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I just returned from visiting my local hospital ER. Posted on all doors entering the er were signs stating to turn off all cell phones because they could cause problems for equipment. However Ifound it interesting that all members of the hospitals er staff were carrying NEXTEL's and used them quite frequnetly in the PTT mode. Wouldn't these cause the same interferance as my Cell Phone?

As I walked through the enterance after being out in the drive way making a call I watched the signal meter on my Motorla Startac go from Full strength to no signal as I went through the double doors- is it possible that they are using a system to block the cell phone signals? Another family member of mine was also carrying a phone from a different carrier and lost all coverage right inside the doors.

I am not too familiar with it But Most "TELEMETRY" devices (monitors for your health) are now wireless. I do recall seeing a company making a "jammer" for that same reason.

ESSEX503 wrote:I am not too familiar with it But Most "TELEMETRY" devices (monitors for your health) are now wireless. I do recall seeing a company making a "jammer" for that same reason.

I believe that medical telemetry is licenced under ISM, part 18 FCC rules. Cell phones and NexT-Enron operate at 800 MHz (for the most part, excluding PCS.) ISM devices would be around 915 MHz (shared with hams.)

For the most part, cell phones in an ER shouldn't cause someone to die, persa. Most of the wireless stuff is almost all telementry... sending stuff like EKG back to the nurse's desk. Most of Part 18 stuff [ should ] be designed well enough to be as immune to interference as possiable. Obviously, if the staff could use Nex-Hell direct-connect, and no one had problems, then the equipment must be immune.

I think this is sort of like the "no cell phones in the commercial airplane" rule. We all know airplanes radios are on VHF, which is miles away from 800 MHz. The odds of cell phones interfering with VHF is very slim. There has [ never ] been an NTSB incident report linking cell phones to aircraft problems. In fact, most personal aircraft pilots use cell phones themselves, while they are flying. I think it boils down to airlines wanting you to shell out $$$ to use the phone in the seat back infront of you.

In the case of hospitals, I believe that they don't want you distubing the peace with your phone ringing. I suspect they use the "interference" reason, because it sounds like a better excuse.

Given these facts, I can only advise against using a 900 MHz HT in a hospital.

Interference may be the "excuse" but money is the real reason behind the no cell phone policy. Hospitals and other institutiuons make money off of the revenues of the pay phones, usually a contracted "split" with the pay phone provider. Also, the room phones generate revenue for direct dialed ld calls. If you look closely at most major hospitals they have quite a number of base station radios on their roofs, including quite a few cellular base stations, maybe up to 45 channels with an erp of up to 100 wats per channel. The main reason for the aircraft ban is not the FAA but the FCC. The rules were enacted to protect cell systems from multiple access requests from a single user. Not quite as much a problem with today's digital cell system

Stmills wrote:I just returned from visiting my local hospital ER. Posted on all doors entering the er were signs stating to turn off all cell phones because they could cause problems for equipment. However Ifound it interesting that all members of the hospitals er staff were carrying NEXTEL's and used them quite frequnetly in the PTT mode. .

Nextel sucks. I am surprised that any business is stupid enough to use their crap. I know I've said it many times.

Most hospitals, like the hospitals near me use on-site repeater systems- mostly UHF for their needs. Why the hell would anyone want their signal travelling miles to get repeated when they could have their very own reliable on-site system. People are getting 'stupider' all of the time.

-Josh

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Nextel: How business gets dumb.

The reason cell phones are banned in hospitals is that there is the possibility of causing equipment malfunction by way of AM like "audio rectification" in medical equipment. If you put a TDMA cell phone next (on top of... like within an inch or two) to an infusion pump, EKG, or other life support device, the constant on/off/on/off repetition of the TDMA RF can be picked up by any wire... rectified in electronics or whatever... Analog measurements get skewed, and digital processes can't distinguish ones from zeros.... bottom line is that the equipment can malfunction, alarms will go off, etc. About 10 years ago, pacemakers were also affected if one was to put the phone right on the chest. Today's pacemakers have better RF immunity specifically due to cell phones.

So AMPS analog phones with constant emissions could cause issues while changing channels or when keyed up or down (remember, audio rectification is an AM detector process). The FM broadcast of AMPS isn't so bad for digital... but Analog measurements could be skewed by the bias the RF detection provides.

So what about CDMA? Unlikely to cause problems since it is max 250 mW, and a continuous wide band emission. Haven't tested this though.

The only justification to this is in the ICU wards, or EMERG. In keeping with the KISS principle, they simply ban it everywhere. So I'm in the Pharmacy of a large hospital after walking in off the street, when my yet not turned off phone rings. The lady behind the counter starts yelling at me and suggesting it could be my grandmother walking by with a pacemaker... my use of the phone could kill her... and on she goes babbling away ad nauseum. How do you argue with a babbling old woman who isn't technical and doesn't know any better?

