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Old 09-28-2015, 03:50 PM
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Default The Importance of Radio Monitoring and Situational Awareness During Emergencies



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On forums like this you see a lot of folks talking about how to communicate, intentional two way contact with other parties. And there are as many possible answers as there are specific situations, no one answer works for everyone. But there is another aspect of communications that sometimes gets mentioned, but seldom gets discussed in depth, and that is monitoring radio signals to see what is going on in the World or around you.

For me personally, monitoring plays a part in my plans. I am willing to bet it does to some extent for most people, even if only an AM/FM portable radio. Certainly all radio stuff falls way behind the basics, food, shelter, water, security, etc, but once the basics of survival are take care of other things, like information, start to be somewhat important.

What do I mean by radio monitoring, and why monitor?

I mean just listening to any radio communications or transmissions. This can range from local AM or FM radio stations, international shortwave stations, local public service stations, military communications, or pretty much any kind of radio transmission you can think of. Why do it? Because information may be useful to figure out how widespread an event is or how long it may go on.

I have no idea where this thread will go, if it goes anyplace. But I would suggest we talk about what can be monitored, why you might want to monitor it, and last what hardware could you use to monitor it.

A quick list of things to monitor, I am sure stuff will get added:

AM/FM radio
International SW broadcast radio
Ham radio
Public Service radio
Various private or citizens radio services (FRS, GMRS, MURS, CB, etc)
VHF Military communications
HF (SW) Utility communications (aviation, maritime, military, etc)
VHF and UHF air band

A couple of words on propagation.

Propagation is the way radio waves travel from the source to the listener / receiver. Different frequencies of operation propagate differently.

Keep in mind that any of these signals that are in the HF (High Frequency, 3000 to 30000 kHz or 3 to 30 MHz) and MF (300 to 3000 kHz or 0.3 to 3 MHz) ranges are going to be greatly impacted by propagation in those bands. Certain frequencies (typically below 12000 kHz) work well at night, others (typically above 10000 kHz) work well during the day. All of them are very dependent on multiple natural conditions, such as solar activity. Learning how to generally predict what bands will be useful and what will not for a certain application does take some small effort. Learning all the possibly influencing factors and how to better leverage those can take a good bit more time.

The VHF (30 to 300 MHz) and UHF (300 to 3000 MHz) bands are much less variable, and much easier to predict in a general way. They also generally do not change with the day / night cycle. While VHF and UHF can indeed have long distance sky wave propagation they more typically are limited to line-of-sight, they typically work to just beyond the radio horizon.

I’ll kick off a few quick descriptions of different kinds of signals and why they might be good to monitor.

T!

Last edited by cdvaight; 02-19-2016 at 06:34 AM.. Reason: Requested title change
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Old 09-28-2015, 03:51 PM
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Default Radio monitoring for situational awareness, AM/FM radio

AM/FM radio. Remember that AM means Amplitude Modulation and FM means Frequency Modulation. Many services use AM and FM modes, but what I am talking about here are the specific “AM broadcast band” and “FM broadcast band”.

This is a no-brainer, in an emergency situation almost everyone will, at one time or another and when not in immediate danger, try to tune an AM/FM radio to get a handle on the situation. Depending on what the situation is this could be a well informed source, or it might be as in the dark as anyone else.

FM radio operates in a small portion of the VHF band (the “FM band” in the US is 88 to 108 MHz) and is typically fairly short ranged, 100 miles is a long way under some conditions, although that is for sure not the max range for everyone. The stations are often capable of operation for a limited time on backup power, some of them for extended periods. So this could be a good source for local issues. Of course, the stations typically belong to a network, and also have access to national or international information, assuming those networks are in operation. I believe all FM stations in the US are required to have a minimum level of interoperability with the EAS (Emergency Alert System). In theory this is a way for the government to get information to the people in times of emergency.

AM radio operates in the MF band (the “AM Broadcast band” in the US is 540 to 1710 kHz, or 0.54 to 1.71 MHz) and can be very long ranged. This band has some interesting propagation, it can be moderate to long range during daylight hours and very long ranged at night. While the information carried on these transmissions will be similar to that found in the FM band, and these stations carry similar EAS requirements, the fact it can carry much longer ranges means this is a potential opportunity to hear what is happening in other areas, or what people in other areas are being told.

