DUP, Anan Step Atten, S-ATT, ATT on TX ??

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DUP, Anan Step Atten, S-ATT, ATT on TX ??

Postby K9RX » Mon Jul 31, 2017 12:53 am

Scott,

I thought about putting this on the yahoo group but wanted a smaller audience, and to keep it here for general reference - and hopefully have YOU answer it ... thanks

OK - I've gone through the manual, again, and have the following questions:

I don't believe these things are covered or at least not in depth like I'd like in the 8000 manual.

1) What does "Anan Step Atten" do? There is an option under GENERAL/OPTIONS for this.. I assume - but don't want to - that this is the 31 db step atten at the input to the RX. But why (have the ability to) disable it?
Why not just always have it inline and set at 0 as default?
Not in the 8K manual.

2) What is the S-ATT?
I see it when I go to xmit ... but I've no clue what it is?
what it does?
What I'm suppose to adjust it to?
Its not in the manual (or at least not as "S-ATT" ... it is however seen on the face of the program at times in a few of the pictures)

3) What is the ATT on TX (GENERAL | ANT/FIlters | Antenna)? (I suspect this and "S-ATT" are one in the same ... )
Again - what do I adjust it to - when do i use it?
How is it used?
The manual says to avoid overload in the receiver? HUH?! No mention of DUP being on so I'd assume the receiver is not working during xmit, or is it (unless DUP is on)?
And if there's a potential issue of overload why is it a user setable function?!

4) And finally the big question: What the heck is DUP?! I know - it is DUPLEX ... or so it would appear. I'm told to leave it on ...
but I would like to know what it does and how it is hooked up internally.
The manual says and I quote:

"The ANAN-8000DLE transceivers switch the selected antenna [ANT1, ANT2, or ANT3] to ground during transmit, "

I would venture a guess this isn't the case. I'm guessing it shorts the input to RX1 to ground? Or through a 50 ohm load to act as a sense for the signal greatly attenuated? But I'd rather not guess - what DOES it do?!

The reason why I ask is I'm still not able to get a 'nice' "receiver" like view of the Xmit signal. But I'll save that for another post under another topic header once i have a clearer understanding of the above items.


Gary
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Re: DUP, Anan Step Atten, S-ATT, ATT on TX ??

Postby w-u-2-o » Mon Jul 31, 2017 1:40 am

Well, I hate to think it's a smaller audience!

The 8000 "manual", or User Guide, is substantially similar to all of the other User Guides, so don't single it out.

Step atten, or step attenuator: study the block diagrams in all of the user manuals. You will see that there are two switched attenuators on the PA/RF boards on the 100, 100B, 100D, 200D and 8000. They are a 10 and a 20dB attenuator, that can be used singly or together to obtain 10, 20 or 30dB of attenuation. There is also a digitally controlled step attenuator on the SDR board itself, Hermes through Orion Mk II, they are all the same in this latter respect. This step attenuator can provide between 0 and 31dB of attenuation in 1dB steps, in together with the other switched attenuators or separately.

If you double click on the "ATT" control legend in the main UI, you can switch between a mode that uses the switched attenuators and the step attenuator together to obtain the listed values of attenuation in the drop down menu, and another mode that uses the step attenuator exclusively. I this latter mode you can obtain more accuracy in the level of attenuation you want but are limited to a maximum attenuation of 31dB.

1) Going into Setup > Options and turning on "ANAN Step Attenuator" is the same as double clicking in the main UI to change receive attenuator modes.

2) S-ATT in the main UI denotes that you are in Step Attenuator mode instead of "normal" attenuator mode, as described above.

3) The ATT on Tx option is used to invoke the amount of attenuation you want in the step attenuator when transmitting. This level is saved separately for each band. It is used to adjust the signal level when using both DUP and PureSignal, separately or together.

4) DUP, or Duplex Mode, causes the RF that is present on the 8000 PS INPUT connector to be processed by RX1 and shown on the spectral display during TX. With DUP turned off you only see a representation of what is going to the DAC. With DUP turned on you see the real deal, normally either from the built in, internal coupler, or from an external coupler on the output of an external amplifier. Since the receiver is working at the same time as the transmitter, the radio is essentially in a full duplex mode, hence the "DUP" nomenclature. You pretty much always want DUP to be on.

To get your "nice view", you need to be sure that your ATT on Tx value is correct for each band, and you need to adjust your amplitude scaling in Setup > Display > TX appropriately. I use Max 20, Min -70, Step 2, Align Center, however YMMV. Adjust to taste.

Note for non-8000 users: on the 100D and the 200D, with the Rev. 24 PA/RF board you automatically get the internal coupler output unless you choose "Bypass on TX", and connect an external coupler to the Bypass input. On older revision PA/RF boards you automatically get the results of internal crosstalk instead of a designed in, internal coupler, or you use the Ext 1 input and select "Ext 1 on TX".

3) ATT on Tx revisited: when PureSignal is used and Auto Attenuate is selected (as it should always be except under very special cases), the Step Attenuator will automatically be driven to the correct value during TX for you.

73,

Scott
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Re: DUP, Anan Step Atten, S-ATT, ATT on TX ??

