St. Louis Listeners Guide to
Scanner Radio Frequencies

Listen to everybody in St. Louis!

Local police, county sheriffs, state police, FBI agents, Coast Guard, air ambulances, Radio & TV station reporters, hospital personnel, Rams football/Cardinals baseball team frequencies, railroads, forestry & conservation, highway departments, amateur radio repeaters and much more! There's even a business and a county-by-county listing so you can check on what your local school, water department or newspaper is talking about on their private frequency.

This scanner guide is your key to the most popular, interesting, exciting (and boring) conversations on the airwaves!

As you probably noticed, when given just lists of frequencies, determining where to start is often a very daunting and difficult task... especially if it’s your first scanner or you’re new to the area.

Presented here are frequencies that form the foundation of the public safety system and other important frequencies that are used in the area.

This isn’t meant to be a complete list of everything there is to listen to (you can find a much more complete listing for the area here St. Louis Frequencies), but this guide is intended to be more of a "get you started in the right direction" type of document.

Each entry is presented with its common name, the receive frequency in MHz (unless noted otherwise), a Private-Line (PL, also called CTCSS) tone where appropriate, and a brief description of the service or agency.

If you have one of the scanners that can be programmed with a computer, chances are that there may already be a St. Louis Missouri frequency file setup for your radio! All you need to do is go to this page Computer Programmable Scanners where you can download a frequency database file specifically designed for the St. Louis area.

This site offers just about everything that a scanner enthusiast would need. However, if you can't find what you are looking for here, I would strongly suggest you visit some of the sites in the links section.

Public Safety Frequencies

Point-to-Point   -   155.370  (CSQ)
The "point", as it is sometimes called, is used by all area police departments to coordinate activities between the surrounding counties and municipalities. If something major is happening and additional manpower is needed, or a pursuit is crossing into another jurisdiction, you will hear it on the "point".

RIOT Channel   -   154.725  (CSQ)
Radio for Interagency Operations and Tactics (R.I.O.T.), sometimes it is also called "Channel-11" or "RIOT-A" by county police, is used for special operations where all the units involved will switch to this channel and leave the main dispatch frequency free for normal traffic. It is often put into use during bank hold-up (hostage situations), search for missing children, barricaded subject calls and during presidential visits. There are currently five RIOT channels labeled "A" through "D" that are assigned for public safety and are sharing among area police, fire and emergency medical service agencies. County police mobile and portable units have capability on all five channels, as does the County's Mobile Command Post.

Fire Mutual Aid   -   154.280  (CSQ)
Mutual Aid is the fire department's point-to-point. Used to coordinate apparatus/manpower for major fires.

Aircraft Frequencies

ARCH Dispatch (Helicopter Transport)   -   461.525  (pl 192.8)
ARCH is the Area Rescue Consortium of Hospitals, a lot of the activity is just hospital to hospital transfers, but if there's an incident with serious injuries, ARCH is often the quickest route to the hospital during the "golden hour".

Aircraft Emergency   -   121.500  (AM mode)
Sometimes called the "guard frequency" - this frequency is used only for emergency voice communications. This is the main VHF distress frequency used in all ICAO countries. The UHF (military) equivalent is 243.000

Weather Frequencies

St. Louis Area Weather (NOAA)   -   162.550  (CSQ)
NOAA weather forecasts for the local area are broadcast 24-hours a day, 7-days a week. For radios that support Specific Area Message Encoding / Federal Information Processing Standards (SAME/FIPS) codes, they are as follows St. Louis County: 029189, St. Louis City: 029510, a complete list for all Missouri Counties can be found here.

In addition to the standard from the National Weather Bureau on the 162 MHz weather frequencies there are several other agencies that transmit various types of weather information.

The Coast Guard broadcasts weather alerts on VHF Marine Channel 16 (156.800 MHz) in the marine band. This marine channel is designated as the "International Distress Safety and Calling Channel"

Weather alerts are also broadcast from all the local airports as part of the Automatic Terminal Information Service (ATIS); Lambert (120.450 MHz, AM mode), Spirit (134.800 MHz, AM mode).

Skywarn   -   146.940 MHz  (pl 141.3)
When there is impending severe weather, or a tornado is spotted in the area, the local weather spotters (many of whom are also amateur radio operators), that participate in the St. Louis Skywarn program are often the first to report it. Information gathered from the individual spotters in the field is then relayed to the main St. Louis NOAA office for distribution.

Listening to the Input Frequency

One nice thing about agencies that use repeaters is you can hear all the mobile units no matter how far away from you they are. One bad thing about agencies that use repeaters is you can hear all the mobile units no matter how far away from you they are!

