Category:944 Radio Operation: Difference between revisions

MoDOT is authorized by the Federal Communications Commission to operate a statewide two-way radio communications system. This system is licensed in the Highway Maintenance and Local Government Public Safety Radio Service.

This system may be referred to as a "dual use" system. Normally it is used for routine highway business but during times of declared emergency it augments Civil Defense.

Stations in the Highway Maintenance Radio Service are authorized to transmit communications essential to official activities of the licensee.

The radio system primarily provides direction and rapid dissemination of information to field vehicles. This facilitates the maintenance and construction of highways and promotes safety and the protection of life and property. It is not intended to replace the use of the mail, telephone or other common communication services.

944.1 Radio System Description

The system is a high band mobile relay radio composed of a number of land stations and mobile units. Eight frequencies are used in the system. Separate transmit and receive frequencies are assigned to each of three Channels A, B or C. The seventh frequency, along with the mobile radio transmit frequency assigned to Channel A, form the St. Louis metro channel. Likewise, the eighth frequency, along with the mobile radio transmit frequency assigned to Channel B, form the Kansas City metro channel.

Channel A is assigned to Districts 1, 5, 7 and 10, Channel B is assigned to Districts 2, 6 and 8 and Channel C is assigned to Districts 3, 4 and 9. The radio system utilizes mobile repeaters to repeat (re-transmit) all signals transmitted by mobile units or control stations. This process strengthens the signal, thus extending the talking range of the mobile and control stations.

MoDOT also uses handheld UHF radios with a range of one to two miles for communications within work zones. These radios operate on a different frequency band and are totally separate from the mobiles. Handheld units are not capable of long-range communications and can not be used to communicate to mobile or base stations within the statewide radio system.

Normal radio communication is carried through a mobile relay that is located at one of our tower sites. For vehicle-to-vehicle communications, both vehicles must be in range of the same mobile relay. The normal range for the mobile relay varies between a 25- to 60-mile radius of the tower site, depending upon the terrain, weather conditions and height of the tower. A vehicle will be able to contact their district office via the nearest mobile relay. All vehicles equipped with a radio within the range of the mobile relay will hear all messages transmitted.

Tone-coded switches are placed in each receiver in the mobile relay station that turn on the station. Each station within a district has its own assigned tone. The radio control head of the mobile unit contains the corresponding tone encoders that enable the mobile operator to turn on the various mobile relay stations within their respective district.

The system uses two types of mobile units. They are referred to as district-only radios and statewide radios. District-only units are single channel units with one frequency to transmit on and one frequency to receive on and are capable of district-wide operation. Statewide radio units are three channel units that have three transmit frequencies and three receive frequencies and are capable of a statewide operation.

A statewide radio unit also has the capabilities of using the St. Louis and Kansas City metro channels along with the car-to-car communication described below.

The car-to-car communication allows direct communication between cars equipped with three channel units without going through the mobile relay. The range of this communication is less than that through the mobile relay. The normal range varies between 5 and 15 miles from each car. As with the mobile relay, the range is affected by the terrain, weather conditions and the position of the car. If the car is positioned on a hill, communication will be at its optimum. Each district is assigned a main channel. To reduce interference it is recommended that car-to-car communication take place on a channel other than the main channel for that district. Car-to-car communications is encouraged to help reduce congestion on the normal communications channels.

All mobile radios bear an MHTD inventory tag. In the case of 100-watt radios, this tag usually will be on the Transmit/Receive unit, located either in the truck or behind the seat.

944.2 Operating a Mobile Unit

Classes of instruction on the proper operation and procedure will be held periodically in the district.

To place a mobile unit in operation, first turn the Off-On control to the on position. As this is done, the "ON" indicator will light, indicating the unit is on and the receiver is in operation. The volume can be increased by turning the volume control knob in a clockwise direction. Off-On control and/or volume control is accomplished by way of push buttons on newer radio units.

The tower selection tone push button should now be pushed in which corresponds to the tone assigned to the nearest mobile relay station. Tower selection on newer radio units is shown on radio's display face.

