Radio Communication in Film Production

A breakdown in communications can be one of the worst nightmares of production. Rarely do things go exactly according to plan. Here is some information and methods that I have used over the years and am offering as guidelines to establish a system for yourself.

Radios with "Private Line" and other tone squelch systems only keep you from NOT hearing the other traffic that is out there on your frequency that is NOT tone coded with the same tone code as your radios. Your transmissions will be heard and can interfere with other traffic that you DO NOT hear on your radio. Proper

operation of your equipment requires that you to listen to a clear channel without tone squelch before you transmit. This is not easy on some sets and most people don't do it. Swearing is out of line and illegal. Low power 2 watt or less units keep your transmissions local and do not transmit all over town. This is an advantage and disadvantage. Your range will be limited.

A "gain" accessory car roof antenna alone will greatly increase your transmit and receive ability. A radio inside a car is not very efficient. It is wise to have a roof antenna on the lead and last car of a caravan. A 3 db. gain antenna is better than a dipole antenna. They cost more and have to be tuned to the frequency that you are using. You have to be careful that you don't have a cable problem that actually cuts your range to less than a radio with no roof antenna. Compare reception with and without your roof antenna.

You can check the relative output of radios and antennae with a field strength meter from Radio Shack. The position of the field strength meter relative to the antenna will affect your results. Make comparisons with the field strength meter at the same position, like on a grip stand. Slight changes in position will make a difference. Add a small collapsible antenna to the meter to add power adjustment ability. You can also "distance-test" units RECEIVING with the antenna off, the unit in and out of a car, with and without roof antenna, at up to a distance of 1/2 mile. BUT DO NOT TRANSMIT WITHOUT AN ANTENNA ATTACHED TO A RADIO. Higher power units will burn out their final amplifier if no antenna is attached when transmitting. DANGER! Higher power, 10 watt and above, can cause RF burns and possible radiation problems such as retinal detachment, with continued use close to the body.

I have found the linear amplifier solution quite effective. It puts the amplifier and antenna at a safer distance from you. The problem with the amplifier sold by Motorola is that it has no power on or transmit indicators. It clicks when you transmit but that is hard to hear in a car. Adding LED transmitting indicators would be an easy job for a good radio technician.

A hiking water bottle bag works well to hold smaller radios and many other things. The earwig microphone/earphone units do not work well if another unit is close by. The ear wig transmits voice through the ear canal. Another unit nearby hears your voice transmitting, turns on the voice operated circuit and feedback occurs.

A very useful unit is the Motorola Minitor, a small paging receiver for police and firemen. They used to cost about $300, but are probably less now. They can be tone squelched (Private Line). You can give them to people that you don't want transmitting. With head phones or an earpiece inside hearing protectors they can be very useful for high noise level situations for actors, noisy equipment operators, motorcycle riders, fog machine operators and focus pullers that are getting focus marks by radio. A hand wave from the person receiving will tell you that they hear and understand. Also available are monitor/receivers from Radio Shack and others that can be tuned to your frequencies. Radio Shack has in mid-1990 some very reasonable monitor receivers with crystals. Some of these units can also receive Aircraft Band for use shooting airplanes. (See Shooting Ground to Air). These units will also receive weather forecasts.

Be careful to make sure which channel people are supposed to use. Mark the radio or tape off the channel switch. There are many other radio frequencies that are illegal to use for our purposes. You are in danger of interfering with legitimate traffic on these bands. The FCC does watch some of these bands closely and will come down hard on abuse.

Citizen band radios are of use in the few areas where there is no existing radio traffic. There are some 49. mhz. (mc) voice actuated citizen band units that are useful on stage. They have low power and do not receive much from other sources. They are cheap and disposable.

One of the most difficult production problems with radios is to keep chit-chat and singing off the air. It is illegal, wastes batteries that may be needed, and interferes with other traffic. This is especially true on private line radios, when people think that no one else is listening.

There are available 6 db gain antennae that, mounted at some height, will extend the range of your radio many times. They can be rigged on a pole on the side of a parked truck. Low loss cable RG-11(50 Ohm foam) will help even more. See your supplier. Antenna Specialties has many of these items. Motorola sells some of them. Corner reflectors and Yagi antennae will increase your range even more, but they have to be pointed in the right direction and have to be made for the right frequency. I don't know of any commercial suppliers at this time. Cellular phones have helped much in the last few years. Here again roof antennae help a lot. There is talk of Yagi's for fringe areas. The signal strength indicator on the phone will tell you a lot about how well your antenna is working. Portable frequency meters are now quite reasonable. You can check your transmit frequency, but not your receive frequency. Signal generators that can do that are more expensive.

If you are in a fringe area with a car, put your radio or cel phone on the corner metal of your car the furthest from the receiving transmitter. It should help.

