One of the great things about running
the ANAN rigs with OpenHPSDR mRX PS is
that the developers have made it possible
to get up and running out of the box very
quickly. It's nearly a plug-and-play
operation and it's not unusual to tune
across the band and hear a station that is
on the air only a few minutes after
unboxing their new ANAN. That being said,
the developers have also provided users
with numerous settings that offer lots of
control over the quality of the signal
they transmit on the bands. This quick
setup guide is a simple step-by-step walk
through of how to adjust some critical
settings in the TX audio processing chain
of OpenHPSDR mRX PS. One additional note
to those who are coming from the Flex
version of PowerSDR: Keep in mind that the
entire TX audio chain in OpenHPSDR mRX is
very different from what you worked with
in PowerSDR. It is all new from
front-to-back and the adjustment procedure
in the software is made far simpler by
look-ahead algorithms that prevent
clipping and distortion products in the TX
audio chain. In fact, you will find that
it is impossible to drive the Leveler
beyond 0.4 dB or the ALC
beyond 0 dB. The comments below from
Warren - NR0V (one of the lead developers
of OpenHPSDR mRX) are an excellent
description of what we should aim to do
when setting the levels in the transmit
"To drive the audio chain in
PowerSDR mRX in the way the design
intends, you should be frequently
hitting 0dB on the ALC meter; frequently
hitting 0dB on the Leveler if it is in
use; and achieving 0dB or above on MIC
if the Leveler is not in use. The speech
processor we have in PowerSDR mRX PS is
NOT the old compander that was used some
time ago, it is a much different
algorithm, as are the Leveler and ALC
- For those operators who know their way around the setup menus in PowerSDR mRX simply follow the short list of 4 steps directly below. Click on the active links for a more detailed explanation if needed:
With the TX multimeter set for MIC,
select your source (Mic in, Line in, or
VAC) and then set the audio level so your
voice peaks are regularly reaching
close to 0 dB.
2. With the TX multimeter set for EQ, adjust the equalizer sliders for a flat response, then set the Preamp slider so your voice peaks are regularly reaching close to but not exceeding 0 dB.
3. With the TX multimeter set for LEVELER, adjust the Max Gain so voice peaks are regularly reaching 0 dB.
4. With the TX multimeter set for ALC, check to make sure your voice peaks are reaching 0 dB. If necessary, adjust the LEVELER so that your voice peaks regularly hit 0 dB. Note that this is essential for the Pure Signal algorithm to operate properly.
Those are the basic steps for setting
up the initial levels in the TX audio
chain. Go ahead and plug your headphones
in, enable the MON function, adjust your
TX Transmit Filter settings, and adjust
your TX frequency response using the EQ
sliders. If desired, enable the COMP
setting and adjust it according to your
preference. Re-check your levels again and
when you are done, save all your settings
into a new TX Profile.
those operators who are new to
PowerSDR mRX, the detailed
step-by-step instructions below
should help you to get your levels
set up optimally.
Follow for Adjusting
the Gain Settings Throughout
the PowerSDR mRX TX Audio Chain
1. Connect the ANAN to a 50 ohm dummy
load and select one of the voice modes in
PowerSDR mRX. For now, select the Default
2. If you have the COMP button
enabled on the front panel GUI of PowerSDR
mRX, unselect it now.
3. In the upper left corner of
PowerSDR mRX, click on Setup and
when the tabbed interface comes up click
on the Transmit tab to bring up
the menu that is shown in the image below.
4. If you are using a microphone plugged into the front panel MIC jack then select Mic In for the source. If you are using an external audio chain into the back panel DB-25 line level input then select Line In for the source. If the 20dB Mic Boost option is checked I would suggest unchecking it for now. Keep in mind that if your microphone produces low output then you would want to come back to this setting and enable it to assure that enough gain is present to drive the audio chain adequately.
5. In the upper right corner of the
PowerSDR mRX interface use the TX dropdown
in the meter to select Mic as
shown in the picture below. This allows
you to view the level of the first audio
stage of your ANAN.
It's not necessary to produce RF at this time so slide your Drive level down to "0" and then switch the rig to transmit. Speak into your microphone as you would when making a contact and observe your mic level in the TX Meter. Adjust this level so that it reaches close to 0 dB on voice peaks. Adjust the MIC slider to the right if you need more gain, or to the left if you need less gain. If you find that you are unable to set the gain high enough, go back and enable the 20dB Mic Boost setting in the Transmit tab and try again. When you are getting close to 0 dB on most voice peaks proceed to the next step.
6. Now, press the TX EQ
button on the front panel of the PowerSDR
mRX user interface and then set the TX
meter to EQ. This allows you to
view the level of your second audio stage.
From the drop down menus along the top
left of the PowerSDR mRX interface, select
Equalizer and position it on your
desktop so that you can access the
Transmit Equalizer easily. I would suggest
that you enable the 10 band equalizer
function at this time if you have not
already done so, and for now, leave the EQ
7. Note that the MIC gain and the EQ gain are actually two adjustable gain stages in series, with the output of the EQ stage being the one that is critical. At this particular point in the TX audio chain there is no limiting, so pushing the peak levels beyond 0 dB at this stage may cause ADC clipping which will result in a distorted TX signal. Observe the TX meter EQ level as you speak into the microphone and adjust the Preamp slider on the left side of the EQ interface so that your maximum peaks reach close to but do not exceed 0 dB. When the level is satisfactory, proceed to the next step.