To transmit, the ignition switch must be on and the vehicle engine should be running. The radio operator should delay transmitting immediately after turning radio on to ensure that other radio communications are completed.

Statewide (three channel) units are operated similarly but with one exception. These units are equipped with a Channel Selector switch that enables the operator to transmit and receive on Channel A, B or C. This switch must be in the proper position for correct operation. In the case of radios with a display and MODE up/down control, scroll through the modes until arriving at the proper channel-letter/tone-number combination (A1, B2, C7, etc.).

944.3 Mobile Unit Operating Procedure

Due to the number of mobile units in this system, proper radio operating procedure is essential for maximum efficiency.

Think first of what you are going to say, keep phrases short, and speak distinctly and slowly so that the receiving operator may clearly understand your message. In order to keep airtime at a minimum, make use of the Operating Code Signals.

Pick up microphone, hold it close to the mouth but at an angle of about 45^o, squeeze the push-to-talk (PTT) button on the microphone and start to talk. For units equipped with push-to-talk automatic identification and sidetone, hold the PTT button until the sidetone stops, then begin speaking. Release the PTT button as soon as you are finished.

Long messages should be broken into phrases with occasional pauses to permit the receiving operator to check doubtful words.

Numbers should be given as individual numbers. Thus Unit 4203 would be pronounced, unit four-two-zero-three.

When initiating a call, give your assigned call sign first, then give the call sign of the unit you are calling. The unit called will answer by giving their assigned call sign. You may now proceed with your message.

When the communication is over, the unit initiating the call shall announce the FCC assigned call sign KC 6343 when operating on Channels A and B, or KN 5291 when operating on Channel C. The metro channels use KC6343. Base stations use the unique call signs assigned to them.

Unit call assignments are given farther down in this article. Some positions are designated by their base of operation; others are designated by a unit number. Due to transfers, retirements, promotions, etc., no attempt to list names has been made. Any such list would soon become out of date. However, cards showing unit call assignments for districts should be available from either the district office or the radio shop.

944.3.1 Examples of Normal Radio Communication Between Vehicles

Assume both units are within range of the same mobile relay station. The calling operator selects the correct tone for that station and calls:

"Unit 4201 to Unit 4218"

(Say as "Unit four-two-zero-one to Unit four-two-one-eight")

"Unit 4218"

"Code 20"

"Junction Routes 50 and 58"

"Code 4, KN 5291"

An example

"Unit 1201 to Unit 1721"

"Unit 1721"

"Code 26 Junction 169 and Mitchell"

"Code 4"

"KC 6343"

If there is any question about which mobile relay is being used, designate the station in the call.

Another example

"Unit 9213 to Unit 9202 on Leasburg"

(Use name of mobile relay, not the tone letter.)

Communications should proceed as shown above.

When calling, give the called unit sufficient time to respond before repeating your call. It may be that the receiving operator is a short distance away from the radio-equipped vehicle. After the second call, if no answer is received, again wait for approximately one minute and, if no answer is heard, sign off. Any further calling at this time is unnecessary and causes undue interference while serving no useful purpose. The called unit did not answer for one of the following reasons:

1. Equipment inoperative;

2. Operator out of vehicle; or

3. Vehicle out of range of the repeater.

The first condition requires the service of a radio technician to correct and no amount of calling will correct the defect.

The second and third conditions require that the operator either returns to radio-equipped vehicle, or that the receiving operator will eventually come within range of the mobile relay being used. Additional time should be allowed before making another call.

Also for the third condition, you may request the district operator to locate the called unit and relay your message.

As a fairly reliable indication that your radio and the selected repeater are both within range and working, watch for reception of the repeater's delayed turn-off. When releasing the PTT button, you should hear a short hum or hiss; also, your busy light, if so equipped, will be lit for this duration. Although checking most of the system, this test does not verify transmission of voice audio.

Car-to-car communication should be handled in a similar manner as described above.