Meanwhile the hospital security has 5W UHF portables, the cops are walking in with their 800 MHz radios, and even the ambulance attendance have radios in EMERG. My little CDMA phone working the cell site across the street is at 5 mW only because of the 30 dB plate glass window loss.
Now I hear some old folks homes have followed suit.... it is just public hysteria.

Would you believe that one gasoline chain in Canada has banned use of cell phones at their gas pumps? They were worried about the chance a spark would set off a nasty chain of events. This directive has been largely ignored. The phones aren't intrinsically safe (I guess they have never had to be approved for use in a mine or grain elevator ).

You will also notice that if you go into cellular switches or some computer facilities, two-way portables are banned. At our facilities, cell phones are still OK... until some idiot will put their competitors TDMA phone into a electronics nest of sorts and crash things.

Other examples of RF immunity by design: Quality phones are often good to 7 V/m so you don't hear that CBer next door, security equipment 20 to 50 V/m so it doesn't false with a 30W two-way radio mobile outside the house, while all equipment certified to work on aircraft carriers or navy ships with their high power radar... 200 V/m!!! Keep in mind that a flourescent tube will light up in your hand at about 250 to 300 V/m.

The airplane receiver and electronics ban during landing and take off is to avoid oscillator or CPU "birdies" on aviation frequencies. Try to explain to a stewardess that your receiver is direct conversion and doesn't employ a LO?!?! Good Luck!

Cell phone ban in aircraft is because cellular is a TERRESTIAL service. A phone active in an aircraft at high altitude would illuminate too many cell sites causing havoc...

RFDude

Josh wrote:

Stmills wrote:I just returned from visiting my local hospital ER. Posted on all doors entering the er were signs stating to turn off all cell phones because they could cause problems for equipment. However Ifound it interesting that all members of the hospitals er staff were carrying NEXTEL's and used them quite frequnetly in the PTT mode. .

Nextel sucks. I am surprised that any business is stupid enough to use their crap. I know I've said it many times.

Most hospitals, like the hospitals near me use on-site repeater systems- mostly UHF for their needs. Why the hell would anyone want their signal travelling miles to get repeated when they could have their very own reliable on-site system. People are getting 'stupider' all of the time.

-Josh

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Nextel: How business gets dumb.

Hey, Nextel's stock is down to less than 5 bucks a share. You think they might go Enron Up before the year is over? would that not be grand?

As stated by the previous poster, TDMA radios cause more RFI than anything, so they blanket ban all personal RF devices. I have NEVER experienced RFI from my 800MHz CDMA Star-Tac and on my second job at a broadcast facility where I am surrounded by A/V gear. But some moron with a Craptel phone WALKING by drives some of the older Sony Betacam decks wild.

CDMA rocks. TDMA blows goats...any wonder why Nextel really sucks?

At hospitals that I work at on occasion, I/we are told that using our cell phones are ok as long as we don't use them near ER/Surgery/ICU and to keep it on vibrate to not draw attention to ourselves.

It's funny how the VA Hospital that I service has no requirement about cell phones. But I hear the Biomed/Electronic guys go ballistic when they get equipment turned in for repair because it gave weird readings but only to check out fine in the shop... That's the government for ya

As for Nextel stock, unfortunately, if the stock plummets any more, they can still file for Asset Protection and still operate for awhile. If it gets to the point that they still don't make money, they get sold and somebody else runs with the ball for awhile. I've seen it hapen to Lucent/Celestica and ICG Netcom. I'm sure it happens more than that but those are the two instances that I recall.

Personally, here's to hoping that if someone buys them out, that they will sell off the bits and pieces of the spectrum that they occupy back to the SMR's and set fire to what's left! Maybe everybody on Batlabs could pitch-in a nickel to buy them out... Here's to wishing!

bubbasnest wrote:Personally, here's to hoping that if someone buys them out, that they will sell off the bits and pieces of the spectrum that they occupy back to the SMR's and set fire to what's left! Maybe everybody on Batlabs could pitch-in a nickel to buy them out... Here's to wishing!

One could only hope. I'd definitly pitch in, I'm sure the people at http:\\nextel.bawk.net would, too!

-Josh

Nice site, nothing lke a Nextel bash!

let me slide off topic a hare...Are the Nextel phones/radios capable of simplex operation say inside a building in a fringe area that signals drop to zero once you enter?

The question has been asked before but I don't believe there was a definitive answer (actually, the answer was yes and no so who's right?)

A couple of years ago, I met a Nextel salesman, When i asked him that question. He said, that Nextel did it for one company who needed a few hundred phones and that was the only way they would sign up.

As of today, who knows. Toadys phones might not be capable of doing that.

But there are always some hackers out there willing to try.

LT

From what I've read here, and elsewhere, No, Nextel phones are not capable of simplex operations.

