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OTS Buddy Phone System

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OTS Buddy Phone System

The Buddy Phone® D2 is a digital, micro-miniature, ultrasonic transceiver allowing communication between two or more scuba divers or surface stations.

OTS Buddy Phone System

OTS Buddy Phone System
OTS Buddy Phone Through Water Communications
OTS Buddy Phone Through Water Communications
OTS Buddy Phone Through Water Communications
OTS Buddy Phone Through Water Communications 	OTS Buddy Phone Through Water Communications
Guardian Mask with Buddy Phone Black
Guardian Mask with Buddy Phone Blue
Guardian Mask with Buddy Phone Red
OTS Buddy Phone System
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The Buddy Phone® D2 is a digital, micro-miniature, ultrasonic transceiver allowing communication between two or more scuba divers or surface stations. Using "Digital Signal Processing" (DSP) techniques, the Buddy Phone produces uncompromising speech clarity. Special digital filters, combined with the latest diver microphone technology, virtually eliminate unwanted noise and distortion. With the addition of an Aquacom® surface transceiver, communications between the surface and divers are possible.

The Buddy Phone utilizes the push-to-talk method, which has been shown to be the most reliable way to activate the transmitter. The greatest advantage of the push-to-talk method compared to a voice activated system (VOX) is the elimination of the VOX delay required between transmission and reception that can result in lost communications.

The Buddy Phone is worn over the ear and is mounted on the mask strap. The diver hears through an integrated earphone that is built into the rear cover of the Buddy Phone® housing. Innovative digital squelch technology actually distinguishes between noise and voice to activate sound reception only when voice is transmitted, no matter how much background noise is present. The result is squelch that can be used even at longer ranges, a great benefit especially in high-noise environments such as coral reefs.

All Buddy Phones can receive communications from all other Buddy Phone® transceivers within range and on the same frequency. The SP-100D Surface Buddy Phone is available from OTS for communications between divers and anyone on the surface. See Table 1 for a list of several other compatible transceivers manufactured by OTS.

The Buddy Phone has been engineered with simplicity in mind. There are no physical adjustments other than the usual mask strap adjustments and installation of the 2nd-stage regulator (although no installation is required with the MKII series Buddy Phones).

TABLE 1: Other Transceivers Compatible with the Buddy Phone

Brand Diver Transceivers Surface Transceivers
Aquacom® SSB-2010 STX-101 surface station
  SSB-1001B STX-101M surface station
Magnacom® MAG-1003D MAG-1001S (standard)
  MAG-1004HS MAG-1004-PS portable surface unit


The RX-100 receive-only Buddy Phone® is designed as a listening device to be used with all compatible transceivers within range and on the same frequency. To install the RX-100, fully insert the mask strap into the strap retainer slot on the RX-100 so that it is positioned over the ear. Entering the water causes the RX-100 to power up into receive/standby mode, ready to receive a message. Note: This is a single frequency device; the frequency must align with the chosen frequency on the 2-Channel Buddy Phone in order to operate effectively.

The transceiver package contains the electronics, earphone, battery compartment, strap retainer, and the battery plug. The transceiver package is worn over the ear, held by the mask strap, and forced into position by the partially arched headband/earpiece.

The earphone is designed to allow easy listening through most hoods. However, it is designed to be most effective when directly over the ear canal. There are many ways to enhance the earphone efficiency. Some diving hoods that are particularly thick may require alteration. When necessary, a thin 1/32-inch membrane of neoprene or latex rubber, approximately 1 inch in diameter, can be stitched or cemented to the inside of the hood. A 3/4-inch hole is cut into the hood before the membrane is installed. The Buddy Phone is worn over the opening in the hood and therefore prevents the exchange of heat from the diver's head. This modification provides an “acoustic window” between the Buddy Phone® earphone and the diver's eardrum.

It is important that the diver adjust the transceiver package so that the earphone is directly over the ear canal. This placement will ensure that maximum volume is delivered to the diver. The transceiver can be adjusted forward and backward on the strap as well as up and down. The diver should equalize his ears for maximum hearing sensitivity.

Some people with particularly sensitive hearing may find the volume too loud. Under these circumstances, the Buddy Phone can be moved to a less ideal position on the diver's head, thereby reducing the volume; or a small piece of wetsuit material can be added to the earphone opening.

Many of our Buddy Phones are available with your choice of microphone. Our standard microphones are the ME-16R Hot-Mic® and the Super Mic®.