944.3.2 Examples of Normal Radio Communication Between Vehicles and Station Operation

Calling your district office when in range of the office local mobile relay station:

An example

"Unit 5203 to Highway 5"

"Highway 5"

"Code 49, Hartsburg"

"Code 4. Will send assistance."

"Code 4. KC 6343"

"KFN 582"

In communications between any mobile unit and any district or main office, both shall announce their respective call signs at the end of the communication.

When calling a base station through an outlying mobile relay, designate the station being used in the call.

Another example

"Unit 10204 to Highway 10 on Taum Sauk"

(Use name of mobile relay, not the tone letter.)

"Highway 10"

"Code 18"

"Code 19"

"Code 4, KC 6343"

"KFN 583"

The use of courtesy and good operating procedures, as well as careful observation of the rules and regulations set forth in this article, will aid in providing good communications to all users of the system.

Always use a mobile relay known to be in good communication range of your location. To do otherwise will result in poor communication, noise and interference to others.

944.4 Safety Rules for Mobile Operation

Keep radio away from blasting caps. Radio frequency energy from sources such as two-way radios can set off blasting caps without having any physical connection with the blasting circuit.

The following rules are to be followed by all MoDOT personnel:

1. Turn radio off if within 300 ft. of any electric blasting operation.

2. Never carry caps in a vehicle equipped with two-way radio unless they are in an all-metal can. This can shall be a (minimum) 24-gauge iron box lined with wood or rubber.

3. If electric caps are within 300 ft. of any two-way radio transmitter, keep tightly enclosed in an all-metal can. Never open when transmitter is in use.

4. Do not transmit or run motor around gas leaks.

5. Turn radio, as well as motor, off when filling gas tank.

6. Do not keep gasoline can in trunk of radio-equipped vehicle.

7. Do not allow liquids to spill into the control head. If washing out a truck do not allow water to get to either the control head or the transfer/receive unit.

8. Before jump starting, welding, or battery charging, turn off radio and disconnect fuse.

9. Do not crush, pinch, or modify wiring to the radio.

944.4.1 The "Do" List

1. Do listen before you transmit.

2. Plan what you are going to say.

3. Speak clearly and distinctly.

4. Do use proper codes and operating procedures.

5. Keep conversations short.

6. Run engine when transmitting to minimize battery drain.

7. Do use courtesy and consideration for others in using your radio.

8. Do use a repeater station in range of your location.

9. Do transmit from high locations whenever possible. Radio signals go further and are heard better from high points.

10. Do use car-to-car communication for short distance radio communication.

11. Keep vehicle battery, generator, regulator and ignition system in good condition. Periodically check battery fluid. Clean away corrosion and install new terminals and protector discs at battery as needed. Deteriorated battery connections have been the leading cause of radio failure.

12. Turn radio off at end of day.

13. Periodically check antenna load coil, if so equipped, to determine if it is separating from its brass threaded insert. Report any missing, bent, or loose parts to the radio shop.

944.4.2 The "Don't" List

1. Do not use profane language.

2. Do not call other units by the driver's name. Use assigned call numbers.

3. Do not change or adjust any radio parts inside the transmitter-receiver unit. This must be done by licensed servicemen only.

944.5 Rules and Regulations

1. Communications from mobile units, and especially emergency communications, have precedence over all other messages.

2. All communications, regardless of their nature, must be kept as short as possible.

3. All mobile and base station operators shall take reasonable precaution to prevent unnecessary interference.

4. Only persons duly authorized by the department shall operate radio equipment.

5. Profane or obscene language shall not be used.

6. No person shall use a call sign other than the one assigned to the station on which they are transmitting.

7. No person shall transmit unnecessary, unidentified or superfluous radio communications.

8. No operator shall willfully damage, cause damage to, or permit to be damaged any radio apparatus or installation in any licensed radio station.

9. No operator shall willfully or maliciously interfere with or cause interference to any radio communication or signal.

10. FCC radio identification tags must remain affixed to the equipment.

11. Any new unit call sign number not listed in the mobile unit directory must have clearance from the Signal and Lighting Engineer before being used.

