How can I knock down a Marine VHF broadcast?

[gesucks]

The bottom line is while you technically may be able to accomplish this. It is illegal and prohibited. End of story.

 

[ecps92]

How can I knock down a Marine VHF broadcast?

I am putting together a hands-on emergency broadcast exercise as part of a damage control section of a safety at sea event this May (Hands On Safety At Sea Seminar at SUNY Maritime – Storm Trysail Club). We want to simulate emergency calls on ch16 and DSC calls, we want to do this on actual VHF radios and will be close to a busy commercial waterway.

Can I put an attenuator on the coaxial cable between the radio and antenna of each unit to minimize the broad cast range down to a short distance say 500 yards? For example considering 25W output will a 50-Watt N Connector Attenuator DC to 3GHz 50 Ohm (30dB) Amazon.com work? 30watt? 10watt? Etc ?

Call/Talk to the the USCG about how THEY want you to actually transmit a Distress call for a simulation.
They may likely suggest a specific channel and phrases to use, they may also say, DON'T actually transmit, simulate it.

 

[kayn1n32008]

How can I knock down a Marine VHF broadcast?

By NOT transmitting on Ch16 AT ALL unless it actually is an emergency. Period.

We want to simulate emergency calls on ch16 and DSC calls, we want to do this on actual VHF radios and will be close to a busy commercial waterway.

Absolutely DO NOT do this.

Can I put an attenuator on the coaxial cable between the radio and antenna of each unit to minimize the broad cast range down to a short distance say 500 yards? For example considering 25W output will a 50-Watt N Connector Attenuator DC to 3GHz 50 Ohm (30dB) Amazon.com work? 30watt? 10watt? Etc ?

No. No. No. DO NOT TRANSMIT ON CH16 UNLESS ITS AN ACTUAL EMERGENCY. DO NOT TRIGGER A DSC ALERT UNLESS ITS AN ACTUAL EMERGENCY.

Thank you everyone for their input on how to run the training...but that was not my inquiry.

And you were given VERY specific information in response to your inquiry. Just because you don't like it, doesn't mean it isn't valid.

What we want to demonstrate is the function of DSC to make an alert while monitoring 16 with the volume down.

What part of NOT demonstrating DSC by triggering a DSC alert did you NOT understand?

While sailing long distance most radios are turned down as to not disturb the off watch. A lot of offshore sailors are going to satellite for their distance communication needs, however that is one for one communication, in an emergency while out in blue water racing your likely source for assistance is a fellow competitor, thus the desire to demo DSC.

Stop. Just stop.

Go back and read the response in post #11, and click on the link in thatpost.

From the link in post #11:

DSC Test Calls​

DSC-equipped radios include a test call feature which will allow you to call any radio on DSC and receive an automatic acknowledgment in return.

The U.S. Coast Guard offers an automated DSC Test Call capability from each of its Rescue 21 coastal stations. To perform a DSC Test Call with the USCG, enter the coast station group identity “003669999” into the radio’s DSC memory. Once stored, a DSC test call can be made by executing the following three steps:

1. Select “Test Call” from the radio’s DSC menu,
   
2. Select the USCG number entered into memory, and
   
3. Transmit the call.

The radio display should indicate when that test call is acknowledged and display the acknowledging station’s nine-digit identity.

At the very bottom of that page:

***Under no circumstances should a DSC Distress Alert be sent to test your radio.***

Re-read the bold sentence again.

Now, re-read it for a third time.

STOP trying to attenuate the radio transmission to send a DSC Alert.

Okay, last time:

***Under no circumstances should a DSC Distress Alert be sent to test your radio.***

Are you understanding yet?

***Under no circumstances should a DSC Distress Alert be sent to test your radio.***

How about now?

***Under no circumstances should a DSC Distress Alert be sent to test your radio.***


follow what is written in the link in post #11.