DSC VHF Radios

With DSC, new VHF radios offer safety and convenience.

October 4, 2007

Today, the typical marine electronics or equipment catalog may list 30 different fixed-mount, 55-channel-programmable scanning VHF radios, some selling at prices that begin at less than $100! While these are usable, the newer radios, those that are “type accepted” (approved for sale by the FCC) after the beginning of 1999, are a cut above because they are required to have at least a minimum Digital Selective Calling (DSC) with mandatory distress call capability. These radios, often referred to as complying with the “SC-101” specification, sell at prices as low as $150. More capable DSC radios conform to the Class “D” DSC specification and usually have a second receiver that is used to continuously monitor channel 70, the DSC hailing channel-although there is an important distinction to be noted here (see sidebar). Radios that meet this specification usually provide additional features, including expanded memory capacity for storing other vessels’ Maritime Mobile Service Identity (MMSI) numbers and in some models, keypads to facilitate data entry. The highest VHF/DSC radio specification is Class “A” and is required for large ships and other vessels that must meet Global Maritime Distress and Safety System (GMDSS) requirements. While a Class “A” set can be installed on any vessel, the less costly Class “D” radio is the preferred choice for virtually any yacht. With an eye to those VHF radios that meet or exceed the latest criteria for DSC safety and convenience, here are the notable offerings from a range of manufacturers for the 2005 boating season and beyond.

Furuno offers two VHF radios, the Class D FM3000 and the Class A FM8500. The FM3000 operates from the boat’s 12-volt DC supply and covers all of the normal U.S., Canadian and international channels. When connected to a GPS receiver the LCD displays latitude, longitude, in addition to the normal channel ID and mode indications. The optional FM3010 second station microphone allows all non-DSC functions to be controlled from the bridge. The GMDSS compliant Class A FM8500 operates from a 24-volt DC supply and provides coverage for all international channels. A full keyboard facilitates management of the radio’s multiple DSC functions. Contact:

ICOM America’s comprehensive selection of VHF radios includes the SC-101 models M302, M402, M422, M502 and the Class D M602. All of these radios cover the usual 55 communication channels plus the weather channels, with automatic weather alert. The Class D M602 is ICOM’s most capable VHF radio. With its two receivers, one permanently tuned to channel 70, the DSC hailing channel, DSC calls will be heard regardless of which working or weather channel is active. Memory capacity allows up to 100 MMSIs and associated information to be stored for immediate recall. The DSC functions are supported by a full alphanumeric keypad. Contact:


Lowrance offers the LVR-850, a SC-101 radio capable of operating on all U.S., Canadian and international channels plus the NOAA weather channels. The radio can be used in all normal communication modes and to initiate DSC distress, all ships, directory (using a stored MMSI), and “last” call (an immediate return to the last used MMSI). The NOAA weather channels are continually scanned for severe weather alert notification. Contact:

Navman’s VHF radio lineup is comprised of the VHF 7100 and the VHF 7200, both capable of DSC operation per the SC-101 specification. Both radios are capable of sending and receiving DSC calls and can log up to 10 distress calls plus 20 routine calls. Up to 20 MMSIs and associated names can be stored for quick access when making DSC hailing calls. The model 7200 includes a barometric pressure sensor whose output is presented on the LCD in bar graph form along with a predictive icon. Contact:

Northstar is entering the fixed-mount VHF/DSC radio market with the new black box NS100 remote-mount SC-101 Class D radio. All of the radio’s controls and the LCD screen are contained in the handset. Two handsets can be used with the NS100 with an intercom function between handsets. An external loudspeaker is provided in addition to the speaker incorporated in the handset. The built-in loudhailer/foghorn is supported by a 20-watt audio amplifier. The receiver specifications are excellent, offering more than an 80-dB performance margin for adjacent channel selectivity, intermodulation rejection and residual noise. Contact:


