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DSC Test Call

Discussion in 'Ask All Sailors' started by sailboatracer, Mar 15, 2019. Add this thread to a FAQ

  1. StargazerP303

    StargazerP303

    Joined Oct 22, 2014
    254 posts, 80 likes
    Pearson P303 #221
    US RockPort Maine
    Now that's a LOG... Nice PICs! lol did you call it in?
     


  2. jssailem

    jssailem

    Joined Oct 22, 2014
    8,754 posts, 3,750 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    I tried to answer but the signal was garbled.:biggrin:
    :beer:
     


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  3. jssailem

    jssailem

    Joined Oct 22, 2014
    8,754 posts, 3,750 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    That is just an example of what we find in the water.

    I saw a line of logs about a 1/4 mile long along a tide rip. Called that one in as a Sécurité message. It got the attention of one power boat cruiser that was heading toward the logs at about 20knots. Open water.

    Certain areas are more prone to logs than others.
     


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  4. Mark Maulden

    Mark Maulden

    Joined Jan 25, 2011
    1,873 posts, 208 likes
    S2 11.0A
    US Anacortes, WA
    It’s a security.... not a red button pusher. .
     


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  5. jssailem

    jssailem

    Joined Oct 22, 2014
    8,754 posts, 3,750 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    So true Mark. And you need to read the position from the radio or chart plotter. It is not sent automatically.
     


  6. Mark Maulden

    Mark Maulden

    Joined Jan 25, 2011
    1,873 posts, 208 likes
    S2 11.0A
    US Anacortes, WA
    When you’re transiting Harney Channel and a ferry leaves Orcas Is or Shaw Is and stops and you don’t know his intentions, it’s time to talk. You are more maneuverable than the ferry especially in wind. Also, when you make a course decision, make it exaggerated to state your intentions. BTW, there is a sailboat on the bottom off Orcas due to a ferry collision ...
     


    Last edited: Mar 19, 2019
    jssailem likes this.
  7. StargazerP303

    StargazerP303

    Joined Oct 22, 2014
    254 posts, 80 likes
    Pearson P303 #221
    US RockPort Maine
    View attachment 162698
    My wife and daughter sometimes know how to pushes my red buttons... So to speak.. LOL Mark, it's all good here buddy!
    Just remember I lived it on the rocks, so I know what I.. IMO, what to do for my safety and my passengers. IMO. I even before I even get going all passengers have to sit down and we all have a safety session. The where is, what to, when to and how to. In the end, all people feel they know the rules aboard my ship. even including MOB review. I can't tell you how many vessels go out for a day and not one person aboard some ships don't know where the Fire extinguishers are or even how to use the radio. Because I do a lot of work on the boat in the winter time, things get moved to different locations all the time like first aid kits, flare guns, horns, and the list goes on & on. So to make thing simple for me I decided to make one- sheet exploded view picture of the vessel insides showing where everything is and small notes what it may be used for. This works for me and keeps my passengers happy and confident they know what to do. Here's an example. View attachment 162698
     

    Attached Files:



  8. All U Get

    All U Get

    Joined Oct 2, 2008
    2,872 posts, 526 likes
    Pearson/ 530
    US Strafford, NH
    You fellas ought to cruise the Bahamas where they use Ch16 for announcing the daily specials at the local restaurants.
     


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  9. Meriachee

    Meriachee

    Joined Aug 1, 2011
    3,190 posts, 1,065 likes
    Catalina 270
    CA Wabamun - on the orange ball
    Now that is news you can use!
     


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  10. Pearson 39-II

    Pearson 39-II

    Joined Aug 4, 2018
    54 posts, 20 likes
    Pearson Yachts 39-II
    Scotch Bonnet US Punta Gorda, FL
    Trees and logs and ferries and unsuccessful DSC calls acknowledged, but returning to the original posts questions about testing a DSC VHF's distress capability I believe I've found a couple of ways to do that while not actually broadcasting the call to the USCG Rescue 21 System.

    Overview: Bring a secondary VHF radio aboard your boat. It could be your handheld VHF, or an older non-DSC capable VHF you replaced with your newer DSC capable radio, or a buddy’s handheld that you borrow, etc. The only requirements for the secondary are:

    1) It can tune to VHF channel 70, (the DSC channel), and
    2) If it is not itself DSC capable, or if it has the same MMSI as your primary VHF it needs to have an audio output jack.