12. Any mobile unit operator temporarily filling the job of another person will use the unit call sign number of the position they are occupying.

13. Adjustment of radio equipment shall not be made by anyone unless duly licensed and authorized to do so.

14. Confidential information shall not be transmitted.

944.6 Operating the Base Station

Due to individual requirements at the district offices, equipment and control consoles will vary from station to station. Any person undertaking the operation of a base station for the first time should have the help of an operator experienced at that station, or may ask the assistance of any of the radio personnel. Operating instructions will be available at each control point. These instructions explain how to set up that particular station for the desired operation. Since the station has been set up, communications may continue on a push-to-talk basis.

The base station operator has the responsibility of set a good example of operating the mobile units including good clear speech and being cooperative. The use of proper codes and good operating procedure will help establish good communications. The base station operator must become acquainted with the capabilities and limitations of the system in order to best route calls and to be able to advise mobile unit operators about their communications.

The use of proper radio procedure is demonstrated in the examples given here.

Normal Radio Communication

When calling a mobile unit known to be within communication range of the local mobile relay, the operator makes the proper set up and calls:

"Highway 10 to Unit 10201"(Say as "Highway ten to unit ten-two-zero-one")

"Unit 10201"

"Code 21, this office"

"Code 4"

"KJI 565"

"KC 6343"

When calling a mobile unit on an outlying relay:

"Highway 8 to Unit 8750 on Romance"

"Unit 8750"

"Code 20"

"Gainesville Maintenance Building"

"Code 4, KLP 801"

"KC 6343"

When calling an adjacent district office, use channel assigned to that district:

"Highway 5 to Highway 6 on Warrenton Channel 2"

"Highway 6"

"Code 82, Mr. Jones, Holiday Inn"

"Code 4"

"KFN 581"

When a mobile unit calls on a local relay:

"Unit 5211 to Highway 5"

"Highway 5"

"Ice beginning to form on Rocheport Bridge"

"Code 4"

"KC 6343"

"KFN 582"

When a mobile unit calls on an outlying relay:

"Unit 1214 to Highway 1 on Martinsville"

"Highway 1"

"Code 7"

"Code 4"

"KC 6343"

"KGY 337"

The additional examples shown under "Mobile Unit Operating Procedure" also have application by the base station operator and should be studied along with the examples in this article.

The operating procedure shown in this article is the only procedure authorized for the system. The procedure is designed to aid in handling communications traffic and is based on simplicity and elimination of superfluous words and the use of common courtesy and consideration.

944.7 Station Logs

All messages transmitted from the main office or district offices to another shall be recorded in the station log.

The District Operator will fill in the TIME, STATION CONTACTED, CALL SIGN OF TRANSMITTER USED and REMARKS COLUMN of the log sheet. Both the transmitting and receiving operators will enter the contact in the station log.

The station log shall be kept on a locally provided form following the example shown herein.

An operator opening the station at the beginning of the day or coming on duty must "sign on" by entering their name in the "Operator" column. Initials are not satisfactory. The operator who signs on is responsible for the operation of the station, correct procedure used by the mobile operators, and must be present for the period for which they are responsible. Other authorized persons may transmit during this time, but the operator in charge will make all entries in the log and monitor all transmissions made during this tour of duty. When going off duty at the end of the day or when being relieved the proper entries must be made. Applicable entries in the "Remarks" column for signing on and off would be Station Open, Off Duty, On Duty or Station Closed.

The initial and final log entry for any one day will show the date and time. All other entries will show only the time, and include a.m. or p.m. Entries will be made each time another base station is contacted. The entry will show time, FCC call sign of the transmitter used for the contact, and the nature of the communication.

The log must be kept in ink to establish a permanent record. No erasures are permitted. To make a correction, line out error and initial the correct entry.

Entries shall be made regarding any unusual occurrences affecting radio operations or happening on or to the highway system. The radio log is a permanent record and will be retained for a minimum of one year.