What happens if you only want to hear the activity when they're in your local neighborhood? Well, that's where the input frequency comes in handy! Program your scanner with the input frequencies and you'll only be able hear the mobile units when they are relatively close to you; if you are interested only in nearby events, monitoring the input will alert you to them.

A good example of where you may only be interested in what's happening in your neighborhood is the electric utility: Ameren/U.E. Wouldn't it be nice to get a heads-up when they're going to shutoff the power to your neighborhood to replace a transformer or whatnot? While you can program their entire EDACS system into your trunktracker and listen to only the talkgroup(s) associated with your area... that still generates 100's of calls a day! By programming in just the input frequencies you will only hear their radio transmissions when they are working within the proximity of your home.

Of course this "trick" isn’t just limited to Ameren/UE, it can be used with any service or agency that has a repeater system setup.

For UHF, 400, 800 and 900 MHz frequencies finding the input offset (provided you know the output!) is easy. There are standard pairs used for repeater input/output frequencies within these bands, thus the following table can be used to determine the repeater offset spacing and resulting input frequency:

Whereas frequencies below 400Mhz there exists no guidelines, except within the HAM bands. Finding the repeater input frequency used within VHF-Hi/Lo bands requires a bit of detective work... although to narrow the search you can assume a few things:

1. They are not going to be cross-band, for example a 155 MHz output will not have a 42 MHz input frequency or vice versa.
2. The input will be at least 600 kHz (.6 MHz) away from the output frequency.
3. Generally the input frequency will be within 4-8 MHz of the output frequency.

A search of the FCC database based on callsign will many times turn up the input/output pair. They should be listed as "mobile" and "mobile relay" (repeater) in the ULS report.

FCC Frequency Database

In a simplex system, the base station is licensed as "FB" (fixed base), and mobiles and portables are licensed as "MO" (mobile). In a repeater system the base station is licensed as "FB2", with the mobiles and portables still being licensed as "MO". Any service labled with a "Y_" is a trunk system: "YG" represents a trunked business license, "YW" would represent a trunked public service license and "YX" would represent an experimental trunked license. "IG" and "PW" represent a conventional frequency license.

While the FCC data is a good starting ground, it should be verified with a frequency counter or though monitoring before relying entirely on it.

Frequency Searching

I think one of the most overlooked features on a scanner has to be the search function. Dedicating a scanner to just searching can end up being a very worthwhile and rewarding experience. There are many things unpublished or suppressed in the FCC data and searching is the only way to find these frequencies, plus it's the only way to seek out unlicensed users. All the recent scanners have the ability to lockout known or unwanted channels in search mode, so this makes searching for just the unknown frequencies a lot easier. Also, setting the search limits to include only a small portion of the spectrum, say a 5 or 10 MHz chunk, usually works the best. The Uniden BC250D and BC785D can search at 300 frequencies per second, thus searching the 150.000 to 160.000 public safety band (approximately 1335 channels at a spacing of 7.5 kHz) takes just a little over 4-seconds.

Exploring the spectrum by searching is when you really start finding the cool stuff to listen to!

CTCSS Tone Can Help ID User

Using the Continuous Tone Coded Squelch System (CTCSS) decoder built into your scanner can tell you a lot about the frequencies you're monitoring... in fact it may even help to identify a particular agency or user.

Most agencies often use the same CTCSS tone on all their frequencies; St. Louis County PD uses 103.5 (with a few exceptions), County Parks Department uses 88.5, the U.S. Military uses 150.0, etc. Therefore, in the event you come across a frequency that isn't listed anywhere, a quick check of the CTCSS tone being used against other users who use the same tone in the area may very well help to resolve the mystery.

There are also two other variants of the CTCSS tone; DCS, which stands for Digital Coded Squelch, it's an alternate version of the CTCSS tone squelch that uses a digital value to open the radio's squelch as opposed to a sub-audible tone used by CTCSS. It is used with analog radio transmissions and many scanners that support CTCSS also support DCS. Digital radios use what's called a Network Access Code (NAC) which is more or less like a CTCSS/DCS tone on a digital system. The NAC function is not currently available on any scanners.

A partial list of CTCSS tones and their typical user can be found here.

FYI - There are 51 standard CTCSS tones with only about a dozen of these commonly used. A conversion chart that converts between PL Frequency, EIA Designator, Wolfsburg Code, GE/Ericsson and Motorola Designator can be found here. There are 104 DCS tones, which can be sent as 'normal' or 'inverted' for a total of 208 tones. There are 4,095 different NAC codes and 65,535 different Talkgroups available for use within the P25 standard.

Reducing or Eliminating Squelch Tail

You may have noticed that some radios emit a burst of noise that can last for up to 1/2 second in some receiver/decoder combinations at the end of each received transmission this is called a squelch tail or squelch crash.

On frequencies using Carrier Squelch (CSQ) there will always be a squelch tail no matter what you do, you may be able to adjust the squelch control to reduce it slightly, but it cannot be totally eliminated.

