Published by Davicom on April 30 2015

In North America, most consumer and professional electronic equipment must conform to FCC or Industry Canada standards. These standards govern the unintentional RF emission levels allowed from equipment and are useful as far as reducing the overall “RF background” noise present in our society. Without these standards, bad design and the race to the cheapest product would quickly make the electromagnetic spectrum unusable due to the generation of parasitic signals.


On the other hand, our modern lives are increasingly dependent on intentional RF emitters such as cell phones, Wi-Fi networks, microwave links, television and radio broadcast transmitters, public safety radios and mobile/fixed radios and repeaters. These intentional emitters legally produce RF signals (some at very high levels) in many frequency bands of the electromagnetic spectrum.


In our line of business, I’d say that electromagnetic immunity is more important than electromagnetic emissions since our monitoring equipment will often be used on remote sites with RF transmitters. Since there are no mandatory standards for immunity in North America, and since we do want to ensure our equipment will operate correctly in complex/hostile electromagnetic environments, our fall-back solution is to use the European CE Immunity standards that are part of the European EMC Directive.


These standards, which were developed in the mid to late 90’s have evolved over time with the addition/refinement of different product categories. The category under which we now test our Davicom Remote Monitoring and Control Units is Information Technology equipment and the levels of immunity for this category are defined in the EN 55024 standard.


The actual procedures for the tests are described in another set of standards. For example the Radiated RF immunity procedure is described in EN 61000-4-3. In these tests, a device under test (or DUT) is placed in a high-level RF field and monitored for any change in its behaviour. This field can be produced by an antenna in an anechoic chamber, or by a transmission line in a Transverse Electromagnetic Cell (or TEM Cell). Comlab uses a large TEM cell.


Electromagnetic immunity is concerned with much more than just radiated RF. Think of any time a spark jumps from your fingertip onto your computer’s keyboard (and your computer crashes!).  These sparks are known as electrostatic discharges (or ESD) and are also the subject of an EM immunity standard, in this case the test procedure is described in EN 61000-4-2. Tests are carried out with an ESD Gun that generates sparks of up to 15kV which are applied to the DUT while monitoring its behavior.


EM immunity extends into the wired aspect of electronic equipment also. By different inductive and capacitive principles, RF energy can be coupled into various conductors leading into and out of equipment. This RF energy can wreak havoc with circuit and software operation if it is not controlled, filtered and eliminated. The procedure for carrying out these tests for immunity to conducted RF energy is described in EN 61000-4-6. The tests are performed with a high-power RF signal generator and a clamp-on inductive loop to inject the RF energy into the cables of the DUT while monitoring its operation.


EM immunity even covers the field of utility power. Although you may have a tendency to take your utility power for granted, and assume that it is delivered to you as a nice clean 120V, 60 Hz (or 240 V, 50 Hz) sine wave, this is never the case. The utility power spectrum is a jungle of parasitic signals, harmonics, overloads, glitches, back EMF peaks and even lightning surges. This is another area where testing the immunity of equipment is important to ensure reliable operation.


If lightning hits the power utility pole feeding your site, you want your equipment to survive this back-door attack into your system. This is where the tests for surge voltages described in EN 61000-4-5 come in handy. These tests are performed with a special device that capacitively injects large surge voltages on the power cord while checking for proper behavior of the equipment.


If your power line is also feeding large motors, air conditioning compressors, and your high-power transmitter, you don’t want power glitches, such as your transmitter suddenly shutting down for protection, to crash your remote control system. The tests described in EN 61000-4-4 simulate these conditions.


When these standards first came out, they seemed very intimidating and difficult to satisfy. However, hard work, good design practices, practical RF experience and continuous testing in our EMC lab over the years have produced consistent results at satisfying and even surpassing these standards for all our products.



Thank-you to the participants in our first DEX breakfast!

Published by Davicom on April 22 2015


A big thank-you to all the participants and presenters at our first Davicom Exchange (or DEX) breakfast at Harrah’s in Las Vegas during the 2015 NAB.


