Isotrope Links


David Maxson to Present at NAB Show 2016

Isotrope’s David Maxson will be giving a presentation about 2 new kinds of interference in the FM band at the NAB Show 2016, Tuesday April 19th in Las Vegas. A preview of the presentation can be found in the NAB Preview edition of Radio World magazine. Read more here.

Automobile Key Fob Dead Zones in the News Again

David Maxson was interviewed by Fox-TV Chicago on the subject of car key fobs mysteriously not working in a certain area. The situation is similar to one David solved in Yonkers, New York. Here’s an excerpt from the story:

So what could be the source of that powerful interference? David Maxson is a wireless expert for the Isotrope company in Massachusetts.

“I’ve had about four phone calls from various places around the country. Yours might be the fifth,” Maxson said.

Maxson said some dead zones have been linked to shopping centers using radio signals to keep track of their shopping carts and reduce their theft. Another, he found, was caused by the light control panel used by a nightclub’s disk jockey.

“It was designed in a way that it was not sharing the spectrum properly with the key fobs. So it was preventing people from in front of the bar from being able to start their cars when they were ready to leave,” said Maxson.

Maxson said if your key fob does fail, try holding it as close as you can to the sensor it’s looking for, which might be the car’s antenna or the button you use to start your car.

See the interview here and you can read the full story here.


Comparison of Utah Wireless Broadband Speeds

In 2011 and again in 2013, Isotrope conducted a project that measured wireless broadband speeds for the State of Utah.  The project was funded by the State Broadband Initiative (SBI) of the National Telecommunications and Information Administration (NTIA). This past summer Isotrope prepared a Comparison Report, comparing the results from 2011 and 2013 drive tests.

An excerpt from the report:

Generally, there were several significant improvements in the availability of broadband service in Utah from 2011 to 2013. We see that 3G broadband speeds increased amongst all the carriers, perhaps in part by upgrading 3G technologies at the cell sites, and perhaps in part due to the upgrading of backhaul capabilities necessary to support 4G LTE at each cell site.

You may download the full report from the State of Utah Broadband Project here.

Defining “Public Safety Grade”

Isotrope has worked with Public Safety agencies in the past to recommend ways to harden their communications systems.  The Public Safety Telecommunications Council recently released a report “Defining Public Safety Grade
Systems and Facilities”.  The report focuses on the implementation of a Public Safety Broadband Network, i.e. Firstnet, but these standards and recommendations apply to Land Mobile Radio (LMR) communication facilities as well. A copy of the report can be found here.

Wireless Building Permits – A Cautionary Tale

One of the great existential conundrums is “How do you know what you know?”  I recently have seen a series of unrelated building permit applications for new or modified wireless facilities that were missing key information and the presenters firmly believed in the diligence of their submissions.  One thing these applications had in common (and not all applications are like this) was that the structural analysis was incomplete.

I read one application with a beautiful analysis of the integrity of the proposed camouflaged antenna mount.  It would hold together in the worst of hurricanes.  A note among many notes said that the analysis did not include analysis of the roof structure to which it would be attached because invasive techniques would be required to do so.  That means someone would have to cut open the flat roof and inspect the underlying joist work and wall connections.  Then a design would have to be created to ensure that the beautifully designed structure would not tear the roof off in the same hurricane. Yet the applicant’s agent and its attorney each firmly believed that all the necessary due diligence had been done and presented in the application.

In another case, a similar claim was made for attaching upgraded equipment to a water tank.  The mount was calculated and the notes indicated the tank was assumed to be in good shape and the existing studs welded to the tank were assumed to be up to the task.  The Professional Engineer stamped a letter certifying this.  Maybe if it is well-known that the tank and bolts are indeed within specification based on recent analysis or recent installation under construction control it might be OK to gloss over how the entire system will work. Not so here.

In this case, the error was compounded by the fact that two years ago, a modification that occurred did not look anything like what was proposed, and included a newly welded mount that had not received the tank owner’s approval or that of the Building Official.  Moreover, the existing mounts had missing studs, which the PE two years ago said should be repaired.  They never were.  So the new PE certification is based on a series of assumptions that a simple visual inspection would have contradicted.