For frequencies with a PL tone set, there are two different methods use to eliminate the squelch tail.

Some radio manufactures, mostly Motorola models, but Kenwood, Vertex, Icom, EF Johnson and Ericsson use a similar method, incorporate a function called Reverse Burst that modifies the last few milliseconds of the PL tone to force the receiver to squelch before dropping the transmit carrier. To work properly, a tone needs to be set up in each radio - the Motorola programming option is called "and squelch". The net result is that the transmitter goes off the air and the receiver hears absolutely nothing at the end of the transmission - no noise burst - just dead silence.

Many scanning radios that decode PL tones still will not recognize a Reverse Burst tone. The Radio Shack PRO-96 scanner is an exception to this rule and does properly decode Reverse Burst PL tones.

An alternative way to eliminate the squelch burst, in a way that's compatible with all radios - not just Motorola radios, is done by removing (dropping) the PL tone while keeping the transmitter active for a few milliseconds (obviously this is done by the system tech!), all users benefit by having their receivers squelch up before the transmitter goes off the air, thereby eliminating that annoying noise burst at the end of a transmission.

FYI - DPL tones incorporate a universal standard "reverse bust" type function that automatically eliminates any squelch tail, provided the radio fully supports decoding of the DCS standard.

Explaining Trunked Radio Systems

A very simplified explanation:
The St. Louis City police use a Motorola trunked system, which means that the district cars and dispatcher aren't assigned a permanent frequency, instead they get assigned a talkgroup number.

When a district car or dispatcher's radio is keyed up, a frequency is assigned to their talkgroup on a temporary basis by the trunking controller from a pool of available frequencies at the time. As long as the radio remains keyed up (plus some hangtime), that talkgroup remains assigned to that particular frequency. Once the communication exchange is through the frequency goes back into the pool of frequencies for assignment to the next user and talkgroup.

Any scanner capable of receiving 800Mhz frequencies can be used to scan and listen to this system, but to monitor this kind of system efficiently (by scanning talkgroups instead of frequencies) you will need a scanner capable of following Motorola Type-2 trunking systems (there are a lot of models that support this!). Both Uniden and Radio Shack make scanners capable of tracking these trunked systems.

FYI... The original 800 MHz trunking band is from 851.0125 to 865.9875 and was initially allocated with 25 kHz spacing. Later the FCC added 866.0000 to 868.9875 to the 800 MHz band with a spacing of 12.5 kHz. As conditions became crowded along the Mexican border states those in-between channels in the 851.0125 - 865.9875 band were then allocated as needed - these are known as the splinter channels. Most of the country, including St. Louis, does not use splinter frequencies.

Frequency Conversion

The tuning location of a station can be expressed in frequency (kHz or MHz) or in wavelength (meters). The following information can help you make the necessary conversions.

1 MHz (million) = 1,000 kHz (thousand)

To convert MHz to kHz, multiply the number of megahertz by 1,000:
30.620 (MHz) x 1,000 = 30,620.0 kHz

To convert from kHz to MHz, divide the number of kilohertz by 1,000:
127,800.0 (kHz) / 1,000 = 127.800 MHz

To convert MHz to meters, divide 300 by the number of megahertz:
300/144 MHz = 2 meters

More Tips and Guides!

Mall Scanning - Traditionally, the day after Thanksgiving (also known as "Black Friday") marks the beginning of the holiday shopping season, and typically one of the busiest shopping days of the year. I've had some of my best scanning, listening to the mall's security keeping would-be shoplifters under a watchful eye...

Hollywood comes to St. Louis! - Film crews make a good opportunity for scanner enthusiasts to polish up some of their frequency hunting skills. While there are common frequencies designated for video production services sometimes they will wind up on the itinerant frequencies (the "star" & "dot" frequencies are a good bet)...

Monitoring Federal Communications - I think most are going to find that monitoring the federal frequencies, be it military communication or governmental agencies, to be rather boring; they just aren't that active and this somewhat discourages them. Certainly the federal agencies are not going to have the level of radio traffic as your local police and fire department. Furthermore, some agencies/frequencies are related to events, such as disasters; so unless there's a disaster, fire, or a training exercise to simulate agency response than the frequencies will remain quiet. However, when these channels do become active it’s usually some pretty exciting stuff to listen to...

Wildlife Tracking Tags - Over the past few weeks I have been hearing an owl hooting in the evenings... it's been many years since I've seen or heard an owl in the neighborhood, and got thinking about tracking devices. I have no idea if this particular owl is being tracked in a study, but if it were, I had envisioned plugging in a few frequencies into a scanner and being able to follow where it goes during the day and have an early warning when it's around the house. Well, as it turns out, it's not quite that easy...