The DEX, as we’ve come to call it, is the place where people, be they power users, novices, or just wondering if they want to get into the Davicom world, can exchange application information, programming notes, configuration files, workspaces or just browse through the ideas that are posted.


The main DEX location is the Facebook Group (which is different from Davicom’s Facebook Page). The DEX Group, which is private for the time being, is the place where approved members can post files, download files and exchange ideas. Some of these postings will eventually find their way onto the Davicom web site in the Applications Section. Members are also invited to use the Group’s Facebook infrastructure to share Davicom files amongst themselves.


The DEX also has a physical time & location and it is the annual breakfast meeting on Tuesday morning at Harrah’s during the NAB in Las Vegas.


We’re looking forward to seeing your ideas and applications on the Facebook Group and hoping to see you again at next year’s DEX Breakfast!

Final preparation for the spring NAB Show

Published by Davicom on March 31 2015


The annual NAB mega show starts in a bit less than 2 weeks and we’re pretty much all ready. The crates of show-stuff are on their way and we’re ironing out the final details of our first Davicom Exchange forum, or the DEX as we’ve come to call it. We hope this breakfast on Tuesday morning will turn into an annual must-attend event for all our customers and fans who attend the NAB show.

Speaking of the NAB, I’ve always wondered if it was the 2nd biggest show in Vegas after the CES. Well, it turns out that it’s the 3rd biggest. Here is a table of the data from the Las Vegas Convention and Visitors Authority web site. It lists the top-10 shows by number of attendees:

  1.  International CES 2016: 163000
  2. Automotive Aftermarket Industry Week (AAIW) 2015: 140000
  3. National Association of Broadcasters 2015: 98000
  4. Las Vegas Market – Summer 2015: 50000
  5. Las Vegas Market – Winter 2016: 50000
  6. World of Concrete 2016: 48000
  7. ASD Las Vegas – August 2015: 44000
  8. 2015 Pack Expo Las Vegas: 43000
  9. Super Mobility Week: 40000
  10. Nightclub and Bar Show 2016: 39000

I wonder what the booths look like at the Nightclub and Bar Show? 


Lithium Metal Batteries as Cargo in 2015

Published by Davicom on February 10 2015


Questions have come up recently from several customers about shipping the Lithium metal batteries included inside their Davicom units by air. DON’T PANIC. Please see this document from IATA, based on a report from ICAO:

As stated in the IATA note: “It is important to re-iterate that the prohibition on the carriage of lithium metal batteries on passenger aircraft only applies to lithium metal batteries when shipped by themselves (PI 968 Section IA, IB & II). The prohibition does not apply to lithium metal batteries packed with equipment (PI 969) or contained in equipment (PI 970).”

If the question comes up, the small DL 1/3N backup battery inside Davicom units contains only 0.06 g of metallic lithium.

Take back control by having your site control itself.

Published by Davicom on February 4 2015


The “control” aspect of a monitoring and remote control system can often be overlooked or forgotten. Generally, remote control is limited to allowing a remote user to connect to the site and to control stuff. With an intelligent system, the control can be used to do smart things automatically.

Here are 6 examples:


  2. Use the built-in network Pings of your intelligent remote-control system to check for on-site or off-site network continuity and use a relay to power-cycle any elements that don’t respond as expected.


  4. If you have equipment such as a computer or modem that accumulates errors and needs to be reset every few days, use the internal timers and relays of your intelligent remote control system to reset the device automatically every night at 3:00 AM. Although this “preventive” reset may not be the most elegant way to operate on a permanent basis, it can certainly save your B*** while waiting for replacement parts.


  6. OK, so you can do this with a photocell, but the photocell can become dirty and grimy, or burn-out, or be affected by cloud cover or new on-site lighting installations. Instead, use the Sunrise/Sunset flag of your intelligent remote control system to automatically activate a relay when the sun goes down. This flag is calculated mathematically for every day of the year from the site’s latitude and longitude that are entered into the remote control’s configuration settings. In certain jurisdictions, this flag can even be used to trigger the day/night power and pattern changes for AM broadcast stations.


