Q. I have an IPSC system (Master SLR8000, DR3000 and MTR3000 as Peers). The users are complaining about black holes (not enough signal). So they press PTT and cannot make a call. I checked the radio but everything is okay. I went to the exact position to make a call and all is okay. 

Probably there is some RSSI issues and sites oversubscribe one another so I guess that the radio was locked to farther site than the closest.

I want to know if installing the Generic Option Board in the portables and mobile radios can give me  information about the missed calls. If some kind of data is saved in the internal memory of the GOB to see where the radio was trying to PTT; what TX or what site of the zone.

In the next week we begin to start installing GOB in the lab to see what kind of data can be extracted after using a SDK from Motorola Solutions.[*]

A. Before installing option boards, there are some checks you should do, and some questions to ask,  that might get you closer to a potential root cause (or possible root causes).

1. Distinctions and changes.

Without going into the technical details, there are a few questions you should think about. These relate to what; where when and extent/change.

Has this problem been present since the system was turned on? If no, when exactly (date, time) did the problem occur for the first time? And if so, was there anything changed at or just before this time?

 

Does the symptom (user cannot make a call) only occur at certain times? If yes, is there any pattern or corelation to the occurrences or is it just random? 

Does the problem occur in one specific location or area served by a specific repeater (or repeaters)? If yes, what is different about this site/location when compared to other sites or locations?

2. Knowledge and experience.

It sounds like that at this location, the user was able to receive calls but when trying to respond, their radio gave the low-pitched "bonk" tone. This usually indicates that either the signal from the radio was too weak to reach the repeater or the RSSI Threshold was set too high on the repeater.

At the location where the radio user experienced this symptom, what is the received RSSI like?

When a radio is transmitting at the above location, what is the RSSI at the repeater?

Are you able to see which site the radio is currently romaned to? Are users also able to see this? If yes, can you tell which site they were on when this occurred?

The received RSSI (on the radio) is not a good indicator of whether the repeater will hear you or not. A repeater usually has a really strong signal when compared to a portable radio.

The only way to confirm that the radio transmission is being received, is to use the MOTOTRBO Site Survey Tool on the repeater (see below).

A third possibility is that one or more of the repeaters are suffering from interference - hence the questions about when the symptom is seen. Interference is not always easily visible and you may need to eliminate this as a cause

3. Measuring RSSI and the GOB.

Installing the GOB by itself will do nothing and you will not be able to extract any data. 

This is because the GOB does not contain any software. As an example, PMLN8023A (which is used on the R7) contains a 32-bit ARM® Cortex®-M4 RISC processor; 8Mb NOR SPI flash a 3-axis accelerometer and some supporting logic. The board connects to the radio and can access a number of radio parameters.

An application developer can create bespoke software for this board that will allow a customer to perform tasks beyond the standard radio functionality. In your case, the software could record the GPS coordinates and in-call RSSI every few seconds. This then could be read out using a tool they have created. 

I have tried searching for such an application - so far I have not found anything. If I do, I'll post it in the comments (unless someone else beats me to it).

Another (possibly easier) option would be to use the MOTOTRBO Site Survey Tool. This does not use the GOB but instead runs on a PC connected to the radio via the programming cable. I've used in for drive testing to validate system coverage.

The tool gets the received RSSI and GPS coordinates from the radio very few seconds (the cadence can be set). This is logged in a KML file which you can view on Google Earth.

The Site Survey Tool is no longer supported but works and the licence can be extended.

The MOTOTRBO Site Survey Tool can also connect to the repeater and capture radio location data and get the RSSI from the repeater. The radios have to send their location for this to work.

What this does is essentially measure the signal strength of all transmitting radios and plotting this on a map (KML file).

There are more sophisticated tools like TRBONET Watch; GW3-TRBO  or SmartPTT System Monitor which will also measure radio signal strength and location but these are PC based and might not be what you need right now. RDAC is also able to show the live RSSI. The upside with all of these is that the can do this remotely via an IP connection to the system.

* the question was edited for clarity.