The hardware required to monitor AM/FM can run from very small, lightweight, low energy use, portables to this being a sub capability of a more all-encompassing radio. Hand cranked or solar powered options abound. And many ham radio transceivers include some capability in this realm. A simple wire antenna can really extend the range of reception on the AM band, but does little for the FM band.

So to me, regardless of a person’s other monitoring plans, coverage of the AM/FM bands is a near must.

T!
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Old 09-28-2015, 03:51 PM
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Default Radio monitoring for situational awareness, International SW radio

International SW (Short Wave) Radio. In the SW spectrum (the entire HF band and the upper end of the MF band) there are multiple designated smaller segments used for International SW Broadcasting. These signals are very similar to commercial broadcast stations heard in the AM/FM bands. They can run the gamut from music stations, news stations, religious broadcasters, sport stations, etc. The difference is that because of the frequencies used, and the properties of radio propagation in these frequency ranges, they often are intended for reception outside the originating country.

For example North Korea runs the “Voice of Korea”. It is sent in multiple languages, including English, at different times of the day, and it is intended to give their view to the rest of the world.

SW stations often change frequencies and times of operation. This is because propagation conditions change over time, and frequency and time combinations for the winter may not work well for the summer. Since many of these transmissions are aimed at specific regions the station attempts to select frequencies and times that increase the probability that the signal will be usable in the target areas.

There are updated lists available online for the latest schedule. Of course in the event of an emergency you may not be able to get a new update, but an “old” list is often good for months after it was published. And lists are not really necessary, you can always tune and see what is on the air. Lists mostly help if you want to plan to hear a specific station or if you are trying to ID an unknown station.

Since these stations are international local emergencies not in their region do not stop them from sending. Regardless of what happens to your local power grid, or what kind of limitations on operation are imposed by regulation, the international stations will still be there, assuming they have power. While some of them are state mouth pieces and give a heavily slanted view of things, they are a source of information.

In theory they can be jammed, but in practice that is only partially viable. China, North Korea, and Vietnam are three nations who regularly, vigorously, try to stop their citizens from hearing foreign broadcast, and they are only partially successful. China has possibly the largest number of very high power jammers ever used in history, and they still only get good jamming in certain high density population centers, while many of the sparsely populated regions have little or no difficulty hearing the offensive foreign broadcasts.

The gear used to receive these stations is much like the gear used for AM/FM reception, running the gamut from very small, lightweight portables, to big desk top monsters. There are performance advantages to better gear, but that does not mean portables are not usable. Many HF ham radios have a general coverage receiver that can be used to monitor SW broadcasts. Most SW broadcasts are in AM mode, so SSB is often not required, although it can be useful even for AM stations as it has certain advantages to simple AM reception.

Wire antennas can be easily and cheaply built, and can break down into very compact packages.

In my opinion, if you are going to have a portable radio that can receive AM/FM, then find a model that can do SW as well. If you are going to have an HF ham radio then plan on using it to monitor SW BC occasionally.

T!
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Old 09-28-2015, 03:53 PM
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Default Radio monitoring for situational awareness, HF (SW) Utility communications

HF (SW) Utilities. This is a huge subject that could take chapters just to cover the basics. Utilities in this application are any transmission that is not a commercial entertainment or news broadcast. Some examples of Utilities would be maritime (ship to ship and ship to shore), aviation (aviation is often VHF, but over oceans it is on HF, and it can be in wilderness areas also), military, etc signals.

Why monitor these things? In time of emergency ships and aircraft often receive regular updates concerning areas to avoid and why to avoid them. The level of traffic can be an indicator, such as shutting down aviation to a specific region. Various Coast Guards from many nations send out regular advisories. Ship / boat skippers often have good information about ports they were just in or are going to, and it is not uncommon for them to talk it over with other skippers. The military still does a surprising amount of unencrypted HF radio stuff, particularly voice. Most military digital traffic is encrypted, but the level of activity and what frequencies / techniques are in use can be an indicator also.

