Railfan Technology > What are Part 90, Part 95, etc. radios and what does that mean?

A railfan friend of mine asked me one day to explain all the different FCC certification or compliance terms for two-way radios and what they mean for a railfan wanting to use a radio for railfanning.  While the various designations are mostly important for what radio service bands a radio can legally transmit upon, they do have some significance for railfans planning to use a radio to monitor railroad radio channels.  So here goes with some descriptions common to the FCC Rules—and one or more of these may be printed on the box containing the radio or on the label on the radio:

Part 15 Compliant.  Part 15 really isn’t a radio standard, it is a standard that almost all electronic equipment are supposed to meet.  This standard requires that electronic equipment should not emit radio interference (RF) that will interfere with radio communications over the designated radio frequency bands.  Sadly, there is a LOT of electronic equipment out there, notwithstanding the regulation, that does NOT meet Part 15 standards—everything from computers to gas pumps to vehicle electronics, etc.—and can interfere with radio communications.  One of the biggest differences between lower and higher quality two-way radios is their ability to filter out these unwanted signals without also filtering out wanted radio signals.  More about this later.

Part 90.  This is where things get more complicated.  Part 90 regulations pertain to Private Land Mobile Service two-way radio bands.  Specifically for railfans, Part 90 covers the VHF 150 mHz-170 mHz band and the UHF 450 mHz-470 mHz band, a portion of both which are used for railroad radio communications.  To transmit in these bands, a commercial radio must be Part 90 CERTIFIED.  Some radio manufacturers, especially Chinese, will sell radios that are advertised as Part 90 COMPLIANT.  That means that the radio complies with Part 90 standards, but it is still technically illegal to use them to transmit on the Part 90 bands.  While railfans should have no typical (or legal) reason to transmit on the railroad bands, parts of the Part 90 rules are that radios meet relatively strict requirements on the receive and transmit quality of the radio.  One other specific requirement for a radio to maintain a Part 90 certification is that the radio’s actual frequencies can NOT be programmed from the radio’s keypad into the radio in the field.  Now, for the murky part.  There are two other radio services that use part of the range of frequencies within the VHF and/or UHF band, the General Mobile Radio Service (GMRS), under Part 95, and the Amateur radio service (ham radio) under Part 97.   Part 90 radios must adhere to a higher transmission and receive quality standards than GMRS or amateur radios, however, Part 90 radios are not generally considered legal to for use by licensed hams to transmit on the VHF and UHF amateur radio bands, but often are because they are actually complying with a tougher transmission and reception standard than amatuer radios.  Also, Part 90 radios are NOT considered legal to use to transmit on the GMRS bands.  Why?  Because Part 95 contains specific limitation on transmit power that Part 90 certified radios can exceed.
 
Part 95.  GMRS radios are regulated under Part 95.  GMRS consists of 30-odd specific frequencies, some shared with the Family Radio Service (FRS).  They are all in the UHF band.  GMRS radios have become popular with “preppers” in the last few years and, for that reason, often have “extended receive” capability that includes the UHF and VHF railroad radio frequencies.  Some of these radios might be of interest to railfans who are also licensed GMRS radio users.  Receive and transmit quality of these radios can be lower than that of Part 90 compliant radios.  Use of GMRS radios to transmit in the GMRS bands requires a GMRS license.  Use of an FRS radio to transmit only on the Family Radio Service (FRS) channels does not.  GMRS radios can transmit on FRS channels if they meet the FRS standards and when so used do not require a license.
 
Part 97.  This standard applies to amateur radios.  In the aforementioned VHF and UHF bands, amateur radios may transmit in the 144 mHz-148 mHz and 430 mHz-450 mHz frequency ranges.  Most all amateur radios sold today have “extended receive” capabilities in their respective bands (VHF, UHF, or both) that extend into the railroad radio bands.  Except under special circumstances, amateur radios can not be used to transmit outside of the amateur bands.  A common modification allowed for this exception is the “MARS mod,” a modification that allows the radio to transmit “out of band” for use by members of the MARS organization (Military Auxiliary Radio Service).  Some hams make the MARS mod to their radios in case they need to use their radios for emergency communications outside of the amateur bands.  Such communications are generally permitted ONLY if there is a direct threat to life and/or property that can not be communicated under normal communication channels.  Amateur radios are generally built to higher receiver specifications than radio scanners and are thus a popular choice for railroad monitoring by railfans.

