Data slicer for LTRTrunk and LTRDump

[W4KRR]

I use a (modified) MFJ-1213 interface to run Trunker, and it works fine.

I believe I read that this interface doesn't work well, or at all, for the LTRDump and LTRTrunk programs. If this is the case, can the MFJ-1213 interface be modified to work with LTRTrunk and LTRDump? If not, what type of data slicer will work with these two programs?

 

[crayon]

http://www.radioreference.com/modules.php?name=Forums&file=viewtopic&t=13427

 

[mr_hankey]

FWIW, i'm using a pre-built dataslicer from dataslicers.com and it works fine with LTRTrunk

http://www.dataslicers.com/

 

[pro92b]

FWIW, i'm using a pre-built dataslicer from dataslicers.com and it works fine with LTRTrunk

That's an unfiltered slicer so the only way to make it work well on LTR is to feed it filtered signals. Filtered tap points have been identified for the BC780 and PRO-2067. It isn't a good general solution for decoding LTR if you are using a generic wideband discriminator tap.

 

[BANDIT]

This one should work well with LTR and will do a lot more. I ordered one last nite.\
http://www.discriminator.nl/4-level/index-en.html

 

[mr_hankey]

hey BANDIT, looks like a decent alternative to texas2way's "kit".

let us know how it works out.

 

[BANDIT]

I will let you know. Just received an e-mail and it will be shipped this weekend. I just don't know how long it will take to get here hi hi... Again it looks very well made and I won't have to builld it myself. Eyes just ain't as good as they used to be hi hi....

 

[EricCottrell]

This one should work well with LTR and will do a lot more. I ordered one last nite.\
http://www.discriminator.nl/4-level/index-en.html

Hello,

It does not appear to have any filtering so it will work poorly with LTR. The added chip is for the four level decoding.

Without the filtering you may get some decoding when no voice is on the signal. The spotty decode makes it more difficult to determine if the data is valid or invalid. If you have 30 or more data frames during a transmission you can tell it is likely valid. You also miss information transmitted while people are talking such as groups redirected off the home channel, mobile IDs (Passport), and neighbor info (Passport). I also found the filter allowed me to copy noisy signals better. I need a dead full quieting signal to copy without a filter.

The program will work alot better if it gets continuous valid frames. On Passport systems LTRDump and LTRTrunk can determine the frequencies when it gets a neighbor info frame during a transmission.

The difference between filtered and non-filtered data slicers is like night and day.

73 Eric

 

[BANDIT]

Know where I can buy a filtered 4 level?
I have been looking everwhere....

 

[pro92b]

I don't know of any filtered slicers for sale. You have to build it yourself. What's the fascination with a four way slicer? There isn't much it does that the two way type can't do except for pagers and that is of questionable legality.

 

[BANDIT]

Needed for LTR Trunk Systems. Thats what this thread is about.

 

[BANDIT]

Ok, I have a BC785D, Pro2052 and a R8500 all with taps. Using the pass through slicer from www.dataslicers.com. What do I need to be sure I am sending filtered data to the slicer? The BC785D and Pro2052 tap is directly off of I think it was pin 9 on the related chips. The R8500 is using the
9600 packet out jack on the back of the rig. :?:

 

[pro92b]

All your tap points are unfiltered. I don't own any of the radios you mentioned and don't know where the filtered points are.

Regular LTR does not use a control channel so much of the time noise is fed through the slicer when monitoring an LTR channel. The LTR checksum is not very robust so the noise will produce false ID decoding in LTRtrunk. This is a limitation of the LTR protocol.

A partial solution for this would be to add filtering to the program itself to reject invalid repeater numbers. A more complete solution is to add a squelch gate to the slicer to block the discriminator signal when the LTR channel is inactive. I have schematics of suitable slicers posted at http://home.hvc.rr.com/bpetrow/. These are not products you can buy - they must be built by the end user.

MultiNet does transmit a continuous control channel and that eliminates the need for the squelch gate. There are no Passport systems here so I am not certain if they use a continuous control channel.

 

[BANDIT]

Thanks Pro92b. Thats the info I needed. Guess I will have to build my own.
Just cant see to well up close, guess I could look for a pair of those magnafying glasses to put on my head hi hi....