IC-7200 rx audio levels

Hi, new user here. I have an IC-7200 in the shed, running a server instance of wfview on an old Ubuntu 18.04 laptop, with reachback into the house over a wifi link to a desktop client instance of wfview on Ubuntu 20.04. At this time, I am only using wfview for listening.

This is working reasonably well, though there are some intermittent outages and I will seek to provide more feedback on these issues in the fullness of time.
For now though, I think the biggest issue I face is an inability to get loud audio at the remote client end. I nearly had to change my underwear when I fed some other audio source into the external speaker that I am currently listening to the rig on, but the rx audio via wfview seems to be very quiet.

I have previously had stuff like ARDOP, js8call, fldigi and more recently FreeDV running FB on the shed laptop. It seems that the USB audio codec device doesn’t offer any adjustment in the alsamixer, so it looks like I can’t insert any more rx audio gain upstream of the wfview server. The AF slider on the wfview server seems to control the front speaker audio level on the rig. I have the AF slider on the wfview client set at max. There is much more headroom in the rx audio path, but I just don’t seem to be able to get increase the rx audio level enough. It is useable, but then gets easily drowned out by the usual domestic sounds.

The document here says

A level problem was discovered in the course of this task. Simon reported that the PCM baseband level at the input to HRD was 20 to 30 dB below the expected value. A single-tone test on the radio then revealed that the analog baseband level at the line audio output (ACC socket, Pin 12) was only 30 mV; the specification calls for 100 to 300 mV. As the line audio output drives the USB audio codec directly, this explained the low PCM level which Simon reported.

So, this has me wondering whether wfview should insert 20 to 30dB of digital gain into the rx audio path for the IC-7200? I don’t know if the USB codec levels are similarly deficient on other rig models.

I don’t know the 7200 but other usb equipped rigs have controls that allow the change of usb levels.

I looked at a few examples and maybe the following helps best –

IC 7200 Digital Modes - YouTube.

it shows USB level for the TX path. Not owing the rig, maybe it’s for RX also available; else maybe there is a recording level to be adjusted if you use windows.

Hi Roeland, thanks for the info, but I am fairly convinced that the right answer is to provide a digital gain boost for the IC-7200’s rx audio. I determined quite a long time ago that the rx audio level though USB codec was at a low level, but was in the right ball park for digimode software. Clearly it is not an appropriate level for analogue voice listening though.
The low dynamic range can be seen in most digimode software, where an AGC like action affects the background noise level in the presence of strong signals, even when AGC is turned off.
I think a quick prototype fix could be to provide an rx audio digital gain boost option in the config file, possibly as simple as a number of bits to left shift the PCM samples by, perhaps with an upper limit of 10. With a default of 0, this could allow for quick evaluation of the effects.

first of alll turning AGC off is something you shoudl not do with ICOM’s radios in the 7xxx series.

Secondly, the RX audio level - if too low could potenatially be boosted but the question I still have is this: does your rig have an AF output level for USB? The rigs I own (maybe the 7k not) have USB AF output levels.

If we need to digitally amplify the level only for the 7200, it would be conditional code that applies only to the particular rig and makes stuff more complex – if the rig can do it we basically could stay away from the code tehere.

but then again – I don’t have a 7200 :wink:

No, there is no menu control available to boost the USB Rx audio on the IC-7200, and there seems to be no other way to boost it in the end-to end signal path between rig and remote speaker (on Linux).

Turning off AGC is often useful when running narrow-band digimodes which interfering signals in the passband. Obviously it needs to be re-enabled when using analogue voice modes.

I agree that it would be unfortunate to need to insert a gain stage in the rx audio path where no other audio processing is currently performed. However, it may not be necessary to create a specific path for the IC-7200 audio, if a config file entry for the gain defaulted to 0. It could then be set by the user if the user needed it, and the gain stage could be avoided entirely if the configured gain was 0.

I would be quite happy to dive into the code and have a stab at doing this myself, but I am currently recovering from a bout of Bell’s Palsy, which has caused some severe double vision and I’m not therefore able to comfortably familiarise myself with the code. This seems to be improving on a day by day basis though, so I may start to have a look at the code soon.


A better solution would be to use existing tools available within your operating system to provide this. Something like alsamixer should be able to provide the required boost.

73 Phil M0VSE

I have already mentioned the fact that alsamixer offers no level control of the rx audio from the USB codec at the server end. The same seems to be true of the loopback device added according to the manual.

If the USB Codec doesn’t provide a volume control, I would suggest using the softvol alsa plugin.


Thanks Phil, I shall give that a whirl. I am more familiar with fiddling with pulseaudio than alsa, so had not come across the softvol plugin before.


A pity the rig does not have it; Hope Phil’s sugestion works for you.

re the AGC: both Icom and I disagree (*). Some people think it makes stuff better but it’s not, really.
Use the fastest timing (100ms generally) for digital modes (and CW is a digital mode too) and only switch off if there are NO interfering signals in the passband.

Strong in-band signals will end up in the ADC being fed all ones.


(*) there have been talks about this at some fora – so decided to feed the stuff to my tech rep at ICOM.

Well, I do suffer from very strong impulse noise here too. I almost always have the Noise Blanker set to at least 70% to mitigate that and live with the inter-mod effects, unless I am using a digimode, in which case I will turn off the NB and the AGC. Also, don’t forget that the IC-7200 is a superhet, not an SDR, so this motivation to avoid disabling the AGC may not apply.

I have had a read of the alsa softvol plugin docs and at first glance it doesn’t seem ideal, as it appears that the boosted audio source only goes to the default output device, which doesn’t sound particularly useful at the server end or at the client end (though I may figure out some way to make it useful).

I still think that fixing the issue with the IC-7200 rx audio level within wfview is the approach that I would choose and I will investigate that possibility.

according to the website it’s using a DSP Darren so it will use an ADC to get it into he digital domain.