In short, this can be a huge source of information, but it does require digging to find the nuggets.

Except for scheduled aviation and maritime transmissions these signals are typically unscheduled and transient in nature. A frequency may only carry a few minutes of traffic in an hour. The power levels used are often very modest compared to SW Broadcast stations. If you have not had some experience with this kind of monitoring pre-emergency the chances of this being useful to you post-emergency are small. This is generally not something you can just decide to do and be successful right away, regardless of equipment. And keeping track of what and where you heard something can lead to patterns that you can recognize and exploit, in other words, you have to keep a log to do this half-way well.

This is an area of listening where equipment makes a substantial difference. SSB is a must, and preferably not an SSB setting with a BFO, but rather real, selectable, USB and LSB. Accurate frequency readout is important. Antennas and radio selectivity are important. In general the cheaper the gear the more frustrating it can be in this kind of application.

HF Ham gear with general coverage capability often does fairly well in this application. However, a wide band waterfall display, as many SDRs have, is king here. Some frequencies are in common use, but often the really good stuff can pop up on a freq for a few minutes and not be back on that freq for days or weeks. With a traditionally tuned superhetrodyne radio you must already be tuned to a frequency to even know a transmission has occurred, or you have to tuned across it as it happens, you have to be in the right place at the right time. With a wideband display you can see a signal pop up, click on it, and automatically tune to that signal. You might miss a few seconds of the signal (and with some SDRs not even that) but you know it happened, and probably have an idea of what the signal might have been. That way you can make a decision to look harder at that signal or pass it up and find something else.

These signals have huge potential, but also require the most work to get.

T!
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Old 09-28-2015, 04:45 PM
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Check out the Tecsun PL-660. $130 on Amazon. It has great sensitivity, real SSB and external antenna jack.
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Old 09-28-2015, 11:19 PM
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I would recommend a trucked scanner as an additional monitoring system.
A lot of agencies and departments use a trunked system that makes monitoring difficult with a normal receiver.
With a scanner you can monitor state and local agencies and depending on where you are federal agencies communicating with assets in the field. there are also on the newer scanners that have a close call features that alert when a radio signal is close (most likely signal strength)
I'd recommend checking to see if your local area is using Digital or analog trunking that will help you decide a scanner that will work for you.

for local intel the police, highway department and public works are great sources.

There have been mandates for some agencies to use encryption for "tactical" communications but honestly they can't seem to work out the interoperability between different agencies so they don't seem to use it very often.

Respectfully Submitted
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Old 09-28-2015, 11:27 PM
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Don't forget CB radio. Lots of CB traffic in my area and the locals gossip about everything unusual. When things around them are coming apart, they'll be doing the play by play broadcast.
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Old 09-29-2015, 10:15 AM
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I'm in this debate as to whether or not I should pick up a good trunk tracking digital phase 1 and 2 uniden scanner. I'd love to hear all the local traffic again since everything has been merged, but the near $400 entry tag for the unit is really high.
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Old 09-29-2015, 10:30 AM
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100KHz-1.7GHz Full Band UV HF RTL-SDR USB Tuner Receiver/ R820T+8232 Ham Radio $60.00

Listening to unencrypted Police/Ambulance/Fire/EMS conversations.
Listening to aircraft traffic control conversations.
Tracking aircraft positions like a radar with ADS-B decoding.
Decoding aircraft ACARS short messages.
Scanning trunking radio conversations.

I've never used one but for $60.00 it would be worth a try.
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Old 09-29-2015, 10:38 AM
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THis is from a thread I started here...
https://www.survivalistboards.com/sho...d.php?t=400948
Along the same lines.