Postby K9RX » Mon Jul 31, 2017 3:43 pm

Great - thanks - that helps a great deal.

So another question re "DUP" use ... when I look at W1AEX's video's and the screen shots pasted in his written docs they all look like receive views ... i.e. the floor is -140 db ... but when I TX I don't get this - I have to use the DISPLAY/TX controls as you have suggested ...

I've played with the values - and the cows are close to being home - and still haven't been able to get anything close to what Rob shows regarding simply the noise floor let alone the signal. I'll post an image. (I read your post the other day on how to embed one - can do).


Gary
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Re: DUP, Anan Step Atten, S-ATT, ATT on TX ??

Postby w-u-2-o » Mon Jul 31, 2017 4:08 pm

Yes, please post an image, let's see what you've got. Showing the entire PowerSDR window would be best, so that all of your "front panel" settings are shown. Post your Setup > Display > RX1 and TX settings, too.

When obtaining images from your PC, another really handy tool is the Microsoft supplied "Snipping Tool". It's an accessory application and is available in both Win 7 and Win 10.

73,

Scott
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Re: DUP, Anan Step Atten, S-ATT, ATT on TX ??

Postby K9RX » Mon Jul 31, 2017 5:06 pm

Will do - one thing I didn't state clearly before - I wanted to understand what DUP was and from you I know it is exactly what I thought it was. I didn't want to go in with an assumption ... so if, or since it is indeed RECEIVING the signal - my signal - then why am I directed to adjust the TX settings?! Why wouldn't the same current adjustments for the RX apply? Why does the pan change - it should just remain the same I'd think... before xmit the relays do their job - the RX is 'isolated' ... and just continues on receiving only now the attenuated signal.

THAT is (possibly) the crux of the matter - and what I see in Rob's pictures and videos sure seems to suggest it IS the receiver settings that are 'used' ... but when I xmit - it immediately switches to the TX settings!

Gary
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Re: DUP, Anan Step Atten, S-ATT, ATT on TX ??

Postby w-u-2-o » Mon Jul 31, 2017 5:30 pm

The reason that separate amplitude scaling for the pandapter is provided for RX and TX is because the signal levels are, usually, quite different. Typical RX signal levels at the rear panel antenna connector range from the noise floor of -130dBm, give or take, up to -33dBm (S9+40dB)), although more usually -53 (S9+20dB). Compare this to typical external coupler levels at the rear panel connector (with appropriate coupling and attenuation factors) when transmitting of +10dBm, with IMD products down around -25dBm (non-linearized) or -45dBm (linearized). It's a big difference! Thus, to obtain better resolution the developers have thoughtfully provided the separate scaling factors.

The pitfalls of not having separate scaling factors are easy to appreciate when looking at the waterfall, which lacks such a feature. The waterfall is effectively useless during TX because the RX scaling factors are generally set far too low.

At any rate, you are free to set them to be the same or different, as you please. Take a look at this thread where I offer up my settings for others to try out on receive. For TX, and noting that I use an external coupler and attenuator to obtain approx. +7dBm max. at the rear panel connector, I use 20 max, -70 min (if an IMD product is below -60dBc I don't care about it) and a step size of 2dB.

73,

Scott
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Re: DUP, Anan Step Atten, S-ATT, ATT on TX ??

Postby AB2EZ » Mon Jul 31, 2017 5:55 pm

I completely agree with Scott.

As an additional comment:

I set my TX display settings essentially as Scott does: MAX=+20dBm, MIN=-60dBm, Step= 2dB

But

When using WSJT (where the WSJT app provides a separately derived received waterfall display) ... I set the ANAN's RX 1 waterfall to: "High Level" = -10dBm.

This makes the ANAN's own waterfall pretty much useless when receiving... but it gives me a nice waterfall display of the transmitter output signal. This display of the ANAN's transmitter output, when using WSJT, is particularly useful for seeing if there are any "glitches" being introduced when the WSJT digital audio output passes through the digital path to the ANAN's VAC 1 input.

Stu
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Re: DUP, Anan Step Atten, S-ATT, ATT on TX ??

Postby K9RX » Mon Jul 31, 2017 9:12 pm

Stu - good idea - I like that about WSJT ...

meanwhile - Scott, I see what you're saying but that doesn't address why Rob's videos show a floor of -140! THAT is why I've been assuming it was the same.

With that said - and I might have, I think I have been here before - but i just got the display to look MUCH more normal... how? I happened to notice the NB was on! I turned if off and - wow - normal. With NB on (as I have mentioned previously unfortunately I have lots of noise around here so it is often on) the waveform is constantly jumping around. With it off it is stable ... or at least has been for the few tests I've just done. Hopefully that was it - and indeed this is good info for future questions on this subject. I don't always have NB on - so this might be a coincidence although there is an "ON/OFF" relationship to the jumps I'm seeing in the waveform off of the floor ... we'll see.

Gary
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Re: DUP, Anan Step Atten, S-ATT, ATT on TX ??

Postby w-u-2-o » Mon Jul 31, 2017 10:57 pm

Post a link to the video you are referring to, please.

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