Raymarine’s fixed-mount VHF/DSC radio product line consists of the Ray 53 and the Ray 215, both SC-101 units. These radios offer similar capabilities including the basic DSC functions, weather alert, on-microphone distress key and channel selection. The model 215 allows the addition of a remote, second handset that fully controls all radio functions and can be used as an intercom. Raymarine offers three Class D radios-the model 54, 230 and 240. The Ray 54 is capable of initiating the mandatory DSC distress call plus individual, group, all ships and position request hailing calls. The radio will log up to 10 distress calls plus 20 routine calls. Distress calls may be sent as undesignated or with one of 11 specified reasons to aid the Coast Guard’s response. A 20-entry phonebook is available for storing MMSIs and identification of frequently called stations. The Ray 230 and the newer Ray 240 are remote mounted and can operate with multiple handsets. Contact:

Simrad’s VHF radio product lineup consists of three Class D radios, the RD68 plus two RS80 series units, the panel-controlled RS86 and the handset-controlled RS87. The RS80 series radios can function as intercoms and include loudhailer, automatic and manual foghorn signaling. Provisions are included for additional speakers, remote handsets and optional voice scramblers. The RS87 uses a remotely mounted receiver/transmitter unit, with all controls available on the telephone-like handset. The information contained in a DSC hailing call, calling station’s MMSI, position and type of call can be transferred to a compatible chart plotter. A call log is provided for distress calls, for routine communication calls and as a “telephone” directory for routine calling. Contact: Reader Service # 158.

Standard Horizon offers five DSC-capable fixed-mount radios. The very compact Spectrum GX2355S and Intrepid GX1270S are SC-101 sets capable of performing all of the basic DSC functions including distress signaling, exchanging position information with other DSC radios and presenting DSC-derived position information on a connected chart plotter. Both radios provide channel scanning and automatic weather alert. Standard’s Phantom PS1000 and PS2000 are black box models that allow the radio transceiver to be mounted out of sight with only the RAM microphone located in reach of the helmsman. The Quantum GX3500S is the top of Standard’s fixed-mount VHF radio lineup. A Class D radio, it is equipped with an alphanumeric keypad to facilitate the entry of MMSI and vessel identification data into the DSC directory. The radio can accept two RAM microphones to provide the vessel with both multi-station radio control and intercom functions. Contact:


Uniden’s DSC-capable fixed-mount VHF product line begins with the entry-level Solara, an SC-101 radio, complete with scanning and weather alert capability. The Class D-compliant UM525 is next up in capability and features, and is easily identified by its unusually large and easy-to-read monochrome LCD screen. The model UM625 is the top of the line and provides the advantages of the highest performance specification receiver in the Uniden VHF radio range, plus a 30-watt loudhailer/foghorn and a color LCD screen, a feature not often seen in VHF radios.

Uniden’s experience in the wireless, 2.4 GHz telephone field is evident in the new WHAMx4 wireless digital remote unit. Up to four of these hand-sized units can be used with either the UM525 or UM625 radios, functioning as full-capability remote controls. Contact:

Is it really a Class “D” VHF/DSC radio? As the use of Digital Selective Calling (DSC) to initiate communication with VHF radios becomes more common, the ability of the radio to receive a DSC hailing call on channel 70 will become more and more important. Many of the VHF/DSC radios now in use and on store shelves have a single receiver that scans for calls on channel 70 along with all other scanned channels, yet reception of a signal on any other channel will prevent the radio from receiving a hailing call on 70. Most of these radios are identified as meeting a unique U.S. specification, SC-101.


Radios that have an additional “watch-standing” receiver constantly tuned to channel 70 are generally listed as VHF/DSC Class “D” radios and provide superior DSC functions. However, the Class “D” VHF/DSC radio is defined differently in two separate international specifications, IEC 62238 and ITU-R M.493-10. The IEC specification requires that the radio be equipped with a watch-standing receiver for channel 70 that must always be available to receive calls-it cannot be used to scan or listen to signals on other channels. Virtually every country other than the U.S. requires that a Class “D” VHF/DSC radio comply with the IEC specification.

In the U.S., a radio can be identified as a Class “D” set even if it complies only with the ITU specification. This specification spells out the types of DSC calls the radio must be able to transmit, but it does not require a dedicated channel 70 watch-standing receiver-a single receiver that scans channel 70 is sufficient. Purchasers of Class “D” VHF/DSC radios should examine the radio’s specifications to determine if it meets the IEC specification (has a separate channel 70 receiver) or merely meets the ITU requirement and uses its one receiver to do everything. It’s a big difference.


More Uncategorized