Re: ADE25MH Mixer - warning
#tinysa
Hi Gary - In my version I added a 3dB attenuator pad between the mixer and the 434MHz filters so the mixer does not see a huge mismatch (only roughly 2:1) for frequencies other than 434MHz.? This is an experiment and is not part of Erik's design.? No idea yet if it makes any improvement or not, or if 6dB would be better.? This comprises a series 100R, 150R to ground then another series 100R.? Those values are not ideal but they are the ones I had to hand.
My learning is that the ADE-25 mixer has a different internal arrangement to the ADE-1 mixer.? The ADE-1 is effectively transformer coupled to the RF and IF ports, so the connection to ground does not affect the mixer. The connection to ground via the 150R screwed up the way the diodes in the ADE-25 mixer work.? Add a capacitor between the mixer and the 3dB pad decoupled the DC and all works OK.
For your build with no 3dB pad its all OK as is.
Good luck!
73
Dave M0WID
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Re: New tinySA.exe problem
Is the averaging set to off? Please send a screenshot -- HBTE Files section:? /g/HBTE/filesErik, PD0EK
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If I start up tinySA.exe, input a 10MHz signal and do a scan, it works fine.
If I just change the input to say 11MHz, and do a scan, it shows a lower level 10MHz signal but no 11MHz at all.
If I change the attenuator(like from 0 to -2) or do a different scan (like 20MHz instead of 50MHz) that "resets"
something and I see the new input freq.
If I leave the input freq alone but change amplitude or change the attenuator setting, it displays correctly.
73,
Gary
WB6OGD
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Re: New tinySA.exe uploaded
Jerry,
I just tried to speed up my CH340G.
In DeviceManager, it can only go to 128000 (driver limitation?).
Tried to put that in the Arduino but it can only set normal baud rates, 115200 is therefore is the fastest.
It must be slower to set a freq and read the rssi though?
73,
Gary
WB6GOD
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Re: New tinySA.exe uploaded
The bit-banged SPI interface could also be a factor in the max achievable sample rate if the UART baud rate were increased up from 115.2kbaud. Using hardware SPI pins, the Si4432 could be run at up to 10mhz clock speeds. Looking at the tinySA.ino code, time spent on the SPI interface reading the RSSI is not?accounted for when waiting between samples for the delaytime value specified by the "T" command.? That may explain the mysterious "*2/3" factor here:
>? ? ? while (micros() - old_micros < (delaytime * 100L)*2/3 ) {?delayMicroseconds(100);?}
Could be that was arrived at experimentally to give accurate delays
for the default delaytime of 50 (so 5.0ms), but not accurate at any other delaytime.
? Jerry, KE7ER
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Re: New tinySA.exe uploaded
A few corrections:
> The UART on the Nano can go considerably faster than 115kbaud:
>? ? ?
The CH340G datasheet states:
" CH340 supports common baud rate: 50,75,100,110,134.5,150,300,600,900,1200,1800,2400,3600,4800,9600,14400,19200,28800, 33600,38400, 56000,57600,76800,115200,128000,153600,230400,460800,921600,1500000,2000000 and so on."
The 115.2 kbaud limitation in the CH340 datasheet I saw previously was apparently only with regard to IrDA links.
So no need to go to the CP2102.
> Then we're good up to 1000kbaud if it can successfully negotiate the baud rate between the ATMega328P and the CP2102.
Been awhile since I've messed Nano's.
But now that I think of it, I guess both ends do get explicitly configured to a specific baud rate.
No negotiation required.
Most of the digital stuff I do is 3.3v these days, using the Nano's 5v IO pins to drive 3.3v devices is problematic.
The ATMega382P chip on the Nano will run at 3.3v, but is only guaranteed to work with a clock of up to 13mhz or so.
However, many have found it to work fine on 3.3v using the standard 16mhz clock used on the 5.0v Nano.
But you can configure it to divide that clock by two, bringing the processor clock down to 8mhz.
? ??
? ??
Might be worth looking into, as the Nano is very very cheap.
As you can see from the second link, there are some hardware changes required as well.
The CH340 datasheet says it will work fine at 3.3v as well.
Jerry, KE7ER
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Re: New tinySA.exe uploaded
Some Arduino boards have a processor chip that integrates a USB interface.
Sending data with the Serial command would not involve any UART at all,?
could be relatively fast.
The UART on the Nano can go considerably faster than 115kbaud:
? ??
However, the CH340G UART-to-USB chip used on the Nano clones does max out at 115kbaud.
? ??
We could go around the CH340G chip by hooking up an external UART-to-USB dongle like this
? ??
to the ATMega382P's RX and TX pins.? Then we're good up to 1000kbaud if it can successfully
negotiate the baud rate between the ATMega328P and the CP2102.
Regardless how it's done, I doubt there is any need for more than the 64byte buffer
implemented by the Arduino Serial library.