Scanning at Racing Events - The following are some tips I've prepared for getting the best out of your scanner at any racing event, but with the upcoming IRL event I thought now would be a good time to share them with you...

St. Louis County Fair and Air Show - I imagine some of these frequencies will travel well outside of the fairgrounds, especially the repeaters and air show channels, the handheld UHF radios are probably no more than 2-watts so they won't get very far, but if you're close enough you might be able to listen in on the action from the comfort of your own home...

Forest Park Balloon Race - Balloonists are equipped with VHF Air Band radios and commonly use itinerant frequencies (FRS/GMRS/MURS) for communications between the balloon and chase vehicle...

What else can you monitor?

Besides listening to public safety, there are many, many other things you can hear! Here are just a few things you can try:

• Amateur Radio -- Listen to the hams go on and on about their "equipment" and how they do it until their giga-hertz!
• Cable Repair Guys -- The guys who repair and maintain the local cable television system.
• Cab and Towing Companies -- Tow truck frequencies get busy in winter and cabbies and tow drivers can be a very entertaining bunch. Cabs are especially fun on St. Patrick’s Day and New Years!
• Civilian Air -- Always active and the pilot to pilot chatter is great. The Aircraft Communications Addressing And Reporting System (ACARS) data that all aircrafts transmit is another area to investigate.
• Construction Crews -- All construction companies use some sort of radio or paging systems.
• Data Transmissions -- River level and flow transmitters / NOAA weather maps and conditions / Aircraft Communications Addressing And Reporting System (ACARS) / remote water, gas and electric meters. (Anyone have anymore information on any of these?)
• Fast Food Joints -- Drive-Thru order windows and intercoms. You'll have to be pretty close to hear them (1/2-mile range at most), because these are very low-power transmitters.
• GMRS, FRS, MURS and Itinerant Business Frequencies -- Lots of action by all sorts of users. Most of the users of these types of radio systems aren’t even aware others may be listening in!
• Local Radio and TV stations -- Most TV stations have radios to dispatch news crews to noteworthy events, plus they use radios to coordinate live remote links from the news trucks.
• Manufacturing Factories -- Ford & Chrysler Car Plants, Monsanto, Anheuser-Busch, Ralston Purina, etc. They all have radio systems, not only for maintenance and security, but for coordinating operations.
• Marine Band -- Barge and riverboat traffic on the Mississippi river goes on 24-hours a day, 7-days a week, 52-weeks a year!
• Military Air -- A few of the Air-Air refueling routes can be heard in St. Louis area. Pilot to pilot chatter, again, is also pretty interesting.
• Municipal Workers -- Street department and state and county road crews during summer storms (uprooted trees) and in the winter (snow covered roads) are always interesting.
• Railroads -- Can be interesting at times, even if you aren't a rabid rail fan.
• Recreation -- The Zoo, Amusement Parks, Casinos, Dinner Theaters, etc. They all make use of wireless communications.
• Retail Shops & Stores -- The local hardware store, Wal-Mart, K-Mart, Target and all the area shopping malls use radios to communicate between maintenance and security personnel.
• Schools / Colleges -- School busses and college security patrols... all sorts of drama... better than a soap opera!
• Telephone repairmen -- Like the electric company you can learn much about the phone company and its system just by listening. Although most SWBT activity, these days, doesn't seem to be over their radio frequencies anymore.
• Utilities -- Great for storms and storm repairs, you can also learn quite a bit about the local power grid. Don't forget the sewer, water and gas companies for road closures during repairs.
• VHF Low Band -- Search between 30 and 54 MHz when the skip conditions are good and you can hear stuff from all over.
• Wireless Microphones -- Used for schools, churches, meetings, bingo halls, city council meetings. Seldom do they realize their meetings are being broadcasted for nearly a 1/2-mile radius... makes eavesdropping easy!

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WHAT IS STLASE?

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St. Louis Area Scanner Enthusiasts

The St. Louis Area Scanner Enthusiasts (StLASE) group is an association of likeminded individuals whose primary focus is monitoring public safety communications in and around the greater St. Louis area, though all other types of radio monitoring are supported and discussed.

Also welcomed are discussions related to the various types of wideband scanning receivers available from Alinco, AOR, Bearcat (Electra), Drake, Icom, Kenwood, Motorola, Radio Shack (Patrolman), Regency, Uniden, Yaesu, Yupiteru, and even Homebrew Equipment!

There are no formal membership procedures, secrete handshakes, ID cards, or dues, and you do not need to have an Amateur Radio (HAM Radio) License. Anyone wishing to make meaningful contributions, or just learn about the hobby are more than welcomed to join!

Below are the email addresses related to the St. Louis Area Scanner Enthusiasts (StLASE) group that you'll need to begin participating in this list: