OPB,

Thanks for the background in the alphabet soup.

Still, a few questions remain, why did the FRA allow so many incompatible PTS systems to be implemented? Makes for that 'lead' locomotive be on the headend of every train using PTS be from that home RR. Sure, I understand the pride and familiarization of equipment involved, but still, why not make a countrywide standard? They are doing it with ERTMS and some smaller interconnecting railways in Europe (ATC in Sweden and Norway).

I see that the ACSES II system uses similar beacons as the PTS system for the protection of curves, speeds, etc and can provide for exact train location.

But still, why was GPS used instead of a terrestrial based, train to beacon type PTS system? GPS seems to me as a very fragile link in the chain when it comes to interference. Just look at the controvercy surrounding the FCC and Lightsquared using a band for terrestrial wireless data right next to the GPS frequencies; "...being one billion or more times more powerful than GPS signals received on Earth". A terrestrial system that exclusively uses track beacons might be a little more robust, but as with all physical ground based systems, susceptible to damage.


Going another step in the discussion of PTS and interoperability...being an Amateur Radio operator and radio enthusiast, I will await the day that I see Amtrak Locomotives equipped with more than 8 antennas for all the data that needs to flow in and out of them just to make it across the country. Lets see... on Amtrak 156: Qualcomm radome, Sinclair Excaliber VHF voice, Sinclair Excaliber UHF Fred, two Mobile Mark customizable antennas (that can have: GPS, WiFi, WiMAX, GSM, LTE 700-band, AWS, PTC 220 or UHF), and what looks like a radome covered VHF antenna.

Yet to be installed, either Sti-co or Sinclair lowband for BNSF PTS and 220MHz for UP (perhaps the 220MHz already filled by the Mobile Mark antenna listed above). I have however seen recent photos of Amtrak's Locomotives 73 and 74 with the same Sti-co low band antennas you see on BNSF units.

That would make for 8 antennas...looks like real estate on the roofs is going to be getting scarce!

-K