroad Telemetry with a Kenwood NX-320

A few weeks ago I picked up a gently used Kenwood NX-320K2 off of "the auction site" to see how it might work for picking up railroad telemetry --- HOTD/EOTD/DPU/RCL signals.  My radio is the 450-520 Mhz version.  I programmed it with Kenwood's KPG-141D software (did not use the 'narrowband' DN version of the softwaare because I also wanted to monitor the GMRS frequencies on the same radio).  The radio itself is very small --- smaller than the Kenwood NX-210 and NX-200 that I also have for railfanning -- and seems like a good choice for packing around as a reliable telemetry monitor...

Yesterday I gave it a test as I was heading from Myrtle Beach to the NASCAR race in Darlington and knew my route would come within about 8 miles of the CSX yard in Florence, SC.  On the roof of my Jeep Grand Cherokee I had a magnet mount NMO antenna base with a Larson 450-470 MHZ antenna (about 6 inches tall) mounted right in the center of my roof.  Sure enough about 10 miles out, I stared to get the "chirps."  The chirps -- both HOTD and EOTD were still being picked up from Florence to the north side of Darlington (also 10 miles from the Florence CSX Yard).  I was on the way to Floyd, SC to kill some time before heading to the track to see if there was any action in the South Carolina Central RR yard in Floyd -- there was none; the power was just chillin' in the 80 degree temps on a Sunday.  There were no chirps from the SCCRR in Floyd which means everything I was picking up was from Florence on CSX.  

Now I really have no frame of reference as to whether this is poor, OK or good performance.  Using a roofmount NMO antenna --- what kind of distance can one normally expect for telemetry on flat to moderately rolling terrain?  Is it reasonable to expect to pick up telemetry signals within a 10-mile radius?  I'm guessing 10 miles is not reasonable to expect up in the Altoona, PA area where the hills are much bigger...    Anyone else using a Kenwood or Icom commercial radio for telemetry?

Bob

Keep in mind that the DPU equipment is capable of re-broadcasting the EOT signal, the feature is 'suppose to be' turned off when not in DPU operation. Also there are ground based EOT repeaters for specific areas, which really confuses trying to estimate range. In most terminals it sounds like a high speed ping pong game on steroids.

The performance you've described sounds about right for a DPU or re-broadcast EOT. Because of terrain variations it's difficult make a comparison. I've been happy with EOT's at 2 -3 miles but DPU or re-broadcast EOT at 10 to 20 miles. But a hill top repeater makes it all useless for comparison. My areas have been Northern California and PRB related areas of Wyoming using a hand held Yeasu.

Before DPU's became prevalent the EOT at 2-3 miles was pretty common.



Edited 1 time(s). Last edit at 03/23/26 13:13 by TCnR.

With a portable radio, it is common to only hear train telemetry chirps for a maximum of 3-7 miles, at most.  With a  mobile antenna, that range can increase to 10-15 miles.  A couple of things to remember--the train telemetry signals are deliberately weak and low wattage--they are designed to be clearly heard for about the length of a train and not a lot more than that.  If the signal travels much farther than that, it can "collide" with signals from other trains.  Railroads will put repeaters for telemetry signals in areas where the various telemetry devices on a train may be out of line-of-sight with one another--tunnels, canyons, etc.   This is because UHF signals tend to be very line-of-sight signals.  This also  means that one may hear more distant train telemetry signals if you and the train are located are in good line-of-sight of one another.  In areas with heavy train traffic, or in yards, etc., train telemetry monitors essentially becomes useless--there will be something "squawking" all the time.  Where it is most useful is in rural areas with a moderate to few quantity of trains.  Then it can useful to detect if a train is moving within fair proximity to you.  

Incidentally, the Kenwood 320 is a very good UHF portable radio.  Unfortunately, the digital protocol that the train telemetry devices use is not NXDN.  I've heard that some railfan radio tinkerers have cracked the digital code for train telemetry, but I've never personally seen or been told how they did it.



Edited 2 time(s). Last edit at 03/24/26 08:43 by WW.