DoomLabs RadioTech - Radios used by Dead By Dawn

Introduction

Team Dead By Dawn finds radio communication essential for effective team play. They're useful for on-field communications as well as off field communication & co-ordination.

Once you decide to use radios for your squad you will need to consider your choices and make a thoughtfull decision. You don't all need to use the exact same equipment but it must at least be compatible and have adequate range & capabilities. In team Dead By Dawn we use several makes & models of radios. This for several reasons. The first is that this just evolved, the second is that everybody has preferences - some prioritize compactness - some prioritize ruggedness - some prioritize based on cost.

When considering radio choices you will need to ensure that you have adequate power, adequate intersection of frequencies (channels), and adequate intersection of CTCSS codes (so called Privacy Codes).

First of all, avoid the inexpensive "personal communicators" in the 27 & 49 mhz bands. These inexpensive, low power, radios are next to worthless. You want an FRS if not GMRS class radio. Also note that not all FRS radios transmit at the same power level and neither do the GMRS radios. Choose FRS or GMRS based on your squad's needs - and I suggest testing on your worst-for-radio field with a couple of radios before you comit to something that might not work well.

Note also that the range you achieve will often be substantially less than that advertised. This is because advertised distances are absolute maximum distances and over clear terrain at that. If there are any woods and/or hills your range will be substantially reduced. Your carry will also affect distance, particularly if it's on your chest and you're crawling in your ghuillie suite - you will have substantially reduced range.

Here's a general range chart:

Power	Advertised Range	Likely Range
500ms (0.5W)	2 miles	Maybe Wayne's World; small local fields
1 W (GMRS only)	3 miles	Maybe Wayne's World; small local fields
2 W (GMRS only)	5 miles	Wayne's World, Most of Skirmish
5W (GMRS only)	7-10 miles	Good coverage of Skirmish

Team Radio Models

The following are links to and manuals of radios used by Dead By Dawn.

Radio Shack GMRS Model 190_0903_5W
Audiovox_GMRS_Model 1525

Double pin headsets; lightweight - likely the most fragile - but very compact; comes with NiMH batteries & chargers.

Cobra PR1000
Cobra PR 1100
Uniden GMRS480 15-channel FRS/GMRS Product Info; Manual

Notes: Uses the single pin headsets
Bonuses: water-resistant, nickel rechargeables and earbud/ptt included.

GMRS / FRS Cross Reference Chart

GMRS / FRS Cross Ref Chart

Speaker Mics, Headsets, and Ear Buds

You must choose accessories carefully, especially if you are mixing brands. In particular, we've had problems with accessory items triggering the "Call" function when keying the mic. This is one sure way to have your own team members "modify your setup" as soon as they can track you down.

The best setup is a mic and speaker mounted in your headset. This way it is always there and working an can often be used hands free (though watch VOX - it's less than useful in practice). Headset mounting is also much quieter in use and less likely to reveal your position with talking or listening.

While you can mount ear bud setups into your mask, the best setup, bar none, are the MotoComm motorcycle headsets mounted in your mask. These are designed for noisy environments and you'll find the speakers loud and the microphones sensitive and directional. A truly unbeatable combination. And, while not cheap (~$60) you'll find yourself wishing you'd bought one first after you've tossed / broken alot of cheaper junk - so watch the false enconomy of cheaper goods.

Throat Mics

We're starting to use Throat Mics. They're great for many reasons. They're quiet for both talking and listening (good for snipers), and they're also great as they don't mount in your helmet. Mask on or off you're always in communication, not so with the Motocomm mounted in the mask. I've also gone through a couple sets of cables for the Motocomm Headsets and the cables can be tangle monsters. While I love the quality of the Motocomm Headsets many of us are slowly switching to the Throat Mics.

The current choice and an excellent price is this headset from Robert at Cops911.com: http://www.cops911.com/category.asp?id=131

Robert has sponsored us - but that's not affecting my opinion. Robert's just a great guy and his products are very high quality. Trust Doom on this. Tell Robert that DBD DOOM or Marksman setn you.

