LTR Mapping with Uniden DMA

From The RadioReference Wiki

The following is a method for Mapping an LTR System for Uniden DMA scanners. With DMA scanners, you can create up to 20 systems, each with one of the frequencies 20 times, or create one system with 20 sites with the XT scanners. This greatly decreases the time to map, and then to positively ID LCN's.

Finding most active LCN's

  • Program all of the frequencies under the same call sign, or even different call signs for the same Licensee, or FRN, in the same general location.
  • Create up to 20 LTR systems and sites with titles like System 1, site 1; System 2, site 2, etc. In this example, we are going to assuming the system only has 8 frequencies.
463.6750,  464.9875, 463.8625, 463.2375,  461.6500,  463.5375, 464.3500, 461.8250      

In that case, you would only create up to 8 system, and enter the frequencies like this, assigning System Quick Keys(SQK) to each which are NOT ones already assigned.

Site 1 SQK-31     Site 2 SQK-32 
463.675 | 01      464.9875  | 01     
463.675 | 02      464.9875  | 02     
463.675 | 03      464.9875  | 03     
463.675 | 04      464.9875  | 04     
463.675 | 05      464.9875  | 05     
463.675 | 06      464.9875  | 06     
463.675 | 07      464.9875  | 07     
463.675 | 08      464.9875  | 08     
463.675 | 09      464.9875  | 09     
463.675 | 10      464.9875  | 10     
463.675 | 11      464.9875  | 11     
463.675 | 12      464.9875  | 12     
463.675 | 13      464.9875  | 13     
463.675 | 14      464.9875  | 14     
463.675 | 15      464.9875  | 15     
463.675 | 16      464.9875  | 16     
463.675 | 17      464.9875  | 17     
463.675 | 18      464.9875  | 18     
463.675 | 19      464.9875  | 19     
463.675 | 20      464.9875  | 20

Note: Some DMA scanners, such as the BC246T, may not let you enter duplicate frequencies in different LCN slots. The only way to get around that limitation is to get software which WILL let you enter duplicate frequencies. See: Uniden DMA Software Support

  • Make sure you set the system delay to 5 sec, and the site hold time to 0 (usually the default).
  • If you have logging software, you can make as many systems as there are frequencies associated with the call sign
  • If you don't have logging software, it is probably best to only create 3-4 systems at a time so you can keep track of them. As you identify the frequency/LCN for the 1st few systems, you can go on to change the frequencies in them to the next 3 or 4 frequencies.
  • Start Scanning in the IDsearch mode, and take note of the HH's display on each frequency. The active ones probably have users assigned, and the most frequently displayed HH will be the actual HH.
  • Once you have several HH's identified, create a new LTR system with a name that helps identify, such as Scranton LTR, and enter the frequencies and their associated LCN's. Be sure to assign a System Quick Key which has not been assigned to any other system. For example:
Scranton LTR SQK=30
Frequency   LCN
463.6750   | 01
464.9875   | 02     
           | 03
           | 04
463.8625   | 05
           | 06
463.2375   | 07
           | 08
  • Start Scanning in the IDsearch mode, and take note of the HH's display on each frequency. Since half of the LCN's have been ID'd, you should hear mostly complete conversations from both base and mobile. If the majority of TGID's seem to have HH's that match the LCN's, you can probably move on to identify the less frequently used GOTO channels.

Finding GOTO channels

Since this systems has only 8 frequencies, and you have identified 4,

  • Using assigned quick keys, turn off all systems except the 4 that contain unidentified frequencies from step 1. The reason is that traffic on the GOTO channels is sparser, and you need to eliminate all traffic except those systems in order to find the infrequently used channels
  • Since most LTR systems have one or more conventional frequencies, it would be wise to monitor the remaining 4 one at a time first to see if you get any TGID's. You can also put them in a conventional group to see if you get any PL/DPL in the search mode. If you find conventional frequencies, you can eliminate these in the next step.
  • In this step, you only need to record which of the 4 systems are actually receiving traffic. The LCN's will not necessarily be correct since the user's TGID HH will show when he is sent to a GOTO channel. In other words, you will have no clue as to what the 4 system's channels real LCN will be. However, you may see LCN's that you have not identified yet. For example, you may see an LCN HH=03 and HH=06, which are not ones you have identified. This is a clue that there may be an 03 and an 06.

Identifying the GOTO LCN's

This is the place where DMA scanners and logging software really shine. Since you can create many systems with only 1 frequency/LCN pair, you can much more quickly confirm LCN's than with bank scanners.

With logging software, you can let the scanner run during Business hours, and be 90% sure (see comment at end of this section) of the LCN if you log ANY TGID's for the system with only 1 freq/LCN pair.

  • Looking at the ones identified, it is logical to assume that there are probably LCN's 03, 04, 06, 08, and possibly 09. Clues from previous effort may provide better guesses.
  • The problem with all of the preceding methods of putting the same frequency in multiple positions is that you never really get a definitive readout of the actual LCN. In this next step, we can solve that problem.
  • If you got "hits" on all 4 frequencies in the preceding step, make 5 or more new systems for the 1st GOTO frequency for each of the possible "holes" in the map. Assign quick keys not in use with other systems.
System 1          System 2       System 3       System 4      System 5
461.6500 | 03   461.6500 | 04   461.6500 | 06  461.6500 | 08  461.6500 | 09 
  • Start Scanning in the IDsearch mode. If you get ANY hits in any of these systems, you will be 90% sure that the correct LCN is the only one you have programmed in that system. For example, if you get 0-01-101 in System 2, you will know that this is GOTO LCN 04, even though the TGID 0-01-101 is NOT 04. What it means is that 0-01-101 was sent to LCN 04 due to existing traffic on LCN 01.
  • For example, if you have Identified 461.6500 as LCN 04, change the frequencies in the 4 systems to the next one you found active in Finding GOTO channels:
System 1         System 2        System 3         System 4       System 5
463.5375 | 03   461.6500 | 04  463.5375 | 06    463.5375 | 08  463.5375 | 09
  • You should probably disable System 2 with a quick key since you have already verified it as LCN 04, but this is not necessary.
  • Repeat this for each of the unidentified frequencies.
  • If you fail to get any hits on one or more of these frequencies after several weekdays, start over with LCN's 10 - 15.
  • Users from other systems might have the same frequencies but with different LCN's. Consequently, once you get the Scranton LTR mapped with these GOTO LCN's, you need to monitor the system to be certain they belong to the one you are mapping.
  • An obvious question is why we didn't create 10 more systems with single frequencies in with LCN's 10-20. You could, but the time it takes to scan all those systems would likely mean that you would miss the very sporadic traffic on the GOTO channels. Most systems don't have huge gaps between LCN's so you start with the most obvious "holes" in the map.

Software Use

Often, systems are designed to use only the ODD channel numbers, and are assigned from lowest to highest frequency in the system. If you use software with logging, you can easily log these TGID and their associated frequencies. This helps since most of the LTR systems are active while you are at work. The problem with logging is that you can get false TGID's, or ones from other systems that will easily fool you into thinking you have LCN's for the GOTO.

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