Active "Hang" AGC

Ken - NM9P

An interesting option for AGC might be to allow one or two different custom AGC profiles where the user could program different time constants depending upon the need. I remember an article in Ham Radio magazine (in the 70's or 80's it was the most technical of all the ham rags) by Ulrich Rohde about what I will call an "Active Hang AGC" that was amazing. It could shift from fast/med/slow, but instead of the decay merely being set by the fast/med/slow setting, it was steady until the "hang" constant timed out, then went quickly back to full gain. The kicker was that if you were on slow setting, a brief static burst would essentially blank your receiver until the slow time constant ran out. So to combat this, there was a second timer that said "don't activate the "hang" timer until the signal has been active for a certain amount of time." this way, even if you were in slow AGC, a short burst would be acted upon as if it was a Fast AGC, but a voice or CW signal activated the "hang" timer and the hang would stay for the amount of time set by the fast/med/slow hang constant. It was an amazing concept implemented in Rohde receivers in the 70's & 80's. Now if we had a custom AGC system like that, with all the different constants definable, I would JUMP at that one! It would be especially nice if I could set one for CW and another for SSB as "Custom 1" and "Custom 2." variable constants could include: Attack - (how quickly gain is reduced) Decay 1 - (how long it would take to ramp the gain back to full after AGC activation, if it were not being returned after the Hang Timer...If only using these two parameters, and Hang Time is set to Zero, this time constant is the same as Fast/Med/Slow in a traditional AGC.) Decay 2 - (how quickly to return to full gain after hang timer expires....can be different, preferably much shorter, than Decay 1 when using Hang AGC.) Hang Time - (Time to wait before returning to full gain...If this is set to zero, then the AGC functions only with Attack and Decay 1) Hang Delay - (How long a signal must be present before Hang Timer is activated - i.e. noise burst protection) Pre-Hang Decay - (How quickly to return to full gain for signals that do not activate Hang Timer...can be different from Decay 1 & Decay 2. Preferably much shorter than both or at least as short as Decay 2) I may have left one or two additional parameters out. This would constitute a perfect AGC system for me. By adjusting various parameters, the user could define them just like any other traditional rig's AGC by using only Attack and Decay 1, or they can utilize the "Hang AGC" features simply by adding the numbers for Hang Time & Decay 2. They could add even more utility by using the full blown "Active Hang AGC" by adding numbers for Hang Delay and Pre-hang Decay. If these are too many parameters, the scenario could be simplified by only having Attack, Decay, Hang Time, and Hang Delay, and stipulating that the Decay time during the Hang Time constant is a long number that is irrelevant since the gain will be returned at the end of the hang time at the speed of the "Decay" setting. There are a variety of variations to this options, but the key is to have adjustable attack, return-to-gain Decay, Hang Time, and especially the "Active Hang AGC" parts of Hang Delay and Pre-hang Decay. This could be implemented as part of the regular AGC system, or made part of a "Power User" or "Expert Mode" option list. What do you think? Ken - NM9P

Dan -- KC4GO

So it's an AGC-T Lab that your looking for Wonder if that can be done via API.

Lee - N2LEE

Ken, the sad part about this request is I guarantee it would create a support nightmare for Flex and a so much confusion on the part of 90% of the users.

Sometimes when a software develop implements too many options it can actually detract from a product.

Don't misunderstand. I would like to have a better AGC as well but would hate to be the one to support this questions this would generate.

Lee - N2LEE

Kevin, one of the most difficult issues in product develop is making a product that is "usable". A lot of companies can build a product that includes every possible feature but few can make it easy to use and understand.

Look at some of the current analog radios on the market. The menu systems are so freaking complicated and multi-layered that they can often become extremely difficult to use. Yea its great if you are on the engineering staff and want to see how many features you can cram in one box. But for the user, finding and using these features are a horrible experience.

My point was Flex can build any feature people ask for but the question is:

1. How large of a market would use a feature ?
2. How can a potentially complex feature be made easy to use ?

One of the issues in adoption of SDR radios is they are complex, require a computer and do not have knobs.

The reason users want knobs, aside from tactical feedback, is they can hit one button or knob to control a function. If Flex makes SmartSDR so complex and difficult to use by having complex menus and settings then they will alienate the very audience they are trying to attract.

This might not be the best analogy but I see parallels between Apple and Linux.  Flex is more like Apple, they are trying to build a solid, easy to use and reliable platform. It's complex under the covers but they still understand they are building a RADIO not just a piece of software. Products like Anan are more like a kit or like LInux. Linux users can add-on open source software software and all kinds of bells and whistles but it has the potential become complex and unstable very quickly.

Nothing wrong with either approach but based on my experience working in product development, I believe that Flex is taking the long term view of the market. It seems to me they realize their success is tied to the middle of product lifecycle bell curve. Yes there are early adopters which would be the Flex 1000, 3000, 5000 product line. But the 6XXX series has to be successful in the mainstream market for Flex to survive upcoming knob sdr radio invasion. 

All of this is a long way of saying, if they are not careful they can add so many features that they destroy the adoption of that product their target market.