This led to the “How do you know what you know?” question.  An eager project agent assured me that everything in the past had been done by the book, and not to worry.  Nothing would have gone on that water tank without proper structural analysis, owner approval and Building Official approval.  When I asked “How do you know?”  He got a bit testy and sputtered that his employer and the town would never have it any other way.  Digging into the history and making a site visit, I found he did not really know that which he firmly believed.

Then in another case, an applicant proposes to replace a one-foot wide flimsy guyed radio tower with one some seven feet wide, including new foundation and guy anchors.  The only structural analysis was in the form of a “typical” drawing of the new antenna mounts and a note that the tower design was yet to be determined, all with a PE stamp on the drawings.  Building officials are responsible for deciding whether a licensed contractor or a licensed engineer should be controlling construction and signing off.  They usually look for evidence the structural design and foundation design have been produced and signed for in advance of construction.  Construction control is the final step in ensuring the result will be structurally to code.  None of this was imposed by the Building Official.  The tail was wagging the dog on this one.  The antenna and mount would be just fine; never mind that there is a non-existent tower and foundation that will magically appear to hold them up.

In all three cases, the Building Official was unaware there was missing information.  A quick read of the documents would lead one to believe all was in order.  The one question Building Officials can ask when reviewing wireless building permit applications is in two parts: “Is this project going to be code compliant end-to-end when it is done, and how will we know?”

Isotrope has Moved!

As we get ready to start a new year, Isotrope is pleased to announce that we have expanded into new space. The move was a long one, about 30ft as we moved from one building to the other. Though we may miss the charm of the former space in a 300 year old house, we are excited about the new space as it will help us better serve our clients.

Our new address:

Isotrope, LLC
503 Main Street
Medfield, MA 02052


Your mileage may be different: Reflections on megabits per second and miles per day.

Read David Maxson’s article for “Above Ground Level Magazine” ( chronicling the Isotrope project that measured wireless broadband speeds for the State of Utah.  The project was funded by the State Broadband Initiative (SBI) of the National Telecommunications and Information Administration (NTIA).  In the article Mr. Maxson talks about theoretical wireless broadband speeds by wireless technology and how Isotrope went about measuring bandwidth speeds out on the roads of Utah.

Here is an excerpt:

With the officially defined threshold for broadband service (768/200Mbps) and an online broadband map showing data service availability by provider, the state of Utah sought other ways to look at the question. The Utah broadband website has an online speed test that broadband subscribers are invited to run. Such test tools provide a useful snapshot of data speeds that subscribers actually obtain where they use their broadband services (wireless and wireline). Of course, the results are entirely dependent on who runs the speed test, the quality of their connection, and the type and condition of their user equipment.

To obtain another glimpse at the geographic distribution of mobile wireless broadband services, the Utah SBI team commissioned a statewide drive test of broadband mobile wireless services. To guide the drive test, Bert Granberg of the Utah Automated Geographic Reference Center (the state’s geographic information systems department) assembled a set of first-, second- and third-class roads spanning the state’s varied terrain and land use. The plan was to reach into every corner of Utah life, including urban, suburban, rural, mountain, valley, canyon, desert, park, range, resort and reservation. Isotrope won the contract to conduct the survey under the auspices of the state’s broadband consultant, International Research Center. Utah is a beautiful place to tour, even if just passing through.

Read the full article here.

Isotrope Drive Testing Services

Isotrope now offers comprehensive in-house drive testing services.   Our carrier class test gear measures CDMA, 1xRTT, EVDO, GSM, GPRS/EDGE/UMTS, HSPA and LTE technologies.   Isotrope provides benchmarking of data as well as voice calls.  The test platform, combined with our carrier class signal propagation modeling software, provides comprehensive benchmarking services.  In addition to measuring outdoor wireless signals for macro cell and DAS, Isotrope is also equipped to do indoor DAS benchmarking.

Contact Isotrope for more information.

The Oldies have never sounded so good!

