Hypothetical Scenario: What would happen?

[Webslinger]

An event happens that shuts down the electrical grid and cell phone service. My wife and I are trying to communicate using GMRS radio. We have already tested our HT's and determined Tx/Rx distance in our community so that we might stay in contact from certain pre-planned locations. I have programmed a privacy tone into our radios on a specific channel (not 8-14, and not any repeaters), so that we can hopefully communicate without interference.

Now, let's say that channel is 17. My wife and I are within simplex communication range, again with a programmed privacy tone, and their are 20 other GMRS radios within that same range using the same channel, but they have not programmed in the privacy code my wife and I are using. So questions...

If all GMRS operators within range are using channel 17 and transmitting at the same time, what happens? Will the channel be overwhelmed by traffic, and would that traffic interfere with my ability to communicate with my wife, and vice-versa, even though we are using a privacy tone? I understand the privacy tone isn't real privacy, and others on the channel will hear what we say. My goal is to have a clear and uninterrupted means of communication with my wife.

Thoughts?

[WRQC527]

1 minute ago, Webslinger said:

So, is GMRS not a practical solution in a grid down scenario?

It is. But it is not the only way. The solution, if you will, is a toolbag full of useful tools. Each one has uses and limitations. GMRS is limited to UHF, and a few channels. Ham radio, on the other hand, includes a buttload of frequencies on VHF, UHF, HF, and many different modes. Lots of us have both GMRS and amateur radio in our toolbags. The more options you have, the better your chances are of successfully communicating.

[back4more70]

4 minutes ago, Webslinger said:

An event happens that shuts down the electrical grid and cell phone service. My wife and I are trying to communicate using GMRS radio. We have already tested our HT's and determined Tx/Rx distance in our community so that we might stay in contact from certain pre-planned locations. I have programmed privacy codes into our radios on a specific channel (not 8-14, and not any repeaters), so that we can hopefully communicate without interference.

Now, let's say that channel is 17. My wife and I are within simplex communication range, again with programmed privacy tone, and their are 20 other GMRS radios within that same range using the same channel, but they have not programmed in the privacy code my wife and I are using. So questions...

If all GMRS operators within range are using channel 17 and transmitting at the same time, what happens? Will the channel be overwhelmed by traffic, and would that traffic interfere with my ability to communicate with my wife, and vice-versa, even though we are using a privacy tone? I understand the privacy tone isn't real privacy, and others on the channel will hear what we say. My goal is to have a clear and uninterrupted means of communication with my wife.

Thoughts?

I would think that if there is traffic on the channel, then even though you have filtering codes setup, you would still have some kind of interference such as garbled communications, spotty reception, etc.  I am curious what the smarter-than-me folks on here have to say.

[OffRoaderX]

Yes, there will be interference.

[back4more70]

There probably won't be too many folks using MURS though 

[Sshannon]

15 minutes ago, Webslinger said:

An event happens that shuts down the electrical grid and cell phone service. My wife and I are trying to communicate using GMRS radio. We have already tested our HT's and determined Tx/Rx distance in our community so that we might stay in contact from certain pre-planned locations. I have programmed a privacy tone into our radios on a specific channel (not 8-14, and not any repeaters), so that we can hopefully communicate without interference.

Now, let's say that channel is 17. My wife and I are within simplex communication range, again with a programmed privacy tone, and their are 20 other GMRS radios within that same range using the same channel, but they have not programmed in the privacy code my wife and I are using. So questions...

If all GMRS operators within range are using channel 17 and transmitting at the same time, what happens? Will the channel be overwhelmed by traffic, and would that traffic interfere with my ability to communicate with my wife, and vice-versa, even though we are using a privacy tone? I understand the privacy tone isn't real privacy, and others on the channel will hear what we say. My goal is to have a clear and uninterrupted means of communication with my wife.

Thoughts?

GMRS uses FM, frequency modulation.  One of the characteristics of FM is that a receiver “captures” the strongest transmitter on a frequency.  It will do so regardless of the tone, because the CTCSS or DCS has nothing to do with reception.  The tone is only used to determine whether or not to audibly reproduce the received signal. So, if your wife and somebody else who is closer to you are using channel 17, you might never hear your wife.

That is why aircraft do not use FM. Instead they use AM or amplitude modulation.  An AM receiver can receive and reproduce multiple signals on the same frequency simultaneously, allowing a person to break into a conversation if needed. 

[Lscott]

22 minutes ago, Webslinger said:

If all GMRS operators within range are using channel 17 and transmitting at the same time, what happens?

A lot of mutual interference and signal jamming. That of course depends on the length of the transmissions and power levels. Long winded communications using 50 watt mobiles would be the worse case.

[WRQC527]

40 minutes ago, Webslinger said:

If all GMRS operators within range are using channel 17 and transmitting at the same time, what happens?

You end up with a cacophony of incomprehensible signals. Sometimes the strongest signal will win. 

