Standard-Horizon GX1400 VHF Marine Band DSC Radio

VHF Marine Band radios, protocol, radio communication theory, practical advice; AIS; DSC; MMSI; EPIRB.
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Standard-Horizon GX1400 VHF Marine Band DSC Radio

Postby jimh » Sat Nov 09, 2019 11:59 am

Fig. 1. GX1400 radio in black case. The noise-cancelling microphone includes five buttons: PTT, Channel UP-DOWN, Hi-Lo power, and jump to 16.
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Standard-Horizon has added three VHF Marine Band radios with Digital Selective Calling to their line of fixed-mount 25-Watt radios. The model variations are:
  • GX1400 base model DSC Class-D radio; available in white or black case;
  • GX1400GPS adds a 66-channel internal GPS receiver; available in white or black case;
  • GX1400GPS/E adds 66-channel internal GPS receiver and ATIS; it is a European-only model; available only in black case

(Note that all VHF Marine Band DSC radios intended to be sold in Europe are generally being configured with an integral GNSS receiver based on the most recent ITU recommendation. ATIS or Automatic Transmitter Identification System is a protocol used only on European Inland Waterways. Each time the radio PTT microphone button is released at the end of a transmission, an ATIS radio automatically transmits a unique code identifying the transmitter.)

The most significant features of the GX1400 radios are:
  • astonishing low price
  • integrated GPS receiver on GPS models
  • IPX8 submersible
  • NMEA-0183 interface
  • compact size
  • three front panel soft keys for user interface
  • three-year warranty
  • permits reset of MMSI in the field by the user with appropriate code supplied by manufacturer
  • meets ITU Recommendation for Class-D DSC radio
The GX1400 radios have the FCC ID K6630653X3D, and Yaesu Musen Co., Ltd. (the parent of Standard-Horizon) received a grant of equipment authorization certification issued under the authority of the Federal Communications Commission by Timco Engineering, Inc. of Newberry, Florida, on April 8, 2019. This is typical of the process used by the FCC in which they have delegated authority for issuing grants of equipment authorization certification to recognized testing laboratories in the USA. Timco Enginering is a recognized Telecommunications Certification Body or TCB for licensed radio transmitters in the Maritime Radio Service Part 80 of the FCC Rules. More information about TCB procedures is provided in a separate article.

A discount retailer show the GX1400 base radio for sale at about $120, which I consider to be an astonishing low price for a device of this complexity and excellence in design and manufacture. The prevailing price for the GX1400GPS is just $20 more at about $140.

GPS Receiver
The integral GPS receiver is described only as a "66-channel". (The use of the term "channels" in describing GPS receivers is explained in a separate article.) The receiver sensitivity is specified as -147 dBm, and time-to-first-fix from a cold start is impressively stated as 1-minute typical. No mention is made of ability to receive other navigation satellite constellations such as GALILEO or GLONASS. The GPS system specification for signal level is no less than -130 dBm at the earth's surface. The receiver in the GX1400 should provide 17 dB of reserve sensitivity.

IPX8 Rating
The GX1400 is rated as environmental resistant to IPX8, which requires the ability to endure 30-minute immersion at a depth of 5-feet. The radio should be tolerant of mounting in open area of a boat.

NMEA-0183 Capabilities

All the GX1400 radios provide a NMEA-0183 serial port to interface the radio with other devices, notably a GPS receiver for input of position data to the radio and a chart plotter for display of position data contained in output from the radio. The NMEA-0183 port provides the proper differential signals for TALKER and LISTENER, and uses the correct wire insulation colors:

  • TALKER A = White
  • TALKER B = Brown
  • LISTENER A = Yellow
  • LISTENER B = Green

The user manual also describes in a narrative the proper method for interconnecting with a non-differential NMEA-0183 interface (i.e., take LISTENER B to ground and float TALKER B). Unfortunately, the user manual does not use the proper signal names, and continues to refer to the NMEA-0183 signals as having polarities and as input and output.

All the GX1400 radios can output DSC and DSE NMEA-0183 sentences. The GPS models output GGA, GLL, GNS, RMC, GSA, and GSV sentences. All GX1400 radios can accept GGA, GLL, GNS, RMC, GSA, and GSV from external devices.

Unlike the more expensive GX1800 series radios, the GX1400 radios do not provide a NMEA-2000 interface.

The radio front dimensions are 6.14-inches (156mm) Wide x 2.4-inches (61mm) High. The front panel of the radio projects forward from a bulkhead mounting 1.58-inches (40mm). The overall depth of the radio is 4.44-inches (112.5mm) (These values are taken from a dimensional drawing in the user manual and conflict with dimensions give in some promotional literature.)

User Interface
The GX1400 radio has extensive operator controls on the front panel. The on-off power is controlled by a dedicated red ON-OFF button, not part of any other control function. Volume and Squelch are provided on separate rotary knobs rather than concentric knobs. The volume knob is at the upper right corner of the enclosure, where it is easily reached. The squelch knob is at the lower right corner, and is unlikely to be confused with volume.

To give the operator further awareness of a channel-in-use (or channel-busy) condition, an annunciator lamp in the upper left illuminates when the receiver squelch has opened. Curiously the lamp indicator is green, which usually indicates a safe condition. This seems somewhat unexpected and perhaps inappropriate.

