ATT and ZZPA command behavior

w9mdb
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ATT and ZZPA command behavior

Postby w9mdb » Sun Apr 25, 2021 4:59 am

I'm trying to make sense of the ZZPA command and the ATT selector on Thetis.
AGC on Fixd

Using the selector
0dB = ZZPA1
-10dB = ZZPA2 = -140
-20dB = ZZPA0 = -130
-30dB = ZZPA8 = -120 yet ZZPA8; does nothing

If I look at the signal level for what the level is now.
ZZPA0 = -130
ZZPA1 = -150
ZZPA2 = -140 -- but ZZPA then reports ZZPA7;
ZZPA3 = -130
ZZPA4 = -120
ZZPA5 = -110
ZZPA6 = -100
ZZPA7 does nothing

All this looks very confusing. I'm trying to program FLRig's "PRE" button to adjust the ATT but it looks like it varies across rigs and I have no way to figure out which rig is talking. Besides the strange mapping here.

It also appears to me that select values are inverted -- ZZPA0 selects -20dB on the ATT pulldown and that does not sound like ATT is "off".

Mike W9MDB
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w-u-2-o
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Re: ATT and ZZPA command behavior

Postby w-u-2-o » Sun Apr 25, 2021 2:16 pm

Using Thetis 2.8.11 and an 8000 (Orion MKII)...

Asserting ZZPA; as a query returns 1 for 0dB, 7 for -10dB, 0 for -20dB, and 8 for -30dB. This is consistent and reliable.

Asserting ZZPAx; as a command:

Where x = 1, this reliably selects 0dB.
Where x = 2, this reliably selects -10dB.
Where x = 3, this reliably selects -20dB.
Where x = 4, this reliably selects -30dB.

Also, remember that ZZRX reports on and controls the step attenuator.

As always, finding good documentation is a challenge. One must refer to both the CAT command reference and also look at the catstructs.xml file, but ultimately some experimentation is in order because, as is the case here, there are a lot things that are not well documented. Thankfully, testing is easy by using the Test CAT Commands facility found in Setup > CAT Control > CAT.
w9mdb
Posts: 216
Joined: Sun Apr 09, 2017 5:53 pm

Re: ATT and ZZPA command behavior

Postby w9mdb » Sun Apr 25, 2021 2:33 pm

Why aren't they symmetrical?

ZZPA2 returns ZZPA7 for example.

This make validating a setting confusing...

And why does ZZPA0 mean the middle attenuation instead of the least?
If you "turn off the preamp" that should mean minimum signal and not the middle of the attenuation.
w9mdb
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Re: ATT and ZZPA command behavior

Postby w9mdb » Sun Apr 25, 2021 2:34 pm

And the other problem is that the different Flex models have different meanings.

I guess all the Apache's are the same?
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w-u-2-o
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Re: ATT and ZZPA command behavior

Postby w-u-2-o » Sun Apr 25, 2021 4:26 pm

w9mdb wrote:I guess all the Apache's are the same?
I would not make that assumption.

I tried looking through the code but it's so convoluted I couldn't follow it. I did see code that implies setting the ATT control is the same across all hardware types. But I'm not at all sure about reading that setting.
w9mdb
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Re: ATT and ZZPA command behavior

Postby w9mdb » Sun Apr 25, 2021 4:37 pm

I'm making updates to both FLRig and hamlib.
So I guess I'll just have to disable this ability and everybody can just use the selector in Thetis.

In concert with other ZZ commands I'd like to see one in dB rather than some arbitrary index.
So we could do
ZZPX0; for 0dB
ZZPX-10: for -10dB
ZZPX-5: might round up to 10 and a query would show ZZPX-10;

I'll have to look at the code.

And another command which could retrieve the allowable values or at least where we could find out what

Mike
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w-u-2-o
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Re: ATT and ZZPA command behavior

Postby w-u-2-o » Sun Apr 25, 2021 5:06 pm

w9mdb wrote:In concert with other ZZ commands I'd like to see one in dB rather than some arbitrary index.
That already exists. Go back and read my first post again. It works perfectly. And it's really a better method. My console is always set up for S-ATT.
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I2NOY
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Location: Milano - Italy

Re: ATT and ZZPA command behavior

Postby I2NOY » Wed Jun 16, 2021 7:55 am

As I am a newbie, someone can explain in few words what is the use of step attenuator that I can find in Thetis configuration?
Many thanks,
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w-u-2-o
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Re: ATT and ZZPA command behavior

Postby w-u-2-o » Wed Jun 16, 2021 9:57 am

I2NOY wrote:As I am a newbie, someone can explain in few words what is the use of step attenuator that I can find in Thetis configuration?
Many thanks,

Also a newbie to forum etiquette, it would seem ;)

When asking a new question, one not directly related to the particular forum topic that makes you think of the question, it is better to start a new forum topic with your new question. This way it is easier for people to find the answer in future forum searches and prevents "topic drift".

Because this is a receiver hardware design question, please start a new topic with your question in this forum: viewforum.php?f=17 where I'm sure many folks including myself will be happy to answer it :)

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