My first line of defense is my radio scanner. I work in a major metro area and have my scanner set to local PD and FD. This lets me know, ahead of the general public, of many potentially dangerous situations. Most of the time you don’t have to hear the first call from dispatch to understand the danger. Many times I can discern the unusual activity I am monitoring for just by the vocal tone, duration, and speech pattern of the radio traffic. Certain phrases are always giveaways… Shooting…Scene is not secure, is one of them. Here in the city, during Ferguson and after I was able to monitor possible civil unrest and plan accordingly, mostly just avoiding the area and sometimes leaving early for the day or even setting the building I work in on lock down. Other things I listen for are active fugitive/ suspect searches, reports of large groups of people, business owners requesting police for crowd control/traffic control for long lines at gas stations, banks, ATMs. When I am out at large local events like Festivals and State Fairs, I always try to find the in house security/ operations frequencies to monitor.

Social Media especially twitter has been useful for tracking potential protest movements. Get to know the local organizers/antagonizers in your area on twitter and you can track when an where they will protest. Weather Alerts and Breaking news items outside of the immediate area. Most News outlets will let you sign up for Breaking News alert texts. Your local NOAA, CERT, and many PD and FD departments all have twitter accounts.

Of course this website for the big stuff – ebola, terror attack, national stuff.

I use the RSOE EDIS text alert for international events and earthquakes.

The suspicious 0bservers site has been a daily watch for me on the way to work in the morning to see whats up in the solar system. Thanks to 13ella for that one.

For Local Traffic events MDOT (Missouri Dept of Transportation) has a great app that uses realtime traffic monitoring data to show on a map or text alert for traffic incidents and road closures. It will even show road closures due to flooding statewide. These are probably available for your metro area and state as well.
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Old 09-29-2015, 10:50 AM
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There's Broadcastify.com http://www.broadcastify.com/listen/

Free web based scanner feeds for every state and many local networks.
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Old 09-29-2015, 10:59 AM
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Quote:
Originally Posted by kk4ltq View Post
100KHz-1.7GHz Full Band UV HF RTL-SDR USB Tuner Receiver/ R820T+8232 Ham Radio $60.00

Listening to unencrypted Police/Ambulance/Fire/EMS conversations.
Listening to aircraft traffic control conversations.
Tracking aircraft positions like a radar with ADS-B decoding.
Decoding aircraft ACARS short messages.
Scanning trunking radio conversations.

I've never used one but for $60.00 it would be worth a try.
I acutally have one of the SDR setups that works great as an analog scanner. I'm prety darn advanced as a compute tech/IT guy, but I had great struggle getting the digital and trunk functions to work correctly after several days of messing with it. Maybe I'd try again before buying it but yikes is it hard to make work right together.
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Old 09-29-2015, 11:03 AM
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Great thread, really appreciate folks putting the effort into posts like these filled with information, facts and recommendations. Half of a communications plan should be listening, sometimes that will be more important in times of emergency rather than speaking.

Let's keep this conversation rolling!
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Old 09-29-2015, 11:09 AM
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Quote:
Originally Posted by swatpup102 View Post
I'm in this debate as to whether or not I should pick up a good trunk tracking digital phase 1 and 2 uniden scanner. I'd love to hear all the local traffic again since everything has been merged, but the near $400 entry tag for the unit is really high.
I also had this conversation with myself and decided to take the plunge, am very glad I did as it has opened up a whole new world of listening in my area. No longer do have to wonder what the state troopers or sheriff deputies are up to on the interstate and highways in my AO.
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Old 09-29-2015, 11:12 AM
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I work in an office environment so being able to monitor radios at work is difficult. I do have a small am/fm/sw radio on my desk that can be powered off a USB port from my computer then normally run a single ear bud so that I can listen without others hearing yet still hear what is going on around me. I also keep a Baofeng programmed with all the local emergency frequencies in my bag that I pull out once everyone else leaves. My truck also has CB and an additional handheld CB in the console.

I think this next year one of my main focuses is going to be prepping comms gear for the family and setting up some standards with our little group.
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Old 09-29-2015, 11:56 AM
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Quote:
Originally Posted by remus View Post
I work in an office environment so being able to monitor radios at work is difficult. I do have a small am/fm/sw radio on my desk that can be powered off a USB port from my computer then normally run a single ear bud so that I can listen without others hearing yet still hear what is going on around me. I also keep a Baofeng programmed with all the local emergency frequencies in my bag that I pull out once everyone else leaves. My truck also has CB and an additional handheld CB in the console.

