Category Archives: DMR

time slots are NOT trunking

We have run into quite a few “green” salespeople lately.  They seem to be telling customers that by moving to a MOTOTRBO Conventional or IP Site Connect (a.k.a. DMR Tier II) system that they are getting the benefits of trunking.  This is simply NOT the case.

DMR utilizes TDMA to allow different users to share the same channel, by dividing it into “time slots”.  In a standard configuration, talkgroups are statically assigned to time slots.

Let’s assume an example case with the following:

  • 20 administrative talkgroup users
  • 10 security talkgroup users
  • 10 maintenance talkgroup users

Since the administrative talkgroup has more users, you decide to assign it to time slot 1.  You decide to assign the other two talkgroups to time slot 2.

If security is using their radios and maintenance needs to talk, can they?  No.  Why?  Because both groups are statically assigned to time slot 2.  If security is using time slot 2, maintenance cannot.  This does not change whether or not time slot 1 is in use.  So, while it is true that “you’ll have double the capacity“, you won’t have an efficient way to use that capacity.

In order to efficiently use capacity, you need trunking, which allows for talkgroups to be dynamically assigned.  If you are looking to efficiently use capacity, please contact us at (804) 625-4233 or sales AT richmondrf DOT com.

Why aren’t we TDMA fanboys

A fanboy is defined as “A person who loves something without question.”

Accepting things without question is counter to part of our mission to provide radio communication solutions that provide choice, performance, and best-value.

Here are some of the reasons that we don’t just accept TDMA without question:

Many of the comparisons above are between TDMA and FDMA.  I don’t want you to get the wrong impression; I don’t think FDMA is perfect.  (As a matter of fact, recently a really smart friend predicted that CDMA will ultimately win this battle.)  On the other hand, I do want to encourage you to think about things like interference, coverage, and cost before purchasing a new radio communication solution.

(some of) the power of Radio over IP

Lately, in the lab, we have been tinkering with Radio Over IP Gateways.  Since we love standards, we spent a significant amount of time with Icom America’s VE-PG3, because it “speaks” the Session Initiation Protocol (SIP).

Just like most other Radio Over IP Gateways in the marketplace, the VE-PG3 can connect two or more radio sites over an IP network.  In this configuration, received radio audio is bridged to opposing radio sites of the network.  This bridge mode can connect dispersed radio sites over the network and can provide cross band, cross category communication.

This technology is already in use by the Virginia State Police.  They call it COMLINC (Commonwealth’s Link to Interoperable Communications).  It enables adjoining jurisdictions totally different radio systems (such as Hanover County’s 800 MHz system and Powhatan County’s VHF system) to be connected.  This is how they are going to catch you if you go speeding from Hanover into Powhatan!

I believe that we will see this technology being used even more in the near future.  One example I can think of is Virginia’s electric cooperatives.  If Northern Neck Electric Cooperative (IDAS on 153MHz) needs to talk to Rappahanock Electric Cooperative (TaitNet MPT 1327 on 217MHz), this is a great way to make it happen.

But, going beyond connecting two or more radio sites is where the VE-PG3 really starts to shine, because it can convert radio audio into SIP.

These were some of the immediate benefits that we were able to see in the lab:

  1. Eliminate EXPENSIVE virtual radio/dispatcher software on PCs by using any SIP softphone/hard phone. (Hint, here are 20 FREE SIP Softphones.)
  2. Use a SIP softphone on any device (think Android, iPhone, etc.) to talk to your radios.
  3. Use a SIP Trunk to talk to your radios. Anyone with any phone can call a telephone number and talk to your radios.
  4. Use all of the features of Asterisk on your radio system. Imagine the literally endless possibilities:
  • Get Call Detail Records for all of your radio traffic
  • Record all of your radio traffic
  • (Conference Bridging.) Bridge any mix of any number of PCs, Androids, iPhones, analog phones, radio systems, paging systems, etc.

If you couldn’t tell, we are excited to see standards coming to the Radio over IP marketplace.

If you are looking to take advantage of Radio over IP, please contact us at (804) 625-4233 or sales AT richmondrf DOT com.

Are we creating a modern Tower of Babel?

You need only look at our Twitter Bio to recognize the fact that we are advocates of standards-based radio communication solutions.  However, in reading a recent forum post (and reflecting on some of our blog posts), we realized that the wireless industry may not share the same affinity for standards-based radio communication solutions.

