ANAN 200D - P2 - distorted audio

[Max]

Max, "Regarding Visual Gain", I discovered the DSP issue by trying to get the wrong piece of hardware properly calibrated using the Visual Gain control. It went extremely wonky before I could achieve calibration. I am not sure what feature in the system went bad. All the DSP should float nicely since it uses "float", 32 bit floating point numbers. And as I typed that I thought of settings for noise reduction, agc, and possibly the overload blanking. They do shift nicely with the way Simon gets visual gain by multiplying all samples by a visual gain "constant". Simon should probably look into that.

{^_^} (I just passed it along to Simon.)

Actually Joanne my tip of disconnecting antenna to set noise at "zero S-point". Seems to work perfectly with my HL2, but on the Airspy HF+ it certainly does not. Interesting to note there is no hardware AGC in the Hermes Lite 2, only LNA Gain which I never have to touch once set, regardless of the presence of strong signals or change of band. The front end just seems bomb-proof.

Seems the hardware AGC in the HF+ messes things up so it's extremely hard to get any kind of meaningful calibration by starting out with antenna disconnected. Just as soon as AGC is turned on the whole noise floor shoots up. Conversely, trying to operate it with AGC off produces some pretty nasty results on a band late night with lots of very loud signals. So getting any meaningful S-meter calibration is very hard.

It's interesting to see (I think I have this right) that Yousef's own SDR# does not come with any kind of S-meter as standard. Maybe that's why? I think somehow his very active AGC profiles are fundamental in some way to getting the performance from the HF+ but make any kind of calibration extremely difficult or maybe impossible?

Max

[gm8arv]

There is an SNR indication, in dB, on the right-hand side of the display.

David

[jdow]

Max, when setup for maximum dynamic range a no antenna input reference level may be meaningless because the P-P of the residual noise might (should?) fall below one bit transition on the ADC. With an antenna connected external noise and signals provide some data that can be averaged causing an ability to run below that single bit transition threshold. Of course, at HF that's moot. There is so much noise there that this averaging effect takes place regardless. With an antenna that is suitable for transmitting you can put in a 30dB attenuator below about 5 MHz and not affect SNR when the band is open. Mid day it is a lot quieter due to propagation conditions. Calibration is best performed with instruments. Anything else is to loosey goosey for anything serious. Relying on a radio having X dB noise figure and Y Hz bandwidth to apply Boltzmann noise calculations for calibration is kidding yourself by 5 to God Only Really Knows dB.

David, you means the signal level scale on the right? That's not rightly an SNR or even SINAD indication.

{^_^}

[KA1GJU]

Max, I don't see a rise in the noise floor with your method on mine. There's a miniscule hint of a rise, but nothing really obvious. But there is a 'thump' or pulse, but
noise floor returns immediately back to previous levels.

Re: AirspyHF+, Disconnect antenna, DSP AGC Medium, adjust visual gain to ~0 (S-meter) noise, toggling Hardware AGC OFF/LOW/HIGH. There is a bump, but it returns to ~0.

Image is me cycling AGG OFF, LOW, HIGH:


73 Kriss KA1GJU

[gm8arv]

> David, you means the signal level scale on the right? That's not rightly an SNR or even SINAD indication.

I should have said "level", I think!

[jdow]

Makes sense, gm8arv.
{^_^}

[la6gh]

Happy New Year to all,
Thank you for your kind comments, I've been hunting on other fields during Christmas ...

Attached is a screenshot showing both Console and Thetis taken
more or less at the same moment.

I'm not sure I know what I'm doing, but I now feel, as has
been suggested by jdow, that a gain setting is way too high,
but I simply fail to find what setting that might be.

I love Console and have used it for Q-100 work (not with the ANAN)

I don't really need it for my ANAN 200D as Thetis is doing fine.
But I'm challanged when something doesn't work as expected....

I hope someone will point out what I have missed.

73 de LA6GH
Nils

[jdow]

OK, how are you using the ANAN200 (HL2)? It looks like you have external radio selected. And in the panes on the left titled "Radio" at the top I do not see a pane titled "Radio", which is the controls you want. Instead I see a closed pane for "External radio". And for an HL2 type radio I would expect to see the transmit panes. Although they can be switched off which you may have done intentionally. If you are using it as an IF monitor for something else in this example then I'd expect some form of gain controls in that closed "External radio" pane.

{^_^}