DMR Tier III the open standard for radio communications

When we found this post we were so excited, having hunted for over one year for this, discovering it on this website was an thrilling time for me.

Private mobile radio is fast becoming an essential communications solution�to support the operational needs of utilities companies, airports, oil and gas pipelines and emergency services.
When compared to public cellular services, it delivers improved coverage, reliability and resistance, contention, security, group communications and performance.
The digital landscape is crowded, though, with a number of public safety digital standards such as TETRA, P25 as well as low cost digital solutions including DMR (Digital Mobile Radio), dPMR (digital Private Mobile Radio), NXDN and PDT (Professional Digital Trunking).
DMR is coming out on top thanks to the open standard nature of DMR Tier III trunking, which is driving its emergence, ongoing development and adoption across global markets.
But do open standards matter? While open standards are less important in the small system market, they are critical to the long-term case for the walkie talkie system in the medium to large systems sector, and it is here that open standard DMR Tier III will dominate.
Essentially, DMR Tier III trunking features a control channel on each radio site and allocates traffic channels on demand making it frequency efficient and enabling a large number of users to share a relatively small number of channels. Radio sites can easily be inter-connected, usually using IP connections, making it possible to deploy systems ranging from a single site to hundreds of sites spread over a large geographical area.
The open standard way
The DMR standard includes the facility for implementers to provide �manufacturer extensions�, enabling manufacturers to provide proprietary features within the framework of the DMR air interface definition. This allows them to complement the standard set of DMR call functions with their specific facilities.
This has the advantage of enabling customers to request specific functionalities to support the manufacturer�s business operation needs and also enables them to provide innovative features that differentiate their solutions from others implementing the same standard.
One disadvantage to this offering is that interoperability can only be possible for those features that are fully defined by the standard and that customers using manufacturer extensions are effectively locked in to a single manufacturer solution rather than enjoying the vendor choice that a standard enables.
To address the pros and cons, the�DMR Association (DMRA)�has struck a balance between robustness and cost with their interoperability process, which focuses on testing the conformance of products against the published standard that describes the over-air signalling. The DMRA facilitates testing between a terminal manufacturer and an infrastructure manufacturer, and the two parties carry out the testing against a standard test specification. Test results and logs of all messages sent over air are recorded during the testing and then are inspected by one or more independent third parties during a detailed review meeting. Only after the independent third parties are satisfied that the equipment under test has conformed to the open standard specification is an interoperability certificate issued.
Ongoing standards development
Whilst this facility can be useful, extensive use of manufacturer extensions would call into question whether DMR was a standard that delivers interoperability (and therefore vendor choice) or whether it results in proprietary solutions rather than following an open standard.
The answer to this lies in the work of the DMR Association. The DMRA has a technical working group � made up of competing manufacturers � who collaborate to ensure the standard succeeds. Any proprietary features from the manufacturers, which are believed to have wide market appeal or have useful features the standard doesn�t yet specify, are debated in the group. They are then developed to further advance the standard to the benefit all of the manufacturers and indeed the customers who choose to implement DMR technology.
The DMRA is further developing the standard to meet future market demands by identifying important new features and ensuring these are developed and included in new releases of the ETSI standards.
The future of DMR Tier III
Open standards are critical to providing long-term support and stability to customers. The adoption of the standard by a critical mass ensures its longevity over other similar competing technologies that have lower levels of support by offering the market vendor choice and maintaining low costs.
Is DMR Tier III radio communications� open standard for the future? Yes. Due to DMRA�s authority, the robust and well-supported interoperability programme and the long-term commitment of a large number of manufacturers, it is emerging as the most successful low cost digital technology for complex projects � and therefore the open standard that no other private mobile Icom walkie talkies can contend with.
Source – http://www.telecomstechnews.com/news/2014/apr/25/dmr-tier-iii-open-standard-radio-communications/

What Causes the ‘Static’ Sound on Two way radios

With very little information on the internet about walkie talkie over’s, it is very rare when we get a chance to re post, with permission, an article from this industry.

Essentially, radio static during a call is a sign that the signal strength is degrading (or that there is no signal coming through at all). When signal strength degrades sufficiently, the static sound emerges.

When there is no message coming through, it’s a slightly different story. A Walkie Talkie has what’s known as a ‘squelch’ control circuit that keeps tabs on the signal strength. The squelch circuit will mute the speaker as soon as it realizes that there is no signal coming through to the device. This is, essentially, the same function as your TV has when it cuts off an unavailable channel after a preset time. However, in the moments before your walkie-talkie ‘squelches’ the sound, you will hear static, or ‘white noise’ as its also called.

‘Squelching’ is a pretty vital part of any/all broadcasting equipment. The method used in your walkie-talkie is called a ‘carrier squelch’ and is more than likely to be manually adjustable.

From Wikipedia (as of 17th of May 2013):

“A carrier squelch or noise squelch is the most simple variant of all. It operates strictly on the signal strength, such as when a television mutes the audio or blanks the video on “empty” channels, or when a walkie talkie mutes the audio when no signal is present. In some designs, the squelch threshold is preset. For example, television squelch settings are usually preset. Receivers in base stations at remote mountain top sites are usually not adjustable remotely from the control point.
In devices such as two-way radios (also known as radiotelephones), the squelch can be adjusted with a knob, others have push buttons or a sequence of button presses. This setting adjusts the threshold at which signals will open (un-mute) the audio channel. Backing off the control will turn on the audio, and the operator will hear white noise (also called “static” or squelch noise) if there is no signal present”.

So what is ‘white noise?’ According to Joe Shambro, writing for About.com’s guide to home recording,

“White noise is a static sound that has equal energy on every frequency. Think about this for a second: every frequency from 20Hz to 20kHz is equally represented at the same velocity; this type of frequency scale is called a “linear” scale. This gives the noise a uniform, static sound that the human ear detects as somewhat harsh and heavy-handed toward the high frequencies. However, white noise represents a very unnatural way of presenting frequency data in terms of how our ears work.”

If you’re experiencing signal degradation on your walkie talkie, there may be several causes for this. ‘Wireless Woman’ a blogger with an excellent site about two-way radios, has this to say:

“Signal loss can happen in any number of places in the system. Antennas may not properly direct the signal toward the horizon. Cables to repeaters may need replacement. Connectors can be corroded. Finally, the quality of the system may not be adequate. The old adage “you get what you pay for” certainly applies to two-way radios, and their quality does vary. Receiver specifications, engineering, tuning, the antenna, and even design generally improve as the price increases. This really happened: Two public safety officers were at a scene. One was using a radio that cost more that twice as much as the other. Guess which one could hear and which one couldn’t?”

So there you go.