New RR frequency use

[labdog98f]

Does anyone that is "in the know" know if the new 7.5KHz steps will have voice or data on them?

I ask this because of all of the talk about using HAM radios (VX-150, IC-V8, IC-R5, VR-120, etc.), but the HAM radios do not support the 7.5 KHz step (they only do 5.0 or 6.25). If there will only be data on the new channels then we are o.k., but if they have voice or a mix of the two then we need to have radios/scanners that support the 7.5 step and do narrow (N)FM to avoid adjacent channel interference.

Can anyone shed some light on this and also how soon the new channels will start to see regular use?

Scott

 

[Thunderbolt]

As I understand it, they will be used for data and voice transmissions. The goal is take the frequency spectrum available and use it more efficiently, by having carriers upgrade to modern radio equipment. That being said, the overall goal was to have switched over by 2005, but I believe that was put off until 2010 or 2012 at the earliest. Mostly in part, due to the costs of all the railroads requiring new radios.

73's

Ron

 

[hulka]

OK. Is the spacing going to be 7.5 though? I thought after 12.5 was 6.5?

Kevin

 

[Thunderbolt]

OK. Is the spacing going to be 7.5 though? I thought after 12.5 was 6.5?

Kevin

Yes, the future Railroad (VHF-High band) spacing will be 7.5 KHz. The current spacing is 15 KHz, and if you divide that by 2 you end up with 7.5 KHz. Further the 6.25 KHz spacing is for the UHF band, which is currently spaced at 12.5 KHz.

I know a lot of us are going to have to purchase new scanners in the future, especially with many of the Class 1 roads taking a strong look at switching some of their operations over to Project 25 digital. Currently, BNSF and NS have been upgrading their FCC licenses for both analog and digital modes, for the future switchover. However, that won't be for a couple of more years in most locations.

73's

Ron

 

[DPD1]

I wouldn't be surprised if actual road radio use stays analog for quite some time... Off rail ops has started using a little digital, and that will probably increase. But on rail use would mean a very expensive implementation, and there's really not a huge need for it. There's a lot less operators now then there were 20-30 years ago, and they didn't have radio problems then. I think the licensing is more for protection... Just in case they need it, as opposed to there actually being a plan to change. Industries are grabbing freqs all the time, and never using them. They just don't want to get left out in the cold in case things do change.

Dave
-DPD Productions - Featuring the TrainTenna LP Gain RR Scanner Antenna-
http://eje.railfan.net/dpdp/

 

[kb2vxa]

Hi all,

"I ask this because of all of the talk about using HAM radios (VX-150, IC-V8, IC-R5, VR-120, etc.), but the HAM radios do not support the 7.5 KHz step (they only do 5.0 or 6.25)."
My IC-706Mk2G will go down to 100Hz (0.1KHz) steps and receives DC to light all modes except AP25 digital, you're thinking of the wrong radios.

"If there will only be data on the new channels then we are o.k., but if they have voice or a mix of the two then we need to have radios/scanners that support the 7.5 step and do narrow (N)FM to avoid adjacent channel interference."
First of all you don't need a 7.5KHz step to center the splinter channels, (four decimal places) use the 12.5KHz step. It sounds illogical but that's the way it's done. Second, the better scanners support WFM, FM, NFM, AM and AP25 on all frequencies. Third, you'll never find an active adjacent except on CB, the FCC never assigns them within a 50 mile radius of a fixed station and common carriers such as railroads that "own" the whole band segment avoid them by mutual agreement. BTW, data will bleed just the same as voice, it uses the same bandwidth.

Receivers may be FM or NFM for technical reasons. Simply stated, if the signal doesn't fill out the IF passband there will be a marked reduction in receive volume and possibly sideband clipping and/or dropout if the deviation exceeds the width of the "window". A good rule of thumb is set all your channels to FM and pick out those with low volume. Reset them to NFM to equalize the volume across all the channels. This won't work with digital so it really doesn't matter, the volume is determined by the digital stream and is what it is.

 

[hulka]

Is the "HAM radios" that they use "Project 25" or there own version of digital? I saw that they have digital for hams now but is it the same standard?

 

[kb2vxa]

Hi Hulka and rail fans,

The FCC hasn't approved P-25 for Amateur use. Icom and one other have included digital voice in some of thier products but the two are incompatible. What we really need is a bit of open source software and a standard codec to make it real. Meanwhile check out Icom America for the digital HT I hope to win.

Hams use all sorts of digital modes, I have been using AX25 packet for the last 10 years and have hopes of stirring some interest in others used on HF on the VHF/UHF bands.