I cannot lie; I’ve aged into the “Greatest Hits” demographic.  I find myself regularly listening to one of the 2 “Greatest Hits” stations here in Boston.  Now, they used to be called “Oldies” but over the last few years, the music from the 50’s and 60’s has been phased out in favor of 70’s and now 80’s.  They’re still oldies but Greatest Hits is more PC.  Oldies? Isn’t that what our grandparents listened to?   I like the music from the 70’s.   It’s what I was listening to in my formative years.  Oh sure, you’ll still hear a song from the 60’s but it will likely be Motown or the Beatles.   And yes, I still like to keep up with today’s music, and you can get a good idea about what’s going on by listening to the Top-40 station for sixty minutes (or as long as the ear will take).  Okay, what’s the point?  What I’ve been noticing is that I’m hearing things in old songs I never heard before.  Instruments are crisp, percussion distinct, backup vocals, stereo separation, etc.   That got me to thinking.   We’ve never heard these songs like this before.   When we first heard these pop hits on the radio, it was on AM.  they were being played off EQ’d 45’s through early solid state audio equipment,  pre-historic audio processing and tubed AM transmitters.   The total harmonic distortion and inter-modulation distortion was huge.  FM was coming along with slightly better fidelity and stereo, but it was where you went for “progressive rock” or “beautiful music”, the hits were on AM.  Now the songs have been re-mastered, loaded into linear digital playout systems, run through state of the art audio consoles, processed intelligently, and transmitted by state of the art solid state transmitters.  Even if the final transmitter amplifier is a tube, everything that comes before has been built for low distortion.  It’s all really quite remarkable.

When I was the Chief Engineer for the local Top-40 station I always was envious of the engineers over at the Greatest Hits stations.   They always sounded good.   There was nothing I could do to make my station sound like theirs.  I didn’t have re-mastered songs with real instrumentation to run through my air chain.  No, I was stuck with clipped, distorted, overly processed content.   You know that phrase “Garbage in, garbage out”?  In this case it became “Garbage in, more garbage out”.   This leads me to my next point, the improvement in broadcast audio processors.   I recently read a commentary by Frank Foti in Radio World.   Along with Bob Orban, Frank is one of the luminaries in the processing world.   His commentary discussed how with modern technology, processors can be loud but with much less distortion.   The trick is to build loudness in the AGC stage and not in the limiters and clippers.  It’s been tough to do that up until now because AGC control wasn’t up to the task.  Now with better detectors, it can be done.  If I was still in the game at a top-40 station, I’d now have the tools to make the station sound loud without adding more limiting/clipping distortion to the already distorted content.   But, I’d still be listening to those Greatest Hits stations!

DAS the wrong question

A reporter called me to ask about distributed antenna systems (DAS).  I told him that was not the right first question to ask.  Why?  Explanation in a moment. His community is hearing its third wireless facility permit application that includes a new tower.  This community is part of a national gem, having a majority of its land mass designated a National Park. Naturally, wireless service providers gravitate toward the developed areas where people live, work and play.  This is where the privately and municipally owned land is.  Rather than try to penetrate the National Park land to site a new tower, it is often most practical to work with the private and municipal land owners where the human activity is concentrated.   Residents see a pattern developing and are concerned that the pristine beauty of the area is being steadily eroded with the addition of each new tower.

Picture of a DAS installation on Nantucket utility pole

DAS installation on Nantucket utility pole

As often happens in the public permitting process, concerned residents look for what they consider to be a better way to facilitate the provision of personal wireless services.  The idea of DAS is very enticing to people who would prefer not to live with towers.  Antennas on utility poles.  Low power levels. What’s not to like?  This begets the question, why can’t we have a DAS in our community? Usually I get a call from a representative of the permitting Board, or a concerned resident.  In this case, the local paper was working on a feature story to examine the issues.


Now we are back to the starting point, “Mr. Maxson, what’s keeping DAS from being put in this community?”  I thought, should I give him the radio frequency engineer’s answer (“it depends”), or the facilitator’s answer (is this the right first question to ask?)?  Since the caller was a reporter, I certainly did not want to start with the pros and cons of DAS when the context of the problem had to be explored first.