You should have your units checked periodically. It is important to label units that seem to have a problem. You can exchange batteries to see if that is the problem. You can side by side check for receive and transmit ability. All of the nickel cadmium battery procedures apply to radio nickel cadmium batteries. They should be completely discharged and recharged periodically. Do not discharge them and leave them discharged. It is OK to let the discharge naturally when not being regularly used. They loose about 1% of their charge per day. Labeling each radio and checking them out to each person in writing will make people more responsible for their check in.
Radio Communications in Film Production

A breakdown in communications can be one of the worst nightmares of production. Rarely do things go exactly according to plan. Here is some information and methods that I have used over the years and am offering as guidelines to establish a system for yourself.

Radios with "Private Line" and other tone squelch systems only keep you from NOT hearing the other traffic that is out there on your frequency that is NOT tone coded with the same tone code as your radios. Your transmissions will be heard and can interfere with other traffic that you DO NOT hear on your radio. Proper operation of your equipment requires that you to listen to a clear channel without tone squelch before you transmit. This is not easy on some sets and most people don't do it. Swearing is out of line and illegal. Low power 2 watt or less units keep your transmissions local and do not transmit all over town. This is an advantage and disadvantage. Your range will be limited.

A "gain" accessory car roof antenna alone will greatly increase your transmit and receive ability. A radio inside a car is not very efficient. It is wise to have a roof antenna on the lead and last car of a caravan. A 3 db. gain antenna is better than a dipole antenna. They cost more and have to be tuned to the frequency that you are using. You have to be careful that you don't have a cable problem that actually cuts your range to less than a radio with no roof antenna. Compare reception with and without your roof antenna.

You can check the relative output of radios and antennae with a field strength meter from Radio Shack. The position of the field strength meter relative to the antenna will affect your results. Make comparisons with the field strength meter at the same position, like on a grip stand. Slight changes in position will make a difference. Add a small collapsible antenna to the meter to add power adjustment ability. You can also "distance-test" units RECEIVING with the antenna off, the unit in and out of a car, with and without roof antenna, at up to a distance of 1/2 mile. BUT DO NOT TRANSMIT WITHOUT AN ANTENNA ATTACHED TO A RADIO. Higher power units will burn out their final amplifier if no antenna is attached when transmitting. DANGER! Higher power, 10 watt and above, can cause RF burns and possible radiation problems such as retinal detachment, with continued use close to the body.

I have found the linear amplifier solution quite effective. It puts the amplifier and antenna at a safer distance from you. The problem with the amplifier sold by Motorola is that it has no power on or transmit indicators. It clicks when you transmit but that is hard to hear in a car. Adding LED transmitting indicators would be an easy job for a good radio technician.

A hiking water bottle bag works well to hold smaller radios and many other things. The earwig microphone/earphone units do not work well if another unit is close by. The ear wig transmits voice through the ear canal. Another unit nearby hears your voice transmitting, turns on the voice operated circuit and feedback occurs.

A very useful units are small paging receivers for police and firemen. They used to cost about $300, but are probably less now. They can be tone squelched (Private Line). You can give them to people that you don't want transmitting. With head phones or an earpiece inside hearing protectors they can be very useful for high noise level situations for actors, noisy equipment operators, motorcycle riders, fog machine operators and focus pullers that are getting focus marks by radio. A hand wave from the person receiving will tell you that they hear and understand. Also available are monitor/receivers from Radio Shack and others that can be tuned to your frequencies. Some of these units can also receive Aircraft Band for use shooting airplanes. (See Shooting Ground to Air). These units will also receive weather forecasts.

Be careful to make sure which channel people are supposed to use. Mark the radio or tape off the channel switch. There are many other radio frequencies that are illegal to use for our purposes. You are in danger of interfering with legitimate traffic on these bands. The FCC does watch some of these bands closely and will come down hard on abuse.

Citizen band radios are of use in the few areas where there is no existing radio traffic. There are some 49. mhz. (mc) voice actuated citizen band units that are useful on stage. They have low power and do not receive much from other sources. They are cheap and disposable.

One of the most difficult production problems with radios is to keep chit-chat and singing off the air. It is illegal, wastes batteries that may be needed, and interferes with other traffic. This is especially true on private line radios, when people think that no one else is listening.

There are available 6 db gain antennae that, mounted at some height, will extend the range of your radio many times. They can be rigged on a pole on the side of a parked truck. Low loss cable RG-11 (50 Ohm foam) will help even more. See your supplier. Antenna Specialties has many of these items. Motorola sells some of them. Corner reflectors and Yagi antennae will increase your range even more, but they have to be pointed in the right direction and have to be made for the right frequency. I don't know of any commercial suppliers at this time. Cellular phones have helped much in the last few years. Here again roof antennae help a lot. There is talk of Yagi's for fringe areas. The signal strength indicator on the phone will tell you a lot about how well your antenna is working. Portable frequency meters are now quite reasonable. You can check your transmit frequency, but not your receive frequency. Signal generators that can do that are more expensive.

If you are in a fringe area with a car, put your radio or cel phone on the corner metal of your car the furthest from the receiving transmitter. It should help.

