What frequency range is this antenna??

[radioman24]

Hello! I am a avid train enthusiast. And I see these loop style antennas up and down the B.N.S.F line

I am wondering if they are for voice or Data transmissions? Also what frequency range are they??

Thanks for the help!!

Dan

 

[nomadradio]

Should be 160 MHz more or less. A slew of frequencies in the VHF 2-way band are assigned to railroads, mostly 160MHz and above.

73

 

[BC Coyote]

Railroad frequencies in North America are pretty much all in the 160 to 161.5 range. They have a channelized system that is standard everywhere. I have seen the list online that gives you the frequencies they use and the equivalent channel numbers.
They use a lot of analog voice for dispatch work, and train to train chat, and there are also automatic trouble detectors trackside that radio the engineer as the train passes them and use a computerized voice to detail any problems with the train cars.
They likely use data bursts as well, either before or after each voice transmission.. That's the brrrrrrrt sound you here. All of this is very easily monitored on even the cheapest of handheld scanners, as none of it is digital or scrambled.
Hearing what's happening on the railroads radios adds a whole new dimension to railfanning !

 

[Shockwave]

One thing I'm learning about trains, is they are becoming a new source of interference. Here in Connecticut, the trains have some type of digital transmitter operating around 217 MHz. Every 18 minutes, all of my VHF high band TV channels would lock up in a pulsed sequence that was repetitive.

When I connected the spectrum analyzer to one of the spliter outputs for the TV antenna, it displayed digital blasts of RF shifting frequency all around 217 MHz. Peak signal levels were -10
db each time a train passed at about 1/2 mile away.

That was overloading the front end on all the TV receivers and causing the AGC to pump up and down. Nearly impossible to filter out with its changing frequency, literally hundreds of kilocycles away from the VHF high TV band. It only took six high Q notch filters stager tuned all around the 217 MHz. frequency.

I have to say, our FCC is doing a horrendous job at insuring new services do not cause harmful interference to existing services. The same problem is happening with UHF TV reception and local 5G services popping up just one channel above UHF TV. Removing that interference required two more Silicon Dust UHF pass band filters.

To put the level of misallocated TV interference into perspective, without the traps and filters, 56 TV channels came in reliability. With them, it went up to 118 channels. Few people know how many digital TV stations are available over the air. Even less know how many more are hidden under interference, that should never be taking place.

What happened to things like unused "guard bands" to protect existing services from newly generated interference? How do you drop a new =10db signal, one channel away from your distant -50db signals?

 

[nomadradio]

What happened to things like unused "guard bands"

Follow the money. When spectrum became a commodity, priorities like good engineering went to the back of the bus.

73

 

[Shockwave]

I also noticed as soon as those two big 5G signals showed up on 614 MHz. and 745 MHz. that was the end of anyone using an 800 MHz. scanner in town. The intermod wipes all receivers out on this band, unless it has a tunned, narrow bandwidth front end.