Channel selection is accomplished with two pushbuttons, arranged vertically with up-arrow and down-arrow indicators.

A large 2.6 x 1.4-inch 102 x 56-pixel dot-matrix display has five pushbuttons associated with it arranged in a row below the display; the outer pair are for scrolling horizontally on the display or changing the soft key functions. The inner three are for selecting one of the soft key choices shown on the display. A further enhancement permits the user to custom program three soft key functions to his own liking.

A MENU button for accessing the menus or when held to move to the setup menu, and a CLR (clear) button to cancel selections are located to the right of the display; a red 16/S button for switching the radio to Channel 16 or when held to the SUB channel is to the left of the display.

As required for all DSC radios, a red DISTRESS ALERT button is provided under a hinged access cover.

Standard-Horizon provides a warranty for the GX1400 radios for three-years during which they will repair or replace any defective part in a reasonable time at no cost to the consumer. The warranty has the usual exclusions against improper use and damage from excess moisture. Considering the astonishingly low cost of this device, I doubt the warranty protection would be a factor is deciding to purchase.

Reset of MMSI in the Field
The MMSI entered into the GX1400 cannot be reset without advice from the manufacturer by federal regulation. Standard-Horizon has developed a method to allow the end-user to reset the MMSI in a GX1400 radio that complies with federal regulations and relieves the consumer from having to send the radio to a service center for MMSI reset. This is an excellent feature of the GX1400 (and other models) from Standard-Horizon. I believe at this moment the ability to re-set the MMSI in the field may be a unique feature of Standard-Horizon radios.

As found in many Standard-Horizon radios, the GX1400 radio receiver can be configured to scan for signals. There are two general types of scans:
  • Memory Scan
  • Priority Scan
In Memory Scan mode, the radio starts at the lowest numerical channel entered into the scan memory directory and progresses in numerical order through the other channels in the memory scan. Priority Scan mode is similar, but the radio jumps to the priority channel between each memory channel. The priority channel is set by default to Channel 16, but it can be altered to another channel by the user.

Display Details
Fig. 2. The dot-matrix display of the GX1400
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As seen above in Figure 2, the dot-matrix display provides the user with much information. This view is from the operating mode of the display. The display changes radically when in the menu mode.

The large "16" indicates the channel the radio is currently set to, and the "P" on the left indicates it is the priority channel.

In the upper right a satellite icon indicates the radio has a position fix from satellite. The "USA" indicates the band plan in use for channel assignments. The "25W" indicates the transmit power level.

On the lower left-middle the deduced position from GPS is displayed in degrees and decimal minutes. On the lower right the time of day in hh:mm is shown. "AM" indcates morning. "LOC" indicates local time.

When the display shifts to menu mode, there are hundreds of different presentations, depending on where in the menu hierarchy the user has chosen to navigate. Figure 3 (below) shows a typical display in the menu operation:

Fig. 3. A typical menu screen display. The three legends across the bottom are the functions to be associated with the three push buttons located just below the display.
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The three front-panel push buttons below the display can take on many functions. In the example illustrated, pushing the right button [SELECT] will select the menu choice. Pushing the left button [BACK] exits to the prior menu. Pushing the middle button [MANUAL] allows the user to enter data manually.

DSC Class D
The GX1400 is a DSC radio, which means in order to be manufactured, imported, sold, or installed in the USA it must comply with the ITU-R M.493-13 version of the recommendation. The European version GX1400GPS/E complies with ITU-R M.493-14. Accordingly the radio provides all the features called for in those recommendations.

In addition, this radio can also send POSITION POLL REQUESTS which are not mandatory in Class-D radios. Further, the radio provides an automated function for sending POSITION POLL REQUESTS to one or more ships based on their MMSI as entered into a list in a stored directory, and the frequency of the automatic polling requests can be set to 30-seconds or longer.

The GX1400 radios can also send POSITION POLL REQUEST ACKNOWLEDGEMENTS, that is, they can send back their position in reply to a request for it. The function is not mandatory in Class-D VHF radios.

Rear Panel
The GX1400 rear panel provides for connection of the radio antenna, an external GPS antenna (if used), 12-Volt DC power, and external speaker, NMEA-0183 TALKER and LISTENER pairs, and a ground terminal.
Fig. 4 Rear panel of GX1400 radio.
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External GPS Antenna and External GPS Receiver
The GX1400 radios can use the SCU-38 External GPS Antenna if the radio is mounted in a location that has a poor view of the sky. If the SCU-38 external antenna is connected, it will be used by the internal GPS receiver in preference to the internal antenna.

Fig. 4. The SCU-38 external antenna, useful if the GX1400 radio is mounted in a manner that impairs the internal GPS antenna from getting a clear view of the sky.

In a confusing manner, Standard-Horizon also sells the SCU-31 External GPS "Antenna" which is actually a stand-alone external GPS receiver that requires its own 12-Volt DC power; the SCU-31 outputs NMEA-0183 data and is not just an antenna. If the SCU-31 GPS External Receiver is used, it will interface via NMEA-0183 to the radio.