A Typical Wireless Microphone Equipment Set  

These four items are typical of the equipment found in a wireless microphone set: A Lectrosonics brand VHF band FM radio receiver. The back end of it has a standard XLR-male output plug as well as the battery compartment. The corresponding transmitter; it clips to a person's belt or waistband & has a battery compartment in the back. A condenser lavalier microphone that would plug into the transmitter unit. (top slot in above picture) The antenna is in the microphone cable itself. Be sure you have a small foam wind screen over the microphone element to cut down on wind noise from being outdoors. (the pictured mic is "naked") The flexible whip antenna that would be attached to the receiver unit by way of the 'bayonette' mount coupling on it's right side. (about 9" long for VHF; much shorter for UHF) It should be noted that manufacturers like Lectrosonics began phasing out their VHF-band sets several years ago — now, UHF-band sets are the only new units that may be purchased (VHF sets or individual components are still available on websites such as Ebay, but the manufacturer's service departments are also starting to phase out support for them). Several advantages of the UHF models include the fact that they may be tuned to many different channels within a block of frequencies instead of operating on only a single frequency; this permits much greater interference avoidance. And, the newest units transmit their sound as digital information instead of analog. The very-highest-end UHF digital systems even permit the encryption of the sound data to prevent others from eavesdroppping on the interview conversation. (of course, you are going to pay a serious premium for that capability) Additionally, instead of requiring a 9-inch long flexible 'rubber duckie' antenna such as the one that you see pictured here, UHF units, operating on much higher frequencies (with much lower radio wavelengths) will only require short 'toothpick'-sized antennas ... your recording engineer will appreciate not having two or more long antennas wagging away in front of him as they try to run or bike after the speakers! Don't forget, your recording engineer is going to need something in which to carry all of the equipment. This photo is from the Porta Brace company's website. They offer a variety of belts and harnesses to keep things from bouncing around too badly as well as a whole line of specifically-designed equipment carrying bags to hold the audio recorder, mixer, radio receivers & walkie-talkie. (as well as the spare batteries and other crap that needs to be lugged around) The mixer that is pictured is a Shure FP32a unit, offering 3 input channels and 2 output channels. (stereo!) You would not need to get a separate wireless microphone setup for the recording engineer — he's "right there," so he may use a wired microphone to record his "header" information onto each cassette, flash memory card or other storage medium. Just remember that your mixer will require an input channel for each source ... interviewer, interviewee(s) & recording engineer.

     Consider the following possible scenarios:

• hiking the Lake Lansing North Park woodland trails;
• traipsing across 18 holes of an Oakland County golf course;
• rolling along on bicycles on the Hart-Montague rail-trail;
• taking a barefoot sunset walk on the beach at Hoffmaster State Park on Lake Michigan;
• cruising across Houghton Lake on a pair of jet skis;
• while doing the annual Labor Day Mackinac Bridge walk;
• after dark, sitting in folding chairs, around a crackling fire at a public or private campground.

     The only way that you will be able to record your on-the-go outdoor yackers is to stick microphones right under their mouths, mikes that will be connected to radio transmitters. Those transmitters will require receivers that in turn will be connected to an audio mixer which in turn is connected to the sound recorder (all of it in a mobile equipment bag that is being carried by a huffing & puffing recording engineer).

     And, your interviewer(s) and their interview subject(s) will expect that their hands will be free of encumberances — you can't have them carrying hand-held microphones with plug-on transmitters, hoping that they will keep the mikes sort-of aimed at their own mouths for however many miles that they will be covering over the course of one or more hours.

     On the plus side, the wireless microphones will pick up the natural background sounds at a much lower level than the voices. And, the microphones will be far less obvious to a casual observer. The interview will have the outward appearance of a casual conversation; the likelyhood of some "tourist" butting in on the interview should be lower ("Duh, whatchadooin'?"). Of course, the recording engineer with the belly-bag full of audio equipment that is trailing the interview group is another matter — "why the blue bag and what's the thing with the all the knobs and why are there little black boxes with antennas coming out of them and what's with all of the wires and are you making a moovee and is anybody in it that I know and when is it coming out and where's the camera; is that it up there in that aireoplain ...". My suggestion — make up some business cards on your computer and have a bunch to hand-off to the nosy putzes that may bother you.