ME-16R Hot-Mic® (912086-000)
The patented ME-16R Hot-Mic® is a state-of-the-art 150-ohm, water-resistant dynamic microphone element designed for long, trouble-free use and the highest intelligibility possible.

Although the Hot-Mic is trouble free, it should be maintained. Rinse it with freshwater after use to get all dirt, debris, and salt water from the grill. Dry it with a clean, soft towel. If the element ever needs to be replaced, it is easily removed by unscrewing the two small screws located on its base.

Getting the microphone wet does not harm it, but its element can withstand only an 8- to 10-foot depth/pressure differential. If you removed your diving FFM at the back of the boat and the microphone became wet, there would be no problem; but if you dropped it more than 8 to 10 feet into the water, the change in pressure probably would damage the element. In tests at 30 feet we have removed and replaced the FFM without any problem; but if after removing it we had dropped down to 40 feet, the pressure difference may have damaged the microphone.

Super Mic® Depth Master
The Super Mic offers patented technology* that overcomes a limitation of other microphones. It can be used at any depth and—unlike the Hot-Mic and many other microphones—can withstand changes in depth while submerged, remaining undamaged if the diver descends with the mask flooded (e.g., on removal and stowage of the mask when switching to a different air supply system). It is a ceramic microphone with a compact, lightweight design and noise-cancelling properties, reducing background noises for clearer communications. When only the highest quality of intelligibility is required, the Hot-Mic is the preferred choice; but the Super Mic's intelligibility is sufficient for most diving situations.

To assure clear communications when using the Super Mic, it should be no more than 1/4 inch from the corner of the diver’s mouth.  After each dive, clean the Super Mic by rinsing it with freshwater and drying it with a clean, soft towel. No other maintenance is required. Note: Do not press on the microphone diaphragm; doing so may cause damage.

The Buddy Phone is activated on submersion. Activating water contacts (the two screws located on the front of the housing) serve as the sensor electrodes. When the diver enters the water, a small electric current flows between these contacts.  When the diver exits the water and the current flow ceases, the associated circuitry switches the power off. There is a delay built into the switch circuitry. The delay lasts for about five minutes and is useful for surface checks (air tests). One important tip: Do not place the Buddy Phone on a wet surface or wet material; the unit would stay on using battery power.

The range of the Buddy Phone has been limited to that which is required by the recreational scuba diver. As with any acoustic underwater communication system, there are directions around the diver's body that are less sensitive than other directions. The Buddy Phone is less sensitive in a line that projects directly from the diver's opposite ear. This area is known as a “shadow zone.” The Buddy Phone will not transmit through solid objects such as a ship's hull, rocks, etc. Reception is still possible around these objects as a result of reflections from the surface or ocean floor.

There is a low-battery alarm to announce a low-battery condition (see the Low-Battery Alert section). Replacement of the battery restores receiver clarity. The transmitter will not suffer as much loss in clarity due to a weak battery, but the range will be reduced.

It is extremely important that the battery cover area is thoroughly dry before opening it to replace the battery. Water entering the housing can corrode the battery contact springs, resulting in system failure. The battery cover o-ring surfaces on the housing and the cover should be inspected for dirt and debris and removed with a soft cloth. Do not use a sharp object to clean the o-ring groove or the mating surface on the housing. Scratching these surfaces can allow water to leak past the o-ring.


The OTS Buddy Phone has the following specification:

Nominal Range: 50 to 500 meters depending on sea conditions & noise levels.
Transmission Type: Ultrasound using upper single sideband (USB)
Transmit Output Power: 0.5 watts PEP (peak envelope power)
Standard Frequency (PEP):

  • Recall & tone: Freq. A (Channel 1): 32.768 kHz USB
  • Freq. B (Channel 4): 31.250 kHz

Audio Bandwidth: 300 to 3,000 Hz
Automatic Gain Control: Greater than 80 dB
Earphone: Ceramic
Microphone: ME-16R Hot-Mic (Dynamic) or Super Mic (Standard)(Ceramic)
Transducer: Ceramic cylinder
Battery Type: Alkaline 9V or Ultralife® lithium 9V or 9V Li-polymer rechargeable. Batteries not included
Maximum Operating Depth: 130 feet in sea water (fsw)
Weight in Air:

  • Buddy Phone® for FFM: 8.1 oz,
  • XT-100: 13 oz., including HM-2,
  • RX-100: 7 oz.

Product Documents

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