Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 29-07-2010, 06:42   #1
Registered User

Join Date: Jul 2010
Posts: 4
Command Mic Transmit Audio

I was wondering if anyone with a remote microphone could answer a simple question for me. If the radio is transmitting on the main microphone, does the transmitted audio come back over the remote microphone? Could the person at the helm hear what the person below deck was saying through the command mic?
newbie123 is offline   Reply With Quote
Old 29-07-2010, 15:16   #2
Moderator
 
Jim Cate's Avatar

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 21,155
Quote:
Originally Posted by newbie123 View Post
I was wondering if anyone with a remote microphone could answer a simple question for me. If the radio is transmitting on the main microphone, does the transmitted audio come back over the remote microphone? Could the person at the helm hear what the person below deck was saying through the command mic?
G'Day mate,

For an Icom command mike/M-422 combo the answer is no.

Cheers,

Jim
__________________
Jim and Ann s/v Insatiable II, lying Port Cygnet Tasmania once again.
Jim Cate is online now   Reply With Quote
Old 29-07-2010, 16:02   #3
Registered User

Join Date: Jan 2008
Posts: 165
ditto with our raymarine vhf
__________________
S/V Katabatik
Leopard 46
San Francisco, CA
stacy is offline   Reply With Quote
Old 29-07-2010, 16:16   #4
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: Eastern Tennessee
Boat: Research vessel for a university, retired now.
Posts: 10,406
You could though have two radios, one on transmit and one on receive on the same channel and that would work...although probably illegal for marine band VHF. It would be an abuse of the purpose of a VHF, plus you would be transmitting your one-way conversation all over the harbor, even on one watt. If you want to do this then FRS walkie-talkies work well onboard and they are more certainly more private.
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 30-07-2010, 01:13   #5
Registered User
 
richardhula's Avatar

Join Date: Nov 2008
Location: UK
Boat: S M Hudson 60' narrowboat
Posts: 347
Send a message via Skype™ to richardhula
Quote:
Originally Posted by newbie123 View Post
I was wondering if anyone with a remote microphone could answer a simple question for me. If the radio is transmitting on the main microphone, does the transmitted audio come back over the remote microphone? Could the person at the helm hear what the person below deck was saying through the command mic?
Most have an intercom mode between base set & remote command mike. You are not going to get this option when transmitting using either mike though.
__________________
Richard

If in doubt RTFM
richardhula is offline   Reply With Quote
Old 30-07-2010, 08:24   #6
Registered User

Join Date: Jul 2010
Posts: 4
I figured it wouldn't have the transmitted audio, but it was worth a shot. I certainly wouldn't have a way of testing that on my own without buying a new radio. I appreciate the quick replies.

The goal with this project is to interface a licensed shore VHF marine station to a recording system. This is used for SAR operations, and there are many situations where we would like to go back after an incident and review how communications were handled. If the command mic would output the transmit audio too, I could just take it apart and tap the speaker connection in there. I've called and emailed several companies, and everyone has told me this was impossible to do for less than $2,000 per radio for a class A DSC radio that interfaces with a VDR. I just found a company that markets a "Marine DVR" that interfaces with most VHF marine radios, but they don't seem to sell the interface cables - only the entire DVR. I know that what I'm trying to do is possible now, but I just need to figure out how to do it.

Thanks for the help!
newbie123 is offline   Reply With Quote
Old 30-07-2010, 10:18   #7
Registered User

Join Date: Apr 2007
Posts: 718
Why not just use another cheap VHF or scanner with it's audio output to the DVR which would then record both sides of the communications?

Eric
fairbank56 is offline   Reply With Quote
Old 30-07-2010, 11:33   #8
Registered User

Join Date: Jul 2010
Posts: 4
That was my first thought too, but VHF communications are simplex and the radio's antenna is at about 200 ft AGL. It would be prohibitively expensive to put another antenna on the tower that would have equal receive capabilities, and having a dedicated radio for the recorder would require us to change the channel in two places instead of one.

The direction I'm heading right now is to find a VHF with a removable microphone (like the IC-M60) and get in touch with the DVR company and pray that they will sell just the interface cable. I'd appreciate any other suggestions this forum might have for me.

Thanks!
newbie123 is offline   Reply With Quote
Old 30-07-2010, 17:58   #9
Registered User

Join Date: Apr 2007
Posts: 718
The Icom M-604 has a pigtail microphone jack on the back of the unit that is electrically in parallel with the microphone jack on the front of the unit so all you need to do is connect this to the DVR assuming the MIC level is enough to drive the DVR for recording of the transmit audio. Do you have a link for the marine DVR?

Eric
fairbank56 is offline   Reply With Quote
Old 31-07-2010, 13:01   #10
Registered User

Join Date: Jul 2010
Location: Montana
Posts: 391
OK, you want to record audio on a particular channel, for some defined period...for training during SAR ops?

I don't understand your comment about the scanner....just put it on the simplex/output freq and record on a DVR or whatever. If it's recording the output of the repeater it doesn't matter that your antenna is lower - unless you're outside the antenna aperture. Thats why repeater outputs are on high antennas: For big coverage.

If you want to record local simplex chatter on handhelds, a similar receive-only device will work, at the scene. You can put it in an otterbox or something for waterproofing. There are very inexpensive VOX (voice activated switching) switches available as well, to save tape/space.

