Date   
Re: Audio AVC

Jack Brabham - KZ5A
 

I don't think I have ever heard a argument in favor of slow attack AGC before. 

73 Jack KZ5A


On 4/22/2019 9:19 PM, Jerry Gaffke via Groups.Io wrote:
If you digitize the audio, you could delay it to match your pokey AGC scheme (and fancy audio filters and such too).
That's what many SDR rigs do.
In extreme cases it's like talking over a satellite link, and conversation becomes unnatural.


On Mon, Apr 22, 2019 at 06:44 PM, James Lynes wrote:
I wondered about this approach myself.  I figured there would be too much time lag in the software path to be effective(untested).
 


Re: Raduino reinforcement, 3d printed

Wayne Leake
 

 Staples would be a good bet for me.
 However, I have the drawback that it is 60 miles from me, and I cannot afford the trip most of the time, much less added cost.
 I had a bad weekend with my Truck, which cost me some $$ for parts, plus I was kinda looking at old Macintosh computers on Ebay, and happened to decide to look at GE Suitcase programmers.
 I have one, but the HHC (hand held computer) was blown, as well as the power supply, by roof leakage, dang...
 So I looked at Panssonic HHC's on Ebay, and found one with power supply and stuff for a low price.
 Except it decided to not want to turn on when the seller tested it once more before shipping.
 We agreed on a partial refund, and I looked at another working HHC, for a lower price, and a make offer. I made an offer, he countered, and I have bought it.
So have blown my funds for a good while, with other stuff.
 I do like the 3D printing, though I don't really like not having metal cases.
 But would be great for stuff like bezels and more.

Re: Audio AVC

Tom, wb6b
 

On Mon, Apr 22, 2019 at 05:45 PM, Hasan Murtaza wrote:
Control the pot resistance (and hence the transistor amplification) with a digital output pin of the arduino
This isn't requiring the micro controller to do any heavy duty DSP type processing. I think it would be very fast. An Arduino Nano may be fast enough.

However, as time has marched on, there are new faster (and cheap) options. Two that come to mind are ESP32 that Jack mentioned and the "Blue Pill".

The ESP32 is great because of it's fast processor speed. And it has WiFi and Bluetooth integrated right onto the chip. The BLE (Blue Tooth Low Energy) is especially interesting as you could control your uBitx directly from an iPhone app. (Apple only lets BLE connections work on apps where they don't go through an, I imagine expensive, approval process).

The Blue Pill, while "only" having a 72Mhz clock speed, 64KB of flash and 20KB of RAM is still vastly more powerful than the Nano. The STM32F103C8 chip used on the Blue Pill has USB built right into the chip. Great for many types of projects you would want to build, as no need for a separate USB chip keeps down the cost of the project/product.  

Now I must make a confession, I have another HF rig besides the uBitx. I like the "squelch" it has. Well kind of. It really is not all that consistent in where you set it, or totally reliable, or stable. (I'm always having to tweak it.)

Image an ESP32 or Blue Pill that actually does process the audio, into and out of the chip. You could make an improved "signal/noise" assessment in software. But, by also delaying the audio slightly through the chip, the point where the software decides the the signal is signal, not noise, could be time shifted back to the start of the desired beginning of the signal, rather than chopping off the first part of what someone is saying. (As happens now with the analog squelch on my rig). This type of squelch would be a great addition to the uBitx, too. So a little delay in the software can be a benefit.

Tom, wb6b
 

Re: wiring up a cw paddle ref 54899 #bitx20

Kelly Mabry
 

Ok, so i studied the thread and the ubitx.net website to wire up my vibroplex paddle for the ubitx.  I am using a sunil amateurradiokits.in case and front panel board. I have used a 10k and a 2.18k resistor as part of my voltage  divider.  Using 3.5 mm stereo plug, and when i plug the paddle in and try to send, only the dits work, no dashes. I measure the resistance  between the paddle and tip, and paddle and ring and get the expected 2.18k and 10k resistances. It's a new paddle.  Confused. 

73, 
Kelly K5AID 

Re: wiring up a cw paddle ref 54899 #bitx20

Tom, wb6b
 

Hi,

If you are not already, you may want to try the CEC firmware. I believe that software allows you to adjust for the actual voltages seen on the analog input pin for the dots and dashes. There could be considerable variation in the voltages seen with a random selection of Nano boards. 

Assuming the issue in not something to do with wiring, you could experiment with a variable resistor (pot) on the key input and see what values produce dots and dashes, and adjust your resistors accordingly.

Tom, wb6b

Re: wiring up a cw paddle ref 54899 #bitx20

Kelly Mabry
 

Hi Tom, i am using v1.12 of CEC fw. I will try to adjust my dash resistor. I think i have a 10k pot lying around somewhere...Thanks!!
73, Kelly K5AID 

Re: Audio AVC

MadRadioModder
 

Wow!  Jack is an ESP32 convert!

