Date   
Re: No Boot-Up (after spikes)

Ted
 

Hi, John. 


I got a Nano generic to load up the diagnostic sketch, attached it to the Raduino (out of the radio), and ran through the control function tests. It saw the i2c bus and the si5351.  I ran through it kind of fast and didn't take notes on what ports were connected on each. I wanted to try a $18 genuine Nano board for kicks, as I've been skeptical of using that up to now. 

It seems I can program both the generic and the genuine board just fine but, after that initial test, I can't the the comm port monitor to see Nano output from either board, Of course I swapped comm ports to match the two different boards..  The first time I connected, I received menu lines immediately (you know, like old TNC work or with dial-up modem setups). Since then,no readback.  It seems like the more simple stuff is the most frustrating.  Maybe some sleep will fix this.  See you in the AM.  

And, thanks for the tip on the diagnostics. It's just what I was hoping for, actually, as it takes away a lot of guesswork.


- Ted

Re: No Boot-Up (after spikes)

Ted
 

Joe,

After fixing the first Raduino shorting, no luck. Maybe it's done, not sure yet. Somewhere along the line of hooking up a spare, I got pin 3 (Clock #2) and pin 4 (Gnd) a bit close for a while. It probably remained that way for 10 minutes or so while trying to trace any reasonable answer to the original problem. Anyway, the 2.8" Nextion is toast (reason unknown) and when I hook this radio to my other uBitx 3.5" screen, that screen likewise sits on the initial boot-up with zeros where the Nano information should show up.

As to your question, if I press screen buttons, I get the same false action that one gets while in the Debug mode in the Nextion software.  Ig's powered up but not speaking to anything, same as the original screen, 5 (now toast) Nano boards, and two Raduino boards (one might be dead). 

I can't wait unitl it's warm enough to go sailing again.  


With appreciation,

Ted
K3RTA

Re: Confused about how AGC works?

Tom, wb6b
 

HI,

An additional, somewhat oversimplified, way to look at the AGC control loop is this:
 
If you consider the transistor (or other type of amplifier in the control part of the loop) provides 180 degrees of phase shift then an addition delay of 180 degrees is all that is needed for the control loop to go from being a control loop to an oscillator. This can be done with as little as two equal RC time constant type delays chained together. 
 
Assuming there are delays in the AGC control loop due to other components not being infinitely fast, or other circuit compromises, you can make sure one of the RC time constant delays is much larger than the rest. That will swamp out the effects of the other delays. Many AGC circuit go even further by causing the AGC to cut in fast but restore the gain at a slower rate. 
 
If there was no delay in the control loop the AGC might be so good as to adjust the gain microsecond by microsecond and result in an output signal (audio) of zero volts AC, across every cycle of the audio. 
 
Finally if you are controlling a system with a lot of inertia (such as the hot water temperature to your shower head, air conditioning, motors or the melting temperature of the heated head of your 3D printer) another type of control loop, called the PID loop, is used.
 
In the PID loop the rate of change of the temperature/speed/whatever is fed into the control voltage to help the loop anticipate when to shut off (or turn on) just ahead of the desired value, so the temperature/…/…  will arrive at but not overshoot the desired value (set point).
 
The PID loop would likely not be as beneficial in an AGC circuit when your neighbor down the street keys up his kilowatt with his beam pointed your way, at there is nothing gradual to anticipate. So simpler control loops are the better choice for AGC.

Tom, wb6b

Re: No Boot-Up (after spikes)

Joe Puma
 

Sounds like you’ve had some bad luck. Order some new parts and just push through it. 

73
Joe
KD2NFC 




On Apr 19, 2019, at 9:52 PM, Ted via Groups.Io <k3rta@...> wrote:

Joe,

After fixing the first Raduino shorting, no luck. Maybe it's done, not sure yet. Somewhere along the line of hooking up a spare, I got pin 3 (Clock #2) and pin 4 (Gnd) a bit close for a while. It probably remained that way for 10 minutes or so while trying to trace any reasonable answer to the original problem. Anyway, the 2.8" Nextion is toast (reason unknown) and when I hook this radio to my other uBitx 3.5" screen, that screen likewise sits on the initial boot-up with zeros where the Nano information should show up.