    You then transmit a real DSC Red-Button Pressed Distress call on a VHF radio disconnected from its antenna. Only you receive that call on a second, adjacent VHF radio. You read the distress call data directly on that second VHF if it is DSC capable. Otherwise you pass the call data from it as an audio signal to a computer running a freeware DSC Decoding program. That program then shows you the data content of your distress call. The details of how to do this are in the attached .PDF file.

    This does not test the USCG side of the system but does test your side - your radio and its registration and programming. Combined with the loopback test described by Jssailem at https://www.navcen.uscg.gov/?pageName=DSCTesting which does test your and the USCG 's radio connection should either reveal the gaps you need to fix or pretty good confidence that when it hits the fan your red panic button will do its job.
     

    Attached Files:



    Last edited: Apr 17, 2019 at 1:32 PM
  11. jssailem

    jssailem

    Joined Oct 22, 2014
    8,754 posts, 3,750 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    @Pearson 39-II
    Nice write up, but a word of caution. Perhaps the current radios are built with more durable parts, in my training we were cautioned “Never Key a Mike with out an antenna attached to the radio”.

    The issue is there is no where for the transmit power to go and it could burn up the transmitter final stage. Note that the DSC Emergency transmission is designed to operate in “High Power Mode”, 25 W of transmission power.

    Granted my training is with older equipment, and the new radios my have circuit protection if a transmit signal would damage the radio.

    I would be cautious in attempting to follow the test plan with out first checking the manufacturers instructions regarding transmitting without an antenna.
     


    Last edited: Apr 15, 2019 at 7:01 AM
  12. sesmith

    sesmith

    Joined Jul 1, 2010
    639 posts, 127 likes
    Seaward 25, Catalina 350
    US Ithaca, NY
    My newer radios have the same warning.
     


  13. LeslieTroyer

    LeslieTroyer

    Joined May 20, 2016
    2,502 posts, 1,144 likes
    Catalina 36 MK1
    US Everett, WA
    I believe most radios also have DSC relay for emergency calls. Might your other radio relay your test call to the world??
     


    Pearson 39-II likes this.
  14. Tally Ho

    Tally Ho

    Joined Jan 7, 2011
    1,250 posts, 245 likes
    Oday 322
    US East Chicago, IN
    In my area, all of the big Lakers and tugs use channel 16 to alert security that they are entering or leaving the lake, or calling for a draw bridge opening. But if a leisure boat calls for a radio check, the CG will scold you.

    I have called a big boat to make sure they see me, and I get my radio check.

    Greg
     


  15. Pearson 39-II

    Pearson 39-II

    Joined Aug 4, 2018
    54 posts, 20 likes
    Pearson Yachts 39-II
    Scotch Bonnet US Punta Gorda, FL
    Les, good question. The Class A DSC Radios on large ships and on shore stations are required to have the ability to transmit DSC Relay calls. The class D recreational vessel radios that we all typically operate are required to be able to receive and acknowledge DSC Relay calls but not to transmit them. My Std Horizon (Yaesu) GX2200 and Lowrance Link-2 Handheld are DSC Class D and can only receive Relay calls. The older fixed VHF I tested with as my Secondary VHF is an old Std Horizon Eclipse which is not DSC capable at all.
     


  16. Pearson 39-II

    Pearson 39-II

    Joined Aug 4, 2018
    54 posts, 20 likes
    Pearson Yachts 39-II
    Scotch Bonnet US Punta Gorda, FL
    @jjssailem Your comments re: the risk of damaging the antenna-less VHF transmitter circuits are well taken and a valid concern. In fact the owner's manuals for both my modern Std Horizon (Yaesu) GX2200 and my fairly new Lowrance Link-2 handheld do advise not even keying the microphone PTT transmit button with no antenna connected. [Curiously my old Std Horizon GS1246S Eclipse VHF 's manual never mentions this].
    Online research, however, mostly confirmed my own experiences. Lots of operators in the Ham, CB, SSB, and VHF communities reported they and many others they know had occasionally tried, usually accidentally, to transmit with no antenna and no dummy antenna load connected and yet went on to find no damage had occurred. Typical accidents were after they had forgotten to reconnect their antennas after disconnecting due to storm lightning. Others involved their kids. But, yes, there were also incidents where damage did occur, though I found no details of those incidents.

