November 2013 Inbox
Monday, November 25, 2013 | Comments

Following are comments we’ve received from readers about recent online and print news and articles. If you’d like to comment on an article, email edit@RRMediaGroup.com.

In response to “Standards Work for VHF TETRA Complete, Vendors Assess Demand from Dec. 2

Editor:

I expect the new TETRA VHF portable radio antenna length will be approximately 160 millimeters, which in my opinion, will be uncomfortable for the end user.

Matar Salah Matar

O&M System Engineer
Arabian Al Kanar

 

Editor:

We are pleased to inform you that our company has already developed a complete VHF TETRA solution.

Jean-Marc Cavalier Lachgar
Indirect Sales Manager
ETELM

 


 

In response to “Panel Examines E9-1-1 Phase II Location Accuracy, Delivery Issues” from Nov. 25

Editor:

From the article: “Location technologies have inherent limitations, and delivering location information has always come with tradeoffs, said Ryan Jensen, director of technology and compliance for T-Mobile. “Public safety has historically said that high accuracy is the top priority,” said Jensen. “They don’t want a bad location quickly. They want an accurate location even if it takes a little while.”

I have some historical perspective that might be beneficial here. Before my retirement in 2005, I was a co-owner of and principal consultant for GeoComm, which was the provider of the E9-1-1 wireless Phase II mapping system for the nation's first Phase II compliant 9-1-1 county in the United States (St. Clair County, Ill., in 2001). I recall being in meetings with representatives of Verizon Wireless, the county's first Phase II provider and debating and discussing the question of "Do we, the public-safety answering point (PSAP), want location that is not close to 100 percent accurate quickly, so quickly that it could be used for call routing based on caller's approximate location as opposed to routing based on cell site and sector, or do we want location that is more close to 100 percent accurate, even if we have to wait longer for it?”

Using an interesting analogy in those meetings, I responded that in many wireline 9-1-1 calls, we were quite used to getting locations that were not close to 100 percent accurate or definitive — most calls from multiline telephone systems (MLTS) serving large institutions such as school districts or college campuses — and had been receiving them for decades. We had learned how to interrogate callers in such cases (9-1-1 calls from PBX or Centrex classes of service), but at least we got as good a location as the automatic location information (ALI) database had the instant we got the call. I went on to argue that we wanted at least that good a service from wireless Phase II. The carriers as stated by Verizon believed, instead, that the requirements of the FCC's Phase II accuracy rules in effect at that time meant that they could not send a location until it met those accuracy requirements, and for them to do so would place them in legal jeopardy. 

I said then, and I repeat now, that is nonsense. 

Simply put, carriers should provide the best wireless device location they have at the instant the call's location is known, and if that location is soon enough in the call-set-up process that it can be used for call routing, it should be used for said routing. Such a practice could eliminate the need to transfer thousands of wireless 9-1-1 calls each day. In any event, that “best we know at this instant” location should also be provided in the initial dip of the ALI database, along with an advisory in the ALI stream to the effect of "best we have right now — check back for better in a few seconds.”

Finally, I was the coordinator of a very early Phase II trial project in 1998, which we demonstrated live on the floor of the 1998 Association of Public-Safety Communications Officials (APCO) International Conference in Minneapolis. In that project we delivered location to within a dozen or so yards for every call consistently with the initial call set-up, and actually used that derived caller's location (and this was way before GPS-enabled phones!) for selectively routing these calls delivered over an existing E9-1-1 network between two different simulated PSAPs for two adjoining rural counties. 

Unfortunately, it appears as if things haven't progressed too far in the field during the past 15 years. 

Paul Linnee

 

Editor:

This statement from the article puzzles me:

Jeanna Green, network development engineer at Sprint, said nothing has changed about the technology or the delivery process to cause the declines in delivery of locations. Voice calls typically take between 4 and 8 seconds to arrive at a public-safety answering point (PSAP), she said.

“Generally, this is not enough time for the satellites to calculate the position of a handset. A rebid must be done,” said Green.

What I'm puzzled about is the statement that GPS satellites somehow "calculate the position of the handset." GPS satellites are precisely timed beacon transmitters using onboard atomic clocks. Handsets and navigation receivers make timing measurements on those transmissions and, along with data that describes precisely the orbit of each satellite, they calculate the position — either within the handset itself or in the carrier's network using measurements reported by the handset.

How it's done and how long it takes is up to the handset and the carrier's network; the satellites are not involved in that process. "Aided" GPS means that the wireless carrier's network delivers the orbital data directly and quickly to the handset. That enables a fix from a cold start as required for E9-1-1 to be performed (again, by the handset) in seconds rather than the minutes that would be required for the receiver to obtain those parameters directly on the very slow data channel broadcast by the satellites. I don't know whether any GPS receiver can calculate an accurate fix in 8 seconds from a cold start.

I'm curious whether this question was addressed: Because it seems to be pitched as a solution, how often is a re-bid or allowing more time to perform the fix successful, particularly in GPS-challenged environments such as indoors and urban canyons?

Don Mills

Editor's Response:

Panelists addressed the question of the number of calls that receive Phase II location after rebidding.