Jerry, KE7ER
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On Tue, Jan 28, 2020 at 08:33 AM, Jerry Gaffke wrote:
The Nano's ATMega382P chip sends Serial data out over a 115kbaud UART link to the USB chip.
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Re: New tinySA.exe uploaded
Arduino's vary, I have no idea what they all do with regard to the UART link..
But let's assume the Nano, which is probably the least capable of what folks here are using.
The Nano's ATMega382P chip sends Serial data out over a 115kbaud UART link to the USB chip.
That UART link is almost certainly the bottleneck, as the slowest that USB 1.0 operates is 1.5mbits/sec.
If the USB chip is ridiculously slow on single bytes, the queue maintained in the RAM by the Serial library
(I assume 64 bytes) will back up and you will get some nice long bursts anyway.
Each RSSI sample is 3 bytes, an 'x' followed by two binary bytes of data.
Over the UART link, that's 30 bits, including start bit and (I assume) one stop bit.
At 115kbaud, each sample takes 30/115000.0 = 0.00026 seconds to transfer, or 0.26 milliseconds.
So if the delaytime between samples is kept at 0.3 milliseconds or more, the UART should be able to keep up.
I believe the "T" command operates in units of 100us, so that's a minimum of 3 as an arg to the "T" command.
My point is, if the Serial library is giving us a 64 byte send buffer in RAM already,
there is no point in having any RAM buffers in tinySA.iso when targeting the Nano.
If your Arduino has a 115kbaud link involved in sending out Serial data, that is the bottleneck, not USB.
A UART has no protocol beyond the bit level,? sending out data as packets is not any more efficient.
And if USB is the bottleneck, it would have to be an awfully stupid USB implementation of
the slowest possible USB standard to not?keep up with a delaytime of "T 1", or 100 microseconds.
If you did want faster data transfers, then remove the 'x', so two bytes per RSSI sample.
If the '{' at the start of the transfer is not sufficient to keep everything in sync,
than we'd best fix whatever is trashing data transfers.
Jerry, KE7ER
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On Tue, Jan 28, 2020 at 03:44 AM, <erik@...> wrote:
The reason is speed if you are using CDC over USB
USB CDC transfers have substantial overhead so the more bytes you send in one send the faster?
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On Tue, Jan 28, 2020 at 08:12 AM, Dan Reynolds wrote:
SBL-1
Officially rated till 500MHz so just as the ADE-1 I expect it will perform fine. ? -- HBTE Files section:? /g/HBTE/filesErik, PD0EK
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Re: 3.3V compatible Arduino boards
#tinysa
Daniel and Dan,
I am using cheap 5V Arduino Nano V3? (ATmega328P) (about $3.50) with 4 channel FET level converter ($1).
Works fine with the BUFFERSIZE fix.
Erik is using Arduino Zero (3v).
I am not using? a display and encoder yet though.
73,
Gary
WB6OGD
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Erik, I have some brand new mini circuits TFM-2+ mixers, actually a tube on 18 of them. I will upload a data sheet to your folder. I believe this is a military spec version of the SBL-1 if I remember right. It is a level 7 mixer though. Would it work for the tinySA?
If they would work - I would be happy to sell/trade to others in the group that are in the US. I'm sure we can work something out. I know MC parts can be hard to procure. I bought this tube at Dayton a few years ago.
--
Dan Reynolds - KB9JLO
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Re: 3.3V compatible Arduino boards
#tinysa
Hi colleagues,
I have two questions. Can?I use Arduino Uno or Mega2560 with level converters?
In a parallel stage wouldn't it be appropriate for the Nextion Enhanced NX8048K050? It's not cheap but it can relieve Arduino of tasks.
Daniel
YO8SAK
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Re: SI4432 Module Modifications
#tinysa
On Mon, Jan 27, 2020 at 02:33 PM, wb6ogd wrote:
I am just like you.. wanting to be a real RF engineer but have a long way to go.
Every project I build I get more of an education than I even expected.. they never work the first time ;-)
I say build the tinySA!? Now that mine is basically working I am really excited.
