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Railroad/Railfan Monitoring Forum - This is the place to discuss monitoring railroad communications.

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  #1 (permalink)  
Old 10-06-2018, 8:21 PM
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Default Distributed Power Frequencies?

I've noticed alot more DPU trains run through my area of Virginia [Petersburg], on both NS and CSXT, Is there a set of frequencies specifically set for DPU? I see the database lists "Remote Control Locomotive {RCL}, but I don't see anything explicitly for DPU operations, even if it's just a data burst like on the EOTD/HOTD, I'd like to have some idea of if the 200+ car coal train, or NS 23G is using DPU other than taking a guess based simply upon the fact that the ET44AC, ES44AC, ES44DC [NS], etc is on the lead of the train. Thanks.
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Old 10-06-2018, 9:14 PM
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UHF, and they are so short you'll almost never hear it. The radios will often change freq and use the best available at the time. The commands and query's are very short as compared to EOT systems at a lower than DPU data rate.

Its fast enough that the uniden close call won't even catch it parked next to a locomotive.
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Old 10-06-2018, 9:19 PM
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Thank you, That's very helpful as I am using a Uniden BCD396XT, so I won't worry about DPU monitoring. Thanks for your response.
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Old 10-06-2018, 10:28 PM
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It would be nice for the fan community, but nothing really solid to do so.
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Old 10-06-2018, 11:54 PM
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Try listening to TX 452.925 MHz / RX 457.925 MHz and also TX 452.950 MHz / RX 457.950 MHz and see if that helps you, Trey.
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Old 10-07-2018, 11:40 PM
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The generally accepted standard is that the DPU frequency in use is dictated by the last digit of the train's lead locomotive's road number....

3, 7 = 452.925
2, 6 = 452.950
1, 5, 9 = 457.925
0, 4, 8 = 457.950

There are units out there, particularly on BNSF, which are non-confirming to the generally accepted standard, but at least 95% of the time it holds true. If you're interested in decoding DPU data, do a search in Google for SoftDPU and you'll find what you need.
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Old 10-08-2018, 11:10 AM
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I tried listening, but everything seemed to be EOTD/HOTD bleed over, I saw plenty of traffic, quite a bit of data transmitted over the DPU channels but none seen.
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Old 10-12-2018, 4:13 PM
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I found monitoring DPU and EOT with the software mentioned above quite interesting. Just set up a scan list to scan only the relevant frequencies and you'll be fine.

https://groups.yahoo.com/neo/groups/SoftEOT/info

I've done both with Motorola P1225 and Maxtrac radios. If their scan speed can keep up, I'm sure any modern scanner can.
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Old 10-12-2018, 9:06 PM
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The DPU channels listed in Post 6 are usually able to be heard up to a couple of miles or so away in open terrain. Out in the flat desert where I live I can get CloseCall hits on my mobile scanners up to a mile or so away at times on the DPU channels. In built up areas the range is going to be less.



DPU radios seem to be able to be heard further away than the EOT's on 457.9375/452.9375, I don't know if they use more powerful radios or not.



In my usual routes along the UP's Sunset Route about half the UP trains have DPU's and these are a great way to tell when they are in the area. They run pretty fast out here, the track speed limit for freight is 70 on much of the track and they do every bit of that so even if you hear one a mile away it is going to be on top of you pretty quickly.
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Old 10-13-2018, 11:37 PM
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Quote:
Originally Posted by N9JIG View Post
DPU radios seem to be able to be heard further away than the EOT's on 457.9375/452.9375, I don't know if they use more powerful radios or not
Yes, Distributed power data radios transmit at a higher power than the EOT. EOT's transmit at 8 watts...
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Old 10-16-2018, 10:02 PM
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Quote:
Originally Posted by dapaq2 View Post
Yes, Distributed power data radios transmit at a higher power than the EOT. EOT's transmit at 8 watts...
There's still quite a few 2.5 watt ATX's and first gen Quantums out there on the road on NS. Which is amazing since FCC Determination 10-2293 was issued almost 8 years ago now.
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