A blog about MOTOTRBO and other things.

26 March 2015

Dynamic Mixed Mode

Dynamic Mixed Mode (DMM) allows customers to easily migrate from analogue to digital with minimal disruption. It works by allowing analogue and digital radio users to use the same repeater. 

In DMM, the repeater dynamically switches between analog and digital modes based on the call it receives from radios. If an analogue radio transmits, the repeater switches to analogue mode to repeat that call. However, the repeater only repeats analog calls that are qualified by PL (DPL/TPL) - this is important as CSQ (Carrier Squelch) operation could result in the repeater staying in analogue mode and thus becoming inaccessible to digital radio users. 

If a digital radio transmits, then the repeater switches to digital mode to repeat the digital call if the call uses the right color code. While the repeater repeats one analogue call at a time, it can repeat twp digital calls at the same time, one on each logical channel. The repeater cannot however repeat an analogue and digital call at the same time.

Dynamic Mixed Mode is a repeater only configuration . For radios, one simply needs to configure a scan list containing an analogue channel and a digital channel. MOTOTRBO radios support both analogue and digital operation. 
The legacy analogue radios will not be able to do digital and the technology used in these radios cannot discern between an analogue and digital transmission.  It therefore makes sense to configure these radios with DPL/TPL so that they can block out the digital bursts on the channel during a digital call. It is also adviseable not to use TPL frequencies 67 and 103,5Hz as the DMR transmissions can mimic these two tones.

Dynamic Mixed Mode does not support the following configurations/features:
  • IP Site Connect configuration - This means that in Dynamic Mixed Mode, the repeater can only repeat the digital calls over-the-air and cannot send the voice/data packets over the IP network. The status of the repeater and the control of the repeater cannot be performed from a remote PC application like RDAC-IP.
  • Capacity Plus configuration - This means that in Dynamic Mixed Mode, trunking the logical channels of multiple MOTOTRBO repeaters as per Capacity Plus is not supported.
  • FCC Type-I and Type-II monitoring - Since FCC Type-I and Type-II monitoring are not supported in single site analog operation in any of the earlier MOTOTRBO releases, it is also not supported in Dynamic Mixed Mode single site operation.
  • Transmit Interrupt feature - The Voice Interrupt, Emergency Voice Interrupt, Remote Voice Dekey, and Data Over Voice Interrupt features are presently not supported in Dynamic Mixed Mode systems.
  • RDAC over IP feature - RDAC over local USB and connections via GPIO are supported. RDAC over the network is NOT supported.
  • Repeater Knockdown - In Dynamic Mixed Mode systems, this feature is not supported during an ongoing digital transmission.
  • PTT on a 4-wire interface - In Dynamic Mixed Mode systems, this feature is not supported during a digital repeat operation.

11 February 2015

Colour Code?

In digital mode, all MOTOTRBO radios support a feature known as Color Code (USA: Color, everywhere else: Colour). In fact this is defined in the ETSI DMR standard.

In a MOTOTRBO radio or repeater, there is a color code field which allows the selection of one of 15 colour codes. A radio which has been programmed with colour code 1 will not be able to transmit on a repeater configured with colour code 2 and so forth. A radio can be configured with multiple colour codes - one for each channel. A repeater can only be configured with one colour code.

Colour code is useful because it can prevent radios from one site or system mistakenly roaming to another site or system which uses the same frequencies. Although there is activity from the neighboring system, the radio will ignore all transmissions from the other system because it has a different colour code.

This is also useful for telecommunication regulators who have to allocate the same frequency to two DMR licencees in the same region. The regulator simply has to specify a colour code in the licence conditions - much like PL/DPL was used in analogue as a guard tone.

There is a limitation of course, if two geographically adjacent radio systems use the same frequencies, yet use a different colour code, there will be audio quality issues in the area where radio users are able to receive signals from both systems at roughly the same signal strength.

MOTOTRBO radios can also be configured to be "polite" to other systems using the same frequency. In the CPS, it is possible to set the TX Admit Criteria to be Color Code Free. This will only permit the radio to transmit if there is no signal, or if the signal present on the receive frequency has the same colour code.

On simplex channels which employ DCDM, colour code 15 is reserved for inter-radio synchronization signaling - so only 0 to 14 may be used on systems that use this feature.

Although not intended for this, colour code also provides an additional mechanism to prevent casual eavesdroppers. More determined (resolute) eavesdroppers will however be able to determine the colour code using a scanner and a decoder application. In such cases Enhanced Privacy or 256 bit AES should be used.

19 January 2015

Because it's more than push to talk...

Motorola's Application Developer Programme allows software developers to create outstanding applications for customers to harness the true potential of MOTOTRBO. The Application Partners have proven expertise and are committed to deliver wold-class applications for use in a wide range of industry and government sectors (read more about this here).

These applications, combined with Motorola's extensive experience in radio systems and critical solutions, produce the power behind the delivered solution. These partnerships enable Motorola's Channel Partners to provide a diverse range of high quality; integrated and customer focused solutions.

Here is a presentation highlighting how these customers have benefited from this partnership. To find out more about Motorola's Application Developer Programme, click here.

Another standard for Intrinsically Safe equipment?

Here is an interesting article - which I somehow missed - that appeared in Mission Critical Communications some time ago. I checked my records and found I was traveling at that time (so I guess I can be excused).

In 2013, the Telecommunications Industry Association released ANSI/TIA-4950. This standard defines the requirements for Battery-Powered, Portable Land Mobile Radio Applications in Class I, II, and III, Division 1, Hazardous (Classified) Locations.

ANSI/TIA-4950 was developed to provide a standalone set of intrinsic safety requirements that address issues unique to two way radio equipment used in both classified and non-classified environments. These requirements however do not impede the traditional levels of RF performance in two-way radio systems.

Certification for ANSI/TIA-4950 is carried out by UL. UL has been involved in hazardous locations certification testing since 1930. They are a well established testing house with a proven track record and expertise in all area classifications, protection methods and product categories.

The Telecommunications Industry Association represents manufacturers and suppliers of global communications networks through standards development, policy and advocacy, business opportunities, market intelligence, and events and networking. TIA is accredited by the American National Standards Institute (ANSI). More information about ANSI/TIA-4950 can be found here.

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The postings on this site are my own and do not necessarily represent the positions, strategies, or opinions of my employer, Motorola Solutions.

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