cell phones and repeater towers and natural disasters

[nec208]

I have 3 questions.

I was thinking to my self today are cell phones and repeater towers are there the answer? Like that say a natural disaster a tornado or hurricane the cell phones will not work or the PD,FD and EMS do to repeater towers down.Would mobile repeater or just using lower frequencies and higher power not be better?

Also I understand big cities going to 700Mhz but why smaller cities?And how long to a scanner comes out to pick up 700 MHz?

I understand cell phones are illegal to pick up on your scanner in the US and have to be blocked out but why? Most cell phones are digital now and there is no scanner that can monitor that digital and by law no scanner maker will make a scanner to pick up that digital.And even if you could pick it up , you will have to be in 2 or 3 KM from the cell phone.And you cannot track the person cell phone ID or program the person cell phone ID into the scanner.So why block it if you cannot pick it up?

 

[n4yek]

I have 3 questions.

I was thinking to my self today are cell phones and repeater towers are there the answer? Like that say a natural disaster a tornado or hurricane the cell phones will not work or the PD,FD and EMS do to repeater towers down.Would mobile repeater or just using lower frequencies and higher power not be better?

It can be a mess when storms knock out repeaters, but a lot of cities have multiple sites and frequencies they can use if such a storm did take place. They can use lower frequencies if they have the equipment,
a lot of agencies still have low band freqs allocated to them by the FCC.

Also I understand big cities going to 700Mhz but why smaller cities?And how long to a scanner comes out to pick up 700 MHz?

The FCC is doing a band-plan change, so all cities big or small have to follow it.
Scanners built today can utilize 700 MHz, my Uniden 396T can tune those freqs.

I understand cell phones are illegal to pick up on your scanner in the US and have to be blocked out but why? Most cell phones are digital now and there is no scanner that can monitor that digital and by law no scanner maker will make a scanner to pick up that digital.And even if you could pick it up , you will have to be in 2 or 3 KM from the cell phone.And you cannot track the person cell phone ID or program the person cell phone ID into the scanner.So why block it if you cannot pick it up?

That desicion was made when the cell phones were still in the 800 MHz range and analog, they have since gone digital and are mainly in the GHz range now. The law still remains and until it changes, you have to obey it if you are a company building scanner for the US.

 

[nec208]

but a lot of cities have multiple sites and frequencies they can use if such a storm did take place

Can you elaborate here?

The FCC is doing a band-plan change, so all cities big or small have to follow it.
Scanners built today can utilize 700 MHz, my Uniden 396T can tune those freqs.

But what about trunk systems in the 700 MHz? Any scanner can pick that up?

 

[SAR923]

Many jursidictions have multiple towers and backup sites so it will be less likely that they will all be destroyed at the same time. Even if they are, portable repeaters can be set up within a few hours. Worse comes to worse, you send a unit up to the top of a hill and he can act as a human repeter for simplex frequencies.

Not all scanners can pick up 700 MHz. The Uniden 396/996 and the GRE 500/600 can trunk track in the 700 MHz range. The PRO-96/2096 can receive 700 MHz by using the Win96 extended coverage option but they can't trunk track in that range. The switch to 700 MHz may be either mandated by the FCC or the system managers may opt for it if it's open in thier area. The size of the city, town, or county has nothing to do with this choice.

 

[Stick0413]

The FCC is doing a band-plan change, so all cities big or small have to follow it.
Scanners built today can utilize 700 MHz, my Uniden 396T can tune those freqs.

They are not forcing everyone to go to 700 MHz. It is just an option out there. There are still systems being built in VHF, UHF, and 800 (Trunking and Non-Trunking).

Also have never seen (or heard) a thing, here or elsewhere, that says the FCC is making everyone go to 700MHz.

 

[DaveNF2G]

The FCC is refarming the 700 MHz band, so agencies that want to use the band will have to follow the new plan. Anyone who is already operating there might have to change frequencies.

 

[LEH]

I can speak for natural disaster, first hand.

In 2003, Hurricane Isabel visited much of the mid Atlantic area. In my area, our public service systems remained on line throughout. The three closest are trunked. They did have a couple of power interruptions as they had to switch to generator power or auxiliary towers.

One small city did go completely off the air, but not from damage to their radio towers, their dispatch center flooded from the storm surge. The county took over their 911 service and dispatch. Though their dispatches were limited by most roads being impassible (like under six or more feet of water).

Cell phones on the other hand were very hit and miss. Most towers lost their power, so cell service died. As power slowly came back up, so did cell service. But many people were still without because they had no power at their homes and could not charge their cell batteries.

I even lost my land line phone. Switch lost power but mainly from downed lines. Though when mine came up, I had a phone that ran off the phone line power and could use it. Many people only had cordless or other externally powered phones and were still dead until they got electricity back. There was a run on old style phones right after the hurricane.

Several of my neighbors had 'cable' phone service. They were without phones until power came back up and the cable lines were fixed.

Basically, most public service systems are designed with back up to work in emergencies. I mean after all, they are emergency services and if they can't work during an emergency, then something is very wrong.

