I found a good reason to have coupling if ref level is set to 20dB or higher
The noise floor with the widest RBW is, with a ref level of 20dB just visible if attenuation is set to 10 dB
So if a user sets the reflevel to 20 or 30dB, applying a minimum automatic attenuation of 10 or 20dB does not harm as you are not able to see the noise floor so an elevated noise floor does no harm and it protects the tinySA.

Seems whatever I try to do results in a "complex division by zero" error. Setting marker, clicking on trace...
I am running it from the Anaconda prompt, and I get first error right after starting saver:
Second one when entering frequency in marker 1 box
Gary
W9TD

On Wed, Aug 26, 2020 at 07:49 AM, Jean-Roger Roy wrote:

Erik, Herb

From my return of experience with different spectrum analyzers :

For old style / vintage equipment such a HP8558B, the reference level rotating button is mechanically coupled with the input attenuator (see picture). So the attenuator value follows the set reference level. However you can pull one part of the button for disengage this coupling function (as for manual setting on the tiny SA). The purpose is to have always the most suited RF signal at mixer level, regarding choosen reference level.


For most recent equipments, let's say 1990 and beyond, they increase their attenuation value automatically when the reference level is set to higher values. I have worked with HP8591 or FSA family fron Rohde et Schwarz, and it is always the same behavior. Please note that there is no "power level discover" at first sweep, like on the TinySA. You must pay attention at the default level settings before doing any measurements ! Practically most of (professionnal) users rely on RefLevel regarding RF input level. For professional equipment, it is sometimes hard to find what is the best tradeoff for the value of input attenuator (IIP3, noise figure, etc.). When required the user can decide to set (carefully !) the attenuator at 0 dB, in order to get the best sensitivity.

Now as I am retired, I own a Siglent spectrum analyzer which follows the same rules. Just as an example, here is the behavior for the (auto) attenuator about my Siglent analyzer :

Manual RefLevel set at -10 dBm, Auto Attenuator fixed at 10 dB
Manual RefLevel set at 0 dBm, Auto Attenuator fixed at 20 dB
Manual RefLevel set at +10 dBm, Auto Attenuator fixed at 30 dB

For information there are also intermediate values for attenuator such as 15 dB or 25 dB, when the Reflevel is set at -5 dBm or +5 dBm.

I understand your reasoning, as I just check what is the behavior of the tinySA according to RF input level. You have an automatic setting attenuation, that does not exist on all spectrum analyzers. The Siglent has something similar called "Auto Tune", but it doesn't work at first startup (sweep) of the equipment. RefLevel remains always at 0 dBm, so you need to pay attention at the level settings before starting any measurement.?

I understand perfectly the strategy in order to protect the first stages of the tinySA. My feeling is that there is nothing to change at this side, but if possible introducing the RefLevel driving when working manually. After all, if the user decides to set manually attenuator value or RefLevel, it means normally that he understands what it does. Any of these actions are equally dangerous (not RFLevel for the moment) ! Considering tinySA specifications (Wiki page), and its behavior, could we imagine roughly something like this (input level never exceeds +10 dBm, or +20 dBm for a very short duration) :

Manual RefLevel set at +30 dBm, Auto Attenuator fixed at 30 dB
Manual RefLevel set at +20 dBm, Auto Attenuator fixed at 20 dB
Manual RefLevel set at +10 dBm, Auto Attenuator fixed at 10 dB
Manual RefLevel set at 0 dBm, Auto Attenuator at 0 dB

It could be better for "educationnal purpose" (attenuation value increases with higher RefLevel) to have this kind of behavior, but it could be challenging considering the existing AGC strategy, so don't worry or waste time on this topic. Any of view of other users could be welcome.

Jean-Roger,
? ?Excellent response.? I think you hit it on the head that graduating from the tinySA to a professional level scope will be easier if the user is already familiar with attenuation value increasing with higher RefLevel.? But as you also reasoned, with the existing tinySA AGC strategy it may not be worth the risk of breaking the current well working interface.

? Its only users like ourselves that have used commercial grade equipment that question the automatic coupling between reflevel and attenuation.? Students, enthusiasts and hobbyists won't miss it, and it may be a good thing for them to learn to make the proper settings adjustments? manually.

- Herb

For any attenuation applied the displayed level always reflects the level at the input , regardless of the applied attenuation

My 2 cents: if manual attenuation is selected the IF gain should compensate so the reference level stays the same.
Gary
W9TD

For a first time user, would it be better to have coupled (e.g starting attenuation level) equal to refelevel if reflevel >= 0?
Or should it be better to go to coupled mode if the reflevel is manually set to >=0?
Or leave like it is now?

