Eot

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kf5qgf

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I'm sorry, I'm sure this topic has been beaten to death, but I'm curious is there a program to decode eot signals? I've tried eotmon, to no avail, i've got a request in for the softeot group on yahoo, but it's been in for over a week now with no response. I've been trying a headphone cable from the headphone jack to the mic in jack on the computer with eotmon running, and turned my squelch all the way down so it gets the whole signal. Any help would be great, have no worries, I've thoroughly googled the problem with no results. Thanks,

Craig N.
 

WX9EMS

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What model radio you using? Some of the discriminator taps are pretty easy to do...provided you have some basic soldering skills.
 

WX9EMS

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Definitely check the above link, but if you still have questions, I will do some looking around and see what I can come up with to try and help make it easier. Most mods seem to involve tying into a test point (TP) and common ground. But if there isn't one, you can just locate the discriminator itself and locate the input pin to it and tie in there. I did that with my Bearcat 350A, and it works great.
 

kf5qgf

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Ok So I used some alligator clips and a mono jack to connect to tp4 and the ground, and of course, wouldn't you know it this is the one night that not a single train has come by (I live about 8 miles south of a yard about a mile off the main so they come through every 8-12 minutes during high traffic) So this brings my next question, is there a way to check if this is the baseband audio on this test point? I've only found one other person who has added a discriminator point to a 404 and while he's a member here on RR, he hasn't been active in 5 months and doesn't have the option to send them a pm.
 

dispatcher812

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You can decode that? I did not know that. I have the frequencies in my scanner and listen for the chirp. I use i as my kind of train radar. I have heard that long before I saw or knew a train was near. I know what the EOT is but what does it sound like when it is decoded?
 

WX9EMS

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Not exactly sure what you mean by what it "sounds" like when it is decoded. In ATCS, it decodes the data burst, it is 1200 baud FSK. IIRC it shows min pressure, max pressure, movement, light on, remaining battery...it has been a long time since I have used ATCS to decode a EOT...memory a bit fuzzy on details right now.

To answer your question Craig, you should hear low level audio, whether it be a hiss or radio traffic...there should be no volume or squelch control if you have it done right. The point behind the tap is to get the raw audio before it goes through amplifiers, filters, ect. Put it on a active frequency like one of the wx frequencies to test that there is audio there.
 

KK4HHQ

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Craig, the SoftEOT membership questionnaire has been sent to you by email. If your email account has a "spam" box, please check it. If you don't find the message there, let me know and I'll get it to you by other means.

Mike, discriminator output is not a requirement for decoding the EOT protocol if you use the right technique for MSK demodulation. The main lobe of the spectrum lies entirely below 2250 Hz and is barely distorted by the audio processing circuitry in most receivers.
 

kf5qgf

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KK4HHQ Just found it in my inbox, I was checking the wrong e-mail inbox (embarrassed) and sent it back. Happy if this means no discriminator output.
 

WX9EMS

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Mike, discriminator output is not a requirement for decoding the EOT protocol if you use the right technique for MSK demodulation. The main lobe of the spectrum lies entirely below 2250 Hz and is barely distorted by the audio processing circuitry in most receivers.
Maybe you could share this info with the rest of us. A DSP program maybe and notch filter below 2250Hz? My BC350A required a discriminator tap to decode EOT transmissions using ATCS. I tried it first without it and no dice, afterwards...success. I can't say anything about SoftEOT, never heard of it until of lately.
 

KK4HHQ

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Maybe you could share this info with the rest of us. A DSP program maybe and notch filter below 2250Hz? My BC350A required a discriminator tap to decode EOT transmissions using ATCS. I tried it first without it and no dice, afterwards...success. I can't say anything about SoftEOT, never heard of it until of lately.
I'll go one better and share a complete implementation:

http://groups.yahoo.com/group/SoftEOT/

The EOT demodulator in ATCSmon / eotmon is very sensitive to the effects of audio output circuitry. I don't know if it's phase distortion or the minimal attenuation of the higher frequency components that breaks it, but it's finicky. SoftEOT performs equally well with audio or discriminator output.

Matt
 

WX9EMS

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Sounds good to me. I rarely get the chance to decode any EOT signals since I moved. I'll have to join and check it out. I used to decode WSOR when it came into Darien and when it left Spring Grove. I miss that location. Thanks for the link.
 
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