Friday, April 01, 2011

IC-9100 USB audio issue

No, I haven't gone and bought an Icom IC-9100. Nor am I planning to. However, through the JT65-HF Google group I learned of an issue that could be a serious annoyance to anyone who owns one of these radios and wishes to use it for digital modes on a computer that runs Windows XP. The issue is that the audio output from the radio is at a fixed level and cannot be altered. I thought it deserved wider publicity, because if I had been thinking of buying an IC-9100 I would have found this out the hard way, and I don't think many people would be happy at having to buy a new computer to go with their £3000 radio.

The IC-9100 (and the IC-7600) both have USB connections between the rig and the radio. Hailed by many as the way to go (though not by me) this single connection provides both a virtual serial port for rig control and a USB sound device for digital modes. Unfortunately under Windows XP when you select the Icom sound device and open the mixer settings to set the audio level from the radio there is no slider. It is fixed. I'm told there isn't a control in the radio itself to change the level either.

Most digital mode programs don't have a level control within the software, they expect you to use the Windows level controls. So if your waterfall is bright yellow because the audio level is too high there is nothing you can do if you own one of these Icom radios (except, presumably, use the good old-fashioned analogue audio connections.)

Progress. Don't you love it?


Paul Stam PAØK said...

Hi Julian, that's not good. I work digi modes the old fashion way, with VOX and mic. So it's important for me to change the audio slider when needed. Why did they do a fix audio? Very strange. 73 Paul

Unknown said...

I understand it's only a problem in XP, not Vista or Win 7. I also understand it's a limitation of a system driver that the Icom uses, rather than something provided by Icom. That doesn't make it any less of a problem if you're an XP user, though.

The one with no shadow said...

I'm no ICOM 9100 owner, nor I will ever be due to the skyhigh priced tag, but I was wondering. Even if audio level is fixed regarding the USB interface, wouldn't a right turn of the "RF Gain" knob fix that in a second or so?

Unknown said...

Yes, I've seen that suggested as a workaround. But wouldn't that reduce sensitivity?

The one with no shadow said...

No, not when it comes to digital modes, I believe.

When a continuous carrier is FSK modulated, its content is usually intended to be decoded with a c/n better than 1. This applies to RTTY, olivia, psk.

Modes that are designed to use fragmented SNR (negative in dB) theorize that all frequencies the carrier would occupy are within almost the same narrow level boundaries and on frequencies that can be preset and have known Δf.

Therefore if RF gain is set to have the actual band noise

(or even interference,

or set to maximum signal within the passband, or even higher to distort the powerful interfering signal but still less than intermodulating it, as in -1 db intermodulation, set at a glance right before the "comb" effect occurs in the waterfall)

equal 0dbfs, all signals within the passband can still be receivable, even if the signal is under noise.

Yet, user still has arrows in the quiver like PBT and Notch to isolate interference and attenuator or roofing fitering or even a combination of those to fix the problem.

In any case, I fail on trying to imagine *any* situation in which one would have to adjust "just" the ADC input level to "fix" a situation in which the desired signal is buried in interference and obtain data if the problem is ADC input level set too *high*.

If you go for WSPR over EME using cryo LNA's and search for reflections of some QRP transmission to the moon, then yes, there could be a problem having fixed audio levels and trying to get noise to 0 dBFS, but if you used cryogenic amplifier techniques, would you settle for the embedded audio card? HiHi!

Thanks for the mind stretch, my friend!

(remember, IANNES, aka No Native English Speaker, Hihi!!!)


Steve GW7AAV said...

If you can afford an Icom IC-9100 just to do digi-modes on I am sure you will already have the latest up to date operating system too.

It sounds like they just haven't made the drivers backward compatible.

I wonder about Linux?

The one with no shadow said...
This comment has been removed by the author.
g0uwk said...

I use WSJT software with my IC-7600via usb connection,
Yes the audio level is fixed from the rig but WSJT software allows audio gain adjustment on the specJT window.
For me this works fine and I use the IC-7600 for MS (FSK & JT6M) on 70mhz with a transverter, it works flawlessly.
I use XP and have no issues, expect the same from the IC-9100

A Greener Shade of Geek said...

While I am annoyed at Icom for not making the audio output adjustable at the MENU setting (just like the audio input level), I own a 9100 and have been using it VERY successfully with JT65-HF since March. It is an excellent performing rig with fantastic noise reduction and great sensitivity. As long as you use Windows 7, which has a built-in audio adjustment slider control and set it to 1 or 2, then you are all set.