Ken - NM9P

One item I forgot to add in my post is a "parameter reset" button in the AGC drop down menu, which would reset the custom AGC parameters to some default values to provide easy recovery when someone really messes it up! (;p)

Ken - NM9P

Agreed, the rig should be easy to operate, but shouldn't sacrifice ultimate performance in the name of simplicity. That is why I am in favor of optional "expert mode" and "parameter reset" buttons for potentially complicated subsystems like filter parameters, AGC constants, DSL, etc. I don't think it needs to be either/or... Ken - NM9P

Lee - N2LEE

Ken I think you and are actually in agreement. I too would like to see better noise reduction and AGC improvements.

The parameter reset is something I have been asking for as well. My suggestion was a simple one. If you double click  on the name/title of a slider it would reset that option to default. Also as far as I know Smartsdr does not utilized the Right mouse button for any features. My guess was so that you could operate the radio without a mouse, such as with a device like the Maestro. But a right mouse button could also bring up an array of options for each setting such as reset or presets.

My caution was that of creeping feature-itist. 

Ken - NM9P

[Humor button activated].....

Perhaps FRS needs to implement some sort of "ability certification testing" which, when passed, the user will be given the secret code which will unlock the "expert mode" menus for the rig?  Otherwise, they get the "standard user interface."  [grin]

[Humor button deactivated].....

Actually, you and I are pretty much in agreement.

One of the things I enjoyed when I moved from the 1500 to the 6500 was how simple and intuitive most of the interface has been.  It took a few days to really get the hang of it, but it wasn't long before moving back to play with the 1500 became more and more frustrating in comparison.

I have also appreciated is that almost all of the menu adjustments are only one or at most two mouse clicks deep and categorized logically enough that it is pretty intuitive to navigate, unlike some rigs where things can be buried several layers down in a labyrinth of winding pathways.

Yet, after three years with the 6500, and having sold my 1500, there are a few functions that I miss being able to customize.  (RX Filters, Filter Buttons, AGC Characteristics, Some other DSP functions like NR, NB, ANF, etc.)  Thus my desire for "Advanced User Options."  But I think that they can and should be folded into the excellent user interface that we have in SSDR, with "Reset to Default" buttons on various modules to provide quick and easy recovery for those who are still learning the system and haven't mastered it yet. (Or experienced users trying to push the edge of the performance envelope and find themselves "over the edge!".

HCampbell WB4IVF

[humor button reactivated]  Yep, an “ability certification test” might be a good way to avoid the law of unintended consequences.  I liked the comment by one of the Flex folks (Tim or Steve?) that whenever Flex agreed to a new user control, a programmer would quip “somewhere another angel just lost its wings”.

Howard

Tim - W4TME

That particular quote is credited to Steve.

Jay Nation

 (humor button) Click it! at least, I"ll be laughing. 

An expert mode button, with with a mouse hover tooltip, that reads, "No! Your not worthy YET!".

 SDRgadgets

73, Jay - NO5J

Lee - N2LEE

"Sorry this feature can not be activated until you complete this simple 25 question test." LOL

EA4GLI

There is always the Advanced vs Simple setup options. Video cards drivers do that.

Ken - NM9P

"Show me your degree, and I'll give you the key!"

Lee - N2LEE

No problem. I have several. 15 degrees, 45 degrees and 90 degrees.

W9OY

Ten Tec had a hang AGC back in late 70's and 80's.  Worked OK but I wouldn't waste any radio resources for it.  It's only really useful when talking o very strong stations and you cn easily emulate the effect simply by turning down AGC-T

73  W9OY

Tim - W4TME

I have an infinite number of degrees of freedom, but I am limited in the Z plane. ;-)

G8ZPX

@Lee N2LEE,

With respect, FRS are not selling iphones to the IQ0 Muppet market. We are sophisticated users of complex products and we should not be controlled like children. 

When Apple decided to impose restrictive practices on the user base such as blocking Flash player etc, that was the day my iPhone went on eBay. Since then I only buy Android phones for my family and my staff.

Buyers have the freedom to vote with their feet, designers need to take note.

Don't really mind too much about the AGC question, but locked-down design practices are a big turn off to technical buyers.

mikeatthebeach .

If you want radio's with no real adjustments you can buy any of the big 3 Japanese HF rigs !

G8ZPX

Mike, to be fair even the Icom 7300 has a vast array of settings and customization such as filter shape profiles that work by mode and by band etc. I don't think AGC is one of them though.

If we can't have infinite AGC slider controls like Ken wishes, then why not at least predefined AGC profiles?

Tim - W4TME

While ham radio is a technical hobby, not everyone's knowledge and comprehension of these technical aspects are the same.  If they were, then we would not need a support organization HI  HI.  To Lee's point, the original PowerSDR software exposed a lot of controls to the underlying features (aka "nerd knobs").  Lots of buttons to push, knobs to twist, and sliders to side.  Because of this paradigm, it was very easy to get  FLEX SDR in a state where it just didn't work very well and we fielded a lot of support calls due to it (we still do as a matter of fact).  This resulted in a less than satisfactory user experience.  So when we started developing SmartSDR, we purposely engineered features to minimize the number of nerd knobs.

Even today, with a single threshold control for ACG (AGC-T), we still get a lot of support calls where the report is the radio is deaf or not receiving and find the AGC-T set to 10.  So we evaluate very seriously changing a feature to add more nerd knobs as we need to strike a balance between usability and maintaining an overall positive user experience.