Jeana Green of Sprint said Phase II location information would be available on 77-89 percent of 9-1-1 calls after a re-bid is initiated. Terry Hall, past president of the Association of Public-Safety Communications Officials (APCO) International, indicated his data indicates automatic rebidding can increase Phase II location availability to 70 percent of calls, up from about 42 percent.

 


 

In response to “The Nordic Region’s Cross-Border Communications” from the Quarter 4 2013 issue of RadioResource International magazine

Editor:

I read your article by Ingela Rundström regarding Rakel in Sweden. On Page 32, it is claimed that ”all the exchanges and base stations are equipped with backup power.” This may very well be the case, but last week, due to the storm Hilda, very large areas in northern Sweden lost major parts of their critical mission communications. This was due to just power failures! With support from the Swedish defense forces, diesel aggregates were hastily localized and put in service, which in some way relieved the situation.

As so many times before, history repeats itself...

Björn Lindgren
Executive Director
GE (USA) Mobile Radio Europe

 


 

In response to “NENA’s ICE 8 Tests NG 9-1-1 Multimedia Call Capabilities” from Nov. 25

Editor:

As an industrial and organizational psychologist who has been associated with the public-safety dispatcher field for the past 15 years, I have the following thoughts.

During this test, was any research conducted as to how much longer it takes a call-taker to open, review and interpret images and real-time video as opposed to receiving information only using telephone conversations or text messaging?

Since it appears logical that it would take longer to open, review, and interpret images and real-time video as opposed to simply receiving either voice-based or written messages, how many additional staff members would be required to receive, open, review, interpret and forward images and real-time videos as needed when compared to the current staffing levels? How are these additional personnel going to be funded? Isn’t this something everyone should be talking about in advance of adding this technology?

Was any research conducted concerning the level of cognitive load that is added to a call-taker’s work and/or the potentially negative performance decrements associated with additional modalities of information being provided, such as when they switch between entering data in ALL CAPs (which many CAD systems are set to) and using upper- and lower-case letters when responding to emails? How might this additional cognitive load negatively impact call-takers with additional turnover, stress or burnout?

Was any research conducted as to whether responders in the field will have the time or resources to receive, view, and interpret images and real-time video?

What steps is the National Emergency Number Association (NENA) taking to conduct and publish such research in advance of advocating its use?

Jim Kuthy
Principal Consultant
Biddle Consulting Group
Folsom, Calif.

 


 

In response to “Frequency Coordinators Work on Agreement for Coordinating 800 MHz Vacated Spectrum” from Nov. 12

Editor:

800 MHz users — Do you think your rebanding/interference issues are over now that you’re on the new 800 MHz spectrum vacated by Sprint Nextel? Think again.

There is a positive benefit about moving to the new 800 MHz rebanded spectrum. Many of Sprint’s former iDEN subscribers have bidirectional amplifiers (BDAs) installed in buildings all over the United States. I estimate the number of old iDEN BDAs to be several thousand nationwide. These BDAs were installed to enhance Nextel Direct Connect users with in-building coverage. In the Chicago metro area alone, there are around 1,000 or more. No one knows for certain, not even Sprint. These old BDAs have the unintended positive effect of providing public-safety radio users with improved in-building radio coverage they may not have enjoyed before rebanding. That’s because many of the BDAs were tuned to the 806/856 MHz radio spectrum Sprint once occupied. Because of rebanding, public-safety radio users have moved to the old radio spectrum that Sprint Nextel used to occupy. The unexpected benefit of having portable radio coverage inside buildings that have the old Sprint BDAs in them can be considered a good thing for us as long as the BDAs work properly.

Now for the bad news about the old iDEN BDAs: If just one of these BDAs starts to malfunction, it can wreak havoc on your 800 MHz radio system. When these BDAs fail, they spray harmful carriers into your base station receivers. When this happens, the portable radios have to compete with the noise generated by the bad BDA, and most of the time, the portable radio loses. Now try to find the one needle in the haystack BDA that is interfering with your radio system, and you start to see what a nightmare it can be to resolve in a timely manner. My county alone is 850 square miles.

Mike McNamara
Lieutenant
Will County (Ill.) Office of Emergency Management and Communications

 

Editor:

In low-density areas in many states, public-safety communications may only exist in VHF. Almost 99 percent of the 800 MHz spectrum is not used and will never be used in my state, but yet it is unavailable to a private SMR business that wishes to serve rural areas with new technology and to support roaming activities for city customers as they travel and work. There is only one other commercial user in my particular state in 800 MHz, and we are more than 1,000 miles apart, so why can't I expand my networks?

I need to expand, and the FCC says that I can't because only public safety can license frequencies for use in any state. If I'm an incumbent 800 MHz SMR operator, I can only construct and use them "not for profit" for five years? And then start selling airtime on them? That makes no sense at all. What are my options if I want to expand the use of my system now? No one can give me a straight answer. I need to put up eight more sites, and I'm stuck.

Gary Peters
ProComm Alaska

 


 

Click here for the October 2013 Inbox.
Click here for the September 2013 Inbox.
Click here for the August 2013 Inbox.


 



 
 
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