You should have your units checked periodically. It is important to label units that seem to have a problem. You can exchange batteries to see if that is the problem. You can side by side check for receive and transmit ability. All of the nickel cadmium battery procedures apply to radio nickel cadmium batteries. They should be discharged in the radio and recharged periodically. Do not discharge them and leave them discharged. It is OK to let the discharge naturally when not being regularly used. They loose about 1% of their charge per day. Labeling each radio and checking them out to each person in writing will make people more responsible for their check in.

Sometimes leaving a charger with crew people and making them responsible for the recharging at night works. You can transmit to help find radios at the end of the day. They turn up under seats and in equipment bags. Spare batteries are handy for the AD (assistant director) and others who are on the air all day

There are car chargers for some units. Transmitting draws 20 times battery power as receive and 50 times more than a squelched radio. Some chargers have contact problems with the radio when placed into the charger. Some contacts get dirt in them, others need the springs bent. If the charge light doesn't come on, check for this. Carry a power strip for plugging in multiple chargers. Make sure when you turn off room lights that you don't turn off the socket that is charging the radios.

A 10 watt unit with a roof antenna will cover a lot of ground. The older Motorola PT 400's are hard to repair now-a-days and the new ones are quite expensive. There are other mobile units that can be packaged with a camera battery to make a portable, powerful unit. Remember that the antennae is most important. We had some mobile units permanently installed in some vehicles. They are quite reasonable, reliable and quite maintenance free. Permanently wired units fare better than plug in units. Cigarette lighter plugs are just OK at best. Lighter socket "y" plugs are handy for more than one unit tied to the cigarette lighter plug

The sun spot situation is still not good for any radio communications. There are areas where radios don't work well even within line of sight and 1/2 mile apart. Out in the California desert near Red Mountain we are amazed at the poor reception. We ended up using car horn signals for action. Mount Tamalpias also has problems.

Communicating by radio is an art. You have to put yourself in the person's shoes on the other end. What does HE see? You can describe something that you can see, such as a line up with the sun, his boat and the camera that he can not see from his viewpoint. If you say "up or down the coast", "closer or farther", "to your right or left" he will understand better.

Remember that local people do not talk movie language. Screen, stage or camera-right may be confusing. Counter-clockwise may not be understood. Think before you speak.

I personally hate bull horns, but they do have their uses for large crowds. You can feed a walkie talkie, or monitor receiver into a portable amplifier, or boom box and have a radio bull horn at a comfortable distance from the transmitter to avoid feedback.

It is difficult or impossible to legally get radios into other countries. Many of the local radios are fair at best.

Since I wrote this there have been many cheaper radios available and should be checked out.

© Copyright 1999-2004 Ron Dexter. All Rights Reserved.
Sometimes leaving a charger with crew people and making them responsible for the recharging at night works. You can transmit to help find radios at the end of the day. They turn up under seats and in equipment bags. Spare batteries are handy for the AD (assistant director) and others who are on the air all day

There are car chargers for some units. Transmitting draws 20 times battery power as receive and 50 times more than a squelched radio. Some chargers have contact problems with the radio when placed into the charger. Some contacts get dirt in them, others need the springs bent. If the charge light doesn't come on, check for this. Carry a power strip for plugging in multiple chargers. Make sure when you turn off room lights that you don't turn off the socket that is charging the radios.

A 10 watt unit with a roof antenna will cover a lot of ground. The older Motorola PT 400's are hard to repair now-a-days and the new ones are quite expensive. There are other mobile units that can be packaged with a camera battery to make a portable, powerful unit. Remember that the antennae is most important. We had some mobile units permanently installed in some vehicles. They are quite reasonable, reliable and quite maintenance free. Permanently wired units fare better than plug in units. Cigarette lighter plugs are just OK at best. Lighter socket "y" plugs are handy for more than one unit tied to the cigarette lighter plug

The sun spot situation is still not good for any radio communications. There are areas where radios don't work well even within line of sight and 1/2 mile apart. Out in the California desert near Red Mountain we are amazed at the poor reception. We ended up using car horn signals for action. Mount Tamalpias also has problems.

Communicating by radio is an art. You have to put yourself in the person's shoes on the other end. What does HE see? You can describe something that you can see, such as a line up with the sun, his boat and the camera that he can not see from his viewpoint. If you say "up or down the coast", "closer or farther", "to your right or left" he will understand better.

Remember that local people do not talk movie language. Screen, stage or camera-right may be confusing. Counter-clockwise may not be understood. Think before you speak.

I personally hate bull horns, but they do have their uses for large crowds. You can feed a Minitor, walkie talkie, or monitor receiver into a portable amplifier, or boom box and have a radio bull horn at a comfortable distance from the transmitter to avoid feedback.

It is difficult or impossible to legally get radios into other countries. Many of the local radios are fair at best.

© Copyright 1999-2004 Ron Dexter. All Rights Reserved.