Question For P25 PPL

[celltech25]

I have a question about P25 and 6.25 khz and its affect on the Railroads. The Fcc is mandating that all railroads upgrade there radios to 6.25 Khz P25 to free up more Air Bandwidth for other projects.

Now my question.

The Local Railroad here Tech is a good friend of mine and he asked me this. CSX has made and aggreement to use ICOM or Kenwood radios for there transistion and has advised all other railroads they need to go the same route for compatibility. Why would you have to use Kenwood or ICOM, why Cant's you use Motorola as well? Only reason CSX gave them was there engineeers say the Kenwood and Icom have a better prtocol format for p25 and 6.25 than the motorola so the Motorolas will nto work because there format is totally different. Is this True?

[Josh]

I don't know if what you say is true or not, but one thing is certain... and that is that Motorola doesn't make a clean-cab radio anymore.

-Josh

[PhillyPhoto]

The Local Railroad here Tech is a good friend of mine and he asked me this. CSX has made and aggreement to use ICOM or Kenwood radios for there transistion and has advised all other railroads they need to go the same route for compatibility. Why would you have to use Kenwood or ICOM, why Cant's you use Motorola as well? Only reason CSX gave them was there engineeers say the Kenwood and Icom have a better prtocol format for p25 and 6.25 than the motorola so the Motorolas will nto work because there format is totally different. Is this True?

P25 is an open standard (or "protocol"), and one Motorola has been using for years. It sounds like the salespeople at Kenwood and Icom are trying to get the sale, so they're saying Motorola makes an inferior product. Other companies will NOT have to go the same route for voice compatibility. Like I said above, P25 is an open standard, and as long as the radios are configured with the same information (Frequency, NAC, etc) they'll be able to talk to each other just as if you had a Moto and a Kenwood on an analog frequency. More hogwash!

Now when it comes down to the physical product, this is where you'll have to make your decision. You'll have to look at each product's specs, and see which will be easiest to use, and looks like the most durable to your company. Just because a big company like CSX says something, shouldn't make it gospel for everyone. I'm not telling you to get Moto radios, but you should at least consider them in you decision along with Kenwood and Icom.

I'm not too familiar with the 6.25k aspect of it however.

[k2hz]

I am not totally up to date on what Motorola is presently offering for 6.25kHz compliance but my understanding is that Motorola's solution was 2 TDMA voice channels in a 12.5kHz bandwidth. I beleive Kenwood and Icom have a true 6.25 kHz per voice channel solution.

The railroads have to work with 7.5 kHz channel spacing and the FCC shot down the AAR request that all railroad operations be under a nationwide license held by AAR so they could control adjacent channel use. So, a solution that does not allow independent use of 7.5 kHz adjacent channels is not attractive to the railroads.

The railroads also need solutions that support simplex communication with no time delay for switching and other critical operations.

The only "clean cab" radio still made is the GE 12-2 and it does not do digital. Future locomotive radios will probably no longer be AAR standard.

[celltech25]

Correct on the Clean Cab as the rail roads here haven't used those in several years they have been using the cdm series mobiles in both vehicles and locomotives. What we are trying to figure out is if P&L went with the XTL line of mobiles in there locomotives, would they be able to communicate with the icom 5061

ICOM website on the 5061
With the optional UT-119H, the IC-F5061 series provides 6.25kHz digital narrow mode communication that meets the FCC 6.25kHz emission mask requirements for narrow banding, and increases efficiency of channel allocation and use of spectrum. The IC-F5061 series provides 2 optional slots: one for the UT-119H digital unit and one for another option board.

[Wowbagger]

There are 4 competing proposals that I know of for meeting 6.25kHz per channel:

1) Motorola's 2 slot TDMA proposal: 12.5 kHz per channel, 2 conversations per channel. Motorola tried to get APCO to adopt this as the next generation of P25, but was rebuffed. At the physical layer it is the same modulation scheme as P25 (600/1800 Hz symbol deviation, 4800 baud, 4 levels/2 bits per symbol for 9600 bps).
2) The APCO 2 slot TDMA proposal, which is similar to (but not exactly like) the Motorola proposal. Again, it is the same modulation at the physical layer.
3) The Icom/Kenwood "standard", which is a single 6.25kHz channel with a lower bit rate and lower symbol deviation. As such, it is in no way like P25.
4) The APCO CQPSK protocol, which is the same at the protocol level as P25, but uses a complex modulation scheme. However, it is receivable by any APCO-25 radio.

[celltech25]

So Motorola's radio will not talk to the Icom 5061 with the u119h Board then

[Josh]

So Motorola's radio will not talk to the Icom 5061 with the u119h Board then

I don't understand what is being stated here. Locomotives use clean-cab radios, unless you're a short line. I have yet to see some other mobile radio stuffed in a locomotive from a class 1 railroad.