Motocomm Headsets

The MotoComm motorcycle headset products - particularly the MC-500 & MC-700 series products - are the best in-mask headset products available.

The Motocomm headsets come in double pin models - MC-551 & MC-751 - and single pin models - MC-552 & MC-752 and they've got a good compatability chart to ensure you buy the right model

When selecting, it really boils down to the double pin or single pin model based on your radio's needs. Otherwise you'll likely care less whether you bought the MC-551 vs the MC-751. For example the MC-551 vs the MC-751 are essentially identical - the difference was intended for full face vs open face helmets - and you'll find that either zip-ties nicely into your mask. So that's personal choice that will otherwise not affect functioning.

Here's a picture of the internal mounting of an MC-751 in my mask:

To purchase, we like Crawford Motorcycle Supply, but here's a Google Search for Motocomm Headsets.

Speaker Mics

Many players like speaker mics - either as primary microphone - as accessory when in-mask unit is not being worn - or because they bought it first and don't want to invest more $$ in the in-mask headset units.. These are handily clipped to your weak should for a convenient tilt head button-press-to-talk.

Ear Buds

Ear buds are asking for trouble. The speakers are weak, they fall out of your ear, they're not very loud when in-mask mounted, and the microphones are susceptible to call function actuation. Just say no to ear buds.

Headsets

Stand alone headsets, as a base or desk operator would wear look fine, but don't work well in practics. This is because none of the parts are designed to be worn under a mask. So you'll find the band being squished against your head, the speaker squished into your ear (due to the boom & band attachment), and the boom in the wrong place (esp if it's not bendable). And using them is a two step process with your mask.

You may be able to part one out for permanent mounting in your mask - but you'll find the Motocomm units (do we like them?) far superior.

Physical Radio Modifications

Some of our team members physically modify their radios. This is typically to physically remove the Call Button. The call button is essentially never used and is a major source of annoyance in radio communications. On some models it's triggered by double clicking the microphone; on others it's a separate button. You likely can't modify a radio utilizing the double click method but you can physically remove the button on models that have a separate button. You'd be surprised how easy it is for that button to get bumped in play.

That Damned Call Button/Function

"Who's hitting their damned call button!??!!" is often hear over the radio. So it's important to learn how your radio actuates that function so you know how NOT to actuate it in play. We've also found that some accessories, ear buds in particular, are very bad about *always* actuating the call function. So learn how to disable it on your radio (if it's possible; sometimes it's not) whether physically or via controls. Learn how to NOT actuate it. In particular, good PTT techique helps a lot. A weak thumb on the PTT may "bounce" the switch and cause the call function even if you think you just pressed the button.

Privacy Codes / Privacy Channels

Many radios, particularly one oriented towards consumers, tout Privacy Channels. There are no true private channels (though one Motorola I know of does have frequency inversion voice scrambling built in). What you have are Radio Channels which are assigned a specific frequency and you have CTCSS Codes. CTCSS Codes complement Radio Channels and give the appearance of multiple channels - but you don't really have multiple channels and you don't really have privacy.

Radio Channel

Add FRS & GMRS radios operate on fixed frequency channels. These frequencies are assigned by the FCC and are selected by changing the channel on your radio.

All talking you do will be one one of these frequencies. Period. You have no more channels. Your radio may have CTCSS capabilities which give the appearance of Privacy Channels, but all transmissions, CTCSS enabled or not, will be on one of the channels (usually 1..14 or 1..22)

Note that the FCC assigns FRS and GMRS frequencies - and the FCC lists them in order - but the FCC doesn't really assign channel numbers. Your radio manufacturer will tell you, in the owners manual, which frequency corresponds with which channel for that model.

Most FRS only radios will have frequency ->channel assignments that match.

Most FRS/GMRS that have the same number of channels will have frequency-> channel assignments that match. For these the FRS channels typically match other FRS radios (i.e. 1..7 typically matches FRS only 1..7) but the GMRS channel assignments don't line up directly to GMRS only radios.