Older analyzers such as those in the HP141 mainframe had uncoupled rf attenuation and IF gain since they were in separate plugins. The display reference level did read correctly whatever combination was chosen.
Gary
W9TD

On Wed, Aug 26, 2020 at 06:57 AM, hwalker wrote:

Have you given future consideration to adding a marker x peak??console command?

I forgot, will do, see todo list in this groups wiki

Erik, Herb

From my return of experience with different spectrum analyzers :

For old style / vintage equipment such a HP8558B, the reference level rotating button is mechanically coupled with the input attenuator (see picture). So the attenuator value follows the set reference level. However you can pull one part of the button for disengage this coupling function (as for manual setting on the tiny SA). The purpose is to have always the most suited RF signal at mixer level, regarding choosen reference level.



For most recent equipments, let's say 1990 and beyond, they increase their attenuation value automatically when the reference level is set to higher values. I have worked with HP8591 or FSA family fron Rohde et Schwarz, and it is always the same behavior. Please note that there is no "power level discover" at first sweep, like on the TinySA. You must pay attention at the default level settings before doing any measurements ! Practically most of (professionnal) users rely on RefLevel regarding RF input level. For professional equipment, it is sometimes hard to find what is the best tradeoff for the value of input attenuator (IIP3, noise figure, etc.). When required the user can decide to set (carefully !) the attenuator at 0 dB, in order to get the best sensitivity.

Now as I am retired, I own a Siglent spectrum analyzer which follows the same rules. Just as an example, here is the behavior for the (auto) attenuator about my Siglent analyzer :

Manual RefLevel set at -10 dBm, Auto Attenuator fixed at 10 dB
Manual RefLevel set at 0 dBm, Auto Attenuator fixed at 20 dB
Manual RefLevel set at +10 dBm, Auto Attenuator fixed at 30 dB

For information there are also intermediate values for attenuator such as 15 dB or 25 dB, when the Reflevel is set at -5 dBm or +5 dBm.

I understand your reasoning, as I just check what is the behavior of the tinySA according to RF input level. You have an automatic setting attenuation, that does not exist on all spectrum analyzers. The Siglent has something similar called "Auto Tune", but it doesn't work at first startup (sweep) of the equipment. RefLevel remains always at 0 dBm, so you need to pay attention at the level settings before starting any measurement.?

I understand perfectly the strategy in order to protect the first stages of the tinySA. My feeling is that there is nothing to change at this side, but if possible introducing the RefLevel driving when working manually. After all, if the user decides to set manually attenuator value or RefLevel, it means normally that he understands what it does. Any of these actions are equally dangerous (not RFLevel for the moment) ! Considering tinySA specifications (Wiki page), and its behavior, could we imagine roughly something like this (input level never exceeds +10 dBm, or +20 dBm for a very short duration) :

Manual RefLevel set at +30 dBm, Auto Attenuator fixed at 30 dB
Manual RefLevel set at +20 dBm, Auto Attenuator fixed at 20 dB
Manual RefLevel set at +10 dBm, Auto Attenuator fixed at 10 dB
Manual RefLevel set at 0 dBm, Auto Attenuator at 0 dB

It could be better for "educationnal purpose" (attenuation value increases with higher RefLevel) to have this kind of behavior, but it could be challenging considering the existing AGC strategy, so don't worry or waste time on this topic. Any of view of other users could be welcome.

Jean-Roger

On Wed, Aug 26, 2020 at 02:07 AM, Erik Kaashoek wrote:

Do I understand correctly that commercial spectrum analyzers increase their attenuation when you set the ref level to higher values?
F.i. setting the ref level manually to +20dBm should also activate at least 20dB attenuation?
The automatic attenuation and automatic ref level setting will set the attenuation to a high value if strong signals are present but only after one sweep with lower attenuation which may be dangerous for the tinySA
My reasoning was that if you expect a strong signal you set attenuation to a fixed level (say 20dB) and then the reflevel will automatically follow so the attenuation is leading, not the ref level.
Can other users that have experience with commercial spectrum analyzers add how this is expected to work?

Erik,
? On commercial spectrum analyzers I have used there is a coupled and uncoupled mode.? When operating in the coupled mode, changes in reference level also result in changes to the input attenuation. From?Agilent Application Note 1316:

? ?The amplitude represented by the top line of the graticule is the reference level. It is a function of the input attenuation and the IF gain. The reference level control determines the IF gain.