How the (mostly) Chinese radio manufacturer blurred the lines.  More and more radio manufacturers are building radio models with a single chassis, with firmware and software modifications to make the radio Part 90, Part 95, or Part 97 compliant.  Some of the Chinese manufacturers took this one step farther and made it possible for the USER, using desktop or laptop computer software, to “tell” the radio what regulation it would conform to.  For example, the same dual-band radio could be user-programmed with transmit limited to Part 90 frequencies and the keyboard locked from the user being able to modify frequencies from the keyboard interface, thus allowing the Radio to be Part 90 Certified in that configuration.  Or, the user could program the radio to be an amateur radio, with transmit allowed in the amateur bands only, and the keyboard open to frequency entry, making the radio Part 97 compliant.  Or the user could program the radio “open” which would allow transmit on any frequency within the radio’s frequency range and frequency entry permitted from the keypad—such a radio then no longer being either Part 90 or 97 compliant.

Finally, no U.S. federal laws prevent a citizen from owning or possessing a Part 90, 95, or 97 compliant or certified radio as long as the radio is not used to transmit without the proper license, or is not used in conjunction with or to facilitate illegal activity.  Some states and/or local jurisdictions have “scanner laws” that prohibit operation of scanning radios to monitor any or all two-way radio channels, and they may try to extend interpretation of those laws to include amateur, GMRS, or commercial radios with extended receive capabilities.  Herein lies a very good argument for railfans to obtain an amateur radio license—in most of those scanner-regulating jurisdictions, licensed amateur radio operators are exempted from the scanner regulations.
 
So, there you go—a relatively short description of the radio services, and radio compliance and certification requirements.  Please feel free to add questions and comments.
 



Edited 3 time(s). Last edit at 09/19/22 17:21 by WW.

Excellent and informative post.  Thanks for taking the time to do that.
Question re: the Part 90 compliant radios -- do the current models generally support the "narrowband" standard that the railroad have moved / are moving to?  Does that make them a good choice for listening to RR commuication, if used for receiving only?

hotrail Wrote:
-------------------------------------------------------
> Excellent and informative post.  Thanks for
> taking the time to do that.
> Question re: the Part 90 compliant radios -- do
> the current models generally support the
> "narrowband" standard that the railroad have moved
> / are moving to?  Does that make them a good
> choice for listening to RR commuication, if used
> for receiving only?

Any Part 90 certified or compliant radios built after 2012 support analog narrow band.  Some of the newest models can not even be programmed to wide band.  The NXDN digital standard that railroads MAY use are interesting.  NXDN digital radios can often be programmed as narrow-band NXDN--same bandwidth as narrow-band analog or as "very-narrow-band" that is only half as wide as narrow band, as shown here.

Wide band channel spacing 25 kHz
Narrow band channel spacing 12.5 kHz
Very narrow band 6.25 kHz

The current VHF channel width in the AAR railroad channels is 12.5 kHz, though a railroad might run an NXDN radio on very narrow band on a 12.5 kHz width channel.  As noted, as of today, very few railroads are using NXDN, though there is some use out there.  

So, yes, a Part 90 narrow-band analog radio can be very good for monitoring railroad radio traffic.  If one wishes to monitor NXDN, then a commercial NXDN-capable Part 90 radio is really the only good choice--the couple of (quite expensive) NXDN-capable scanners currently available are not very good performers in the railroad band.  I have one that I use for monitoring other types of digital radio communicaitons, but its performance for railroad monitoring is just plain pretty awful.  As with any product, some Part 90 radios perform better than others.  

I do go into a lot detail about NXDN in other posts and threads--I won't bore people with repeating them here.  Suffice it to say that my main mobile railfanning radios are commercial NXDN/analog radios.

Great info, thanks for posting.