TRX-1 DMR HELP

[joeyjimmie]

Still having problems with DMR. Missing many calls.
I have tried many of the suggestions from people on this site.
Changed firmware,played with squelch, DSPL Level Adapt,
ADC gain and DAC gain.
Nothing seems to make it work properly.

I will say that what I do receive is loud and clear.
I can not wait to get this working properly as there are many DMR systems in this area.
E-mailed Whistler but got no response.
Anyone have any tips for me I would appreciate.

 

[troymail]

What are you trying to program/listen to? Trunked? Convnetional? How many sites? How many frequencies? How far are you from the transmit site?

My experience has never involved the need to tweak anything. However, DMR systems/frequencies have footprints that are all over the place - area-wide vs. 1-2 miles...

I will say that I have experimented with various "delay" settings -- depending on the system and how it is configured, in some cases, disabling delay helps. In other cases, I've set the delay up from the default 2 seconds to 5 seconds. There are many factors that go into which one I use.

For scanning, do you only have this one DMR system/frequencies programmed and being scanned or all you scanning it and other things as well?

 

[TAbirdman]

Have you tried putting in the frequencies you're having trouble with in a limit search?

 

[joeyjimmie]

Thanks for all your help..I am starting over programming one DMR trunking system with one site with 5 frequencies. Its tx is within 2or 3 miles of my location. It has a few IDs. I put in the wildcard. I am getting some action. I find if I hear something and stop the scanner on it I get both sides of the conversation most times,
I will keep experimenting with the ideas including the delay setting.

 

[buddrousa]

A shot in the dark would be to turn the attenuator on (GA)

 

[Ubbe]

Set the wildcard TG delay to 10 seconds. Try to set the Dwell time for the system to 3 seconds.

What works best for me are to duplicate all the frequencies (except the control channel) so there are 4 frequencies with the same frequency after each other and then the next 4 within its same frequency....

/Ubbe

 

[JD21960]

ON my WS1080 I set my dwell time on the difficult DMR here for 5.1 seconds and added a wildcard. I'm getting a lot more return calls now and it TRUNKS despite what some say. In addition. I found after looking at the coverage maps in RadioREF for that site It only goes out 5 miles. I'm 14 miles away. People need to check THAT coverage map more often as that could very well be the problem that you're too far away. I bought a 400mhz-520mhz antenna and it shows 4-5 bars now instead of the 1 or 2 prior. THAT makes a big difference. The right antenna for the right frequency. That's the fight, trying to find one that works for all frequencies and getting it up as high as possible. One thing I didn't do... I didn't keep Firmware update 4.3 for the Whistler scanners. I've been going back and forth between 4.1 and 4.3. The difference is pretty big in receiving DMR sites or not. I'm staying on 4.1 until the next change.

 

[sibbley]

I bought a 400mhz-520mhz antenna and it shows 4-5 bars now instead of the 1 or 2 prior. THAT makes a big difference. The right antenna for the right frequency. That's the fight, trying to find one that works for all frequencies and getting it up as high as possible.

Can't stress the above enough. Most of the DMR I listen to is 450-470MHz. I bought an antenna tuned to 460MHz from Smiley antenna for portable use. I use a mobile mag antenna mounted high at work and at home I use an ST2 antenna.

 

[Melv7956]

ON my WS1080 I set my dwell time on the difficult DMR here for 5.1 seconds and added a wildcard. I'm getting a lot more return calls now and it TRUNKS despite what some say. In addition. I found after looking at the coverage maps in RadioREF for that site It only goes out 5 miles. I'm 14 miles away. People need to check THAT coverage map more often as that could very well be the problem that you're too far away. I bought a 400mhz-520mhz antenna and it shows 4-5 bars now instead of the 1 or 2 prior. THAT makes a big difference. The right antenna for the right frequency. That's the fight, trying to find one that works for all frequencies and getting it up as high as possible. One thing I didn't do... I didn't keep Firmware update 4.3 for the Whistler scanners. I've been going back and forth between 4.1 and 4.3. The difference is pretty big in receiving DMR sites or not. I'm staying on 4.1 until the next change.

Fw 4.3 resulted in me missing lots of dmr trunk conversations. Like you I've settled on 4.1. Can you tell me where you purchased the 400-520 MHz antenna? Sounds ideal for me.


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[JD21960]

TRX-1 DMR help

@Melv7956 - Here's the antenna I bought. 400-960Mhz 7dBi, SpectrumForce Yagi Base Antenna | Scanner Master

Works really well for a cheap antenna on 400-500mhz. I'm 14 miles from Ohare Airport and get the United Airlines DMR in great. Also 35-40 miles from Downtown Chicago and their 478.000mhz Digital Fire frequencies. Those come in well with this antenna. I can't really recommend it for 800mhz if you're in an apartment. I think it' would work better in that range in an attic or outside. See my review for it on Scanner Master just below.

 

[Melv7956]

Ah ok my mistake I thought this was a rubber duck type.


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[Ubbe]

My TRX-2 doesn't decode DMR if the signal are 4 bars or lower. Its been like that regardless of FW version. The signal bars pretty much equals the BCD536 but it decodes down to 2 and even at a single bar.