Now I don't recall, and maybe someone from the deep south after Katrina can spread some light, but public service comms still seemed to be up and running. Maybe not 100% for all areas, but there was some form of communication.

As to cell reception. Cell phone companies wanted to be able to 'guarantee' the privacy of their calls on a radio frequency, so Congress bowed to the pressure (or the bribes) and passed legislation making it illegal to monitor or to manufacture or modify to receive cell signals.

Three cheers for Congress. Hiss, hiss boo. Hiss, hiss, boo. Hiss, hiss, boo.

 

[mdulrich]

Can you elaborate here?

For example the fire department I retired from has the main repeater on a TV station's tower. We set up a backup repeater at the main fire station that only has to be powered up and they would be back on the air.

Mike

 

[SAR923]

Lynn,
Very few public safety systems (or any other systems, for that matter) survived Katrina in New Orleans or Mississippi. The New Orleans systems was knocked off the air by flooding of phone switch facilities that the repeater system relied on. Some backup towers had generators that were powered by natural gas. Because of the flooding, they turned off the gas and they went off the air. The few repeaters with gas or diesel backup generators stayed on the air for 12-18 hours until they ran out of fuel. Most were inaccessible because of flooding and, in most cases, the fuel tanks were underwater and couldn't be refilled. NO relied mostly on 800MHz simplex with human repeaters stationed atop tall buildings with portables. It was about five days until FEMA arrived and alternative communications started to be implemented. I have a friend who's a Louisiana state trooper and was in NO during the worst of it. The state system stayed partially operational but he said there were many times he could talk to Baton Rouge but not to a unit five miles from him. They "appropriated" some marine band radios from a boating supply store and used those for short range communications between command posts.

Mississippi was a whole different story. If a tower was within about 5 miles of the coast, it ceased to exist. Many of the coastal cities not only lost their communications systems, the lost almost all their police cars as well. Cell phone service was completely non-existent for days after Katrina and hams actually did some good there, relaying traffic and situation reports from mobile command posts bought down from Jackson. I know that Alabama and Florida sent patrol cars and officers to Mississippi to help replace all the lost patrol cars and fill in for officers who were trying to attend to the destruction of their own homes. Once again, some semblance of communications order was restored when FEMA and DoD assets finally arrived on scene.

Katrina is a once in a lifetime event (I hope) and effective planning for a disaster of that magnitude is almost impossible. There were a lot of inventive solutions to communications problems including just using human runners to carry messages. Police agencies functioned before two way radios and they can do so again when the infrastructure is destroyed.

 

[LEH]

Jim,

Thanks for the fill in on post Katrina damage. I figured the Mississippi coast would suffer as badly or worse than it did in 69 for Camille.

You did bring up a good point on land line communications. A 9-1-1 system is only as good as the communications coming into it and able to go out from it. Even if they are able to transmit, if they cannot get calls from those in need, they are still blind.

I recall reading on Houma, LA (My uncle [dad's brother] lived there until he passed away). They were up and running the day after Katrina and were sending aid to NO.

My kudos to those departments that provided support to those communities devastated by Katrina.

One other point you make, and one that very few have listened to. A disaster like Katrina is impossible to plan for. Devastation on that magnitude cannot be planned for or easily or quickly responded to.

 

[bpckty1]

During the Hurricane Rita evacuation experience, cell phones as voice communications were very hit and miss because of the overload. However, those who used text messaging were almost 100 per cent in competing their calls, since the text messages took up less space on the system and could travel in the gaps between voice comms.

 

[Grog]

During the Hurricane Rita evacuation experience, cell phones as voice communications were very hit and miss because of the overload. However, those who used text messaging were almost 100 per cent in competing their calls, since the text messages took up less space on the system and could travel in the gaps between voice comms.

I'm not a cellphone geek, but I remember reading that text messages travel on the data channels and not the voice channels. Not sure if that's true for all carriers, but interesting if so (and a good/simple explanation).

 

[Stick0413]

As far as the text message thing goes they can get overloaded quickly too... This past New Years Eve it took me about 15 minutes to send a single text.

 

[N8RUS]

When everything else fails........................Amateur radio. And these folks donate their time.

 

[Raccon]

I'm not a cellphone geek, but I remember reading that text messages travel on the data channels and not the voice channels. Not sure if that's true for all carriers, but interesting if so (and a good/simple explanation).

It has been a while but here is what I remember: In GSM systems SMS travel on the control channels, either SDCCH or SACCH. Note that SDCCH or SACCH are logical channels and mapped onto physical channels, i.e. the first timeslot (= the physical channel) that carries the BCCH (Broadcast Control Channel) may include the SDCCH & SACCH, too, among others. If you are in a call you have a TCH+FACCH+SACCH mapped onto one physical channel / timeslot (TCH = Traffic Channel, mainly used for voice).
Operators may opt for one or more additional control channels if capacity requirements demand it, thereby removing one TCH for each SDCCH/8 added.

Note that SMS messages share the channels with other control messages like call setup etc., so it can quickly come to a bottle-neck the more users are located within that cell (which will happen automatically if surrounding cells fail) and/or the more traffic is being generated by the users (because everyone wants to make calls or send SMS).