As the wireless industry moves to digital, different digital technologies are being chosen by different customers.  For example:

So, what happens when there is an emergency and it is critical that the local public safety organization communicates with the local MTA, the local electrical cooperative, a neighboring public safety organization, etc.???  Nothing!!!  None of these radio communication solutions can communicate with the other; we have created a modern day Tower of Babel!  Add encryption into this mess and even fewer organizations can communicate.

In our next post, we hope to address possible solutions to this problem.

Thanks for reading!  And, if you see any typos/mistakes, please contact us at (804) 625-4233 or sales AT richmondrf DOT com.

The digital standards and the manufacturers

In a previous blog post, we referenced the fact that digital standards are maturing.  So, while we were at IWCE, we started a spreadsheet to:

  • compare the digital standards
  • list which manufacturers are involved with which standards

Below is this spreadsheet.  You can learn a lot from it.  For example, there appear to be as many manufacturers focused on DMR (if you add in the Chinese manufacturers) as there are manufacturers focused on P25.  (This is pretty significant when you consider the marketshare of P25 in public safety agencies or the fact that EF Johnson and Midland only have P25 offerings.)

Enjoy!  And, if you see any typos/mistakes, please contact us at (804) 625-4233 or sales AT richmondrf DOT com.

NXDN

DMR

P25 Phase 1

TETRA

kHz

12.5 or 6.25

12.5

12.5

25

FDMA

TDMA

FDMA

TDMA

2-slot

4-slot

EF Johnson

Yes

Harris

Yes

Yes

Yes

Hytera

Yes

Yes

Icom

Yes

Yes

Kenwood

Yes

Yes

Midland

Yes

Motorola

Yes

Yes

Yes

Tait

Yes

Yes

Vertex Standard

Yes

 

The Perfect RF Storm

According to Wikipedia, “perfect storm” is an expression that describes an event where a rare combination of circumstances will aggravate a situation drastically.  We believe that there is a perfect storm brewing in the two-way radio business that can benefit users and dealers alike.  The combination of circumstances are as follows:

  1. FCC narrowbanding mandate.  Organizations, big and small, have failed to meet the January 1, 2013 deadline to cease operating using 25 kHz efficiency technology.  Many counties in Virginia, such as Caroline County, are not yet using 12.5 kHz efficiency technology. Add to this many smaller organizations, such as weekend racers, that are not yet using 12.5 kHz efficiency technology, and you will come to recognize that the opportunity for the two-way radio dealers has seldom been better.
  2. Rise of standards.  In the early years, analog was THE standard for radio communications.  Then, digital came into the marketplace; this created confusion for users and profit for manufacturers, because each manufacturer stated that you need to buy their digital radios to work on their digital systems.  But, as the digital marketplace has matured, so have the standards.  For example, today, it is possible for an inexpensive radio from China to work on a MOTOTRBO system; this is possible because of the DMR standard.  Standards are driving down pricing for users and increasing the need for manufacturers to prove the value of their solutions.
  3. Rise of competition.  We recently had the privilege of attending the 2013 IWCE event in Las Vegas.  It was full of great exhibitors from all over the world.  Many of the exhibitors have names that you would recognize, such as Harris and Motorola.  Some of the exhibitors have names that you might recognize, such as EF Johnson, Icom, Kenwood, and Tait.  Some of the exhibitors, you might never have heard of before.  Looking at our local marketplace, we realized that there are only two (2) radio dealers in Richmond and both of them only provide solutions by a single large manufacturer.  We wish to bring some competition to the Central Virginia marketplace by offering solutions from more than one manufacturer.
  4. Rise of Radio over IP (RoIP).  In our opinion, Radio over IP has the potential to revolutionize interoperability in the two-way radio marketplace.  RoIP can extend a two-way radio system to the entire Internet.  Today, there are already solutions what will enable users to connect analog systems to digital systems.  Bridging systems in Alaska and Hawaii is now a reality.  Being able to dispatch calls from anywhere is no longer a dream.  Applications like this show the power of IP (Internet Protocol) and can surely benefit users.

We are ready to take advantage of this “perfect storm” with you.  If you are still using 25 kHz efficiency technology, are looking to move to a standards-based radio solution, want to consider competitive alternatives, or are looking to take advantage of Radio over IP, please contact us at (804) 625-4233 or sales AT richmondrf DOT com.

As a side note, although 25 kHz efficiency radios can no longer be used in the United States, they can be used in other parts of the world.  So, please make sure to ask us about our trade-in program.