Note that it can be confusing if your squads radio models don't match. It's highly suggested that your team have a standard setup or set of compatible radios with any odd-men out being assigned "Paint 'n Air Boy" duty as well as being responsible for knowing what "13/20" means on his radio AND knowing what any on field "switch to xx/yy" means as well.

CTCSS Codes

CTCSS Codes: "Continous Tone Control Squelch System". This feature is what is commonly touted as providing "Privacy Channels".

There are 64 CTCSS Codes of which 32 are EIA standard tones. They are subaudible tones in the 33 to 254.1 HZ range. If one is selected then that tone is superimposed on your microphone signal and then transmitted on the channel you have selected. If a receiving radio, set to the same channel, also has ANY CTCSS code set then the receiving radio will only break squelch if it receives the matching CTCSS tone (hence the name Continous Tone Control Squelch Control System).

To review what your radio does, setting a CTCSS code puts that radio in the mode where (1) it will always transmit that tone when transmitting your audio, and (2) it will only break squelch if it receives that tone.

Since this is an audio tone that is overlaid on your voice this serves only to keep your radio silent on that particular channel until it receives a matching tone. As such it does not subdivide that channel.

Let's consider a very common - but not commonly understood - CTCSS induced channel collision.

Team Splat On You selected 13/22 (CTCSS 22 on channel 13). Team We Don't Wipe selected 13/11 (CTCSS 11 on channel 13)

Why did they select these? "Because they weren't busy." But, aren't they? What they were really saying is that "I didn't hear anybody else on 13/22 (or 13/11)" Remember that CTCSS only keeps your radio silent, while it listens on that channel, until it receives that CTCSS code as part of the audio. So all they've really said is that nobody is using CTCSS code 11 on channel 13.

So, if Splat On You is transmitting at the same time that We Don't Wipe is transmitting, what is going to happen? They are going to double (CB jargon for collide on the air waives - double up on each other). They are both transmitting on and tying up the same channel! They are interferring with each other and don't even realize it.

This is typically what is happening when the signal from your team mate is strong, yet he is breaking up. More than likely, he is not truly breaking up (his signal is strong isn't it?) But a stronger, or strong enough signal from another radio is interfering. Transmit power as well as proximity of all players sharing that channel will dictate what each player will hear (Bob may hear Tom just fine while Ed thinks Tom is breaking up - but the problem is Bob is near Tom whereas Ed is farther away from Tom and likely nearer another player using the same frequency - hence interfering.

You really don't have any privacy. Here's why. If you don't select a CTCSS code (typically done by selecting 0 on some radios) then your radio will break squelch or let you listen to everything it hears on that channel. So somebody on 13/0 can listen to BOTH Splat On You on 13/22 AND We Don't Wipe on 13/11 at the same time. And you can diagnose doubling on your frequency by setting your code to zero and see if you hear players other than your own team. No Real Privacy.

Note that some radios have a BCLO - Busy Channel LockOut function. This will keep YOU from doubling if somebody is transmitting on that channel (using a different CTCSS code). But (1) not all players know what this means (2) consistently set it and (3) it's hard to use as you have to look at your LCD to see if you are locked out - you can't just key and talk.

Benefits

The benefits of CTCSS are pseudo privacy. I know we said you have no privacy, but with the number of players at scenario games, you will not be able to find a channel (i.e. frequency) that is clear for your team only. If you do not use CTCSS then you will always be listening to continuous chatter of many other teams - and likely garbled chatter as they frequently double on each other. If you DO use CTCSS then your radio will be silent except for your team provided you found a channel/CTCSS combo that nobody else is using.

So CTCSS is usefull but one must understand the common limitation - which is doubling on other players using the same frequency with a different CTCSS tone.

Limitations

The main limitation is doubling on other players using the same frequency with a different CTCSS tone. This is mistaken for poor range and/or lack of power.

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