Data channels in GSM typicall refers to Packet Data, i.e. PDCH. They are basically TCHs reserved for data (e.g. GPRS) though dynamic allocation between the number of TCHs and PDCHs is possible.

 

[jim202]

When Katrina hit the Gulf states, a very important lesson was driven home. Many people in the position
to make decisions on how communications sites were built made some real bad choices. I use to
work for a several cellular companies in the New Orleans area. One systems engineer had a poor
attitude and often took the position if it wasn't his idea, it wasn't going to happen. When it was
suggested that diesel generators be used instead of natural gas for fuel, he chose the natural
gas. When it was suggested that the cell sites be raised off the ground to the 100 year flood
level, he said place it at ground level. When it was suggested that the radio towers be speced
for 150 MPH wind, he said to build them to only 90 MPH wind loading.

This is also carried over into the public safety sector. The same choices were made for many
public safety sites. Build them cheap, build them on the ground, don't build in high wind
survivability. The results are what happened during and after Katrina.

The telephone offices flooded and lost power. A total of 19 telephone switching offices were
knocked out from Katrina. Many went down for the same simple things mentioned above.

Nextel lost the ability to talk with the outside world. When the I-10 bridge spans coming into
New Orleans went down, the fiber cable that was run under the spans also went away. As
Nextel relied on the local Bell South for many of it's long distance service connections, it was
cut off from the rest of the country.

Nextel also didn't believe that is was a good move to install generators at all of it's cell sites.
This became a major problem early into the storm. With no prime power to keep the cell
sites all on the air, as soon as the small batteries went down, the sites went off the air.
It took days for many of these sites to have the roads opened up. As a result, they couldn't
even bring generators to those sites that still had connectivity to the cell switch. Remember
here that you need a data connection from every cell site back to the switching office to make
any of the cell sites work. With so many Bell South offices out of operation, this soon became
a major road block to most cell site operations.

Nextel was not the only service provider that had data circuit issues to get their sites back on
the air. Verizon, T-Mobile, Sprint and the others also all had major troubles. If it wasn't
the lack of power, the lack of a data circuit, it was damaged or missing antennas. All the
radio tower sites had some form of damage. Each and every cell site tower needed to be
climbed, inspected and the antenna systems repaired.

If you thought the cell companies had it bad, the public safety agencies had it even worse.
They had the same problems and then some. Being on the low side for having the money
to build a radio site correctly, many corners were taken on building these sites. Poorly
designed towers came down, those that stayed up had major antenna damage or cables
just yanked off the towers. The equipment shelters were built too low and flooded. The
generators were built low and flooded. The fuel for the generators had too small of a
diesel tank for the ones that used it as fuel. Those that used natural gas or propane
suffered the fate of no fuel after the first 12 to 24 hours.

The state has a good start on migrating to a new 700 MHz trunking system. Many of
the Parishes have chosen to jump onto the new 700 trunking system. I still have a
few concerns as to how these sites have been constructed. Some of them seem to be
on the low side. However, the state has learned that you need at least a week of fuel
for the generators.

Fema made a real jerk out of them selfs. There were several instances where a Parish
had sent a fuel truck to Baton Rouge and paid cash. On the way back, some FEMA people
stopped the trucks and confiscated them. The second time around an armed guard from
the sheriff dept was with the trucks and the FEMA people made the wise move to back out
of the way or get shot.

It may be a good time here to mention that the "National Interoperability" radio channels
played a large part with being able to talk with the different agencies that came to the Gulf
Coast to help. As they were from outside the area, the radio channels in the portables
and mobile radios were non compatible with the local radio channels. It didn't take
but a few seconds to have someone come up with the idea to start communicating on
these "National Interop" channels. Much of the radio traffic right after Katrina was done
on these channels.

I now ask, how many of you pubic safety people have the "National Interop" radio channels
in your radios? If not, why not? These are common channels that are used all around the
country. The major road block that I find in my travels, is that POLITICS play a major role
in how or even if these channels are available. If they are not in your radios, you can't use
them. If you can't use them, you can't communicate with any other agency that may be there
to help you.

Jim

 

[Astrak]

If all else fails HF.

 

[SAR923]

Excellent summary of what went wrong during Katrina, Jim. As I wrote, there's no way that you'll ever have 100% survivability of communications facilities in a disaster the magnitude of Katrina but things would have been much better if some of the simple and not really very expensive steps you outlined had been taken. I my experience managing disasters, most of the communication problems we had were because facilities are built for low end of any possible disaster. 99% of the time, that works fine. When you get the "big one", whether it be hurricanes, floods, or earthquakes. the 1% kicks in, just when you have the most lives and property at stake. The really galling part to me is that DHS is spending huge amounts of money to "upgrade" the communications system but is almost silent on requirements like siting of towers, requirements for backup power, and contingency plans if parts of the system fail. So, we have patrol cars and fire trucks with the very latest whiz-bang communications but they won't be able to talk to anyone when we get a repeat of Katrina if we don't use the lessons learned. We won't, we never do. The next big disaster will occur in another generation who will have forgotten how bad Katrina was and will have made exactly the same mistakes. Sad but such is human nature.