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Old 01-10-2013, 21:57   #1
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Icom 802 Speech Compression

Anyone had their radio updated to enable switching the speech compression function from OFF to ON, and vise versa? How did it work out, and did it really improve your signal? Thanks.
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Old 03-10-2013, 08:59   #2
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Re: Icom 802 Speech Compression

bajatrawler,
Yes...
I have two M-802's and I have turned the speech compressor ON, on both of them, but have done so thru software not thru the "mod" which allows front panel "switching" it on/off...(although it is the same speech compressor and operates the same....so, it matters not whether the speech compressor is turned ON thru software, or thru a hardware "mod" allowing front panel switching On/Off)
Quote:
Originally Posted by bajatrawler View Post
Anyone had their radio updated to enable switching the speech compression function from OFF to ON, and vise versa? How did it work out, and did it really improve your signal? Thanks.
It works great!!
Yes, it DOES really improve your signal!!

Please read over the following thread, which describes this in much detail..
http://www.ssca.org/forum/viewtopic.php?f=5&t=4791

Also this thread (regarding the M-802's "clipping issue"), which is probably MORE IMPORTANT for many Icom M-802 owners!!!
PLEASE READ THIS THREAD!!!
http://www.ssca.org/forum/viewtopic.php?f=5&t=12547




And, there are some other M-802 specific threads and Maritime HF radio threads, etc....that you may find helpful/interesting...
SSCA Forum • View topic - Icom M-802 DSC-Distress Signaling, what really happens!
SSCA Forum • View topic - Icom M-802 use on the Ham Radio Bands

SSCA Forum • View topic - Tips for using an HF-SSB Radio (mostly for newcomers)
SSCA Forum • View topic - HF Radio Freqs, summertime Atlantic crossing, offshore Net..

SSCA Forum • View topic - ICOM 802 - Purchasing a New SSB Radio
SSCA Forum • View topic - USCG to Discontinue ONLY 2mhz Distress Watchkeeping 8-1-2013

SSCA Forum • View topic - Offshore / Hi-Seas Weather data / forecasts
SSCA Forum • View topic - EPIRB Activation? What happens/How to improve rescue odds




bajatrawler, I do hope this helps...


Fair winds

John
s/v Annie Laurie
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Old 03-10-2013, 10:16   #3
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Quote:
Originally Posted by ka4wja View Post
bajatrawler,
Yes...
I have two M-802's and I have turned the speech compressor ON, on both of them, but have done so thru software not thru the "mod" which allows front panel "switching" it on/off...(although it is the same speech compressor and operates the same....so, it matters not whether the speech compressor is turned ON thru software, or thru a hardware "mod" allowing front panel switching On/Off) It works great!!
Yes, it DOES really improve your signal!!

Please read over the following thread, which describes this in much detail..
http://www.ssca.org/forum/viewtopic.php?f=5&t=4791

Also this thread (regarding the M-802's "clipping issue"), which is probably MORE IMPORTANT for many Icom M-802 owners!!!
PLEASE READ THIS THREAD!!!
http://www.ssca.org/forum/viewtopic.php?f=5&t=12547

And, there are some other M-802 specific threads and Maritime HF radio threads, etc....that you may find helpful/interesting...
SSCA Forum • View topic - Icom M-802 DSC-Distress Signaling, what really happens!
SSCA Forum • View topic - Icom M-802 use on the Ham Radio Bands

SSCA Forum • View topic - Tips for using an HF-SSB Radio (mostly for newcomers)
SSCA Forum • View topic - HF Radio Freqs, summertime Atlantic crossing, offshore Net..

SSCA Forum • View topic - ICOM 802 - Purchasing a New SSB Radio
SSCA Forum • View topic - USCG to Discontinue ONLY 2mhz Distress Watchkeeping 8-1-2013

SSCA Forum • View topic - Offshore / Hi-Seas Weather data / forecasts
SSCA Forum • View topic - EPIRB Activation? What happens/How to improve rescue odds

bajatrawler, I do hope this helps...