So I explained to the reporter that rather than jumping to a conclusion (“we need DAS”), the problem has to be identified in the public process, and the range of potential solutions considered.  Certainly the applicants (a tower company and a wireless carrier) have considered ways to find the most “zonable” solution.  A tower company, of course, has an interest in building a new asset – the tower – and may be less interested in potential solutions involving existing structures.  Nevertheless, the wireless carrier is the driver, and seeks a balance between time to market, development cost, and ability to satisfy the coverage objectives.  If local regulations point the carrier to an obvious solution without a new tower, the carrier would almost certainly embrace it. The word “almost” is key here.

The role of the public permitting process is to look over the applicant’s shoulder and validate the proposal against the duly adopted requirements under local ordinances.  What is the coverage objective? How much of it, if any, rises to the level of a significant gap in service under the federal law? Is the proposal in keeping with local goals and regulation?  To what degree is it not? Height? Visual impacts? Design? Locations affected by its proposed presence?

Once a baseline on the proposal is established by gathering information to answer these questions, the question of alternatives finally comes up.  Local regulators should perform due diligence on alternatives anyway, because in addition to analyzing the nature and extent of the gap, evaluating the prospect of alternatives is an element of the permitting board’s responsibility under the ’96 Telecom Act.

Are there other ways to address the coverage objective or the gap?  Would they work well enough? Which ones are more consistent with the purpose and intent of local regulations?

Finally, actual options can be put on the table: Upgrades to existing facilities to reduce the extent of the gap? Other sites for new facilities without a new tower?  Other sites for a new tower? Other locations on the proposed site? Reduced height? Improve design with suitable camouflage or “stealth” decoy?

These alternatives can be explored in the context of the coverage objective or gap. A single site alternative is not necessary.  Are there two sites that collectively have less impact on the community (or are more ordinance-consistent) that could address the coverage objective?


  • Hide antennas in steeples in the center of town, reducing the extent of the gap, and allow a new tower more distant from the center of activity to take up the slack (Proposed tower ¼ mile from historic town center denied in Grafton, MA for this reason).  A tower a mile away was later approved and some carriers are using a church steeple.
  • Find an alternative site that does essentially the same job for coverage with significantly less impact on the ordinance and the community. (Proposed tower in Duxbury, MA was deemed too out in the open and affecting too many residents; applicant and board worked out an alternative at another more wooded and residentially remote site.)
  • Double up on sites to increase overall coverage and eliminate undesirable visual impact. (Proposed tower on prominent ridge at gateway to the town of Ashland, NH was denied; alternative was one tower in the river basin illuminating much of the same territory, and a second tower in the trees on a hillside a mile or so up the interstate to make up the rest of the coverage and add more.)
  • Now we are at the DAS question!  Would interconnecting a series of utility-pole-mounted antenna nodes provide substantial coverage to the gap?  Where would it not reach?  Is that unreached area material to the overall gap?  Would a combination of DAS and strategically placed smaller macro sites achieve the objective in a manner more in keeping with local zoning objectives? ( 1) Wellesley, MA has substantial coverage from towers and buildings; it also has a half-dozen microcells on its utility pole infrastructure where towers don’t reach. It is getting to the point that future installations will be of the DAS flavor rather than microcells. 2) Lower Merion, PA residents sought to avoid a tall tower proposed on a ¼ acre lot at an intersection in the midst of a main line residential area; eight microcells already dotted the area; DAS was developed.  3) According to public record, the well-protected scenic island of Nantucket could have needed eight towers to cover the areas of human activity; a forward-thinking wireless carrier and a DAS company developed a DAS solution, beginning in 2003.)

In sum, while DAS architecture is one of the tools in the box, it is not a panacea.  Residents often want to leave no stone unturned before approving a proposed facility.  The public process should include due diligence, to the extent the regulating Board finds it appropriate, on any potential alternative. Just as toothbrushing is one activity in an overall plan of oral hygiene, evaluating DAS as a potential alternative to a proposed wireless facility is but one part of an overall, systematic process of evaluating a wireless facility permit application.

Mr. Reporter, thanks for calling.  Maybe you can summarize our conversation in a few pithy quotes.  Good luck!