[aprssig] 6.72m Propagation Network Already In Service

[Ryan Butler]

Make sure you forward it to the list (the url for more info) as I'm 
interested in reading more as well.

Ryan, KB0JQO


Ev Tupis wrote:
> Jon,
> This is wonderful information.  I had no idea that it existed.  Please, forward a URL with more info on the propagation study portion of the BNSF monitoring system, would you?
>
> What are you observing as far as meteor propagation on this system?  It seems to be "smack dab" in the middle of the "Meteor Scatter Band" and could be used by Bob in strategizing for his project.
>
> Ev, W2EV
>
>
> ----- Original Message ----
> From: Jon Adams <jon at jonadams.com>
> To: aprssig at lists.tapr.org
> Sent: Sunday, January 6, 2008 1:20:14 AM
> Subject: [aprssig] 6.72m Propagation Network Already In Service
>
>
> Good evening, Ev, Bob and others -
>
> Did you know that the BNSF Railway is running a nice 44.58MHz network 
> with about 600 base stations spread over a great part of the US west of
>  
> the Mississippi? It's 9600 baud, does not rely upon meteor scatter, is 
> called "Extended Line of Sight" propagation, short packets generally, 
> GMSK modulation. About 100-150 locomotives, most of the trackside
>  defect 
> detectors, most of the highway vehicles that also have ability to get
>  up 
> on the rail, have transceivers now as well. All the transceivers are 
> 100W tx and the vehicle/trackside equipment antennas are either loaded 
> 1/4 or full-size halfwave antennas. Base station antennas are coaxial 
> dipoles high up on towers, generally 60-100'. Network is very chatty, 
> but apparently quite efficient, with dozens of packets per minute from 
> any one base station. While it's not exactly continuous duty, when a 
> propagation event occurs, the number of packets per minute can easily 
> top 100. Packet types include location packets, for base and mobile 
> devices, network beacons, telemetry packets, control packets, etc. The 
> network runs in a TDMA polled mode, so the field devices only talk when
>  
> authorized.
>
> The reason I bring this up is that this network is already far more 
> dense than most anything that hams could create. It's a great tool for 
> seeing propagation in real time, and while 6-3/4m is a little longer 
> than 6 and shorter than 10, it's probably a good indicator.
>
> If you listen on 44.58MHz FM narrow, maybe you'll hear the short
>  bursts, 
> especially if you're anywhere near a BNSF line. Here at my qth, I have
>  a 
> receiver specifically for that band and service, and have received 
> packets from as far away as Minnesota. We're looking for hams who would
>  
> be willing to add a dedicated receiver and antenna to their setups to 
> collect this data - we have a server that then plots the current prop
>  on 
> Google Earth as well as web pages that provide specific statistics on 
> the data. There are about 19 receiving sites now, concentrated in AZ
>  and 
> IL, with a few more in SoCal, Washington state, Colorado, Iowa, New 
> Mexico, Wisconsin. The radios we use for reception are generally old 
> boat-anchor Motos, including Micors, Mitreks, Maratracs, Maxtracs, some
>  
> plain-vanilla scanners work fine too. All require direct discriminator 
> output, and a sound card that has really good low-frequency performance
>  
> (there's no scrambling on the data, so there can be really long 
> sequences of zeroes). Nearly all the antennas are homebrew, either 
> vertical dipoles, loaded quarter waves, or fullsize ground planes.
>  
> While this Meteorcomm network does not rely upon meteor scatter, it
>  does 
> provide a fine tool for detecting potential meteor scatter events as 
> well as other ionospheric stuff. And when the skip is in, I'm not sure 
> how their network can deal with the onslaught of packets, but it seems 
> to work fine.
>
> Many of us who are involved with this are hams, with a fair number who 
> are railfans and not hams. What you get in return for participation in 
> this network is the propagation data in digestible format. If you're 
> interested in participating, reply to me off-list.
>
> 73 - Jon N7UV
>
>
>
>
>
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