Fair winds

John
s/v Annie Laurie
Thanks for the reply and the links John.
I have heard that the speech compression feature boosted the transmitted signal, and you confirm that you are pleased with your update. I see that there is some controversy about using it, especially on the marine bands. My usage is primarily the HAM bands in Mexico. I'm debating whether to purchase the software and cable and take it to the boat in Mexico, or bring the radio back this winter for the hardware modification by a vendor in Florida. Have you had any Pactor modem issues after your changes? Is the modification as simple as connecting the radio to a laptop and loading the software? Thanks again for your help.
73's
Steve
ki6sew
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Old 03-10-2013, 10:56   #4
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Re: Icom 802 Speech Compression

Does anyone knows how to modify the M-802 to allow front panel switching on/off of speech compressor?

Marc
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Old 03-10-2013, 12:06   #5
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Re: Icom 802 Speech Compression

There is a resistor matrix on the main board that determines configuration at power up. If anyone has one of the radio's with set mode B enabled, if you remove the cover from the main unit, remove the DSP board from main unit (top) and take a clear photo of the area under the DSP board, we can easily figure this out. In place of a photo, just indicate which positions in the upper half of the resistor matrix have a resistor in them. Alternatively, if your a techie and have the time, just add a 10k resistor to the vacant spots in the resistor matrix until you happen upon the correct one. Iv'e been meaning to do this, but have just not had the time or I just forget about it until the subject comes up again. I believe the mod is the addition of a resistor, not the removal of one of the existing ones connecting to the 5 volt supply rail.

Eric




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Old 03-10-2013, 13:56   #6
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Re: Icom 802 Speech Compression

Quote:
Originally Posted by bajatrawler View Post
I have heard that the speech compression feature boosted the transmitted signal
Hair-splitting: Marine VHF is frequency-modulated (FM), so speech compression doesn't affect the RF strength, but it can increase the apparent loudness and intelligibility of the demodulated audio, which is an improvement.
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Old 03-10-2013, 14:41   #7
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Re: Icom 802 Speech Compression

We are talking HF-SSB, not VHF-FM
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Old 03-10-2013, 18:47   #8
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Re: Icom 802 Speech Compression

Looking at the PC board, except for R3020 and R3404, all other positions are parallel. So adding one or more resistor will decrease the total value. It may take more than one new 10k resistor to get what we are looking for. I think...
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Sur le même bateau, l'homme de terre et l'homme de mer ont deux buts différents. Le but du premier est d'arriver, le but du deuxième est de repartir.
La terre nous tire vers le passé, la mer les pousse vers le futur.- Albert Londres, 1927
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Old 03-10-2013, 19:13   #9
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Re: Icom 802 Speech Compression

They are not in parallel. The round traces in the middle are thru-holes and go to traces on the other side of the board that go to the port/address lines of the microprocessor. The processor reads the port levels which are either at logic high or low depending on if the pull-up resistor is there (high) or not (low).

R3020 and 3019 are not part of the configuration matrix.

Eric
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Old 03-10-2013, 19:15   #10
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Re: Icom 802 Speech Compression

Got It!
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Sur le même bateau, l'homme de terre et l'homme de mer ont deux buts différents. Le but du premier est d'arriver, le but du deuxième est de repartir.
La terre nous tire vers le passé, la mer les pousse vers le futur.- Albert Londres, 1927
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Old 03-10-2013, 21:22   #11
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Re: Icom 802 Speech Compression

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Originally Posted by fairbank56 View Post
We are talking HF-SSB, not VHF-FM
-blush-

oops. sorry.
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Old 21-05-2015, 11:48   #12
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Re: Icom 802 Speech Compression

Hi Eric,

Not sure if you have had time to research the resister required, but after a review of the schematic, R3404 looks very promising. The pictures you provided shows it open and the schematic shows it installed and the only real possibility for changing the start up. The matrix is called initial so I think you were right on track. Unfortunately my 802 is over 1000 miles away in Mexico so I can not try it. If you get a chance, let me know if it works. Regards Terry

Quote:
Originally Posted by fairbank56 View Post
There is a resistor matrix on the main board that determines configuration at power up. If anyone has one of the radio's with set mode B enabled, if you remove the cover from the main unit, remove the DSP board from main unit (top) and take a clear photo of the area under the DSP board, we can easily figure this out. In place of a photo, just indicate which positions in the upper half of the resistor matrix have a resistor in them. Alternatively, if your a techie and have the time, just add a 10k resistor to the vacant spots in the resistor matrix until you happen upon the correct one. Iv'e been meaning to do this, but have just not had the time or I just forget about it until the subject comes up again. I believe the mod is the addition of a resistor, not the removal of one of the existing ones connecting to the 5 volt supply rail.