You could also use a PC with mic in to record.

What am I missing here?
__________________
Healer52 / Lisa, Rick and Angel the Salty Dog
Currently on the hard, looking for a boat
Healer52 is offline   Reply With Quote
Old 31-07-2010, 15:27   #11
Registered User

Join Date: Apr 2007
Posts: 718
Quote:
Originally Posted by Healer52 View Post
If it's recording the output of the repeater it doesn't matter that your antenna is lower - unless you're outside the antenna aperture. Thats why repeater outputs are on high antennas: For big coverage.
I didn't see any mention of a repeater.

Eric
fairbank56 is offline   Reply With Quote
Old 31-07-2010, 16:25   #12
Registered User

Join Date: Dec 2009
Posts: 2,959
Images: 4
Given your requirements re antenna, channel tracking, recording it looks like your only option is to swap in a VHF with a recording option built in (probably some expensive police basestation), OR have an engineer modify your existing radio. The modification would seem to be straightforeward and $2000 sounds about right.
daddle is offline   Reply With Quote
Old 03-08-2010, 05:49   #13
Registered User

Join Date: Jul 2010
Posts: 4
Quote:
Originally Posted by fairbank56 View Post
The Icom M-604 has a pigtail microphone jack on the back of the unit that is electrically in parallel with the microphone jack on the front of the unit so all you need to do is connect this to the DVR assuming the MIC level is enough to drive the DVR for recording of the transmit audio. Do you have a link for the marine DVR?
That's what I was leaning towards right now. (I made a typo in my previous post and said IC-M60 instead.) There don't seem to be many VHF's with removable microphones, and that one has the best receive capabilities I can find for under $2000. If the microphone level is not high enough, is there a way to amplify it from the radio side? Also, I don't see any pinouts in the manual. Do these radios usually have a service manual available?

The marine DVR can be found at this url. I was told that the VHF interface would only work with their DVR and wouldn't be compatible with our PC-based recording system. From a technical standpoint, I don't understand how that would work - audio is audio, right? The only thing I can think of is that maybe they have figured out a way to crack into the command mic interface, and it requires some processing with their proprietary computer software to convert into an audio stream.

Quote:
Originally Posted by Healer52 View Post
I don't understand your comment about the scanner....just put it on the simplex/output freq and record on a DVR or whatever. If it's recording the output of the repeater it doesn't matter that your antenna is lower - unless you're outside the antenna aperture. Thats why repeater outputs are on high antennas: For big coverage.
We don't have a repeater. As much as I'd like for us to have one, we just use standard VHF marine radios for all of our communications. There is only one high antenna for us to use, and it would be difficult and cost prohibitive to add another antenna to our shared tower.

Quote:
Originally Posted by Healer52 View Post
If you want to record local simplex chatter on handhelds, a similar receive-only device will work, at the scene. You can put it in an otterbox or something for waterproofing. There are very inexpensive VOX (voice activated switching) switches available as well, to save tape/space.
If two boats are out of range of each other, the one radio that can hear both of them is at our communications center. It would be possible to record audio at the scene, but it would ideal to keep recording centralized in our communications center. The existing system also runs in the background with no human input required. If the equipment were carried on the boats, it might get turned off accidentally, or the files might not be transferred back to the communications center.

Quote:
Originally Posted by daddle View Post
Given your requirements re antenna, channel tracking, recording it looks like your only option is to swap in a VHF with a recording option built in (probably some expensive police basestation), OR have an engineer modify your existing radio. The modification would seem to be straightforeward and $2000 sounds about right.
A regular land mobile base station like most public safety agencies use would not be type accepted to operate on the VHF marine band. I have had trouble getting this clarified, but the consensus from the radio shops that I have contact is that even with our FCC license, we still need to use type accepted VHF radios - they can't just program a land mobile radio to work on VHF marine frequencies. As much as I'd love to get a Spectra or a shiny new XTL-5000, they just can't be legally programmed.

If it costs $2,000 to modify an existing VHF radio, I'm better off buying a class A DSC radio with a dedicated output to a VDR and a superior receiver. I'm hoping that there is a way to just tap the microphone cable and mix it with the receive audio, since we don't have that kind of budget.
newbie123 is offline   Reply With Quote
Old 03-08-2010, 09:49   #14
Registered User

Join Date: Apr 2007
Posts: 718
Quote:
Originally Posted by newbie123 View Post
If the microphone level is not high enough, is there a way to amplify it from the radio side? Also, I don't see any pinouts in the manual. Do these radios usually have a service manual available?
You could tap off of the Mic amplifier, IC6a on the AF board. I do have a service manual for this radio. Here's the mic pinout.
fairbank56 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Free Online Audio Books . . . Dale The Library 7 10-02-2011 14:31
VHF Radio Transmit Issue claddaghcan Marine Electronics 4 23-04-2010 10:46
Vessels Not Under Command 44'cruisingcat General Sailing Forum 7 08-02-2010 12:43
5.1 Car Audio Dockhead Marine Electronics 8 05-09-2009 17:22
Audio Compass Talbot Marine Electronics 0 22-08-2009 12:46

Advertise Here


All times are GMT -7. The time now is 17:55.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.