     Taking your interview session into the great outdoors is going to elevate the whole project to a substantially higher level of expense and necessary skills. The substantial equipment rental cost, the knowledge & skill of your recording engineer, the mental organization of the interviewer to be able to keep their interview notes in their head ... here's your last chance to hit the [Alt]+[LeftArrow] keys and escape back to the safety of the referring webpage. Stop and consider what you are letting yourself in for before the rest of this page gives you a splitting headache!

     On the microphones page we wrote of the lavalier condenser microphones ("tie-tack") that may be seen being used by tv news & talk show participants. They very nicely satisfy the "no hands" requirement that a mobile interview will require. However, they do require DC ("phantom") power to operate, so whatever wireless (radio) transmitter equipment that is used will also need to supply that necessary DC voltage to the microphone to make it work. (lay in a good supply of the appropriate Alkaline batteries).

     If you've watched any tv reality shows you have seen people handling what look to be black cigarette pack-sized boxes with small antennas and a wire coming out of them; the wire having a small black knob or cylinder at their ends (the microphone itself). Those are the wireless microphone transmitter units. They are designed to be clipped onto a belt or the waist of one's pants, or just to be stuffed into one's pockets (as long as the microphone itself is clipped near the speaker's mouth — the clip looks like a miniature tie clasp, which is often where it gets clipped on tv news anchors; or on their lapel).

     Also restricting your choices of equipment will be the need for the microphone to mate-up with the transmitter ... most of the small belt-pack (clip on) transmitters will require an oddball connector to attach the microphone to the transmitter (many transmitters use a wire in the microphone cable as their antenna — no special connector & 5-wire cable means no transmission will be picked up by the receiver).

     So, if you're going to do this, you should really look at renting an all-in-one solution ... the microphone, transmitter and receiver units all being acquired as an integrated package. This will (hopefully) ensure that the microphone mates with the transmitter & the transmitter operates in a manner consistent with the radio receiver. And, if the recording session is going to be anywhere near water, you had better rent a waterproof set of equipment; you don't want to dunk a transmitter and need to purchase a replacement for it. New UHF transmitter packs may run upwards of $1,000 each, plus another $250 for the microphone that was attached to it.

     Within that phrase, "a manner consistent with the radio receiver," are a bunch of additional considerations that should dissuade you from picking up wireless microphone equipment in an ad-hoc manner. Radio transmitters and receivers are usually tuned to a single radio frequency (or block of radio frequencies)... you had better pick the same frequency (or frequency block) for both units! And, are they both transmitting in the same fashion; AM vs. FM; analog vs. digital; encrypted vs. unencrypted? Got all of these considerations covered? Well, there are more to worry about.

     Just like any of the walkie talkie radios that you might purchase at a local electronics store, wireless microphone systems require that your transmitter stay within a certain distance (range) of the receiver. The really el-cheapo systems might start "dropping out" (the receiver loses an adequate signal level and squelches the resulting static) over as short a distance as 50 feet of separation between the transmitter and the receiver. The much-higher quality broadcast grade units will usually let you get more like 300 feet apart (line-of-sight; few or no obstructions) without loosing the "connection". A bike ride on a trail or a walk through the woods will easily produce a separation of 100 or more feet between transmitters and receivers. Don't scrimp on the transmission range of your system. (top-end systems can reach 1,000 feet under ideal conditions) Don't go by the claimed power output/range of the transmitters ("...up to 50 milli-watts..."); go by the actual, independently-verified power output, range and operating conditions. Never get units who's actual power output is less than 25mw (0.025 watts) & preferably double that (50 milliwatts - 0.050 watts — still, that's only 1/20th of a full watt). The 100 milliwatt units usually are restricted to licensed commercial users (such as tv news crews) but will double your following distance if you can come by some of them.

