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Author Topic:   Hand-held VHF with DSC
BellBoyBob posted 09-12-2007 11:50 PM ET (US)   Profile for BellBoyBob   Send Email to BellBoyBob  
It seems now that one can purchase hand held DSC VHF radios. I am interested in the Standard Horizon HX600S. It does have DSC capability when connected to the NMEA out of a GPS. Have any of you used this radio? I have an MMSI number already entered in my Standard Horizon GX3000S fixed mount VHF DSC radio. Is one allowed to register for a second MMSI number now that the possibility exists to have a back-up handheld VHF DSC radio?
Chuck Tribolet posted 09-13-2007 06:54 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
There should be no problem registering a second MMSI.

I have an earlier version of that radio. I don't consider
the DSC feature terribly useful on a small boat because it
has to sit in its cradle to listen to the GPS. A hand-held
with built-in GPS would be more useful.


bluewaterpirate posted 09-13-2007 08:32 AM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
You can register you assigned MMSI # to as many radios/EPIRBs as you need to.
sail16 posted 09-13-2007 10:24 AM ET (US)     Profile for sail16  Send Email to sail16     
Two things to note regarding the DSC functionality of Standard Horizon hand-helds:

- The only DSC functionality is distress signalling. It does not receive/decode DSC and it can not transmit routine DSC calls.

- The GPS input is optional. It will still transmit DSC distress messages without the connection, though we can debate the value of such a transmission.

jimh posted 09-13-2007 12:36 PM ET (US)     Profile for jimh  Send Email to jimh     
The marine mobile service identity (MMSI) is for the vessel not for the radio, so you can have several radios on a vessel and they should all use the same MMSI.

When a DSC radio transmits the position data in an emergency broadcast it also transmits the age of the position data. Therefore the radio will continue to transmit the position data even after the GPS has been disconnected.

If you abandoned ship and took the handheld radio along in the liferaft, it would transmit the position and time of the last position, so that rescuers can know how old the data is. If you are still on the original vessel and still connected, the age of the position data will be just a few seconds old.

The people who designed this digital signal calling and distress system gave it some forethought.

You may also be able to manually enter a position and time into the radio, although this may depend on how compliant the radio is with the recommendations of the SOLAS and ITU authorities.

jimh posted 09-13-2007 12:39 PM ET (US)     Profile for jimh  Send Email to jimh     
I mentioned this in another discussion. My new Standard Horizon Class-D rated DSC radio alerted me when it noticed that the age of the position data it has was more than two hours old. I had left the radio turned on but had shut off the GPS feeding data to it. Again, I thought this showed some careful design of the system.

Also, if you were still on the vessel and your GPS failed, the radio would transmit the last position and its time. Searchers would use this time stamp to help deduce your current position.

where2 posted 09-17-2007 12:08 AM ET (US)     Profile for where2  Send Email to where2     
I've had interesting discussions with the guys at SH regarding their handheld units and the DSC functionality. The short version was that the interface to the GPS was made though the charging cradle, and that particular part (the charging cradle) was not waterproof.

When in doubt about thier products, visit their website and download the fine owners manuals they have online. If still in doubt, contact them directly via email or phone.

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