? The tinySA can be considered as operating in the uncoupled mode with regards to reference level and input attenuation. The tinySA AGC circuitry does perform automatic input attenuation switching but its dependent on signal level and not reference level setting.

? ? I haven't had a chance to play with the Rigol DSA815 or other offerings in the $1000.00 range.? I suppose attenuation and reference level are by default coupled on those spectrum analyzers.

?- Herb

On Wed, Aug 26, 2020 at 12:17 AM, Erik Kaashoek wrote:

New FW released
Version v1.0-61

Changes:
- After a marker search using the menu, a marker can be moved to any position using the lever.
- When the sweep is paused you can directly select a marker as active marker by touching the marker info and this is reflected in the marker info

Erik,
? The new v1.0-61 peak marker function is working very well, as is the level action for positioning the marker.? I tested all 4 markers with display sweeping and paused and had no issues.

? The peak search function is especially useful? with a narrow span and large bandwidth where the max marker is pegged at the beginning or end of the sweep.? Under the same condition, the peak marker is able to go to the true display global maximum.

? Have you given future consideration to adding a marker x peak??console command?? I currently get this info by reading data 2, finding the max value in data 2, and indexing into the frequency array to get the max value frequency.? Much easier would be to do a marker peak and read the marker info for frequency and value.

? Many thanks for the new functionality.? It feels like a natural part of the marker search menu.

- Herb

Thank you!!

================================================

On Wed, Aug 26, 2020 at 04:51 AM, Igor Jobim wrote:

"Save" command returns as "Save?".

The save command is not yet enabled.
Please remind me if not in the next FW release

On Wed, Aug 26, 2020 at 01:57 AM, Jean-Roger Roy wrote:

Is the first use case (no change on attenuator value, according to set reference level) a deliberate choice, regarding whats happens with other spectrum analyzers

Hi Jean-Roger

As I do not own a commercial product spectrum analyzer (only some I build myself) I do not know how a "normal" spectrum analyzer is supposed to work.?
Do I understand correctly that commercial spectrum analyzers increase their attenuation when you set the ref level to higher values?
F.i. setting the ref level manually to +20dBm should also activate at least 20dB attenuation?
The automatic attenuation and automatic ref level setting will set the attenuation to a high value if strong signals are present but only after one sweep with lower attenuation which may be dangerous for the tinySA
My reasoning was that if you expect a strong signal you set attenuation to a fixed level (say 20dB) and then the reflevel will automatically follow so the attenuation is leading, not the ref level.
Can other users that have experience with commercial spectrum analyzers add how this is expected to work?

Hi Erik and all,

As some of us I received my TinySA a few days ago. Before introducing my question, I would like to congratulate Erik for the provision of a such equipment, unimaginable a few years ago.

Maybe this question has already been answered ?

AUTO default level parameters are a 0 dBm reference level and an attenuator value of 0 dB. Changing manually REF LEVEL to +20 dBm has no effect on the attenuator value (still 0 dB). If I return to AUTO for reference level and change manually ATTENUATE to 20 dB provides a reference level of +20 dBm. It sounds normal for this second use case. Of course we agree here that max level input does never exceed +10 dBm ! Below three snapshots illustrate the three use cases.



Internal 30 MHz signal - Default level values : reference level = 0 dBm, attenuator value = 0 dB




Internal 30 MHz signal : first use case, no change on attenuator value, according to set reference level (+20 dBm)




Internal 30 MHz signal : second use case : reference level (+20 dBm) changes with set attenuator value (20 dB)

Is the first use case (no change on attenuator value, according to set reference level) a deliberate choice, regarding whats happens with other spectrum analyzers ? Or maybe is it a a way for keeping the best dynamic range when using an external attenuator ?

Once again thank you for all your valuable efforts in pushing this nice and amazing tool.

73 from Jean-Roger / F6EGK

New FW released
Version v1.0-61

Changes:
- After a marker search using the menu, a marker can be moved to any position using the lever.
- When the sweep is paused you can directly select a marker as active marker by touching the marker info and this is reflected in the marker info

Dick,

I updated the wiki FW update section:?
Any other places that need improvement?

All members of this group can edit the sub pages of the groups wiki found here:?/g/tinysa/wiki
User contributed content is more than welcome!
If you need a new sub group just ask for it.

No problem, Dick.?

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