  8. Best practices for generator power installations require that the generator be tested periodically to ensure that it can operate correctly in an emergency. If allowed in your jurisdiction, automatic tests can be a great time saver.  Use the internal timers of your intelligent remote control system to set a flag once a week, on Monday morning at 10:00 AM for example. This flag will trigger a relay to start the generator for a predetermined period of, say, 10 minutes, and turn it off afterwards. The test can be logged in the system log. You could even set an audio alarm or siren to sound for 30 seconds before the test to warn any on-site personnel about the imminent generator start-up.


  10. Say you have a backup transmitter located at a different site than your main transmitter. If you have any type of communications link between your two sites, you can use the Unit-to-Unit Commands of your intelligent remote control system to automatically turn on your backup transmitter should the main one fail. Dial-up, IP or even a plain UHF Radio link can be used to send these commands with no intervention on your part. The main site can even automatically tell the backup site to shut down when it is ready to come back on-line.


  12. If you have a compressor at your site to pressurize your transmission lines, it may be important to limit the run-time or duty cycle of the compressor. Some machines are specified to run for a maximum continuous time, otherwise they overheat and can become damaged.  Using the Activity monitoring flags of your intelligent remote control system, you can easily check the run-time of the compressor and automatically turn it off after 10 minutes (for example) of continuous operation.  You can also program a cool-down period and allow the compressor to re-start after a 15 minute rest for example.

Work smarter and not harder. Save time and take back control of your life with a properly configured intelligent site monitoring and control system.

Have questions? Just contact us by going to http://www.davicom.com/contact

5 Cool things you can monitor at your remote site.

Published by Davicom on January 8 2015


You have to agree that a remote control & monitoring system can be very useful at your remote site. Monitoring different voltages, currents, temperatures, pressures, powers, etc. ensures you have full situational awareness 100% of the time.

Aside from the “normal” things that you’d expect to monitor with pretty much any system (voltage, temperature, current, power…), here are 5 more parameters that could be interesting to monitor.


  2. Monitor the status of your on-site LAN or that of your off-site WAN. Using the Network Ping capability of your intelligent remote control system, ping on-site devices such as transmitters, network switches, encoders or satellite receivers. Also consider pinging off-site IP addresses in order to detect any loss of connection to the outside world. If one of these devices or IP addresses fails to respond, you can use the remote control’s built-in relays to power cycle the unresponsive device, network switch or wireless router.


  4. Though used less frequently today, dial-up telephone lines still provide reliable backup communications to your sites. If they aren’t used regularly, they can reveal themselves to be defective when you do need them. An intelligent remote control system that checks for dial-tone every 15 minutes can help prevent critical site blackouts when lines go down. Placing this information, black on white with a time-stamp in the system log can also help you prove to your communications provider that their lines are less than reliable when you’re having intermittent line problems.


  6. If you have a generator at your site, you know that you have a preventive maintenance schedule to follow. Use your intelligent remote control system to cumulate the run time of your generator and to include this information in your system log. That way, it is easy to see when your generator is due for its oil change and related maintenance.


  8. If your site uses a dehydrator/compressor to pressurise your transmission lines, monitor their operational duty-cycle and detect pressure leaks in your lines. Consider using the daily cumulative run time parameter and set a threshold at, for example 20%, or about 288 minutes per day. If your compressor’s run time goes over this limit you can safely say that you have an important leak in your pressure that needs to be repaired. Setting the threshold to lower values can allow you to detect a leak well before it becomes a major problem.


  10. Use your intelligent remote control’s Caller-ID and IP logging capability to see who is accessing (or trying to access) your unit by phone and/or the IP network. This information could be particularly interesting for your IT personnel should they want to monitor the security of your network and communications infrastructure.

These are just a few examples of cool things you can monitor at your remote sites with a properly configured and intelligent remote site monitoring system.