| InterceptRadio.com Forums http://www.interceptradio.com/bbs/ |
|
| 161.250 http://www.interceptradio.com/bbs/viewtopic.php?f=17&t=5217 |
Page 1 of 1 |
| Author: | Brad [ Mon Mar 14, 2011 8:24 pm ] |
| Post subject: | 161.250 |
I've been listening to the BNSF "Line" channel recently (the apparent operation channel north of Seattle and past Everett). Periodically, there will be a tone burst, slight delay, then another tone burst. I then hear the dispatcher talking to someone in the field. Is this some kind of "wake up" tone that's generated by the train radio? Or, is it something generated by the dispatcher to control or alert someone in the field? Does any of that make sense? It appears to originate from a transmitter around Everett or Mukilteo, as I hear those landmarks being mentioned. Does this make sense to anyone? Brad. |
|
| Author: | icom1020 [ Tue Mar 15, 2011 11:58 am ] |
| Post subject: | Re: 161.250 |
The DS normally has a closed squelch for receiving. The DTMF opens up a particular tower and alerts the dispatcher, which opens the squelch. Sometimes they answer right away, sometimes not. |
|
| Author: | Brad [ Tue Mar 15, 2011 7:59 pm ] |
| Post subject: | Re: 161.250 |
Ok, that makes perfect sense. I'll have to listen closer - the tone didn't seem to be DTMF - perhaps one of the two tones is subdued a bit? Or, my speaker is crappy..... Either way, thanks. Brad. |
|
| Author: | KE7JFF [ Wed Mar 16, 2011 10:17 am ] |
| Post subject: | Re: 161.250 |
I hear that sometimes in Portland/Vancouver; they use the tone to wake up the dispatcher. |
|
| Author: | n7maq [ Sat Mar 19, 2011 1:12 am ] |
| Post subject: | Re: 161.250 |
As you are hearing there are two tones, the first one (this could also be a DTMF string) the second one will be the base station's transponder to acknowledge the call. If the train crew does not here the transponder then they know they need to tone the dispatcher again. Jim |
|
| Author: | Brad [ Sat Mar 19, 2011 12:25 pm ] |
| Post subject: | Re: 161.250 |
n7maq wrote: As you are hearing there are two tones, the first one (this could also be a DTMF string) the second one will be the base station's transponder to acknowledge the call. If the train crew does not here the transponder then they know they need to tone the dispatcher again. Jim Yea, I've been listening a little closer over the past few days. I occasionally hear the mobile DTMF strings, followed by the base station with the "acknowledgement" tone. Most of the time, I guess I don't hear the DTMF input, because the trains are likely out of range - but the base station is not. Thanks for the clarification, all. Brad. |
|
| Page 1 of 1 | All times are UTC - 8 hours |
| Copyright © 2013 Interceptradio.com |
|