As to your question, if I press screen buttons, I get the same false action that one gets while in the Debug mode in the Nextion software.  Ig's powered up but not speaking to anything, same as the original screen, 5 (now toast) Nano boards, and two Raduino boards (one might be dead). 

I can't wait unitl it's warm enough to go sailing again.  


With appreciation,

Ted
K3RTA

Re: Confused about how AGC works?

Jerry Gaffke
 

All the AGC circuits proposed in this forum (and there have been many) have a fast attack and then a relatively slow decay.
That way when the QRO guy across town keys up, it saves our ears as much pain as possible, and keeps the gain throttled
back in case he decides to utter yet another syllable.  The fast attack and slow decay thing is non-linear, and thus harder
to model with equations.  

The PID algorithm is worth knowing about, an ideal approach to many feedback loops for us punters:
    https://en.wikipedia.org/wiki/PID_controller
No nasty math, easy to understand. 
You get three knobs, and you twiddle them till the system starts to behave itself.
A good example of where you might want to use PID would be on a heater for an oven-controlled-crystal-oscillator, or OCXO.
A processor such as the Nano would be entirely adequate for implementing the algorithm.
The goal would be to add enough heat when the oven is cold to quickly bring it up to temperature,
but not leave the heater on so long that the oven temperature overshoots and gets too hot.
Note that there will be a time lag between when the heater shuts off and when the
sensor near the quartz crystal sees the temperature stop rising.
This system could easily oscillate if the knobs are set wrong,
with the temperature alternating between too high and too low. 


> The PID loop would likely not be as beneficial in an AGC circuit when your neighbor down the street
> keys up his kilowatt with his beam pointed your way, at there is nothing gradual to anticipate.


In that case, you want the "D" knob turned way up, for a very fast AGC attack.
However, since the PID loop is a linear system, the AGC decay will be equally fast, and that is not what you want.

Jerry, KE7ER


On Fri, Apr 19, 2019 at 07:30 PM, Tom, wb6b wrote:
Many AGC circuit go even further by causing the AGC to cut in fast but restore the gain at a slower rate. 

Re: Confused about how AGC works?

MadRadioModder
 

I tend to use the definition of AGC from the Radio Amateurs Handbook and other IEEE sources that pertain to the Radio-Electronics industry specifically rather than Wiki… which is typically diminished science for the masses from random writers who may or may not actually understand the topic.  The Wiki article you refer to discusses AGC applied to Audio systems, Power systems (generators), Process Control systems (like PID controllers), and even biological systems. While a tiny bit of this definition is applicable to radio systems (feedback with variable gain in some form), it’s by no means specific or useful.  Historically (that being from the late 1930’s and early 40’s when the first patents for AGC were granted), AGC was defined as a closed-loop system that provides attenuation to one or more RF-IF gain stages of a receiver.  The goal was to keep the output level of the receiver constant and prevent gain stages from saturating at high RF front-end input while increasing gain for weak (low voltage) signals yet irrespective if the input.  The underlying algorithms to do this generally consist of signal measurements in the IR-RF chain and post detector, filter and integrator for response shape, to be fed back to a variable attenuator of some type.  Our ears are logarithmic in response (a second outcome of Fletcher-Munson) and since we can (and do often) define signal strength as logarithmic voltage, the feedback algorithm can be linear or semi-linear (logarithmic).  This is called Input-VGA or IVGA (attenuator-amplifier) as opposed to Output-VGA (which is fixed gain amplifier followed by a passive attenuator).   I believe Zenith held one of the first patents on AGC, but it was contested early and proliferated by others while in litigation… and it was evident on a myriad of AM receivers starting in the 50’s and forward.  This is what I know with 45+ years of designing AGC circuits for commercial and military receivers.