I think this next year one of my main focuses is going to be prepping comms gear for the family and setting up some standards with our little group.
http://www.sena.com/product/sr10/
I use this at work with the scanner. It takes the scanner feed and sends it through bluetooth to my hands free device. Has a GREAT range (100m). I also use it a fairs and festivals, It is a LOT less attention grabbing than the MIB ear buds.

I think the new HP 2 from Uniden has builtin blue tooth. I have the 396XT now and cant wait to get a HP2.

Last edited by Walter Tyler; 09-29-2015 at 11:57 AM.. Reason: add text
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Old 09-29-2015, 11:57 AM
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I listen to everything I can get my equipment to pickup.
2 heathkit portable SW
Heathkit 100watt ham transceiver
Drake 200 watt ham transmitter
Ameco 2/6 meter transmitter
2 baofeng uv-5r's
uniden 800mhz scanner
Realistic crystal scanner
Pro 107 trunking scanner
Icom 2SAT portable
and a usbstick and SDR#...

Just waiting for my county to go on the P25 to get a scanner for that....
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Old 09-29-2015, 12:49 PM
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something to think about is manpower. During a short term or local event it's possible to monitor radio traffic with limited manpower. for longer events it becomes more of an issue as there are only so many hours in the day and there are other things that need to get done.

For a team or group having a few people dedicated to communications /signal intel is not a bad idea as it is really a 24/7 job in the real world. unfortunately the real world also has other time constraints and there is never enough time to get even half of the things we need to get done.

Respectfully Submitted.
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Old 09-29-2015, 09:38 PM
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Default Radio Monitoring for Situational Awareness, Ham Radio

Radio Monitoring for Situational Awareness, Ham Radio

Generally when people talk about ham radio and prepping they talk about getting a ham license so that they can have more options for communications. And this is great, I strongly encourage everyone who might need communications in an emergency to pursue a ham license, and besides, it can be great fun. However, licensed or not, monitoring ham radio without transmitting can also provide information. Ham radio is also called the amateur service and Part 97 service (Part 97 is the specific portion of the Code of Federal Regulations that authorize and define ham radio operation).

Why monitor ham radio, even if you are not licensed for operation? Because like everyone else hams like to gossip. They talk about what they see and what they hear with friends and strangers over the air. And between descriptions of that guys pancreatitis and complaints about his back you might hear something important. The more startling or unusual an event the more likely it will be discussed. There is a learning curve here, knowing what, when, and how to tune, and what is being said using some vocal shorthand, takes time to pick up.

Ham radio has allotted pieces of spectrum (chunks of radio frequencies they can legally use under amateur radio service) from the MF band up into the microwave frequencies. They cannot just operate on any old frequency in those ranges that they want to, but specific pieces of that range are allocated for their use. These pieces of spectrum are called "bands". The term bands is not unique to ham radio.

Some of these ham bands are very good for local operations, others are very good for long range operations, and still others are good for medium range operations. The important take away here is that each band is unique, and has attributes that you must understand to get the most out of them.

As a general statement bands in the VHF and UHF ranges, that is to say frequencies above 30 MHz, are good for local communications. These bands are generally limited to "line of site" operation, meaning they do not travel over the curvature of the Earth, so they do not go much beyond the horizon that you can see from your location. They may talk great to a person on a mountaintop you can see 30 miles away, but they often will not work to a person behind a hill only 5 miles away. The use of "repeaters" can change this dramatically for any given location, however from the repeater location itself the same limitation applies.

Frequencies in the MF and HF range, that is frequencies below 30 MHz, are often good for long distance communications under the right conditions. Around the world operations are possible if you select the right band and natural conditions allow. By the same token, these frequencies are much more variable in performance than VHF / UHF, they are much more driven by natural phenomena. There is a steeper learning curve to understand when and how to use any given HF band, but once learned this is a valuable tool.

So by selecting the bands you want to monitor, you can essentially select whether you want local information or information from far away. Keep in mind that most voice communications below 30 MHz is in Sideband (SSB), so if you want to monitor those bands your radio must be SSB capable.