[tweiss3]

Often called a double. Usually ends up with a mess that is incomprehensible. Sometimes it's unknown and unavoidable, but it's one reason you should pay attention to other traffic around. 

[Webslinger]

44 minutes ago, Lscott said:

A lot of mutual interference and signal jamming. That of course depends on the length of the transmissions and power levels. Long winded communications using 50 watt mobiles would be the worse case.

 

47 minutes ago, Sshannon said:

GMRS uses FM, frequency modulation.  One of the characteristics of FM is that a receiver “captures” the strongest transmitter on a frequency.  It will do so regardless of the tone, because the CTCSS or DCS has nothing to do with reception.  The tone is only used to determine whether or not to audibly reproduce the received signal. So, if your wife and somebody else who is closer to you are using channel 17, you might never hear your wife.

That is why aircraft do not use FM. Instead they use AM or amplitude modulation.  An AM receiver can receive and reproduce multiple signals on the same frequency simultaneously, allowing a person to break into a conversation if needed. 

Thanks for the replies.

So, is GMRS not a practical solution in a grid down scenario? Are there any options with GMRS to make communications more reliable, ex: setting up my own private repeater? Would Ham radio be more practical in that there are many more frequencies to choose from thereby limiting the chances that somebody else would interfere with communications? Is there a more reliable and secure way to communicate using options found in amateur radio that aren't too involved and complicated?

What would knowledgeable GMRS and/or Ham operators suggest in such a scenario?

[WRUU653]

Half joking here, if everyone is on 17 move to 15. seriously though if you are really planning on GMRS as a SHTF family plan have a secondary channel choice to go to should your first choice be in use. 

[Sshannon]

25 minutes ago, Webslinger said:

 

Thanks for the replies.

So, is GMRS not a practical solution in a grid down scenario? Are there any options with GMRS to make communications more reliable, ex: setting up my own private repeater? Would Ham radio be more practical in that there are many more frequencies to choose from thereby limiting the chances that somebody else would interfere with communications? Is there a more reliable and secure way to communicate using options found in amateur radio that aren't too involved and complicated?

What would knowledgeable GMRS and/or Ham operators suggest in such a scenario?

Like almost every such general question, the only possible answer is “It depends.”

For short range communications to a group, FM VHF and UHF (including GMRS) shine, if and only if you have plans for what to do in the event of a disaster, interference, zombies with RDF equipment, etc.  You must have backup plans as well and backups to those.

Yes, I believe you need ham radio in the mix and a way to monitor shortwave and broadcast bands. The news you eventually piece together from a GMRS handheld using simplex and its short ranges might be like playing the teenage game of Gossip.

[Webslinger]

6 minutes ago, WRUU653 said:

Half joking here, if everyone is on 17 move to 15. seriously though if you are really planning on GMRS as a SHTF family plan have a secondary channel choice to go to should your first choice be in use. 

I've thought of that, but then wonder if the whole GMRS band might be overwhelmed with traffic in such a scenario. I live on the outskirts of a major metropolitan area. GMRS offers limited channel capabilities, so it could be that that portion of the band is rendered unusable. Overall, it sounds like a combination of communications methods might be in order. So, GMRS, Ham and scanner. Right now I want to find the best option for communicating with my wife between home and her work. I work from home, so that would be my base station so-to-speak.

[WRXB215]

Just save your batteries until everyone else's batteries die. 

[Sshannon]

1 minute ago, WRXB215 said:

Just save your batteries until everyone else's batteries die. 

Or stock up on enough toilet paper and trade it for batteries!  

[back4more70]

1 minute ago, Sshannon said:

Or stock up on enough toilet paper and trade it for batteries!  

Tires, whisky and ammunition.

[Webslinger]

15 minutes ago, Sshannon said:

Like almost every such general question, the only possible answer is “It depends.”

For short range communications to a group, FM VHF and UHF shine, if and only if you have plans for what to do in the event of a disaster, interference, zombies with RDF equipment, etc.  You must have backup plans as well and backups to those.

Yes, I believe you need ham radio in the mix and a way to monitor shortwave and broadcast bands. The news you eventually piece together from a GMRS handheld using simplex and its short ranges might be like playing the teenage game of Gossip.

I started with GMRS one month ago. Got my Ham Technician's license earlier this week. Doing a deep dive into both methods of communication for emergency preparedness. My goals are 1) communication with my wife (empty nesters, so just the two of us, all kids live out of state), and 2) information gathering. Having a good scanner at home, as well as HT's that can scan emergency channels, is my immediate goal; along with finding a secure way to communicate with my wife. Eventually would like to set up mobile GMRS and/or Ham and base station at home. A lot to do and to learn, but figure one step at a time and eventually I'll get there.

[Webslinger]

1 minute ago, back4more70 said:

Tires, whisky and ammunition.

