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From: Jeff Barfett (no email)
Date: Tue Jun 13 2006 - 20:44:21 EDT
So Ahmet, can you build me a prototype with instructions to interface to a
ICOM unit. Great idea! Jeff
-----Original Message-----
From:
[mailto:] On Behalf Of ahmet erkan
Sent: Tuesday, June 13, 2006 2:12 PM
To: ;
Subject: Re: lv-ab: Collision Avoidance Via Radio
Quoting myself :
>The radio manufacturer probably cannot implement a design that broadcasts
>voice periodically on >Ch 16. (Even if they put a switch for the user to
>activate it when at high seas) I suspect the manufacturers would do all the
>sensing at the IF stage (ie: detect and integrate >the CW for 1mS etc)
>where the audio circuits would be oblivious to the transponder like
>exchange
>Ahmet
Quoting a response from Norm :
>The legality of transmitting a call such as you contemplate is
>questionable.
>When I was working as a Merchant Marine Radio Officer it was illegal to
>"broadcast" a transmission from a ship. By "broadcast" the rules meant a
>message that had no designated receiving station but was meant to be heard
>by everyone listening. Distress and weather related messages were
>excepted.
>Norm
Hi Norm,
As stated in my original post, the periodic voice broadcast is not something
suggested for the manufacturers to develop. Even if it is not legal, it
ought to be illegal especially in coastal waters. Again, the suggestion is
to use the RF stages of the radio, oblivious to voice communication. In 50uS
a transmitter can radiate 7840 pulses (ie: more than enough) that can be
received, amplified, detected, integrated, compared and used to latch an
alarm relay. 50uS is the period for 20KHz which is above the audible
frequency threshold for humans. Clearly, there is no problem here.
The "voice broadcast" is a workaround system that would work with any VHF
radio but it requires that a person be on the bridge and hear the voice
message and respond. It would be impossible for the voice broadcast to
interfere with any on going voice communication because the alarm would be
on indicating there is a ship nearby and periodic broadcast function would
be disabled.
Your buddies in the Coast Guard should love this, because they can track
your boat passively without illuminating it with a radar pulse.
Quoting a response from Paul :
>The reason the list probably isn't interested in your idea is that it is
>already being done via AIS. >Burst mode transmissions on specific
>frequencies, specified information strings, interfacing with >radar and
>navigation chartplotters, international mandate. recreational receivers for
>about $300... >Why reinvent the wheel?
Hi Paul,
The reason the list probably isn't interested is my inability to explain
myself. Once a discussion
get going, people with a better command of the language will understand and
rephrase it
in a more understandable way. AIS system is truly impressive but almost
every boat has a VHF radio. The "electronic lookout" or "proximity alarm"
function should not have a significant impact on the cost of a radio either.
People who already have radios should buy a new improved one with the
proximity alarm function, and keep the old one as a spare.
It is not re-inventing the wheel. It is asking for something that is real
simple and should have been asked 100 years ago. (Nobody asked probably
because nobody was interested.)
At least my buddy Jim is interested.
As a great man said once upon a time "You are either with us or against us".
Ha ha.
That was a joke....All the best,
Ahmet
SV8827
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