As far as "narrow banding" goes, I find it silly that the current radios are 25Khz radios using 15Khz spaced channels. There bleed over as it is. I think that 12.5Khz would fit the bill.

Next in my ramblings, the Motorola 12.5Khz TDMA is for business users, and is currently marketed as mototrbo, I wouldn't recommend that for railroad use. Something else will come up that will allow 6.25Khz spacing on a conventional channel from Motorola, so I wouldn't fret yet.

-Josh

[k2hz]

Next in my ramblings, the Motorola 12.5Khz TDMA is for business users, and is currently marketed as mototrbo, I wouldn't recommend that for railroad use. Something else will come up that will allow 6.25Khz spacing on a conventional channel from Motorola, so I wouldn't fret yet.

-Josh

I agree that Mototrbo does not meet the needs of railroads. And, I beleive in a wait and see attitude for an industry standard to develop but I don't think it will come from Motorola.

Motorola seems to have abandoned the railroad market and they are pushing Mototrbo as their solution to narrow banding. It sounds like CSX has decided to go ahead with the real 6.25 kHz technolgy that Kenwood and Icom offer today.

There is a need for something like "clean cab" radio functionality in road locomotives. If some other railroads join CSX in adopting a standard maybe some innovative supplier will offer radios with the Kenwood/Icom technology and a control head with functions like independent AAR TX/RX channel selection, clean cab mounting and 72V power. I would not hold my breath waiting for it to be Motorola.

I am still waiting to see what develops before I recommend any small railroad rush to buy new radios. I had a long discussion on another board with a dealer that was pushing the Motorola "buy our product now or you will be off the air in few years when narrow band rules take effect" sales pitch.

This is the first I heard of this CSX plan and I am interested to see what happens.

[celltech25]

Yes the railroad in question does not use the spectra Clean Cab since it was discontinued they were pulled and replcaed with CDM 1550's there are 64 locomotives and 35 other vehicles that will require switch out. Just trying to figure out the best approach. Guess we are stuck with ICOM since CSX which we do the majority of our business with has chosen the ICOM 5061 as there radio since there engieneers are under the assumption that Motorola does not make a 6.25 khz radio that is compatiable with the kenwood coutnerpart and other icom's

[ai4ui]

Boy that is interesting about CSX. I wonder what is going to happen with all the NS & UP locomotives I see running on the "S" Line through NE Florida. Seems like if CSX goes this route, then so will the other Class I's that they interchange & have trackage rights with.

RG

[Wowbagger]

Next in my ramblings, the Motorola 12.5Khz TDMA is for business users, and is currently marketed as mototrbo

Actually MotoTRBO and Motorola's TDMA APCO-25 extension are quite different.

[Josh]

Yes the railroad in question does not use the spectra Clean Cab since it was discontinued they were pulled and replcaed with CDM 1550's there are 64 locomotives and 35 other vehicles that will require switch out. Just trying to figure out the best approach. Guess we are stuck with ICOM since CSX which we do the majority of our business with has chosen the ICOM 5061 as there radio since there engieneers are under the assumption that Motorola does not make a 6.25 khz radio that is compatiable with the kenwood coutnerpart and other icom's

This doesn't really make a lot of sense to me. What was wrong with the spectra radios? Parts are available and getting cheaper, and just because the manufacturer doesn't support them doesn't mean they are totally obsoleted and should never to be used again. Granted clean-cab radios as they are, are very expensive to purchase.

Using the CDM1550 as an interim radio when the standard is still 25Khz seems like a lot of money wasted, and possibly the workings of some dealer convincing them to make an unnecessary change.

Railroads continue to use the Spectra railroad radios by and large. I am seeing more GE ones come equipped in GE locomotives (who'd have known?) though, and Ast0r Moto ones too.

-Josh

[celltech25]

I understand parts are available for the clean cab radio, But we don't have them and have never had clean cab spectras in any of our locomotives before the cdm's we had x9000's or motrans which have all been phased out over time to cdm's, Why we don't continue to use the cdm's is because the fcc has mandatedthat by june 2009 we have to be using 6.25 khz channel spacing RR wide for all railroads not jsut us but CSX, and all others

[k2hz]

Why we don't continue to use the cdm's is because the fcc has mandatedthat by june 2009 we have to be using 6.25 khz channel spacing RR wide for all railroads not jsut us but CSX, and all others

Where did that June 2009 date come from? Last I knew the date was January 2013 for 12.5 KHz and no deadline for 6.25 ???