ACARS and squelch

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screenersam

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I'm still figuring this out...seems to me the input varies no matter what. background static or whatever.
most posters seem to think squelch should be set so you have the one channel on at all times (usually 131.55). I scan; I have the channels in one bank. I'm willing to miss some data to get more hits. (I don't know what 'baseband' means).
try both, see what works for youse.
 
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DaveNF2G

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You might get more decodes on open squelch because the program will pick up the signal preamble quicker. On the other hand, I get good results scanning ACARS channels and letting the software pick up what it can.
 

ka3jjz

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Two things here - there is no 'baseband audio' for an AM signal. Discriminators aren't involved in AM signal detection, so a tap isn't likely to work well, nor is it needed. It's a 2400 baud signal, as I recall. A simple connection from your speaker out is usually sufficient. Just watch your levels to make sure you don't overdrive it. If you can use a fixed level audio output, like a record out, you can try it, but there might not be enough signal to drive the soundcard properly.

If your scanner happens to open up quickly enough (some do), then scanning may work. However there is a very quick sync signal that is sent prior to the data, and if your software doesn't hear it, it may not decode. Won't hurt to try it both ways - sitting on a channel with the squelch off, or scanning. See what works better for you

Mike
 
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wkm

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I never got PDW to work with acars. Setting levels, there was no happy medium. It is either deaf or spits out hash.
 

ka3jjz

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I suspect PDW spits out ACARS raw data, which is quite difficult to read if you're not familiar with the message labels. When I was fooling around with this quite a ways back, I used ACARSD which translates the message labels and splits off the messages and other data. Makes it a breeze to read.

ACARS data is encoded, and it is tough to read - as I recall, a couple of airlines (Lufthansa?) were starting to encrypt their signal

But that was quite a while ago...Mike
 

wkm

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Just to test the three free acars programs kg-acars, acarsd, and pdw. I ran all three together at the same time. kg and acarsd decoded the messages just fine with levels set to what kg said are good. PDW's decode was not very good at all. Labels and messages would be partial decodes that would guess the alphanumeric if it didn't know. The way the message is displayed are similar to acarsd but it looks like a command prompt.
 

poltergeisty

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Two things here - there is no 'baseband audio' for an AM signal. Discriminators aren't involved in AM signal detection, so a tap isn't likely to work well, nor is it needed. It's a 2400 baud signal, as I recall. A simple connection from your speaker out is usually sufficient. Just watch your levels to make sure you don't overdrive it. If you can use a fixed level audio output, like a record out, you can try it, but there might not be enough signal to drive the soundcard properly.

If your scanner happens to open up quickly enough (some do), then scanning may work. However there is a very quick sync signal that is sent prior to the data, and if your software doesn't hear it, it may not decode. Won't hurt to try it both ways - sitting on a channel with the squelch off, or scanning. See what works better for you

Mike
No wonder why I'm not picking anything up. I hear the digital signal, but no decode. I just bought another stereo cable on eBay so I'll try that. I don't want to unplug the discriminator due to all the junk and desk which is in the way. :lol: Hard to explain.


Just to test the three free acars programs kg-acars, acarsd, and pdw. I ran all three together at the same time. kg and acarsd decoded the messages just fine with levels set to what kg said are good. PDW's decode was not very good at all. Labels and messages would be partial decodes that would guess the alphanumeric if it didn't know. The way the message is displayed are similar to acarsd but it looks like a command prompt.

I'll give KG-ACARS a try. Thanks!
 
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wkm

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I have never had united plot in kg-acars. Have seen them plot in acarsd. There is not standard on the way the positioning is entered so depending on the program you may never see plotting. This why I like running the two at the same time. Also try channel 131.550 it the worldwide freq. I thought it was dead but found out I was mistaken after monitoring it for few hours. Seems to be quite a bit of traffic at times.
 

ATCTech

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131.550 is the North American primary frequency for ARINC, but it's not quite "worldwide". You might also try 136.850, the North American primary (at this point 'only') frequency for SITA. Although there is data exchanged between the two network backbones, an airline/aircraft operator will typically only be a customer of one or the other. There may also be more tertiary coverage areas where both customer bases only have access to one or the other network ground stations,
 

majoco

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I have all the frequencies programed.
...but I hope your'e not trying to scan them. Just sit on one frequency at a time. The first couple of milliseconds are the important bit.
 

screenersam

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I'm using KG-ACARS and notice 136.800 has a lot of United. Question: When do I see an aircraft on the map? All I'm getting is link tests and acknowledgements.
I get very few map plots, one every three-four hours.
most of my hits seem to be on 136.65. I get tons of JetBlue stuff.
 
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DaveNF2G

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You might also try 136.850, the North American primary (at this point 'only') frequency for SITA.
SITA and ARINC are essentially the same organization. Are you referring to VDL-2 mode?
 

ATCTech

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Negative, SITA and ARINC are competitors, not by any means are they the same organization. 136.850 is SITA's primary frequency for North America. Matter of fact, I think it's still their only original mode ACARS frequency on this side of the pond. We provide all their site-level service across Canada. VDL-2 is 136.975 only at this point, and both companies have a presence on it. Both have ground stations here at Toronto as a matter of fact, and we look after that too and all of ARINCs conventional ACARS ground stations.
 
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DaveNF2G

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I had read somewhere that SITA had purchased ARINC, but this appears to have been false.
 
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