Lets break it down by band, and later talk about gear. Specific band allocations vary around the World from region to region, so in general what I post will apply around the World, but some frequencies limits might be slightly different. The specific freqs I list are US allocations.

I am going to very much generalize band capabilities, so don't take ranges and such as gospel, just as a general starting point to consider. Also my descriptions will assume kind of "average" ionospheric conditions. All of these bands will work "line of sight" for local communications, that is communications out to the radio horizon a few miles away. Some of them will work much further than that.

160 Meter Band, sometimes called the "Top Band". This band runs from 1800 to 2000 kHz, or 1.8 to 2.0 MHz. Voice and Morse code, as well as digital data modes, are allowed across the entire band. Voice transmissions will typically be in LSB (Lower Sideband). This band is very short ranged during the daytime, but can be long ranged at night. Because of the way this band propagates it can make for some interesting usage during daylight hours, it is generally short ranged, but gets over hills and into valleys well. If you hear someone here during the daytime they are typically no more than 100 or so miles away, and often closer. At night ranges of several thousand miles are possible, but 1000 or less is much more common. At night this band hits the "medium" ranges well, including the hard to get 50 to 200 miles.

80 meter band, the also sometimes called 75 meters. This band runs from 3500 to 4000 kHz, or 3.5 to 4.0 MHz. From 3500 to 3600 kHz no voice is allowed, only Morse and data. Voice is allowed from 3600 to 4000 kHz. Voice will typically be in LSB. This band is much like 160 meters, it is short ranged during the daylight hours and can go to longer ranges at night. Again, if you hear someone during the daytime they are typically close, probably less than 75 miles. In the daytime this band can be a little shorter ranged than 160, but during the night it is longer ranged. Night time coast to coast communications is frequently possible among better equipped stations, and even modest 100 Watt stations on a wire antenna can regularly do over 1200 miles.

60 meter band. this is a unique band as it is the only band in the US where specific channels are allocated. Voice operation will be only in USB (Upper Sideband) and 5 specific frequencies, 5330.5, 5346.5, 5357, 5371.5, and 5403.5 kHz, are used. Power is limited to 100 Watts ERP. Like 160 and 80, if you hear someone here during the day they are normally not too far away, but a couple hundred miles is possible. At night this band can run longer, with even the 100 Watt ERP limitation allowing over 1000 miles on a pretty regular basis.

40 meter band. Now we are talking real capability. This band runs from 7000 to 7300 kHz, or 7.0 to 7.3 MHz. Voice is allowed from 7125 kHz up and is typically LSB, with CW and data below that frequency. This band regularly runs 300 to 600 miles in the daytime. With an NVIS setup (a specific antenna installation type) it can cover the hard to get 100 to 300 mile range. At night this band can span the nation, and 2000 mile contacts are pretty common. I call this the "regional" band.

30 meter band. This is an odd band, no voice is allowed at all, only data and Morse code, with a power limitation of 200 Watts PEP. The frequency range is 10100 to 10150 kHz, or 10.1 to 10.15 MHz. This is another regional band with performance similar to 40 meters, but with better daytime range.

20 meter band. The 20 meter band runs from 14000 to 14350 kHz, or 14.0 to 14.35 MHz. Voice is allowed from 14150 kHz up and is typically in USB. This is a daytime distance band, during the day thousands of miles are pretty easily possible, assuming conditions are OK. If I want to talk to someone on the other coast during the daytime this is the first band I try, and talking to Europe, or Japan, or Australia, etc, from California is pretty much a daily capability. At night this band can close right down, so that comms over 75 to 100 miles away just is not going to happen. But other times this band can stay open and "long" all night long.

17 meter band. The 17 meter band runs from 18068 to 18168 kHz, or 18.068 to 18.168 MHz. Voice is allowed from 18110 kHz up and is typically USB. The 17 meter band is more or less a daytime band and a bit more dependant on good conditions than 20 meters. Distances similar to 20 meters can easily happen, but the correct conditions are a little less common.

