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  #1 (permalink)  
Old 12-06-2017, 12:40 PM
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Default Portable, reliable comm for very large NYC march

I've been asked to evaluate options for providing radio communications to the organizers of a very large (over 200k expected) march through midtown Manhattan. The march route spans about a mile as the crow flies, and various teams would like to spread out along the route, maintaining reliable communication throughout.

There was a march last year of similar size, and there were widespread complaints that staff could not communicate with each other. We would like to avoid repeating that, if possible.

It seems to me that a mile in midtown is a stretch for most portables, possibly exacerbated by very high crowd density. I'm wondering if anyone has any experience with this type of situation and could recommend the best course in terms of radios, frequencies, repeaters, procedures, etc.

Cost and complexity are important considerations. We'd expect/hope to rent the equipment...
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Old 12-06-2017, 7:24 PM
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Additional note: I spoke with a large, national, renter of comm equipment, and he came back recommending PTT. That's what we used last time and had terrible luck with it.

So it seems like 2-ways + repeaters are our bet? Any specific advice is greatly appreciated!
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Old 12-07-2017, 11:51 AM
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Hams have been doing that sort of thing for years, in NYC and elsewhere.
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Old 12-07-2017, 3:53 PM
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Originally Posted by extan View Post
Additional note: I spoke with a large, national, renter of comm equipment, and he came back recommending PTT. That's what we used last time and had terrible luck with it.

So it seems like 2-ways + repeaters are our bet? Any specific advice is greatly appreciated!
It would help a whole lot to know what you used last year that didn't work.

A mile in a heavy urban area can be a challenge if you are trying to use consumer grade radios, or simplex (radio to radio).

There's also some issues with what band you were using. Some bands will work better in urban environments and others will work better in rural environments.

Ideally, you don't want to buy a bunch of gear for a one day event. You likely are not going to get any sort of reliable two way radio coverage from any sort of consumer grade radios. You'll want to look at renting radios including access to a repeater.

That won't be "cheap", but it'll work and at the end of the day you return all the radios and walk away.
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Old 12-07-2017, 7:11 PM
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PTT is short for "Push To Talk", which is what any two-way radio is. You push a button to talk, and you release it to listen.

If that's what they used last year, then it was most likely user failure to understand how to use the radios properly that caused the issues, not the choice of radios. Going from simplex radios to repeater capable radios won't fix that. It will just allow more people to hear the lack of proper training of those using the radios.

1) You push the transmit button (PTT), wait half a second, then start talking. Don't start talking before you push the button, or at the very same instant that you push the button. This leads to the first word, or at least the first syllable of a word, being missed by everybody else.

2) When you are done talking and are waiting for a reply, you have to release the transmit button (PTT). You won't hear a reply if you keep the transmit button depressed.

3) Only 1 person can talk at the same time. If 2 or more people try to talk at the same time, odds are neither will be understood.

These are the usual points that those who don't know how to use a radio have trouble with. This is why everyone who is assigned a radio needs at least basic training with these points. They also should be taught to speak in a normal, clear voice. Do not raise the volume of your voice, and don't mumble words. Enunciate each word clearly.

Other issues include the volume knob being inadvertently turned down so low that the user doesn't hear anything, but they still try to talk to the other users, not aware that the volume has changed. Or the channel selector knob or button inadvertently changes the channel, putting that user on a completely different channel from everyone else, so the user won't hear anyone, and everyone else won't hear the user.

You should talk to the organizers and find out what exactly the issues were with the radios last year, as well as what make and model of radio(s) were used. (If more than one make and model of radio were used, were they all on the same frequency, with the same CTCSS/DCS, if any? If not, that's another problem.)

Decent commercial grade two-way radios on business frequencies should not have any problem covering a 1 mile distance. Stay away from cheap "bubble-pack" radios, such as FRS or hybrid FRS/GMRS radios. And make sure that everyone who is assigned a radio knows exactly how to use it properly.

John
Peoria, AZ
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Old 12-07-2017, 7:38 PM
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Quote:
Originally Posted by mmckenna View Post
It would help a whole lot to know what you used last year that didn't work.