Wouldn't that be nice though. Cheap (sort-of) Digital walkie talkies (although the audio really sucks)?

Nah, for the power output they produce, and the range you're bound to get in the 800Mhz spectrum 'wasteland' anything (yes even FRS) would be more suiting for short 2 way communications.

-Josh

I dont know what Va hospital the gentleman was referring to but in pittsburgh, they put big freaking signs up on their doors.. Just remeber youre not playing with silly rent-a-cop. they will cite people if you dont get off when they tell you to.

Frank N3OBL
FF/EMT

Dayton. And yes I used my phone right in front of about 75% of the Federal Police Officer force there including the Dispatchers, Chief and Asst. Chief and in front of their Biomedical/Electronics Crew. NOBODY's said a word. Of course I'm not going to use my phone near the ER and ICU/surgery wards but I'm still amazed.

Of course they have serious RF problems anyways because of TV channel 2's transmitter is in close proximity. I had a CATV/RF meter out there checking their CATV lines that we run data on and with no connection to the signal input on the meter I read about +5dB signal on channel 2. Sounds to me like the TV station has some problems.

As for the simplex Nextel's, what I wanted was a cheap form of "encryption". I know they're not encrypted but they might as well be if no one can monitor them! As for power, no big deal with 1/4 watt. That's no different than using a normal HT on simplex. But think about how much RF energy ain't gonna bounce off of your head...

The only "cell phone Ive ever actually seen crash a computer in a gas station was a Nextel being called by another user on the "two way".
Owner of the station said it happened whenever a Nextel walked in and only a Nextel. Yes the phones can be programed for a simplex channel. I think it would be an analog signal if I remember right. You can bet I will be visiting that Nextel Bashing site.

I beleive JOSH and I would get along real well as far as "NEXTSMELL" goes.
Now if we can only get the few million subscribers to agree, may we can get the 800 band back to its normal operation like it was ment to be.
If the "NEXTSMELL" Board of Directors want to visit with the Taliban during an attack from US Troops, let me know. I will pay for your trip.

metro121 wrote:I beleive JOSH and I would get along real well as far as "NEXTSMELL" goes.
Now if we can only get the few million subscribers to agree, may we can get the 800 band back to its normal operation like it was ment to be.
If the "NEXTSMELL" Board of Directors want to visit with the Taliban during an attack from US Troops, let me know. I will pay for your trip.

yeah...the new "Nextel Peace Corps" featuring Rudy Guiliani!

I work for a rural Ambulance and at any one time I have on my belt a VHF (we use for communications between crews), a Fleetnet radio (800MHz) for communication with Dispatch and other agencies and a cell phone (Motorola MicroTAC) with no problems. Almost all (if not all) the hospitals in Winnipeg use VHF pagers (and others, I believe UHF as well) the security guards use pagers and 2-way (UHF I believe) radios and most have cells. Add in the building maintenance, police, other Ambulance services, fire etc., that come into Emergency dept./Hospital and, well you get the picture. I have never been asked to turn off my equipment. I think that the hospitals need to look at other possible causes of EM interference.

The report about a gas station chain up here banning the use of cell phone use is another example of the hysteria created by folk lore. I worked in my fathers service station for 9 years and witnessed all kinds of Sh--. The best one was when the ONLY gas pump service company to service gas station pumps in Winnipeg was cutting an old water down spout on a pump island. Guess what he was using to cut the pipe with. An acitaline (I hope its spelt right) blow torch!!! About 2 feet from a pump!!

I also have to when I get gas today when the kid pumping gas ask me to turn off my car. The reason he sights is that the car might ignite gas fumes. Cars built after 1980 use a sealed system for the ignition as a result, the risk of a "spark" causing an explosion is almost non-existent. You run a greater risk from static electricity causing a explosion, or someone dropping something made of metal onto the cement causing a spark.

Anyway, more food for thought...

There's never been any reproducable evidence that a cellular or PCS phone will cause harmful interference in medical devices. All of the "claims" that have been made were disproven by the companies that make teh "affected" medical gear.

One of the real reasons that they are not allowed in hospitals is because they are annoying. Doctors were getting pissed that their patients were more interested in finishing a conversation on their phones rather than telling them what is wrong or what hurts, or even trying to explain why they passed a kidney stone 3 days ago and are just now showing up to tell them.

They are also annoying. Especially those musical nokia phones.

It really looks like a stupid rule when the hospital security tells you out on front of the hospital that you have to turn off your cell phone while on hospital property, and then he promptly returns to his call on his cell phone.

I was installing a base radio for hospital to medic comms and while I was in some room with a bunch of refridgeration equipment I noticed the electronic gauges would freak out when I keyed up my VHF saber. I'm rather sure it wasn't a positive effect. I don't recall seeing any signs regarding RF usage anywhere.