Coffee, bar soap and toothpaste

[WRUU653]

1 minute ago, Webslinger said:

Coffee, bar soap and toothpaste

Yes! Coffeeeeee ️

[Lscott]

18 minutes ago, Webslinger said:

So, is GMRS not a practical solution in a grid down scenario? Are there any options with GMRS to make communications more reliable, ex: setting up my own private repeater? Would Ham radio be more practical in that there are many more frequencies to choose from thereby limiting the chances that somebody else would interfere with communications? Is there a more reliable and secure way to communicate using options found in amateur radio that aren't too involved and complicated?

Any publicly accessible radio service will have some degree of interference issue. The real question is just how much. Also remember not everyone is going to be on the air at the same time.

If you're looking for a more robust plan then looking at several different radio services would be the route. Part 95 services would be GMRS.FRS, MURS and finally CB Radio. With the exception of GMRS you can buy radios for FRS, MURS and CB, use them with no license requirements.

Then the final option is Ham radio Part 97. The later you need a license, each person, and have to pass an exam to get one. The Tech Class is fairly easy, however some people just don't want to be bothered. It does give you much more spectrum to operate in with and will greatly reduce the likely hood of interference.

None of the two, Part 95 and 97, allow encryption. So, if you need to exchange sensitive information you'll have to either do so illegally with encryption, that's going to be a personal choice and nobody here will publicly recommend it, or find some other method to exchange the information, prearranged codes etc.

I also would NOT depend on a repeater either, Ham or GMRS. Most are simply grid powered and will fail immediately on a grid-down condition. Some do have backup emergency power but may not last that long. Your best bet is assuming you're on your own using direct radio to radio, simplex, communications.

[WRXB215]

3 minutes ago, Lscott said:

Your best bet is assuming you're on your own using direct radio to radio, simplex, communications.

Good advice. And remember, UHF will only get you so far. That may be far enough but if you intend to reach for hundreds of miles, you are going to need HF. To use HF, you will need at least a Technician license. And that only gives you a little sliver of HF. Bumping up to General opens up much more HF.

[Webslinger]

6 minutes ago, Lscott said:

Any publicly accessible radio service will have some degree of interference issue. The real question is just how much. Also remember not everyone is going to be on the air at the same time.

If you're looking for a more robust plan then looking at several different radio services would be the route. Part 95 services would be GMRS.FRS, MURS and finally CB Radio. With the exception of GMRS you can buy radios for FRS, MURS and CB, use them with no license requirements.

Then the final option is Ham radio Part 97. The later you need a license, each person, and have to pass an exam to get one. The Tech Class is fairly easy, however some people just don't want to be bothered. It does give you much more spectrum to operate in with and will greatly reduce the likely hood of interference.

None of the two, Part 95 and 97, allow encryption. So, if you need to exchange sensitive information you'll have to either do so illegally with encryption, that's going to be a personal choice and nobody here will publicly recommend it, or find some other method to exchange the information, prearranged codes etc.

I also would NOT depend on a repeater either, Ham or GMRS. Most are simply grid powered and will fail immediately on a grid-down condition. Some do have backup emergency power but may not last that long. Your best bet is assuming you're on your own using direct radio to radio, simplex, communications.

Thank you for that explanation. Good info. one and all.

[WSAA635]

4 hours ago, back4more70 said:

There probably won't be too many folks using MURS though 

This is kind of my thoughts as well. In an emergency FCC rules don't apply so if you've got a 10 Watt handheld on a MURS VHS channel you should be able to transmit further and with less people on the channel.

[WRUU653]

1 minute ago, WSAA635 said:

This is kind of my thoughts as well. In an emergency FCC rules don't apply so if you've got a 10 Watt handheld on a MURS VHS channel you should be able to transmit further and with less people on the channel.

Depends on what the emergency is if the FCC rules don’t apply.
Now if you are talking about zombies, well everybody knows zombies are inherently drawn to strong HT radio signals next to the brain!

[WRQC527]

8 minutes ago, WRUU653 said:

Now if you are talking about zombies, well everybody knows zombies are inherently drawn to strong HT radio signals

Only if they are held vertically. In any emergency zombie situation, the safest way to hold an HT is horizontally. That way, only other users holding their handhelds horizontally will hear you. It's the polarization equivalent to a CTCSS tone.

[WRHS218]

No matter what radio service you have you would be best served to have a plan. Search for 333 Radio plan for an example. Modify the plan as needed. If the channel/frequency on which you are trying to communicate is overwhelmed have an established plan to move to a predetermined second channel. If that channel/frequency is to busy go to another channel/frequency. You can program your radios with the channels/frequency in the order you want to move if needed. Have a time set up for non emergency communications. Like the plan I referenced, try to make contact for 3 or 4 or 5 minutes, what ever you decide. Write your plan down and have it in several different places that offer easy access. If you don't have a plan when SHTF you will most likely achieve chaos. If GMRS is all you have you can make it work, it just takes planning and forethought if you are serious.