 

I don’t know much about AVC other than it was used in the audio industry and proliferated there for recording and delivery (dBX had a compression form of it).

 

I have no idea what “Transmit AVC is”…

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Friday, April 19, 2019 1:58 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Confused about how AGC works?

 

From 
    https://en.wikipedia.org/wiki/Automatic_gain_control
"Automatic gain control (AGC), also called automatic volume control (AVC), is a closed-loop feedback regulating circuit in an amplifier or chain of amplifiers, ..."
A google search for "AGC vs AVC" shows they are considered synonomous in radio design (but not for power grids), and that AGC is the more modern term.

In this forum, all such circuits for receivers have been getting referred to as AGC.
For some reason, the term AVC has only been used in this forum for automatic level control while transmitting
(Except for these posts from MRM.)
Works well for me, as few of us care that much about AVC while transmitting.
I suggest we keep it that way. 



 


Virus-free. www.avg.com

--

…_. _._

Re: Confused about how AGC works?

Jerry Gaffke
 

Do a google search for "AGC  AVC"
Let me know if you find any hits that draw a distinction.
I only see entries that state they are synonyms.

My 2015 ARRL Handbook has no index entry for AVC,
Perhaps yours is an older edition?

AGC systems, oscillators, and PID algorithms are all closely related as feedback systems.
Learning about one can help understand the others.

Jerry, KE7ER


On Fri, Apr 19, 2019 at 08:16 PM, MadRadioModder wrote:

I tend to use the definition of AGC from the Radio Amateurs Handbook and other IEEE sources that pertain to the Radio-Electronics industry specifically rather than Wiki… which is typically diminished science for the masses from random writers who may or may not actually understand the topic.  The Wiki article you refer to discusses AGC applied to Audio systems, Power systems (generators), Process Control systems (like PID controllers), and even biological systems. While a tiny bit of this definition is applicable to radio systems (feedback with variable gain in some form), it’s by no means specific or useful.  Historically (that being from the late 1930’s and early 40’s when the first patents for AGC were granted), AGC was defined as a closed-loop system that provides attenuation to one or more RF-IF gain stages of a receiver.  The goal was to keep the output level of the receiver constant and prevent gain stages from saturating at high RF front-end input while increasing gain for weak (low voltage) signals yet irrespective if the input.  The underlying algorithms to do this generally consist of signal measurements in the IR-RF chain and post detector, filter and integrator for response shape, to be fed back to a variable attenuator of some type.  Our ears are logarithmic in response (a second outcome of Fletcher-Munson) and since we can (and do often) define signal strength as logarithmic voltage, the feedback algorithm can be linear or semi-linear (logarithmic).  This is called Input-VGA or IVGA (attenuator-amplifier) as opposed to Output-VGA (which is fixed gain amplifier followed by a passive attenuator).   I believe Zenith held one of the first patents on AGC, but it was contested early and proliferated by others while in litigation… and it was evident on a myriad of AM receivers starting in the 50’s and forward.  This is what I know with 45+ years of designing AGC circuits for commercial and military receivers.

 

I don’t know much about AVC other than it was used in the audio industry and proliferated there for recording and delivery (dBX had a compression form of it).

 

I have no idea what “Transmit AVC is”…

 

 

Who has AGC... Fun Facts

MadRadioModder
 

Well I was wrong about Zenith having the first AGC.  It was RCA that sued Zenith over a similar AGC design (now ancient history).  I had to read my old papers again.