As the TRX-2 doesn't like noise in the datasignal I suspect it have something to do with error handling.
All data that are sent wireless needs some sort of method to secure the integrity of the data, or else it will only work with a fully saturated signal without noise and fluctuation.

Usually the data stream are chopped up in small packages and added with checksums and extra databits that will enable the use of forward error correction FEC. Then it is possible to even add missing databit in the decoded data.

Motorola have added RAS, Restricted Access to System, to some systems that will require a key to use and without the key the checksums will be wrong and it will be impossible to use FEC.

Without FEC the range of a system is limit to where noise starts to upset the data decoding.
To me it seems that the TRX-2 isn't using FEC at all, or the FW code is somehow broken. Maybe the TRX-1 FW 4.3 now have the same problem as my TRX-2 always had.

If you manage to get a strong signal with 5 bars the problem of missing error correction will not be noticed, unless you have simulcast problems that produce bit errors.

/Ubbe

 

[VE3SCP]

Touch wood - I am decoding a local DMR site with 1-2 segments on the S meter with an indoor antenna in the office.There are times it is slightly garbled but most times it is fine.

I am using the TRX-1 with FW 4.1. I seem to have issues running FW 4.3 so I back rev'ed.

Scott

 

[Melv7956]

My TRX-2 doesn't decode DMR if the signal are 4 bars or lower. Its been like that regardless of FW version. The signal bars pretty much equals the BCD536 but it decodes down to 2 and even at a single bar.

As the TRX-2 doesn't like noise in the datasignal I suspect it have something to do with error handling.
All data that are sent wireless needs some sort of method to secure the integrity of the data, or else it will only work with a fully saturated signal without noise and fluctuation.

Usually the data stream are chopped up in small packages and added with checksums and extra databits that will enable the use of forward error correction FEC. Then it is possible to even add missing databit in the decoded data.

Motorola have added RAS, Restricted Access to System, to some systems that will require a key to use and without the key the checksums will be wrong and it will be impossible to use FEC.

Without FEC the range of a system is limit to where noise starts to upset the data decoding.
To me it seems that the TRX-2 isn't using FEC at all, or the FW code is somehow broken. Maybe the TRX-1 FW 4.3 now have the same problem as my TRX-2 always had.

If you manage to get a strong signal with 5 bars the problem of missing error correction will not be noticed, unless you have simulcast problems that produce bit errors.

/Ubbe

My trx-1 doesn't require a full signal and it tracks two ras enabled systems I have nearby just fine. Ras is to stop a radio hooking onto the system, it doesn't stop a scanner, if that was the goal they would simply add privacy.


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[dantheman31901]

Could I assume same issues with a P25 system as well? Running latest firmware on TRX-2 and unless it's almost full bars the scanner stops, has trouble locking onto a frequency but no audio at all.


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[Ubbe]

Ras is to stop a radio hooking onto the system

You are right. But it will also have an impact on listening devices. Normally the packets received with bad checksums are ignored and you don't hear anything with a digital radio, or digital scanner.

But if the decoding device accept packets regardless of correct checksums it will produce audio but will have no way of doing error correction without having the correct RAS key for the system.

If a digital motorola basestation that are setup with RAS receives packets without the correct checksums, it will ignore the packets and it will not respond to a foriegn radio that tries to affiliate.

You can read the wordings in Motorola system planner
Info: Restricted Access to System (RAS)

/Ubbe

 

[Melv7956]

You are right. But it will also have an impact on listening devices. Normally the packets received with bad checksums are ignored and you don't hear anything with a digital radio, or digital scanner.

But if the decoding device accept packets regardless of correct checksums it will produce audio but will have no way of doing error correction without having the correct RAS key for the system.

If a digital motorola basestation that are setup with RAS receives packets without the correct checksums, it will ignore the packets and it will not respond to a foriegn radio that tries to affiliate.

You can read the wordings in Motorola system planner
Info: Restricted Access to System (RAS)

/Ubbe

You maybe correct but one of the reasons for fw4.3 was improved ras handling so should get round this. I'm using fw4.1 as i found 4.3 ruined trunking for me and having no issues with local ras enabled systems.


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[Ubbe]

I don't believe there is a way around RAS, only ways to handle it differently. My guess is that when the scanner detects the RAS packets it automaticly changes the "digital squelch" to change the level of bit errors where it mutes the audio. When packets are received without RAS the bit error "squelch" are reset to normal, but perhaps it was done incorrectly in 4.3 so that it hampers the digital reception.

/Ubbe

 

[Drkatzjr45]

I understand how to program frequencies into the applicable "slots"

What I don't understand is how to set the other variables associated with a DMR system,
such as color, LSN.......I think there are three variables

Can anyone help?

 

[Ubbe]

Whistler does not use LSN nor LCN in DMR as it doesn't need to trunk track from the controlchannel.
Color code is only neccesary to enter if you have different sites using the same frequency and you can
hear both sites, a very rare situation.

Whistler scanners are very easy to program for DMR as you do not have to enter any variables.

A couple of updates ago the TRX-2 got the same decoding sensitivity as Uniden, two bars signal
strenght now fully decodes the transmissions.

/Ubbe