944.8 Tower Light Observations

FCC and FAA regulations require that all towers that are lighted shall be inspected once each 24 hours to ensure all lights are functioning properly. The District Engineer in whose district a lighted tower is located is responsible for observation of the tower lights and reporting of failure. The exact procedure of observing and reporting failures will vary as required by the individual tower location and situation.

Daily records shall be maintained to show:

1. Time of observation,

2. Condition of the lights,

3. Action taken if any failures are observed, and

4. Signature of person making the light check.

If a failure is observed, record the:

1. Nature of failure, and

2. Date and time the failure was observed.

The action to be taken depends on the nature of the failure. Should the failure involve a top or beacon light that cannot be repaired within 30 minutes, contact the nearest FAA Flight Service Station and advise them of the failure, location and height of the tower, and make entry in log of the action taken.

Notify radio personnel of the "light out" report as soon as possible during normal business hours. These technicians will check the failure, make repairs, if possible, and advise the district office when repairs are completed or that additional assistance is required. As soon as the light is operating properly, notify the Flight Service Station that service has been restored and enter date, time and nature of repairs in the log.

Notification to the FAA Flight Service Station is not required. Do notify the radio personnel in the following cases of light failures:

1. Side lights not burning;

2. Top light on, but not blinking;

3. Lights burning during daytime hours; or

4. Malfunction of strobe lights during daylight hours on dual lighted towers.

Further on in this article is a list of the FAA Flight Service Stations and the towers required to be lighted. Periodic inspections of the tower lighting system will be made every three (3) months. All personnel are urged to assist in the observance of tower light failures.

944.9 Radio Maintenance

All maintenance of radio equipment in this system will be performed by department personnel who are FCC licensed radio technicians. In some cases, radio maintenance will be provided by contract. No other person will perform maintenance upon any equipment that is a part of this radio system except when so authorized by the licensed radio technicians in emergencies involving the safety of life and property.

The transfer of radio sets from one vehicle to another will be performed only by licensed district radio technicians or under their direct supervision.

944.10 Notice of FCC Checks (Forms)

Radio maintenance and placement records will be kept at the district level for all radio equipment within that district.

List of FAA Flight Service Stations where tower light failures may be reported.

Cape Girardeau

St. Louis

Vichy

Springfield (c s/t)¹

Joplin

Columbia

Kansas City

St. Joseph (c s/t)¹

Kirksville

Quincy, Illinois

¹ Combined Flight Service Station/Control Tower

944.11 Central Office Radio Call Numbers

Table 944.11 Central Office Call Numbers

944.12 District Radio Call Numbers

To provide uniformity and increase radio call numbers available, the following shows district radio call number assignments. There are two options available for assignments. Option A is geographical organization and Option B is divisional organization.

Table 944.12.1 Option A, Geographical Organization District Radio Call Numbers

Table 944.12.2 Option B, Divisional Organization District Radio Call Numbers

944.13 Maintenance Locations

All employees will have an assigned number reserved explicitly for their use.

"Building Name" "1" through "5" will be reserved for supervisory positions and building specialist. Usually "Building Name" "1" will be the building supervisor and "Building Name" "2" will be the assistant building supervisor.

"Building Name" "6" through "9" will be reserved for mechanics. Usually "Building Name" "6" will be the field mechanic and "Building Name" "7" and "8" will be mechanic helpers.

Numbers for maintenance crew leaders and workers will be assigned by the building supervisor starting with Building Name "10".

Numbers are to be assigned to employees, not vehicles or radios.

Individual's names should not be used on the radio.