    It was in the Wiki article on Standing Wave Ratio and antenna Dummy Loads I found “If a transmitter is tested without a load attached to its output terminals such as an antenna or a dummy load, the power will be reflected back into the transmitter, often overheating and damaging it. “ with the key word, to me, being “overheating”.

    Other comments included: "Well, modern radios with their fold-back on high swr... helps protect the finals. "

    "Usually, the transmitter will be designed so that the power device is sufficiently within its ratings that it won't fail into any load, as blowing up into no load is not very nice behaviour. But sometimes, especially for low cost and high power amplifiers... it won't be, and needs that load to prevent reflections."

    "But even when a disconnected antenna causes high dissipation in the final, that won't cause damage until it continues long enough for the temperature to rise. With a small transistor that can happen pretty quickly, but in most cases it is the excessive dissipation over an extended time that causes problems. This doesn't mean that it is good practice, of course, but generally brief lapses of attention such as that don't cause permanent damage as long as they don't go on for too long."

    So I went ahead and tested, with no antennas, and some with my emergency VHF roll-up and telescoping antennas, and in one case with a paperclip inserted into the center conductor of the old radio’s SO-239 antenna connector just to be able to receive the WX channels! In all cases I transmitted only for a second or less, clicking the PTT button just to verify reception in the target radio, or repeatedly allowed the 0.5 second DSC distress transmission on channel 70 with many minutes between any of those. And none of my 3 radios has been damaged.

    Still, since @jssailem’s cautionary comment I contacted the Techs at Yaesu to get professional information. I just got a reply today:
    Question 1. Are the radio's RF transmit circuits protected against damage in the event the radio is PTT keyed with the antenna connection open-circuited as in a dismasting, antenna loss, or even accidental disconnection from the SO-239 connector on the rear panel?
    Answer: “1: There is protection there, but it is not designed for constant use, it will protect it from the odd quick transmission here and there but if you continue to transmit without an antenna you could damage the radio.”
    Question 2. Is it correct that a risk of damage exists if the radio is PTT keyed with no antenna connected due to RF power being reflected back into the transmitter, causing overheating? If that is the failure mode would the very brief transmission of a DSC Distress Call by the radio likely damage the radio's transmit circuits? That is, if one keys the radio for one second the risk of circuit overheating is less than if keying it for 30 or 60 seconds?
    Answer: “2: Again, a brief transmission should not cause any damage but same thing long or repetitive burst will damage the radio.”

    Granted, the questions were specific to my GX2200 and I am no expert in the rather weird engineering of RF electronics. However, my guess is radios modern enough to be DSC capable have also benefited from the modern availability of higher-power components, development of SWR measuring/tuning/protecting software, and the wisdom of radio designers to use these to provide more robust products.

    I’m no advocate – just reporting what I’ve learned and tested and my satisfying results. I have added a cautionary note regarding this issue to my write-up and have replaced my original post attachment with that Rev2 procedure and will attach it also this post.
     

    Attached Files:



    Last edited: Apr 17, 2019 at 1:36 PM
  17. jssailem

    jssailem

    Joined Oct 22, 2014
    8,754 posts, 3,750 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    Nice follow up @Pearson 39-II. It is good to know that the old knowledge still has creditability.

    It is all about the quality of the circuits components. What manufacturer is going to say, "We bought cheap components so we can make a bigger profit on our radios, so don't go testing the circuits by doing something you should not." In reality keying a mike for a second should not kill your transmitter unless the components are really cheap. In my Navy days such action happened and it was evident upon inspecting the burnt out tubes There were good and bad tubes back then. Then came printed circuits. And we learned the same thing. There were good boards and bad boards, good components and bad components. Now a days the circuits or so massed produced and with such small connections that it can be come impossible to know what went wrong. Just replace the whole module.

    I still cling to the basic premise. If it was meant to transmit with out an antenna they would say so.

    I understand that it would be desirable to be able to check the "automated" transmission system. I would support the promotion of a "Safety Test Program" request to the CG.

    Lacking that I think you have to fall back on the possibility that the "Automated" system might not function. It would be prudent to learn the proper method to call in a "MayDay" manually. This means one needs to be aware of their position and be able to communicate it through the system. To some that seems onerous, yet it is the requirement for safe boating. I think it is just common sense. I will use the "automated feature" of my radio but I am going to be able to make a call manually just in case.
     




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