Java program to decode DMR

[Forts]

Gary.... If you could get me a sample of discriminator audio, that would be fantastic!

[gvodvarka]

send me your email to send a file to you. gvodvarka@independentelectronics.com

[1300]

I did try the java DMR. I cannot get it to show anything on the screen. The bar is set for green with an occasional yellow.

What do you think is going wrong.
Setup: winxp, creative es1373, maxtrac with disc tap.
Thanks

[1300]

Here is a short video of what my system is doing.

Replace the x's with t's and you will be good.

hxxp://www.sendspace.com/file/k9jv56

Please let me know what you think.

Thanks

[Forts]

hxxp://www.sendspace.com/file/k9jv56

Sorry, but I'm a little leery of opening random .exe files. Can you perhaps put it in another container (zip, rar etc)?

[Forts]

I took the audio sample that Gary provided of a system using the new RAS technology and passed it along to a friend of mine who is very good at working with audio samples of that nature... Good news is that he was still able to decode the data from it with no difficulty, so it appears RAS will only affect 'real' radios, and currently not decoding software.

[gvodvarka]

That is correct. My radio does not here anything. DSD and DMR Decode both work fine. Gary

[Forts]

Gary: would you be able to make a log of some call activity with DMRDecode and fire that over to me too? I'm curious to see if anything is reported differently.

[inigo88]

RAS sounds suspiciously similar to EDACS ESK, which was cracked. I'll be keeping my fingers crossed.

[Unitrunker]

Originally Posted by inigo88

RAS sounds suspiciously similar to EDACS ESK, which was cracked. I'll be keeping my fingers crossed.

I remember that one. 8^>

[nycap]

Hello all. I just put a tap in an old pro-2006. I get the green bar at the bottom of the screen but i get no information scrolling. I was a little leary of using the .01uf capacitor in the filter but the proper 2.2nf wasnt available. would this inmproper filtering cuase the program not to sync/decode? Or should I be looking for some other reason as to why Im not getting anything? Thanks in advance.

[Forts]

Where did you get the 2.2nF value from? All my taps use 10uF....

[Mike_G_D]

I wouldn't use anything less than .5uf in series for a typical tap. I would really stick to 1uF or greater or else you might filter out too much of the frequencies of interest. 10uF should be fine and I think 2.2uF would be ok as well. 0.5uF or less is pushing it - you will probably attenuate some frequencies of interest depending on the input and output impedances involved. 2.2nF is the same as .0022uF - that is way too small! I don't know where you got the "proper 2.2nF" from. Even 0.01uF is too small. For reference, here is a handy online metric conversion tool: Metric Conversion. And here is a reference for what those values infer mathematically: http://www.telecomabc.com/p/prefix.html. And for reference, be aware that capacitive reactance (impedance or capacitive version of resistance) is equal to 1/(2xPIxFxC) where PI = the value of PI or approx. 3.1415, F is the frequency in Hz, and C is the capacitance in Farads. Looking at this we can see that the impedance goes up as the value of capacitance value goes down; for audio frequencies and those close to that range, values lower than 1uF will significantly add impedance. For example, using 3KHz as an example audio frequency, and 1uF as an example capacitance value, you get about 53.05 ohms. But substituting the capacitance with 0.01uF will give you about 5305.16 ohms; 0.0022uF or 2.2nF will get you about 24114.39 ohms - you can see where this is going and why your .01uF (at least in series) is probably not a good idea.

See if you can change that to a 1uF or greater and I think you'll have better results.

-Mike

-Mike

[nycap]

thanks guys. discriminator.tk recomends using 10k resistor paired with 2.2nf cap. i followed their directions for installing the tap in the pro-2006. i was under the impression that some particular radios need this simple filter to lower the if signal. i thought the larger caps were for accidental grounding.or shorting. is the information on discriminator.tk wrong?

[Mike_G_D]

Originally Posted by nycap

thanks guys. discriminator.tk recomends using 10k resistor paired with 2.2nf cap. i followed their directions for installing the tap in the pro-2006. i was under the impression that some particular radios need this simple filter to lower the if signal. i thought the larger caps were for accidental grounding.or shorting. is the information on discriminator.tk wrong?