A mile in a heavy urban area can be a challenge if you are trying to use consumer grade radios, or simplex (radio to radio).

There's also some issues with what band you were using. Some bands will work better in urban environments and others will work better in rural environments.

Ideally, you don't want to buy a bunch of gear for a one day event. You likely are not going to get any sort of reliable two way radio coverage from any sort of consumer grade radios. You'll want to look at renting radios including access to a repeater.

That won't be "cheap", but it'll work and at the end of the day you return all the radios and walk away.
Gotta agree. Urban areas (especially ones like NYC) are radio killers.
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Old 12-07-2017, 9:48 PM
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Thank you all, very much, for your replies.

Apologies for my unclear description. When I speak of "PTT" I'm referring to push-to-talk (half-duplex) cellphones. I believe Nextel was first to market many years ago, but now ATT and Verizon offer it. It's my understanding that it's packet-switched, running over the data network. Last year the march used "AT&T Kyocera DuraXE 4G LTE E-PTT" and "AT&T Sonim XP5 4G LTE E-PTT". They were a complete failure, I assume primarily because the cell "towers" were completely overwhelmed by the extraordinarily high concentrations of cellphones. (I'm interested in any feedback on this assumption!)

We understand it's a very challenging environment for rf, but the march will go on, and we feel like we have to do the best we can with what we can get. That's what I'm hoping you guys can help us optimize.

I think we're talking about several dozen (maybe up to 60) handsets. These are non-technical volunteers divided into functional groups (eg medical, marshals, legal, stage/speakers, etc) that would like to be in close contact with others in the same group. Each group has a "head", and all the heads would constitute another group, facilitating inter-group communications. (I don't think it's practical to consider obtaining licenses, at least for this march, which is only about 6 weeks away.)

So it seems we are left with VHF/UHF with 2-way radios? I'm thinking if we could station a repeater on each leg of the route, ideally over the heads of the marchers, ideally within line of sight of the neighboring repeaters, it would offer significant benefit. Thoughts?

Perhaps we could park repeater-equipped cars along the route? Perhaps we could mount fairly tall antenna masts on the cars? Or would it be much better to try to find friends with offices directly overlooking the route?

It's not obvious to me what the primary sources of interference are. Is it all of the tightly-packed bodies? Is it rf noise from all the cellphones? Is it the buildings? Is it ambient noise from all the craziness of midtown?

We've had both the CP200 and XPR families recommended to us by rental houses...
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Old 12-07-2017, 9:55 PM
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Contact a local ham radio club about providing communications.
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They will do it for free
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Old 12-07-2017, 10:11 PM
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Originally Posted by MOTEX View Post
Contact a local ham radio club about providing communications.
-
They will do it for free
There's a pretty good chance someone might have a usable repeater. But I wouldn't let them do it free. If they do it, I'd donate some cash to the club. Those repeaters cost money to buy and maintain.
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Old 12-07-2017, 10:34 PM
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There's a pretty good chance someone might have a usable repeater. But I wouldn't let them do it free. If they do it, I'd donate some cash to the club. Those repeaters cost money to buy and maintain.
Wouldn't even a donation violate the FCC rule that states we can't provide communications for hire?

Club membership dues are supposed to be used to buy and maintain repeaters and the like. Clubs should not be asking for donations from groups that they provide communications for.

John
Peoria, AZ
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Old 12-07-2017, 10:36 PM
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Find a local radio shop with coverage in the area and rent from them. Alternatively, the big national rental houses often will contact local dealers and setup the coverage on your behalf. TT
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Old 12-07-2017, 10:47 PM
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Thanks again. I've replied with clarifications, but since I'm new my post awaits approval from a mod. Please forgive the delay
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Old 12-07-2017, 10:54 PM
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Originally Posted by KB7MIB View Post
Wouldn't even a donation violate the FCC rule that states we can't provide communications for hire?

Club membership dues are supposed to be used to buy and maintain repeaters and the like. Clubs should not be asking for donations from groups that they provide communications for.

John
Peoria, AZ
They don't have to ask for it. The guy can donate it.