     The older professional-grade Lectrosonics VHF units that I use have a verified power output of 50mw (0.050 watts) & the UHF units have an output of 70mw (0.070 watts) or 100mw (0.1 watts). Some of the home video & rock band-grade Audio Technica, Azden, Uniden, and other brand units that you may find being offered for rent or sale are rated at 10mw (0.010 watts) or less (barely 20% the rated power of the low-end, VHF band Lectrosonic units). Those transmitters will cut down your following distance by 80% or more ... you'll need to stay within 50 to 60 feet of the the interviewer and subject(s) at all times. Sounds like plenty of distance until you actually try doing it ... not a lot of margin for error (with the error being signal dropout if you get too far behind the interview group).

     The newest Lectrosonics, Sennheiser and Sony digital UHF transmitter units pump out the power, being rated at up to a full 100mw (0.100 watts; 1/10 of a watt) or 250 mw (0.250 watts; a full ¼ of a watt!); they would let you hang way back from the interview group if you're out in the woods or on the bike trail, and give you plenty of room to "float" variable distances behind the group with less likelyhood of signal (& audio) dropouts. If you got the chance to rent some of these units (at a reasonable rate) you'd be in great shape, technically speaking; it's just that due to their licensing requirements you may not qualify to rent some. Oh, well. The 50 & 70 milliwatt units work just dandy, too. (my "fantasy" transmitters would be waterproof, employ secure digital data transmission, have a telemetry stream to send a unit's DC power status back to the receiver so that you could know when the batteries are about to croak and pump out 1,000mw of power — a whole watt — to cut down on the signal drop-outs caused by foliage, structures, sand dunes, ....)

     A caution for those interviews being conducted in a windy location (at the beach; whizzing along on a bicycle) — be sure that your microphones have small foam wind screens on them. Those screens will not entirely eliminate the "whoosh" of the wind across the microphone pickup, but they'll make a big difference to the overall listenability of the recordings; the wind sound will be painfully obvious during the editing phase of the project, and there is usually very little that you can do to remove it (without removing the voices of your speakers as well). This is one of those situations where, if you have a stereo (2-channel) recorder & stereo mixer, put the microphones on different channels ... you might just get lucky, with the whooshing sound being strong on one channel but being mostly absent from the other channel. Later, while editing the recordings you can de-emphasize the bad channel and raise the volume of the clearer channel; the person who was drowned out may still be picked up by the other microphone sufficiently well as to be intelligible.

     And, if you haven't realized it yet, there's another "gotcha" to contend with. At minimum, you will have two people requiring microphones (the interview subject and the interviewer). You're not going to have them tethered to each other with a microphone cable — you will need to have a wireless microphone setup (microphone, transmitter & receiver) for each individual for whom sound needs to be recorded. If you are fortunate enough to be equipped to do a stereo recording, you can put one speaker entirely on the "LEFT" channel, a second speaker entirely on the "RIGHT" channel, and the third speaker (presumably the interviewer) in the "CENTER" (on both channels). Adding a fourth speaker (such as a second interviewer) just means that nobody is in the "CENTER"; they'll each be placed a little more onto one channel than the other (one a little bit "LEFT" and the other a little bit to the "RIGHT"). You will be trying to create the acoustic illusion of the speakers being immobile, arrayed left-to-right before the listener to the recording; it won't matter that all of the speakers themselves are wandering all over the place — they'll still sound as if they are constantly staying in the same relative positions. (one of my next equipment upgrades will involve acquiring a 4 or 8-channel digital recorder ... no need for a mixer in the field; just put each microphone signal into it's own input channel on the recorder. You will still need to adjust each input level on the recorder, but you will love the filtering capability that separate audio channels provide, once you get them into a computer)

     You may not have two transmitters operating on the same frequency ... so, each microphone setup will need to operate on a different frequency. And, because the transmitters operate on frequencies that have been allocated by the FCC for multiple "general-purpose" uses, you need to be careful that the local plumbing supply company isn't dispatching their employees on one of your setup's operating frequencies. (nothing ruins a recording like a plumber discussing someone's clogged sewer line on the same transmission frequency that carries your uncle's interview dialog) At least choosing a UHF-band system (over a VHF-band system) will likely eliminate that problem.

     If you are renting wireless microphone equipment be absolutlely certain that the equipment supplier knows where the units will be operated — renting equipment that is known to work interference-free in Lansing is useless if it is being used in Muskegon on a frequency that a local tv station is using to broadcast their video signal.