My guess is that is simply a typo. They probably meant 2.2uF rather than 2.2nF. Lowering and filtering the discriminator output partly depends on the radio used, as you say. I have an old pro2052 that I directly tap with no resistor or cap and it works fine. But, typically, the series resistor is a good idea so as to provide some isolation between the output impedance of the discriminator and the input impedance of the computer sound card. You don't want to load down the radio discriminator output or you will have problems; however, typically, most sound cards have pretty high input impedances for their auxiliary or line inputs and reasonably high input impedances for their microphone inputs so this may not be a problem - but putting a 10k resistor inline is still a good idea usually and will usually not hurt. The series cap is really only there to prevent DC voltages from being transferred between the discriminator output and the PC sound card input. Again, most modern low cost PC sound cards either have dc isolated inputs or can tolerate DC voltages to some degree on their inputs so this may not be a problem in many cases. High end audio stuff may have direct dc coupled inputs to give them the best low frequency response but they, too, probably have some ability to cope with DC on the audio path - especially if they expect to be used in phantom power professional audio environments. Still, again, putting the cap in is a good idea with one caveat: the cap will filter off some low frequency response. If what you are trying to use consists of signals with important information in the lower audio frequency range then the cap value will become important.

Most people start with a 10K resistor in series with a 10uF cap and experience good results for most signal demodulation/decoding. Depending on your equipment and what you are interested in decoding some experimentation may be required to produce the best results.

-Mike

[IanWraith]

Hello nycap

A couple of things ..

1) Ensure that in the "View" menu "Display Good Frames Only" is disabled. Then see if you see anything.

2) In the "Main" menu enable "Debug Mode" and let us know if you see anything.

Finally are you sure you are monitoring the base side of a DMR repeater ? The program won't work on the mobile side of a DMR repeater or on a DMR simplex channel.

Regards

Ian

[Comint]

Originally Posted by nycap

thanks guys. discriminator.tk recomends using 10k resistor paired with 2.2nf cap. i followed their directions for installing the tap in the pro-2006. i was under the impression that some particular radios need this simple filter to lower the if signal. i thought the larger caps were for accidental grounding.or shorting. is the information on discriminator.tk wrong?

The instructions for installing the Tap in the PRO-2006 has the 2.2nf capacitor going to earth, on the Computer end of the 10K resistor. If that is what you have done, then it shouldn't be causing the problem.

The 4.7uF, or higher value capacitor, mentioned in the other posts, is for a totally different purpose, and has to be in series with the 10K resistor.

--
Comint

[nycap]

Originally Posted by Comint

The instructions for installing the Tap in the PRO-2006 has the 2.2nf capacitor going to earth, on the Computer end of the 10K resistor. If that is what you have done, then it shouldn't be causing the problem.

The 4.7uF, or higher value capacitor, mentioned in the other posts, is for a totally different purpose, and has to be in series with the 10K resistor.

Right. the positive line of the sheilded cable is in contact with the 10k resistor before the cap. the negative is grounded where the cap is grounded. problem is i didnt use the 2.2nf cap becuase i couldnt find one. i used the smallest cap i could find (a .01uf) and i was thinking this might not lower the leaky if signal hence the programs failure to sync/decode.

Thanks.

[nycap]

Originally Posted by IanWraith

Hello nycap

Finally are you sure you are monitoring the base side of a DMR repeater ? The program won't work on the mobile side of a DMR repeater or on a DMR simplex channel.

Ian

The signal comes from one tower. I think it is simplex? I was not aware that a trbo system could use duplex. if they transmit on two freqs should i tune to the other instead?

Thank you.

[IanWraith]

Hi

Originally Posted by nycap

The signal comes from one tower. I think it is simplex? I was not aware that a trbo system could use duplex. if they transmit on two freqs should i tune to the other instead?

You need to tune to the frequency that is transmitted from the tower.

A simplex channel is one where the radios transmit on a single frequency directly to each other usually over a small area. There are a small number of such setups here in the UK but the vast majority of systems use a repeater.

Regards

Ian