 

This is fun fact from the Antique Radio forum circa 1970:  “RCA's Radiola 64 (below, 1929) is credited for being the first radio with AGC. Since the tubes in it were triode 27s, they were difficult to control with a simple rectified carrier, as later circuits had. This set, as well as others in those early days, had to have a DC amplifier to provide the voltage swing to bias the RF and IF stages from normal bias to near cutoff. This circuitry was tricky, but it worked. RCA also had a tuning meter on these sets, supposedly another first. In a couple of years, variable-mu tubes (35/51) came along and made AGC a lot easier. And it got better after that.  Now in general, superheterodynes had AGC, but there were some exceptions. In about 1931, Western Electric made their 10A AM high fidelity tuner. It's monstrous, but it was a TRF with AGC and a tuning meter”.  The Antique Radio guys would eat us alive for not knowing the distinction between AGC and AVC.

 

 


Virus-free. www.avg.com

--

…_. _._

Remote Head?

Dexter N Muir
 


uBitx is a bit difficult to *really* remote: its control and display are done by Arduino, but the unit supplied by default in the 'kit' has that as the 'Raduino", with the 'VFOs' part of that, being the on-board SI5351. This puts RF generation at the 'control head', so any distance of 'remote' has to be minimal.
The solution, it would seem, is homebrewed Arduino control, where the SI5351 can be controlled by the likes of its I2C-bus connection. By this means frequency control can be a non-critical function, with distance achieved digitally: 3 wires (2 active and earth) which do not behave as transmission-lines needing such radical shielding (and can even be optically-isolated)!. This leaves Audio (By 'dongle'?) and PTT/Keying (likewise able to be opto-isolated but also perhaps able to be encoded into the I2C bus?). Some (most?) of these modifications are already being worked on by folks here (and others?)

It's only a short step from the above to full-USB or HDMI - or LAN/internet. Who needs megabuck rigs or even SDR?

I posted most of this on SolderSmoke :)

Re: Who has AGC... Fun Facts

Jerry Gaffke
 

I can believe there is a historical basis for drawing a distinction between AGC and AVC.
And that there are still a few folks that might maintain this difference.
But in 2019, it seems almost everybody just lumps it all together as AGC.

Jerry, KE7ER


On Fri, Apr 19, 2019 at 10:12 PM, MadRadioModder wrote:

The Antique Radio guys would eat us alive for not knowing the distinction between AGC and AVC.

 

Re: Who has AGC... Fun Facts

Jerry Gaffke
 

A curious tidbit about 1920's era radio:
They used to use a rheostat (a big honking pot) on the filament current to vary the gain.

A bit off topic, as I don't recall anybody closing the loop
by driving a servo motor to control that rheostat based on received signal strength. 

Jerry, KE7ER

Re: Who has AGC... Fun Facts

MadRadioModder
 

Schematic of the Radiola 64

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Saturday, April 20, 2019 12:54 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Who has AGC... Fun Facts

 

A curious tidbit about 1920's era radio:
They used to use a rheostat (a big honking pot) on the filament current to vary the gain.

A bit off topic, as I don't recall anybody closing the loop
by driving a servo motor to control that rheostat based on received signal strength. 

Jerry, KE7ER


Virus-free. www.avg.com

--

…_. _._

Re: Remote Head?

Ted
 

Dexter,

Please see my photo folder on this forum. There are other formats by others, maybe not as long an extension but this is one permutation that works so far.

My first attempt at mobilizing a uBitx was with the original 20x2 LED screen. I extended the volume, tuning & function knob, mic of course, and the LED screen by means of a 25-wire printer cable. The Arduino/Raduino stuff remained with the mainboard in a box under the pax seat.

The current model uses a 2.8" Nextion LCD screen on a 4-wire shielded keyboard cable so I can see it at dashboard height. One could have run the rest of the controls to the same location though the screen data nose gets hard to isolate... plus, I wanted the finger controls at a convenient arm-rest position rather than at  a reaching position.  There's also one less microphone cable flopping around right in front of other things.  The tuning/function knob etc are therefore...



...located in a separate control head that's fed with a separate, VGA monitor extension cable.

One nice thing about the latter cable is that it has four separate, shielded paths along with some extras, all shielded again by the outer layer. These can  protect the audio path and stuff.  I can still hear some of the Nextion activity, chiefly the data streams associated with the 2nd Nano and spectrum/s-meter action but mainly on weaker signals with the volume up.

