MARRS Issues

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Js8-5

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May 9, 2017
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Hello,

I'm really hoping someone might have some suggestions for me regarding some problems in having getting the trunk to work for MARRS.

I just purchased a Radio Shack Pro 668 and I'm a bit new to trunking. I have updated the library and tried programming MARRS via the library on the scanner and using the software.

When I run the playlist that contains the MARRS talkgroups, I get nothing but silence. I have noticed if I manually go from entry to entry the signal symbol rapidly goes from full bars to none.

I've tried researching this for hours and followed advice from one forum post and programmed the KC frequencies as conventional. The result was some successful transmissions received that seem to cut out mid broadcast, I assume because the other piece of the broadcast is on a different frequency.

If anyone could give me some ideas on what I might have wrong in the trunking programming or point me in the right direction I'd really appreciate it!

Thank you!
 

WA0CBW

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Dec 8, 2011
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Location
Shawnee Kansas (Kansas City)
Which system are you trying to hear? The MARRS system consists of 8 individual systems that share some common talk groups. Each individual system has talk groups that are not shared. For example if you are listening to the Kansas City Missouri system you may hear some of the shared talk groups from the Wyandotte County system and the rest of the "MARRS" shared talk groups. There are talk groups on the Wyandotte County system that you will only hear if you are monitoring the Wyandotte County system.
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Js8-5

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May 9, 2017
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Which system are you trying to hear? The MARRS system consists of 8 individual systems that share some common talk groups. Each individual system has talk groups that are not shared. For example if you are listening to the Kansas City Missouri system you may hear some of the shared talk groups from the Wyandotte County system and the rest of the "MARRS" shared talk groups. There are talk groups on the Wyandotte County system that you will only hear if you are monitoring the Wyandotte County system.
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Hello,

Thank you for the response! I am currently just starting with getting things programmed, so I am only focusing on the KCPD talkgroups for the playlist I'm working on. My plan is to make additional playlists for KS and other MO jurisdictions, fire/ems, etc.

I programmed the frequencies as conventional just to make sure I could actually receive so it looks like the problem is in the trunk system programming I just can't figure out what. If anyone has some ideas of what might be configured wrong to give me dead air I'd appreciate it! The system is programmed as P25.

Thank you!
 

Js8-5

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May 9, 2017
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Make sure you set the system type as "P25 Auto". I made the mistake of using Motorola 800/900 which is incorrect.
Thank you, I will check that when I get home! Any thoughts on Attenuation, DDT, and AGC settings?

Thanks again for the help!
 

Js8-5

Newbie
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May 9, 2017
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MARRS Settings

Hello Everyone,

I have been researching and experimenting with MARRS for several weeks now and I'm still not quite getting favorable results and I'm hoping someone can give me some pointers.

I've been noticing that for the KC site (focusing mainly on KCPD talkgroups) scanning through a playlist of the talkgroups seems to go through long periods of silence but does display the T symbol as if it is detecting the talkgroups.

I added a RS 800 Mhz antenna and noticed that reception got way clearer but for some reason I seem to be missing parts of conversations here and there and also I frequently get very distorted transmissions that cut in and out. (I don't believe this is encryption because the scanner properly gives me the dial tone and displays ENC for the most part when there's an encrypted transmission.) When this happens, I also notice the signal strength going from high to low rapidly sometimes.

I did discover that I am very close to the 75th and Holmes tower. I'm assuming I'm experiencing simulcast distortion but I don't know what to do!! Please help!

I currently have the following settings based on numerous threads and guides that I've read through:

1. All sites are on separate trunk systems with all frequencies programmed.
2. The systems are programmed as P25 with auto trunk tables.
3. Data Decode Threshold: 15 to 95
4. ATT and Global ATT: OFF
5. DSPLevelAdapt: 52
6. ADC Gain: 0 dB
7. DAC Gain: +4 dB
8. EnMode: Tone
9. EncLevel: -8 dB
10. Global AGC Mode: Off

Any advice or input would be greatly appreciated!

Thank you!
 

talkpair

Member
Joined
Apr 27, 2009
Messages
950
Location
Clinton County, MO
It sounds like you're probably fighting a simulcast issue. You might try changing the attenuation setting. Some people have had luck using a paper clip as antenna.
Where I live, reception is seasonal. It works great when there are no leaves on the trees. Once the trees leaf out, reception is poor. If the wind is blowing when the trees are leafed out, it's impossible.

For grins, I sat on the deck one day and monitored each voice channel individually as a conventional channel for several minutes. I found the quality of the channel remained consistent regardless of which talk group was using it. The decode quality of some voice channels was excellent, while others were very poor. Since each voice channel has it's own personality, it makes troubleshooting a hair pulling experience.

You might try monitoring the voice channels individually like I did........find the channel with the worst decode quality and experiment with it first. If you find something that improves reception, then go back to scanning the trunked system in the usual manner.
 

WA0CBW

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Dec 8, 2011
Messages
1,381
Location
Shawnee Kansas (Kansas City)
Simulcast distortion usually occurs when 2 (or more) sites signals reach your scanner at nearly the same signal strength level. This makes it difficult for the scanners FM de-modulator to pick one site over the others. If you are close to one site (75th and Holmes) your scanner may be overloaded from the strong signal from that site. I would try attenuating the signal as talkpair suggested and see if that helps. Talkpair's idea of finding the worst signal and making the decode adjustments on that particular channel is also a good idea.
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SouthsideDave

Member
Joined
Dec 14, 2011
Messages
11
Location
Kansas City, MO
For monitoring KCPD only, I use only the 4 control channels listed for that site.
Psr 500, Rs 106, Psr 800, uniden 396xt, 996, 436, Home Patrol 1 all set up the same
No cut out issues - picking up alot of traffic, no matter where I am in the metro.
 
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