8. Set the TX meter to Leveler.
Select Setup again and open up the
PowerSDR mRX tab for DSP and go to the AGC/ALC
9. As you transmit and speak into the mic, adjust the Leveler Max Gain (dB) setting upward or downward from the default setting of 5 so that your voice peaks on the TX meter are regularly reaching 0 dB. You will notice that one of the look-ahead-algorithms that is present in the TX audio chain makes it impossible for you to drive the Leveler beyond 0 dB. Think of it as a very effective soft limiter that prevents you from clipping or distorting but gives you an impressive amount of control over the loudness of your transmitted audio. For a little demonstration of the effectiveness of the Leveler visit this page to view a short video showing how the Max Gain settings from 0 to 20 sound to someone else on the receiving end. For now, choose a value where the TX meter starts to hit 0 dB with every voice peak. Move on to the next step when you are satisfied with this setting.
10. Set the TX meter to display ALC and while transmitting, check to make sure that you are regularly reaching 0 dB on voice peaks. If you are not, go back to the Leveler's Max Gain setting and increase the value until your voice peaks push the ALC to 0 dB regularly. You will note that the look-head algorithm at this stage makes it impossible to drive the ALC beyond 0 dB. You can rest assured that as long as the MIC + EQ level is set correctly, there are no worries about distortion as the look-ahead-algorithms in PowerSDR mRX will absolutely prevent your ANAN from clipping and splattering while transmitting. Additionally, when you engage the Pure Signal protocol, it is essential to drive the transmitter hard enough so that the pre-distortion algorithm samples the signal frequently as you are transmitting.
11. I would suggest at this point that you plug some headphones into your ANAN's headphone jack and then enable the MON button in the upper left corner of the PowerSDR mRX user interface. Bring up the software Equalizer again and as you transmit, adjust the equalization of your transmitted signal to suit your audio preference. When you are done with the equalization, check the EQ level with the TX meter to assure that you are reaching near 0 dB at this point of the chain and adjust the EQ Preamp slider as needed.
Note that when you have finished, your
audio should sound smooth and clean. You
can also create custom transmit filters in
PowerSDR mRX to suit the kind of operating
you wish to do. Go to Setup and
then select the Transmit tab in
PowerSDR mRX. In the upper left corner you
will see the High and Low settings
that you can adjust to create a suitable
filter for your needs. In the example
below, I set the low cutoff to 70 cycles
and the high cutoff to 3070 cycles to
create a filter that is exactly 3.0 kHz
wide. Once you've adjusted your transmit
filter, proceed to step 12 down below!
12. When you are all done with your adjustments, do not forget to save them into a TX profile! Each TX profile saves many of your operating parameters including the TX bandwidth filter settings, front panel Mic setting, EQ preamp level with either the 3 or 10 band adjustments, Leveler gain setting, front panel Compressor setting, and RF transmit Drive level. If you do not save your settings, they will be instantly lost when you switch TX profiles! Before you save your first transmit profile, set your Drive level to a setting that you would typically start out with when operating. I like to set all my profiles with the Drive level set to "35" because that works fine with either of my amplifiers and is low enough that no major catastrophes will occur if something in the station is not set correctly. I figure that once I'm ready to engage in a QSO I can manually slide the Drive level to whatever power level is required for the occasion.
To save a profile, in the Transmit
tab as shown in the image above, select
the "Save" button and this will bring up
a dialog box that will allow you to save
your new profile with a unique name. I
usually select a name that identifies the
mode and bandwidth for which the profile
was created, but you can use whatever
system works best for you. It would
also be very wise at this point to make
sure that the two Auto Save TX Profile
options (shown in the image above) are
UNCHECKED so that your TX profiles are
not inadvertently altered as you are
operating! As you can see in the
image below, I have lots of different
transmit profiles to suit operation for
different bands, conditions, and modes so
that my transmitted signal fits in with
whatever is being done by others on the
frequency of operation.
Summary: Once you have
gone through these settings a few times
you'll discover many other settings that
are worth investigating. For example, in
the pictures up above showing the Transmit
tab you will see a check box for CESSB
Overshoot Control. When you engage
the COMP button (underneath the MIC
button in the PowerSDR mRX front panel
GUI) this feature comes alive and does a
beautiful job of increasing your average
RF output without creating excessively
large RF output peaks. I keep this feature
alive with all my transmit profiles by
enabling the COMP button and
setting the slider to a modest level of 1
dB and then saving it to each TX profile.
Advancing the COMP level to higher levels
will increase the processing effect if you
wish. Another feature is the downward
expander which is enabled with the DEXP
button. I have no experience with this
setting but Scott - WU2O has mentioned
that changing the attenuation factor to
100% makes it a hard gate. He prefers a
setting of 90% and notes that 80% is too
soft a gate for his use. It's very
worthwhile to experiment with different
settings while monitoring your own signal
with headphones and the MON button
There are many more settings to investigate but they go beyond the scope of this simple walk through. Hope this helps you get started!
Many thanks to Scott - WU2O for his
many content and clarity suggestions for