Eric




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Old 16-10-2015, 17:38   #13
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Re: Icom 802 Speech Compression

Quote:
Originally Posted by TLSparks View Post
Not sure if you have had time to research the resister required, but after a review of the schematic, R3404 looks very promising. The pictures you provided shows it open and the schematic shows it installed
Actually, the board diagram shows R3404 installed. It's farther off to the right, not next to R3405. Though that position next to R3405 would be a possibility.

My service manual shows R3409 and R3413 as "OTH", that is, for non-USA, non-Canada units, which makes them unlikely candidates (at least I haven't heard that European M802's all have Set Mode B enabled).

Still 5 or so positions to try, if indeed adding a single resistor to that bank is the trick.
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Old 16-10-2015, 18:06   #14
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Re: Icom 802 Speech Compression

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Originally Posted by ka4wja View Post
, it matters not whether the speech compressor is turned ON thru software, or thru a hardware "mod" allowing front panel switching On/Off)
I agree that compression works great for voice and the software works great to turn it on, but there is a significant difference. The hardware mod that enables front panel switching on/off lets you turn compression OFF when transmitting data. The software mod does not let you easily turn off compression when you want to use a digital mode (eg Pactor)

Compression is awful (for you and nearby frequencies) in many digital modes that I use in ham frequencies. I confess I have no proof of compression creating a problem in Pactor, because I did not have my measurement gear when onboard a boat with one of these radios.
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Old 17-10-2015, 10:46   #15
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Re: Icom 802 Speech Compression

svlamorcha,
Without getting into a long discussion of the DSP architecture of the M-802, I can assure you that the M-802's compression does not effect the radio when used with typical sailor's digital modes....not any of the PACTOR modes, nor SITOR, etc...
It is designed to trace/follow analog human speech patterns, and does not effect the tones input from the modem..

This is not to say that other "speech processors" on other radios don't effect other modes....as I believe some do....but the M-802's compression does not!
{I had originally thought that if the M-802's compression did cause issues, the solution is to simply make sure the M-802 is used in one the digital modes (such as AFSK or "e-mail" mode, which always seemed logical), but this proved to be completely unnecessary, as the M-802's compression does not effect the tones from a modem...so, I haven't mentioned this other option, too often...}

Be advised that if the modem (or soundcard) drive levels were properly set with the compression Off, you should check the drive levels (and adjust if necessary) after you've turned the M-802's compression On...

Quote:
Originally Posted by svlamorocha View Post
I agree that compression works great for voice and the software works great to turn it on, but there is a significant difference. The hardware mod that enables front panel switching on/off lets you turn compression OFF when transmitting data. The software mod does not let you easily turn off compression when you want to use a digital mode (eg Pactor)

Compression is awful (for you and nearby frequencies) in many digital modes that I use in ham frequencies. I confess I have no proof of compression creating a problem in Pactor, because I did not have my measurement gear when onboard a boat with one of these radios.



On a side note, when you speak of compression being awful for many digital modes that you use on the ham bands, I assume you're speaking of the various PSK / soundcard / keyboard modes, used with many ham radios...and here you are correct!
But, also understand the truly horrible transmit IMD specs of so many ham radios, especially when over-driven, etc...
While many times the processors in the rigs simply overdrive the rig, some also add their own distortion products....so...many PSK31 ops use about 20-25 watts in order to get their rigs to work well without lots of transmit IMD products...

In any case, if my fellow hams really want to eliminate any distortions caused by the audio section / compressor / processor, etc. when using digital modes, then we should not use this section of the radio (bypass these sections) and drive the rigs the way they are designed to be driven when using these modes, by inputting the tones thru ACC jacks, AF/MOD jacks, etc. thereby eliminating this cause...




Sorry about the rambling....
Bottom line, the M-802's compressor doesn't effect the digital modes..



Fair winds...

John
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