Table 944.13.1 District Locations

Table 944.13.2 Mobile Relay Stations

944.14 Control and Base Stations

Table 944.14 Control and Base Stations

944.15 Operational Fixed Stations

Table 944.15 Operational Fixed Stations

944.16 Scanner Frequencies

Table 944.16 Scanner Frequencies

944.17 Phonetic Alphabet

Table 944.17 Phonetic Alphabet

944.18 Numerals

Table 944.18 Numerals

944.19 Operating Code Signals

Table 944.19 Operating Code Signals

944.20 Glossary of Terms

Audio - sound waves within range of the human ear, typically 30-15,000 Hertz

Automatic Number Identification (ANI) - information transmitted automatically at the beginning of a communication to identify the radio in use

Buzz - low pitched, sizzling sound, as of a bee or door buzzer

Carrier - the radio wave foundation that carries tone, voice, or data

Channel Guard (CG) - General Electric's name for Continuous Tone Coded Squelch

Continuous Tone Coded Squelch (CTCS) - a system transmitting a low frequency audio tone along with the voice. MHTD uses a transmit tone to select the desired repeater, and a receive tone to minimize noise. The tone is filtered out before the speaker.

Control Head - portion of a radio having the on/off, volume, squelch, channel select, display, and other control functions. On mid-power radios, the head is usually an integral part of the unit.

Deviation - Transmit volume, set internally by the tech for optimum legal operation.

Direct - same as Car-to-car

Dual-Tone-Multi-Frequency (DTMF) - Signaling format used in standard telephone systems, consisting of a matrix of four horizontal rows and three vertical rows of buttons, each row having one tone, such that the button activates one horizontal and one vertical tone for a unique two-tone combination.

Federal Communications Commission (FCC) - government agency which allocated radio and other communications frequencies and monitors activity

Gain Antenna - At MHTD, typically a 46-in. rod with load coil that concentrates radiation horizontally, theoretically doubling the effective radiated power of a mobile radio. Used with all mid-power radios and a dump trucks have cab protectors.

Handheld Radio - A self-contained, battery powered radio for short-range communication.

Hang-Up Box (HUB) - Microphone hanger with internal switch activated by presence of microphone.

Hum - a smooth, low pitched sound; for example, a transformer or stuck motor

MDC 1200- Motorola standard for data transmission and automatic identification

Metro Channel - a secondary repeater used in Kansas City and St. Louis have in a more local range and on a different frequency from the regional repeaters

Mobile Radio - a two-way radio installed din a vehicle, capable of transmitting while the vehicle is in motion

Mode - varies with manufacturer's use, but generally refers to each channel or combination of transmit/receive frequencies, tones, and other parameters. Can also be a group of channels.

Modulation - the audio or data superimposed on the carrier

Monitor - reception of all on-frequency signals, with or without the proper tone

Private Line (PL) - Motorola term for Continuous Tone Coded Squelch

Program - Enter the proper configuration of frequencies, tones, and operating parameters into a synthesized radio via a computer and radio interface box

PTT - common abbreviation for Push-To-Talk; the button on the microphone

Repeat - setting of the radio to transmit through a repeater

Repeater - a combination receiver/transmitter/duplexer that re-transmits received communications on another frequency, generally to gain the advantage of a high antenna

Rx - common abbreviation for "Receive"

Selectivity - the ability of a receiver to tune out unwanted frequencies and zero in on the desired one

Sensitivity - the measure of how much signal is required to satisfactorily receive on a radio; the less required, the more sensitive. Typically, 0.5 microvolts or less.

Tag - the oval inventory sticker that is placed on every radio (and other non-rental MHTD equipment). In the case of a 100-watt radio with a separate T/R unit, the tag is placed on the T/R unit.

Talk-Around - same as Car-to-car

Time-Out-Timer (TOT) - Motorola name for a circuit which, after a predetermined time, shuts down transmitter and sounds a tone through speaker. To reset, briefly release the PTT button.

Tone - a steady, single-frequency sound wave in the audio range, such as broadcast with a television test pattern. In our radio system, tones include the sound generated when changing mode or volume on a display faced radio, and the response to attempting to transmit on a receive-only channel; among many other purposes.

T/R Unit - Transmit/Receive Unit - A second enclosure, typically found in 100-watt radio installations, which contains all the radio circuits except controls. Also known as a "drawer" unit, the T/R is generally mounted behind the seat of a truck or in the trunk of a car.

Tx - common abbreviation for "Transmit"