I find the speaker audio, even with a Motorola public-safety type radio speaker,  a bit mild for 70mph highway use so I'm adding a 15-watt amp to it. 



Good luck,

Ted
K3RTA



More Nextion 3.5" tweaks to do

Ted
 

If you're good with C++, here's a good way to spend a rainy morning on a weekend if you know how to do this.  I've done some graphic resizing, as have others, and yet I have not gotten into the nuts and bolts of chart placement with regard to where the programming itself wants to display an image.  I see the subroutine most likely to control this but have been a bit slow on the uptake with regard to results expected.

Here's what I'm trying to do, to complete the full 3.5 " screen polishing:   The CEC screen .htm file for the 3.5" screen was really just a 2.8" screen compiled for a 3.5" window, with unfilled space around it. Likewise, the 3.2" screen was a 2.8" screen that's top-to-bottom the same height but has wasted space to the right of it  That wasn't so difficult to remedy so far as background graphics and button placement, sizing, etc. The sticky point is that, in the cases of spectrum scope displays and such, active graph displays show up on the 3.5" screen where they would have showed up if the 2.8" drawings were still around them.  This is where I've stopped, inasmuch as I can only seem to handle a couple of potentially hemmorage-inducing stressors at once in this hobby.

See these, and consider if your skills in programming might help to expand,relocate, and/or shift the red rectangles into the green ones.





Full credit will be given when I post the result - or if you post, I'll be happy to download them from your repository :)  Tnx in advance.



Later,

Ted
K3RTA

Re: Remote Head?

bobolink
 

On Sat, Apr 20, 2019 at 12:16 AM, Dexter N Muir wrote:
It's only a short step from the above to full-USB or HDMI - or LAN/internet.
-or wireless WiFi/internet or Bluetooth Low Energy (both with appropriate security).

Re: Ubitx batteries / charger #ubitx

_Dave_ K0MBT
 

For my model batteries I recharge at 1c the recommended rate. It isn't hard to have more than one battery.

I have battery powered my ubitxs but kept the battery outside the case. and put a volt meter on the front panel. I put the xt60 connectors for power on all the hf radios. To match the batteries.
Cell imbalance does happen and is the most serious issue with these batteries.

The batteries use a balance charger where each cell has a separate charging lead straight back to the cell.
73

Re: Who has AGC... Fun Facts

Joe Puma
 

I’m taking this discussion in and learning. Jerry you always find a way to educate the group when topics fly by. As I’ve been learning I understood that there is automatic volume control and automatic gain (RF) control. I learned that RF gain control is better to use. For me I just want to be able to hear weak stations and clamp down on the real close ones.  But as to your AGC AVC discussion and why we don’t properly label the two. Show my a radio that has AVC on the knob. I’m a relatively new ham but all I’ve ever seen is AGC. Maybe some of the older tube boat radios used AVC, I don’t know but it’s easy to label it all AGC because I’ve never seen a AVC lable on a radio knob. 

Joe
KD2NFC 



On Apr 20, 2019, at 1:46 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

I can believe there is a historical basis for drawing a distinction between AGC and AVC.
And that there are still a few folks that might maintain this difference.
But in 2019, it seems almost everybody just lumps it all together as AGC.

Jerry, KE7ER

On Fri, Apr 19, 2019 at 10:12 PM, MadRadioModder wrote:

The Antique Radio guys would eat us alive for not knowing the distinction between AGC and AVC.

