Appendix XII – Improving DSC Calling for Cruisers
Discussion
Factory programming only includes one usable calling frequency, 2177.0KHz, for cruiser to cruiser
communications. This is because all the other frequencies are duplex frequency intended for calling
shore stations. 2177.0KHz is not a long range communications frequency. While a higher frequency
might get you to the US from Mexico, 2177.0 KHz, may not make it across the Sea of Cortez during part
of the day or night.
I stumbled across an article in the forum, SSCA Discussion Board. Notes by a fellow cruiser,
John,
KA4WJA on s/v Annie Laurie,
make a lot of sense and will allow for better DSC usage. If you would like to
read all of John’s notes on the subject, go to the forum at:
http://www.ssca.org/forum/phpBB3/viewtopic.php?f=5&t=12613&p=70145#p70145
The Plan
John has been kind enough to authorize my use of his recommendations for the benefit of all cruisers.
As a result, this appendix will remain on my web site even after the second revision of “ICOM IC M802
Made Simple for Cruisers” is released (planned for) next summer. The following is a quote from John
on the SCCA forum:
“
So, in my M-802, I have 2177.0, 4208.0, 6312.5, 8415.0, 12577.5, and 16805.0 khz, programmed as my
DSC Scan frequencies, and in addition to the GMDSS-DSC frequencies, also programmed these in as
"Call Frequencies", both transmit and receive (simplex channels)......
And, that means that when using DSC Watch Mode, I'm scanning those frequencies listening for
"Routine" DSC calls.....”
If the IC M802 is scanning for
2177.0, 4208.0, 6312.5, 8415.0, 12577.5, and 16805.0 khz and we are
calling and receiving/sending acknowledgment on those frequencies, it will be possible to significantly
increase our calling distance with the IC M802 DSC capability.
Issues
In order to effectively utilize DSC calls to other cruisers using John’s approach, we must re-program both
the channels scanned by the IC M802 and the programmed calling frequencies. This process will take
about 15 to 20 minutes. If you have not programmed anything into your radio, this may bring up many
questions. Should you have questions, feel free to contact me at
Re-Program the ICOM IC M802