15, 12, and 10 meter bands. 15 runs from 21000 to 21450 kHz, or 21.0 to 21.45 MHz, 12 runs from 24890 to 24990 kHz, or 24.89 to 24.99 MHz, and 10 runs from 28000 to 29700 kHz or 28.0 to 29.7 MHz. Voice on all three of these bands is in USB, except for the very top end of 10 meters from 29500 to 29700 kHz, that is FM. All of these bands are primarily daytime bands, with very long distances, world spanning, possible under some conditions. "Under some conditions" is kind of important, these bands require just the right conditions to work distances and they often will not "open" (become usable for long distances) at all. You may go days or even weeks without an opening, or you may get an opening every day for weeks, for a few hours or all day. For communications beyond the horizon these bands simply are not dependable, although they can sometimes work long ranges.

6 meter band. 6 runs from 50000 to 54000 kHz, or 50.0 to 54 MHz. This band sometimes acts like 10 or 12 meters, and most of the times acts like a VHF or UHF band. So it can open to long distance communications, but most often it is good for local communications out to or slightly beyond the horizon. Voice is used from 50.1 MHz up, with USB used up to about 50.4 MHz, and FM above that point.

2 meter, 1.25 meter, 70 cm, 33 cm, and 23 cm bands. 2 meters runs from 144 to 148 MHz, 1.25 meters runs from 222 to 225 MHz (there is also a digital portion in the 219 to 220 MHz range), 70 cm runs from 420 to 450 MHz (with some regional limitations prohibiting some frequencies), 33 cm runs form 902 to 928 MHz, and 23 cm runs from 1240 to 1300 MHz. Voice on all of these bands is almost universally FM, although there is some USB operation also. Repeaters are in common use on all of these bands except 1.25 meters. All of these bands are line of site, local communications to the horizon, only. Repeaters and very tall antennas can extend where the horizon is, but just over the horizon is about the limit.

The equipment used will depend on the band you want to hear.

From 6 meters up then a traditional analog scanner with FM works great. Ham gear of course works quite well, and can be purchased to use for monitoring even if you do not have a license. In general I do not recommend getting ham gear just to listen, if you have no intent to get a license, often it is too specialized to be as useful as a wideband scanner or receiver would be. External antennas extend ranges and antenna height has a great impact on local performance.

Below 6 meters, in the HF range, the selection of equipment becomes a bit more iffy. Good equipment will of course be ham gear. General coverage desktop receivers, like the Icom R-75 or the Alinco DX-R8T are generally very good for this application. HF specific SDRs, like the WinRadio G31DDC or G33DDC, the RFSpace Cloud-IQ, the Elad FDM-S2, or the AFEDRI work very well, but require a computer to work. SW portables are generally not very good, they often will work, but not great. To be usable for this such portables must have sideband capability, and preferably selectable USB and LSB, not just a BFO (SSB). The built in antenna of a portable may work for stronger stations, but on average you really need an external antenna. For any of these radio options, from ham gear on down, you can build inexpensive and very good antennas for very modest cost, sometimes less than $10 not counting the coaxial cable.

T!
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Default Radio monitoring for situational awareness, various private or citizens radio service

Radio monitoring for situational awareness, various private or citizens radio services (FRS, GMRS, MURS, CB)

In the event of some kind of emergency many private individuals may be using radio communications who normally do not, or possibly at an elevated level until their power gives out. These could prove interesting information sources for the same reason ham radio can be interesting to monitor, they may discuss information that you do not have, or that could be informative / helpful to you. Further, many of these folks are not well versed in radio communications, so their OSPEC may not be great, and they are more likely to repeat messages, giving you more of an opportunity to catch the data, or say things over the air not realizing how many people can hear them.

Except for CB these services tend to be pretty short ranged. If you hear something on any freq it can be an indicator that someone is not too far away.

There are many different radio services that may fall in this category. I will try to touch on the major ones but if I miss some I am sure someone else will fill in.

CB radio. Citizens Band radio has been around since the 1950’s. No license is require, no paperwork needs to be filed, and used equipment can be found at junk / garage sales and thrift stores any time you want. Of course new equipment is still readily available on the market. All this comes down to a radio service that has lots of assets in the field, readily available to anyone who wants to try and use it.