Here's another thought, though. The OP hasn't stated the purpose of the march but it may be a cause the club won't want to identify with. The commercial company probably wouldn't care. They just want the money.
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Old 12-07-2017, 10:55 PM
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A donation for repeater use to the club is not illegal. paying individuals would be. Our club does a large bicycle race every year and receive a donation from the bike group.
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Old 12-08-2017, 2:33 AM
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Hams can receive payment up to there real costs, but nothing more.
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Old 12-08-2017, 3:00 AM
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I am assuming "PTT" means the Wave PTT solution that integrates Motorola MOTOTRBO with smartphone communications. If that system was lacking, then something went wrong somewhere or they were in an area of the city without proper coverage.

With all due respect, this question should be dealt with by a professional two-way radio supplier. They are the ones who know the coverage area and know what will work. The Wave PTT solution seems overkill for your needs and may have been oversold by a provider or an enthusiast member of your organization. Or maybe someone tried to cut corners to get radio communication without paying for subscriptions.

Everything is two-way radio communication is a compromise. You can get inexpensive radios with private communication, great clarity and long range.

You just can't get all that in one radio.
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Old 12-08-2017, 7:42 AM
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Quote:
Originally Posted by Chickenhawk56 View Post
I am assuming "PTT" means the Wave PTT solution that integrates Motorola MOTOTRBO with smartphone communications. If that system was lacking, then something went wrong somewhere or they were in an area of the city without proper coverage.

With all due respect, this question should be dealt with by a professional two-way radio supplier. They are the ones who know the coverage area and know what will work. The Wave PTT solution seems overkill for your needs and may have been oversold by a provider or an enthusiast member of your organization. Or maybe someone tried to cut corners to get radio communication without paying for subscriptions.

Everything is two-way radio communication is a compromise. You can get inexpensive radios with private communication, great clarity and long range.

You just can't get all that in one radio.
The OP has already stated that they used AT&T's ePTT solution last year.

Wave/Wave-On-Cloud is Motorola's LTE-PTT solution built specifically for integrating with some of their trunking solutions (Connect Plus, Capacity Max, and Astro 25). I believe Wave2 is capable of integrating over a standard ISSI so it could technically be used as a multi-manufacturer solution but it's been awhile since I've messed with it.
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Old 12-08-2017, 9:20 AM
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How many people need to be able to communicate? Ie’ how many radios
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Old 12-08-2017, 10:37 AM
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To the OP (for clarification)... It sounds as if you might have an over-simplified concept of how 2-way radio repeaters work. A typical repeater only re-transmits signals from one radio to others. The effective range will depend on many factors, as others have mentioned. Generally, repeaters do not repeat to one another in order to extend range. Something like this could be done, but would require serious engineering and infrastructure support to accomplish (expensive!)

You also mention the need for discrete "channels" for each group. Without the use of multiple frequency pairs, this capability can best be accomplished only with advanced technology. The use of simple analog radios is not indicated. I would also agree that any solution that uses the public cell phone network will likely prove unreliable due to the vastly increased traffic that such an event (and the on-lookers) would create.

Given the short time frame and the minimal time of use, the only reasonable solution I can see for you is to identify a commercial radio provider who has access to a currently-in-place radio system (probably a multi-site trunked system) and can rent you the user equipment that is required to support your event.

And you would need to do this quickly!

Best of luck,
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Old 12-08-2017, 11:00 AM
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Thanks for the clarifications, that helps.

Quote:
Originally Posted by extan View Post
Thank you all, very much, for your replies.

Apologies for my unclear description. When I speak of "PTT" I'm referring to push-to-talk (half-duplex) cellphones. I believe Nextel was first to market many years ago, but now ATT and Verizon offer it. It's my understanding that it's packet-switched, running over the data network. Last year the march used "AT&T Kyocera DuraXE 4G LTE E-PTT" and "AT&T Sonim XP5 4G LTE E-PTT". They were a complete failure, I assume primarily because the cell "towers" were completely overwhelmed by the extraordinarily high concentrations of cellphones. (I'm interested in any feedback on this assumption!)

