The Standard Horizon DSC channel assignment problem

NOTE: This problem has been resolved as of September, 2015 -- though a major logistic problem remains. There has been NO safety alerts or market withdrawal of affected units. Please read the latest update.


Several Standard Horizon marine VHF transceivers do not properly handle DSC channel assignments.
The problem occurs only when a semi-duplex channel is assigned by a coastal radio station.
Intership simplex channel assignments work just fine.

The problem was first brought to my attention here and here (Norwegian text only, Google Translate may prove useful).

The first problem report was posted on April 21, 2015.

Other Standard Horizon transceivers than the one(s) mentioned in the postings are also affected by the problem.

There are a few video recordings available, detailing the problem. The VLC Media Player can be used for video playback.
Thanks to coastal radio station Tjøme Radio (LGT / MMSI 002570100) for replying to the DSC calls as part of the documentation process (June 15, 2015).


The test setup includes a brand-new Standard Horizon GX1600E from vendor Seatronic/Båtutstyr AS located in Moss, Norway.
S/N: L64B4912xx. Purchase date: June 06, 2015.
For comparison, a low-cost Cobra-brand marine VHF is also used. Both video recordings are shot aboard the same vessel, utilizing the same antenna and power supply.
The recordings are separated by no more than 5 minutes of time.

The test setup


How it ACTUALLY WORKS with the GX1600E and several other Standard Horizon models

Once the coastal radio station responds to the ship-initiated DSC call, a semi-duplex traffic channel is assigned by the coastal station as part of the DSC message exchange. The GX1600E and other Standard Horizon transceivers do not properly process the DSC message from the coastal radio station, showing "CH is not available".

In the actual tests, the coastal radio station assigned semi-duplex channel 07 for handling the voice traffic. The channel assignment was ignored/not properly understood by the GX1600E. The Cobra-brand VHF had no problems properly decoding the DSC message from the coastal radio station, automatically switching to the assigned traffic channel.

(Disregard the shown channel switching to ch. 16 / ch. 08, caused by operator key presses - this part shouldn't really have been included in the video).


Standard Horizon has shipped a number of transceivers containing a firmware bug. My previous experiences with the Standard Horizon brand have been positive ones. It should be noted that previous Standard Horizon models do not suffer from the same problem.

It has come to my attention that Standard Horizon claims that marine VHF/DSC class D transceivers are not required to process DSC channel assignments for semi-duplex channels (Recommendation ITU-R M.493-13).

While a requirement may not be in place, user expectations certainly exist. User expectations are reinforced by:

The issue should be addressed by Standard Horizon ASAP. If not, Standard Horizon marine VHF transceivers may be considered flawed and have a severe commercial drawback when compared to other brands. But first Standard Horizon should have a fair chance to do the right thing: just fix it. Now.

Update - September 2015

Yaesu/Standard Horizon has acknowledged the existence of a problem with the firmware/DSC decoder as emplyed in recent Standard Horizon models available on the Scandinavian market.

A firmware update (v. 2.08) is available, addressing the DSC channel assignment issue. As it seems, the firmware has been available since June 24, 2015.

End-users are advised to contact their local dealer for a firmware upgrade or perform the upgrade themselves. To perform the firmware upgrade, the CT-99 adapter cable and the USB-62B level converter cable are both required. The firmware updater should be available for FREE from your local Standard Horizon dealer.

Yaesu/Standard Horizon has listened to customer feedback and (partially) resolved this issue.

It remains to see how Standard Horizon will notify users of flawed units that an essential firmware upgrade should be applied.

A safety alert to affected customers and a market withdrawal of affected units is indeed appropriate.

Contact information

Torkel M. Jodalen
Tel. (+47) 69252033 / 92422020
Email tmj AT  bitwrap DOT no

Revised: 2016-01-17

(Yes, Yaesu, feel free to send me a free HX870E and the YCE02 software as a THANK YOU for the efforts in detailing the DSC problem).