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Jack Purdum via Groups.Io
Sent: Monday, April 22, 2019 9:04 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Audio AVC

 

Exactly. Consider the ESP32 with 1.3Mb of flash, 350Kb of SRAM, all scooting along at 240Mhz at a price of around $6. It also has two DAC ports. While the DAC ports are only 8 bit, it's better than no DAC. Also, you can program the ESP32 from within the Arduino IDE. So far, I haven't found any libraries that don't work with it. Oh, it also has builtin WIFI and Bluetooth.

 

Jack, W8TEE

 

On Monday, April 22, 2019, 9:37:05 PM EDT, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

 

 

Doing AGC in software would incur added delay, especially with an i2c pot on our beloved little Nano.
We want to keep the attack time as short as possible.
Would be fun to try, perhaps using one of the small ARM processors with fast embedded ADC and DAC capabilities.
Jerry


On Mon, Apr 22, 2019 at 05:45 PM, Hasan Murtaza wrote:

Technically the simplest circuit (for some people) would be a software solution. Send the amplified output to a diode plus capacitor in a peak detector configuration. The capacitor voltage will be a quasi DC signal proportional to the maximum value of the signal. Read it into the arduino via an ADC pin. 

So far, component count =2.

Next replace the collector resistor in the class A common emitter amplifier with a digital potentiometer. Control the pot resistance (and hence the transistor amplification) with a digital output pin of the arduino. Write some software to set the gain based on the measured peak output voltage.

Total parts count is 3. 

If you sample the audio voltage directly you can do even fancier tricks like computing rms value or histograms etc.

Hasan


Virus-free. www.avg.com

--

…_. _._

Re: wiring up a cw paddle ref 54899 #bitx20

Kelly Mabry
 

The same result using a pot to vary dahs... no effect.  No dahs, at all. Im down a power supply so no other rig to compare to at this time.

73, 
Kelly K5AID 

Re: wiring up a cw paddle ref 54899 #bitx20

Tom, wb6b
 

Interesting. Try measuring the voltage on the keyer analog input pin to the Arduino. If it doesn't go up significantly when the resistance is increased, then try an external pull-up (maybe 10k) resistor from 5 volts to the keyer's analog input pin to the Nano. It could be the Nano is outside of specification and its internal pull-up is too weak.

If the voltage does go up, I'm not sure what the answer is.

Another person had a similar problem about six months ago. He went through the same tests, initially with no results, but finally solved it. Maybe, you will hear from him or could try searching the messages on the list. If I think of good search keywords, I'll reply again.

Tom, wb6b

Re: Audio AVC

bobolink
 

I played around with audio processing for the esp32. I limited external components to analog conditioning only. Core 1 did sample service, core 2 frame processing. Sampling on the timer (rather than DMA) added some phase noise.

Now I like the Nordic nRF52840 dongle—$10—M4F, BLE radio, ADC but no DAC.
Still looking for the complete digital audio processor for $10.

wm6h

Re: wiring up a cw paddle ref 54899 #bitx20

Sam Tedesco
 

There was a recent post about having to cut a trace on the front panel board for paddles. 

Re: wiring up a cw paddle ref 54899 #bitx20

Kelly Mabry
 

Yes Sam, Sunil told me the following..The resistor need to be mounted on PCB and a cut is required in one track.

I contacted him due to the circuit board is in his Nextion case kit.

Will do the mod later today

73,
Kelly K5AID 

Re: Audio AVC

Jerry Gaffke
 

Primary hit on using a Nano for AGC is the time it takes to drive a digital pot via the i2c bus,
especially since i2c is also running the si5351 and perhaps a display.
Don't have enough pins to go spi, unless it's a second Nano.
Regardless, way easier to do it with 2 or 3 FET's than it is to trip over software timing every
with every hack to the Nano firmware, or to add an extra processor.


On Mon, Apr 22, 2019 at 09:47 PM, Tom, wb6b wrote:
This isn't requiring the micro controller to do any heavy duty DSP type processing. I think it would be very fast. An Arduino Nano may be fast enough.

Re: Audio AVC

James Lynes
 

Hasan:

Give it a try and report back. It's an interesting idea.

1. What are the required AVC attack and decay times vs, the Nano maximum ADC read rate plus the added I2C/SPI pot communications overhead?

2. Can loop() tolerate any more overhead without impacting the operability of the UI? Adding another processor defeats the original premise of a minimal part count implementation. Maybe it could be implemented in an ISR, but I believe that I read awhile back of issues with I2C and ISRs. Find/develop a custom I2C library?

James

Re: Audio AVC

Jack, W8TEE
 

In a normally clocked Nano, the maximum read rate is 100 microseconds (0.0001sec), or 10,000/second. However, that's just an analog read call. Since something has to be done with the data, the "useful" rate is going to be less.