Understandable failure for a few reasons…

Cell sites only have a specific amount of capacity, and once it's full, calls get rejected. On a normal day, it's not an issue, cell sites are designed for "every day". What they often are not designed for is large events, like a 20,000 person march. Considering just about everyone has a cell phone, and AT&T is one of the more popular carriers, you can imagine what happens when a few thousand people are all trying to talk, upload photos, post on facebook, etc. all at once. Without any sort of prioritization, your calls get lost in the mix.

Cellular companies do have the ability to bring in portable cell sites to solve these sorts of issues, but getting them to do it is hard. Big sporting events, disasters, etc, it can happen, but you'll have a hard time even getting to the people that could make this happen.

The other issue is cellular PTT has an inherent delay. The call setup time can be long, and someone who's not accustomed to using it will often key the device and start talking. The other end misses most of the transmission since the phones/network are still trying to set up the path.

Cellular PTT is good for some applications, but not this.

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We understand it's a very challenging environment for rf, but the march will go on, and we feel like we have to do the best we can with what we can get. That's what I'm hoping you guys can help us optimize.
This is the application where two way radio shines. This is one of the reasons public safety uses their own radio systems and doesn't rely on consumer cellular for their critical voice communications. Good news is that it's easy to rent what you need from a radio shop. This is what they do. They'll set everything up, you show up and use it, and at the end of the day they take it away.

Quote:
Originally Posted by extan View Post
I think we're talking about several dozen (maybe up to 60) handsets. These are non-technical volunteers divided into functional groups (eg medical, marshals, legal, stage/speakers, etc) that would like to be in close contact with others in the same group. Each group has a "head", and all the heads would constitute another group, facilitating inter-group communications. (I don't think it's practical to consider obtaining licenses, at least for this march, which is only about 6 weeks away.)
60 radios won't be an issue for a decent radio shop.

As for "non-technical" volunteers, that's the beauty of a two way radio. They are simple to use. Just make sure it's turned on and you are on the correct channel.

It would be difficult to get a license that fast. While there are ways to do it, it takes some work. But, there's no reason for you to go that route. Since you don't already own the radios, you'll have to rent. The shop that rents you the radios will have the license that covers their use.

Quote:
Originally Posted by extan View Post
So it seems we are left with VHF/UHF with 2-way radios?
That would be the logical solution. Cellular PTT isn't going to work well, as you've discovered. You don't want to rely on amateur radio operators for this as they have to be standing their with the radio, and that adds a layer to your coordination you don't need. While they would have the equipment and skills, it adds a layer you don't need. You want 60 or so volunteers with their own radios to communicate quickly and efficiently. Having to double up each volunteer with a "shadow" radio operator isn't the way to do this.


Quote:
Originally Posted by extan View Post
I'm thinking if we could station a repeater on each leg of the route, ideally over the heads of the marchers, ideally within line of sight of the neighboring repeaters, it would offer significant benefit. Thoughts?
Perhaps we could park repeater-equipped cars along the route? Perhaps we could mount fairly tall antenna masts on the cars? Or would it be much better to try to find friends with offices directly overlooking the route?
I think you are overthinking this. Talk to a radio shop and tell them that you need 60 rental radios and coverage over your area. Let them deal with the engineering side. Chances are they'll have repeaters in the area that will cover what you need. If they need to add additional repeaters, they'll handle that. Ideally the radio shop would have a trunked radio system that would provide everything you need. You'd just show up, grab a radio and go.



Quote:
Originally Posted by extan View Post
It's not obvious to me what the primary sources of interference are. Is it all of the tightly-packed bodies? Is it rf noise from all the cellphones? Is it the buildings? Is it ambient noise from all the craziness of midtown?
Not a complete list:
High RF noise floor.
Interference from other users.
Meat-bag bodies do absorb RF energy really well.
User error.
Reflections off buildings (multipath, etc)


Quote:
Originally Posted by extan View Post
We've had both the CP200 and XPR families recommended to us by rental houses...
Let the radio shop decide that for you. You'll be a radio user, no need to engineer a system. You'll be paying someone to do that.
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