CB radio falls in the frequency range of 26965 to 27405 kHz, this range is channelized into 40 designated channels spaced about every 10 kHz, “outbanders” or “freebanders” (illegal operators using modified or illegally imported gear) use frequencies outside this range, so you may find CB like communications anyplace from about 25000 kHz up to about 28000 kHz. AM, USB, and LSB are the legal modes, but some operators also use FM.

CB radio can give very long distances during daylight hours, however atmospheric conditions have to be right to allow this. Reliable communications during the night time, and during the day time as long as the “skip” (long distance communications) is not in can be had to the radio horizon, typically less than 25 miles. When the skip is in distant stations can swamp local stations, sometimes reducing local usable ranges to just a few miles. It can become an odd situation where you can’t hear the guy three blocks away, but the guy three states away comes in great.

To monitor CB radio you could, of course, use a CB, but better options exist. Most HF ham gear and SW receiving gear will also receive CB, however this can have the same limitations as using a CB. If the radio does not have memorized channels and the ability to scan them you will have to manually switch through them, never a great way to quickly find new conversations. Some scanner radios have the ability to tune this frequency range, but all of those do not have the AM or SSB modes required. As I have mentioned in other posts in this thread, an SDR is great for this. You can set an SDR up to watch the entire band and click on signals as they come up to hear them. Of course, this requires user interaction, and automated tasking can be more convenient.

FRS (Family Radio Service) radio. FRS has been around for about 20 years, and it is kind of like CB, but in the UHF range. FRS radios cover 14 channels in the 462 and 467 MHz range. Power is low, under half a Watt ERP, and modulation type is FM only. No license is required and no paperwork needs to be filed. Radios are plentiful and cheap, sold at many different kinds of retailers across the nation. Kids regularly receive these as toys and families often have them in their camping supplies.

FRS range is fairly limited. Despite what some advertisements claim they are typically limited to a couple of miles maximum, and often less than that. Under ideal conditions they are roughly line of site limited, for example if two stations are on hilltops 15 miles apart and able to see each other they might be able to talk, but two stations on the ground in a city a mile apart may not be able to talk.

To monitor FRS you have many options. Typical programmable scanner radios cover these frequencies, so it is often easy to add them as a “scanned” bank to a scanner. Ham radio 70 cm hand helds often include the ability to receive this range, so the frequencies can be programmed into the scanned memory of those radios also. SDRs like the very cheap RTL SDRs typically cover this range natively (no need for a converter) and so the freqs can be programmed in or manually tuned.

GMRS (General Mobile Radio Service) radio. GMRS is kind of like a high power version of FRS, in fact they share some frequencies. There are 15 frequencies in the 462 and 467 MHz range, 8 of them have repeater pairs, affectively making the number 23 frequencies. The mode of operation is FM and the power limit is up to 50 Watts, although most radios are not near this level of power. GMRS does require a license, but it is simple paperwork and a fee. One license covers all family members.

The GMRS frequency range is line of site limited, so ranges over 25 miles are uncommon, with more realistic ranges being 10 miles or less. GMRS does allow the use of repeaters, and this can greatly increase the coverage.

The options to monitor GMRS are the same as for FRS. Programmable scanners work great, ham radio gear 70 cm can often be programmed for these frequencies (legally receive only), and RTL SDRs work very well.

MURS (Multi Use Radio Service) radio. MURS can be seen as a more versatile VHF version of FRS. This service operates on 5 specific frequencies in the 151 and 154 MHz areas. Many kinds of modulation are allowed, but most common for voice is FM. There are many non-voice applications, such as remote controls. The power limit is 2 Watts. Repeaters are not allowed in this service. No license is required.

Because of the 2 Watt limit and lack of repeaters most MURS communications are relatively short ranged, a couple of miles maybe and often less than that. Under ideal conditions distances of over 10 miles should be possible, but those are going to be the exception, not the rule.

The options to monitor MURS are the same as for FRS and GMRS. Programmable scanners work great, ham radio gear 2 meters can often be programmed for these frequencies (legally receive only), and RTL SDRs work very well.

T!
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