Jack, W8TEE

On Tuesday, April 23, 2019, 9:52:10 AM EDT, James Lynes <jmlynesjr@...> wrote:


Hasan:

Give it a try and report back. It's an interesting idea.

1. What are the required AVC attack and decay times vs, the Nano maximum ADC read rate plus the added I2C/SPI pot communications overhead?

2. Can loop() tolerate any more overhead without impacting the operability of the UI? Adding another processor defeats the original premise of a minimal part count implementation. Maybe it could be implemented in an ISR, but I believe that I read awhile back of issues with I2C and ISRs. Find/develop a custom I2C library?

James

Re: Audio AVC

Jack, W8TEE
 

Al Peter (AC8GY) and I are working on a new Projects book and in it, I took a few minutes to pull my head out of the sand and look around to see what's happening. Rather than limiting it to the Arduino family, we limited our µC's to microcontrollers that can be programmed in the Arduino IDE so the reader doesn't need to learn a new programming environment. The book uses the Arduino Nano, but also the Teensy 3.6, the STM32F103, and ESP32 controllers. It is amazing what less than $10 buys in terms of processing power! What I don't understand is why Atmel hasn't come out with a reasonably-priced competitor to these alternatives.

Jack, W8TEE

On Tuesday, April 23, 2019, 2:18:10 AM EDT, MadRadioModder <madradiomodder@...> wrote:


Wow!  Jack is an ESP32 convert!

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Jack Purdum via Groups.Io
Sent: Monday, April 22, 2019 9:04 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Audio AVC

 

Exactly. Consider the ESP32 with 1.3Mb of flash, 350Kb of SRAM, all scooting along at 240Mhz at a price of around $6. It also has two DAC ports. While the DAC ports are only 8 bit, it's better than no DAC. Also, you can program the ESP32 from within the Arduino IDE. So far, I haven't found any libraries that don't work with it. Oh, it also has builtin WIFI and Bluetooth.

 

Jack, W8TEE

 

On Monday, April 22, 2019, 9:37:05 PM EDT, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

 

 

Doing AGC in software would incur added delay, especially with an i2c pot on our beloved little Nano.
We want to keep the attack time as short as possible.
Would be fun to try, perhaps using one of the small ARM processors with fast embedded ADC and DAC capabilities.
Jerry


On Mon, Apr 22, 2019 at 05:45 PM, Hasan Murtaza wrote:

Technically the simplest circuit (for some people) would be a software solution. Send the amplified output to a diode plus capacitor in a peak detector configuration. The capacitor voltage will be a quasi DC signal proportional to the maximum value of the signal. Read it into the arduino via an ADC pin. 

So far, component count =2.

Next replace the collector resistor in the class A common emitter amplifier with a digital potentiometer. Control the pot resistance (and hence the transistor amplification) with a digital output pin of the arduino. Write some software to set the gain based on the measured peak output voltage.

Total parts count is 3. 

If you sample the audio voltage directly you can do even fancier tricks like computing rms value or histograms etc.

Hasan


Virus-free. www.avg.com

--

…_. _._

Re: Raduino reinforcement, 3d printed

 

I have found several places around town that do 3D printing including Staples, so its just a matter of finding the best one to do the job. I may consider getting my own printer too, (probably a Ender 3), but I'm not sure how often I would use it. Who knows, maybe I would find all kind of things to print. Another problem is, I have a rather small shack/shop and don't really have the room to have it sitting around collecting dust.

Joel
N6ALT

Re: wiring up a cw paddle ref 54899 #bitx20

Sam Tedesco
 

Perfect! I left my front panel as is and brought the dividers to the rear auxiliary board. Key in the front, paddles in the rear.

Re: uBitX For Sale #ubitx

Martin KM6TCD
 

Is this assembled and tested or still in kit form?
 
Sent: Sunday, April 21, 2019 at 8:36 AM
From: "SC" <bill@...>
To: BITX20@groups.io
Subject: Re: [BITX20] uBitX For Sale #ubitx
I am dropping the price to $120, plus shipping, which includes insurance.  If no one wants it at this price, it stays with me.  This is for the complete unaltered kit, plus the complete Amateur Radio Kits Universal Case DA Gray make just for this radio.  The price will not go any lower than this.  The complete kit with case retails near $200.  This is the final offer.

3d Printing

 

Hello all,

 I have seen a few people post about wanting some printing done. I would be happy to help anyone that needs it.

I have a 220*220*250mm build size.

Currently have PLA+ in the following colors: Black, Grey, Natural (semi clear) and reddish orange(like the mics we sell). I will consider other colors and materials upon request. I do not have any ABS at this time.

If you want a print get in touch with me and we can work out something.

I don't have a price standard for this at the moment but I am fair in my pricing.

Please mail me direct: N8DAH at Kit-Projects dot com
--
David

 N8DAH
Kit-Projects.com

Shop is open!