The story, “Years After Sept. 11, Critical Incidents Still Overload Emergency Radios” appeared on NPR’s All Things Considered yesterday afternoon. It talks about some of the problems that police departments and other first responders are having with their digital communications systems, despite spending billions of dollars on them.
The report includes recordings of the police officers expressing their frustration with the system. “I can’t transmit for some reason,” says one, and “We’re having trouble transmitting,” says another. Of course, what’s happening is that the system doesn’t have enough capacity when there’s a lot of traffic, as can happen in emergency situations when multiple police officers and multiple agencies are trying to use the system.
Motorola supplied the system described in the report. They contend that the system operated normally. The report notes, “Motorola Solutions wouldn’t agree to an interview about the complaints heard on the air in Broward County after the Feb. 14 shooting, but in an emailed statement it says the radio system there ‘did not crash and was operating as designed during very busy radio traffic.'” If they were operating as designed, it sounds to me like the design is faulty.
The story does note that user training is a big part of the system failing to meet expectations. In a digital system, continually trying to transmit when the system is already overloaded, only makes things worse. And, I would imagine, that officers probably should take a lesson from amateur radio operators in net operation.
Anyway, I’m not sure that there’s much more of an amateur radio angle here. This is the way that emergency services have decided to go in meeting their communications needs. It sounds like we’re spending an awful lot on these fancy digital communications systems, but I’m not sure we’re getting our money’s worth.
Joshua | DC7IA says
Hi Dan,
I’m in German Red Cross and we use a counry-wide TETRA network. It seems to work great and everybody understands that only one can speak at a time. I think it’s also due to the fact that every user of the network has to attend a course for 2.5 days to learn how to use it. This network is used by the red cross, fire department, all ambulance services and many more users. (All of which are not part of the police force, they have a seperate net or at least seperate talkgroups, I think.) We’ve got local talkgroups, talkgroups for a wide area, country wide and even some EU-wide talkgroups (Geneva convention), which can be used in case of incidents near/on the border to another country. The TETRA network even has to work 50 km into the next country. Our neighbour countries all use incompatible TETRA or other standards. That’s why the area where the network has to work overlaps. I’ve used these TETRA radios and they’re much easier to use for unexperienced radio users. It’s more like using a phone on these motorola / Sepura radios. Whereas on the old analog ones, you need to know the number of the channel in your area and the name of the control center. We use a system not unlike those of call signs, but with words and longer. Example: “control center soest” or “soest 1 ambulance 1” (not exactly these, but like this). This system automatically makes clear to what organizational unit someone belongs and where he comes from. In this case: My town Soest. On TETRA, you only need to know your name, the talkgroup the control center uses and its name, how to switch a radio on and that the big orange button is an emergency button and not a flash light or direct call to the control center or anything like that. Many press the button and wonder why they get help. :)
Just my two cents
vy 73 Joshua, DC7IA
Mike W8MRA says
First off, I’m curious what area of the spectrum that Joshua’s TETRA system is at, and I’ll explain why.
In my opinion, there’s a couple of factors involved with this:
One is that most digital comms are at 800 MHz. A band where just about anything can reflect, refract and absorb a radio signal. Move 2 feet and go from full quieting to long gone. Anyone that plays with the 900 ham band knows what I’m talking about. It’s darn near microwave. It’s great for data that just keeps trying until the parity bits are in perfect harmony. But not a good choice for voice. It’s not the mode, it’s the band.
And nothing is simplex. Two first responders standing next to each other have to make a tower to hear each other. I’m sure many of us have seen at Field Day or another event, where a close radio talking on the input overloads your radio from hearing the output. Same thing. First responders at close quarters at a scene, people swamping out others radios because comms are having to all go thru a repeater. From the different things I’ve read about thru the years, I’ve felt that having “at scene” comms be simplex would alleviate a lot of the issues.
Joshua | DC7IA says
Hi Mike. Our digital communication is entirely based on 70 cm. The old analog radios have been on 2 m and 4 m for cars. We also have some direct channels that can be used in case there’s no working repeater that can be reached. The radios can also act as a repeater, if we have to cover a wide area. So we can place one in a building to repeat to the head of operations outside the building. For bigger buildings, we also have fixed repeaters the owners are forced to install. They sometimes use leaky coax. :)
73!
Tony N2MFT says
TRAINING, TRAINING, TRAINING
Training can’t fix lack of RF channels. Key up, system busy tone. Push again and again till you get a channel assignment. “This thing is not working” Actually it is as designed.
Emergency services all train for what can happen in their discipline. But, they never stress the radio system. Most forget the radio is part of every Emergency exercise as much as the hose, medical equipment or weapon.
A large scale event with 10,000 to 500,00 people is not the same as an emergency. Calm prevails until tragedy happens. Hiding behind encryption only means no listener can hear things falling apart. ANY and most large scale fail when events stress a system. I’ve seen it for decades. Now we have Digital. Panic raises voices. “REPEAT YOUR UNREADABLE.” Or worse!
The sale people sell these high tech systems and then the engineering MUST fulfill the contract. Sales staff are encouraging all new purchases and refitting of existing systems to go digital and encryption. More money for their employers. “No one can hear you.” Right. Even your own system users can’t during extreme traffic situations.
Patch different digital modes together add a dash of panic with not enough RF channels and you have DISASTER. One group told me the salesman said the can have 1,000 Talk Groups on their system. I explained to him that the actual size is limited to 14 at one time if all are online and working. “OH” was his response.
73,
Tony N2MFT
K8AI says
Well said, Tony… Especially regarding the salesmen and the poor engineers who have to implement the mess they make.
Steve C - KE8HXM says
As in all networks, bandwidth is where it gets dicey. This is apparently true of data networks as well as these digital voice networks. There simply isn’t enough pipeline to handle the peak demand, and because of the expense of these communications networks I suspect that emergency response organizations are not buying enough hardware to handle the job for peak needs. In order for them to meet demand the network has to be overbuilt to a certain extent, and the vendors who supply these systems don’t inform their customers of the true nature of this weakness in their systems. Another problem is as others have spoken about, that is there just is not enough of a frequency range to take all that input, so the system fails because there isn’t enough room in the RF sense. I don’t know what the solution is for digital radio, but in networks of computers and server farms there is a timing system that makes the input flow match the hardware’s capacity to process. This is dealt with in the case of mainframe systems via the operating system, and example of which is IBM’s MVS OS, (multiple virtual systems) where the processing load is spread out over the hardware within virtual machines. I don’t know if there is an RF analog, but in this case could software be the solution?
73,
Steve KE8HXM