 

Re: More Nextion 3.5" tweaks to do

Joe Puma
 

I too am working on a 5” layout. Working on background images and moving items are trivial. The graphs are tricky. I was able to move around the lines for the band analyzer from top to bottom. I can’t find where I need to adjust for left and right. I have a email I have to draft to KD8CEC in hopes he can help me. 

image1.jpeg

image2.jpeg

image3.jpeg


Didn’t adjust the height or width here yet. 
image4.jpeg

image5.jpeg

image6.jpeg

image7.jpeg

image8.jpeg


On Apr 20, 2019, at 7:32 AM, Ted via Groups.Io <k3rta@...> wrote:

If you're good with C++, here's a good way to spend a rainy morning on a weekend if you know how to do this.  I've done some graphic resizing, as have others, and yet I have not gotten into the nuts and bolts of chart placement with regard to where the programming itself wants to display an image.  I see the subroutine most likely to control this but have been a bit slow on the uptake with regard to results expected.

Here's what I'm trying to do, to complete the full 3.5 " screen polishing:   The CEC screen .htm file for the 3.5" screen was really just a 2.8" screen compiled for a 3.5" window, with unfilled space around it. Likewise, the 3.2" screen was a 2.8" screen that's top-to-bottom the same height but has wasted space to the right of it  That wasn't so difficult to remedy so far as background graphics and button placement, sizing, etc. The sticky point is that, in the cases of spectrum scope displays and such, active graph displays show up on the 3.5" screen where they would have showed up if the 2.8" drawings were still around them.  This is where I've stopped, inasmuch as I can only seem to handle a couple of potentially hemmorage-inducing stressors at once in this hobby.

See these, and consider if your skills in programming might help to expand,relocate, and/or shift the red rectangles into the green ones.



<Spectrum 35.jpg><SpecCW_35.jpg><Main Screen 35.jpg>

Full credit will be given when I post the result - or if you post, I'll be happy to download them from your repository :)  Tnx in advance.



Later,

Ted
K3RTA

Re: Ubitx batteries / charger #ubitx

Bill Lamm
 

George, have you seen this thread?

https://groups.io/g/BITX20/topic/homebrew_li_ion_battery_pack/31181951?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,31181951

Similar adventure..  I ordered a buck/boost converter and I will have more info when it hits my bench

Re: Who has AGC... Fun Facts

Jerry Gaffke
 

Here's some antiqueradio guys talking about AVC, it is all about controlling RF and IF gain:
This is now commonly called AGC.
    https://www.antiqueradios.com/forums/viewtopic.php?f=6&t=263244
    http://www.johnsvintageradio.com/notes03.html
    https://www.radioremembered.org/detector.htm
    https://www.radiolaguy.com/info/AVC.htm

That last link mentions rheostats on filaments to control gain, though this was not commonly done.
See the final post here:  https://www.vintage-radio.net/forum/showthread.php?t=60467
 
I doubt there are many radios with AVC/AGC that ever did other than adjust the gain of RF and/or IF stages.
There's no real advantage for AGC to mess with the audio stage gain, and it has the disadvantage 
that this does not solve signal overload in earlier stages.  The uBitx and Bitx40 AGC schemes in the forum
often adjust the audio gain, but only because it's the easiest thing to slap in there as an add-on.

Can somebody point to a passage somewhere that claims AVC and AGC are different animals?
Not that it matters much, but I don't want future discussions of AGC schemes on the uBitx/Bitx40
to spend days arguing about the rather silly distinction of whether the controlled gain stage
happens to be operating at 1khz or 12mhz.   

Jerry, KE7ER


On Sat, Apr 20, 2019 at 08:32 AM, Joe Puma wrote:
I’m taking this discussion in and learning. Jerry you always find a way to educate the group when topics fly by. As I’ve been learning I understood that there is automatic volume control and automatic gain (RF) control. I learned that RF gain control is better to use. For me I just want to be able to hear weak stations and clamp down on the real close ones.  But as to your AGC AVC discussion and why we don’t properly label the two. Show my a radio that has AVC on the knob. I’m a relatively new ham but all I’ve ever seen is AGC. Maybe some of the older tube boat radios used AVC, I don’t know but it’s easy to label it all AGC because I’ve never seen a AVC lable on a radio knob.