     Give up yet? You're going to need to pick a frequency band for the equipment to operate on — VHF or UHF (just like tvs). UHF is better but it is in the middle of the current tv spectrum and the equipment is much more expensive to acquire than the older VHF equipment (also making it much more expensive to rent than the VHF microphone transmitters/receiver sets).

     So, in summary, here are the various selection and operation considerations that you will need to reconcile:

• Total Number of Receiver/Transmitter/Microphone sets required (one per voice captured)
• Operating Frequency Band (VHF, UHF, or some of each)
• Operating Methods (AM or FM; analog or digital; clear or encrypted)
• The Viability of each equipment unit's Specific Operating Frequencies (interference avoidance)
• The Operating Range of the units (stated in feet ... this relates to power output of transmitters, in milliwatts)
• Battery power requirements (how many Alkaline cells will you need per day)
• For interviews requiring 3+ equipment unit sets — do you have/can you obtain a battery-powered mixer with adequate mixing channels?
• Do you have/can you obtain a battery-powered recorder?
• Do you have a lightweight set of headphones for the engineer to listen to the recording as it is being made?
• Do you have a means for the recording engineer and/or producer to communicate with the interviewer? (see below - Being a Good Communicator)
• Do you have an equipment carrying bag for the recording engineer to hold all of the equipment he'll be carrying (receivers, mixer, recorder + a boatload of spare batteries & adequate sound storage media)? It should be held up on a harness (best); at least by shoulder straps (engineer gets a sore neck after a while, especially for an all-day recording session, out on the trails, carrying 20 pounds of equipment, ...)
• Do you have a roll of low-tack medical adhesive tape. You are going to want to run the microphone's cable inside of a person's clothing from the place where it is clipped to the transmitter pack on their hip or in the middle of their back. This will prevent the cable from snagging (and being ripped from the back of the microphone) and will immobilize the cord on their flesh or interior clothing. Insist that everyone wear full tops and bottoms ... no barechested males & no bikini swimwear.

     Be prepared to burn through batteries like you never thought possible. Alkaline batteries (usually) should be the only type that you use (almost all others have dramatically shorter operating life spans); for the very latest transmitters some of the new high-output Lithium batteries are recommended. In practice, you turn on the transmitters, receivers, mixer and recorder and leave them on for 3 or 4 or 5 continuous hours, then take a break. During the break the recording engineer swaps out all of the batteries for the next 3 or 4 or 5 hour session.

     Your recording engineer will be buying batteries in bulk packages — a single day's worth of recording two people may easily consume $15 worth of batteries; adding more interview subjects means adding more equipment, meaning more batteries to be burned through per day. Our own transmitter/receiver sets will use a single 9 volt battery per unit, which will last, at best, about one day (8-ish hours). Interviewer & interviewee can easily consume eight 9-volt batteries per day. And, the recorder burns through eight AA-cells every four hours, with the mixer eating another six 9-volt batteries per day.

     A mobile, moving interview will probably entail at least double the expenses of a home-bound session. You really need to want to interview someone to put up with all of the hassle and expense of conducting an interview-in-motion. This should give you a clearer picture of why we charge so much money to conduct a mobile interview for you.
 

A Motorola T6220 walkie talkie. I picked up a pair in a close-out bin at Office Max about 6 years ago — they have a number of uses beside the one described here. These units come with a belt clip, have a headset jack and offer a voice-activate transmit option. And, they eat AA batteries, 3 at a time, two feedings a day.

     Cobra, Motorola, Uniden and other manufacturers market these units, usually found at stores like Best Buy, Staples, Office Max & Office Depot. You will often find them bundled in packages of two units. Since the maximum distance between the two units will only be a few hundred feet you might as well save some money and get the cheapest units offered (lowest-powered). It is reasonable to pay the premium price for the recommended headphone/microphone headset that the walkie talkie uses — assuming that it has a talk-to-transmit (VOX) capability (you may need to go online to the manufacturer's website store to purchase it). Buying sets with a belt clip permits your interviewer to use the unit without needing to hold onto it while they are moving & conversing with the subject. Spending $30 to $50 to purchase a pair of them compares favorably with the cost of a single two or three hour cellphone connection between you engineer and interviewer; and that's if you are not roaming or out someplace with spotty or non-existant cellphone coverage (Lake Michigan beachs are notorious dead zones — a 400-foot tall sand dune between you and the nearest cell tower does a really fabulous job of blocking the signal).

BE SURE that the walkie talkies are not operating on the same frequencies that your wireless microphones are set to transmit at! (a pretty safe bet if you have a UHF wireless microphone setup)

     At the county parks where I work (Lake Lansing South, Lake Lansing North & Lake Lansing Boat Launch) we use this type of walkie-talkie for communication between the rangers & managers. The park manager, standing on the beach grass area outside of his office in the carousel building can communicate clearly with someone on the opposite side of the lake at the boat launch — a distance of about 1½ miles across the lake; obviously a clear, unobstructed, line-on-sight distance. Reaching the rangers working in the park further beyond the boat launch is problematic — standing in the wrong place in the North Park will result in zero reception of the manager's call. Anyway, what this all means for your mobile interview project is that if the recording engineer falls too far behind the interviewer/subjects that he is trailing he will still be able to communicate with that group (due to the greater range of the walkie-talkies). The engineer can tell the group to 'stop talking' because he's lost their microphone's signal, to 'slow down' their pace and let him catch up (and get back within range of their microphones).

     If you have a producer tagging along (back with the recording engineer or out on their own someplace between the engineer and the rest of the group) you will need a third walkie-talkie set. Have one or more videographers? Then you will need a walkie-talkie set for each person. And, if you are videotaping the interview you may need to have a secondary radio transmission setup that will take the output of the mixer and send it, by radio, to a receiver mounted on each camera that will feed the sound into each camera's microphone input jack. (this keeps the sound synchronized with the video of them speaking). Of course, if you have a higher-end digital audio recorder you may synchronize time codes with the cameras and skip the need to record any sound onto the video tapes (it will get placed there later on, during the editing phase of the project).

     If we haven't talked you out of conducting an interview in the great outdoors by now, all we can say is "good luck!" Just be sure to get very familiar with your equipment and conduct some serious practice sessions with it before heading outdoors with your interview subject. Murphy's Law is alive in well in the wild!!!

     If the interview is being conducted mid-May through mid-September, everyone should carry a small to medium bottle of water on their person to ward off dehydration. You may well find yourselves a mile or more from a drinking fountain or vending machine. The best advice for avoiding dehydration is to not conduct your interviews at the height of the mid-day sun. Here in Michigan that means from noon until around 3:30 pm (solar noon is around 1:45 EDT here in the Lansing area).

     In Michigan, anytime from mid-April through the first hard frost, it's mosquito season. Pack plenty of 100% DEET bug repellant; that weenie "herbal" or "natural" mosquito repellant is pretty useless. My second job is as a park ranger ... outdoors ... at night ... feeding the darn things (like that 15% DEET substitute that you got at the dollar store is gonna ward off a cloud of hungry man-eating varmints ... more likely, they'll treat it like gravy covering a prime cut of food). I don't screw around taking half-measures when it comes to bug repellant; neither should you. There are too many serious mosquito-born diseases out there to let them feed, unmolested, upon you.

     If anyone in the group has a medical issue (asthma, diabetes, heart condition, insect sting allergies, etc.) be absolutely certain that their inhalers, glucose monitors, emergency medications, whatever, are on their person before leaving the parking lot; that others in your group know which symptoms indicate the onset of a medical problem or emergency; and what the proper response should be to address those problems in a decisive manner. When you are a mile down a secluded beach, with no cell service, and a medical emergency is happening, you can't afford to take half-measures and just hope for the best.

     And lastly everyone should hit the restroom before heading out ... most of the places that you will be going will not have a whole lot (or any) conveniently located porta-potties. This also means that nobody should be downing a Mega Gulp of prune juice or Super-Grande mocha latte cappuchino immediately before they hit the trail. Bring along a newspaper or magazine, commune with the procelain for 15 minutes (or what passes for it in the parking lot porta-potty) and be "relieved of your burdens" before setting out on the interview.