FB Gary. I hated being alone - Ha, ha! I'm assuming a Arduino Zero clone would work just fine. I'm pretty sure I have some somewhere (anybody else have that problem). I also have some mixers I'm going to ask about. ? -- Dan Reynolds - KB9JLO
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Modifying the LO SI4432 for the extended frequency range of the tinySA
#tinysa
If you want the tinySA to measure above 150MHz you have to modify the LO SI4432 and remove all the low pass and trap filters. As there are many different schematics used for the SI4432 module I can only give generic advice. In below schematic the red components have to be removed and the green connections have to be made. The inductors L0, LM and LM2 can stay but have to be short wired. The inductor LC and capacitor C0 must stay as pull-up for the output  Below a picture of a module with above modification applied. The yellow arrow point to the TX output pin (pin 2) and from there you can trace the inductors (with a small green color coding) to the antenna switch (bottom left) The wire shortcutting the TX low pass filter is clearly visible. In below module there are three inductors in the TX low pass filter compared to two in the schematic above. And I did not yet short the inductor between switch and antenna Be careful not to remove the input/output capacitors of the switch and the SI4432.  The low pass filter between the antenna switch and the antenna connection is not always used. If present, remove capacitors to ground and shorten the inductor With a ohm meter or continuity tester you can trace the route of the inductors from the isolation capacitor connecting to the TX output to the input capacitor of the switch The RX input matching filter does not have to be changed. LR and CR1,CR2 should stay. The RX pins (3,4) of the SI4432 a just below the TX pin (pin 2) -- HBTE Files section:? /g/HBTE/filesErik, PD0EK
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Re: ADE25MH Mixer - warning
#tinysa
No issue. ?Its intended to ne for matching.?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
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On Jan 28, 2020, at 10:56 AM, wb6ogd <garywinblad@...> wrote:
?
My ADE25 module has locations for caps on the inputs and outputs but
they are stuffed with 0 ohm resistors..
It seems to work ok, should I be worried?? Should I put in caps??
What value.
It also has an unstuffed location for an R next to the C.? Same
question.
What 3db pad are you talking about?
73,
Gary
WB6OGD
On 1/26/2020 2:13 PM, m0wid wrote:
Mixer problem - SOLVED
The ADE25 mixers are fine.? They work in a different way to the
ADE1 and needed a capacitor to decouple from the 3dB pad.? The
ADE1 have transformers, so no problem.? A good learning
experience.
The spurs at the harmonic frequencies are I think really are
there.? If spur reduction is turned on the levels of the harmonics
and the fundamental change significantly each scan, so the
readings cannot be trusted.? I can see the harmonic on my Hermes
Lite 2 SDR.
If I run the signal through a low pass filter then the levels of
the harmonics in Tiny-SA drop significantly, but they are still
present.? Interestingly the Nano-VNA measures the attenuation by
the filter at the harmononic frequency of around 30 db, but the
signal on the spectrum only drops by half that.? Further
investigation needed.? Adding a fixed 15db attenuator drops all
the signals by roughly that amount.
73
Dave M0WID
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Re: ADE25MH Mixer - warning
#tinysa
My ADE25 module has locations for caps on the inputs and outputs but
they are stuffed with 0 ohm resistors..
It seems to work ok, should I be worried?? Should I put in caps??
What value.
It also has an unstuffed location for an R next to the C.? Same
question.
What 3db pad are you talking about?
73,
Gary
WB6OGD
On 1/26/2020 2:13 PM, m0wid wrote:
toggle quoted message
Show quoted text
Mixer problem - SOLVED
The ADE25 mixers are fine.? They work in a different way to the
ADE1 and needed a capacitor to decouple from the 3dB pad.? The
ADE1 have transformers, so no problem.? A good learning
experience.
The spurs at the harmonic frequencies are I think really are
there.? If spur reduction is turned on the levels of the harmonics
and the fundamental change significantly each scan, so the
readings cannot be trusted.? I can see the harmonic on my Hermes
Lite 2 SDR.
If I run the signal through a low pass filter then the levels of
the harmonics in Tiny-SA drop significantly, but they are still
present.? Interestingly the Nano-VNA measures the attenuation by
the filter at the harmononic frequency of around 30 db, but the
signal on the spectrum only drops by half that.? Further
investigation needed.? Adding a fixed 15db attenuator drops all
the signals by roughly that amount.
73
Dave M0WID
|
Re: New tinySA.exe uploaded
The reason is speed if you are using CDC over USB USB CDC transfers have substantial overhead so the more bytes you send in one send the faster? -- HBTE Files section:? /g/HBTE/filesErik, PD0EK
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Re: TinySA and phase noise. Understanding the limitations of the SI4432
#spectrum_analyzer
The different is most probably a ground loop, what you saw was the difference between very loose and manually tightened -- HBTE Files section:? /g/HBTE/filesErik, PD0EK
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Re: New tinySA.exe uploaded
I'm not sure what the output buffer does for us other than waste RAM.
Why not send each binary byte on its way individually with Serial.write()? ?
Serial.write() is blocking.
If there is no room for your byte in the transmit serial buffer,
the program will hang up in the Serial.write() function until there is room.
Function Serial.availableForWrite() will tell you how much room remains in the transmit buffer.
If you ask when the system is quiet I believe the answer is 64.
Where we need the buffer is on input, waiting for any command to be terminated with a \n
before parsing.
Jerry, KE7ER
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On Mon, Jan 27, 2020 at 03:33 PM, Jerry Gaffke wrote:
Seems best on Arduino to only ask the Serial library to do low level character IO one byte at a time.
Do everything else in code you have some control over.?
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Re: TinySA and phase noise. Understanding the limitations of the SI4432
#spectrum_analyzer
On Mon, Jan 20, 2020 at 11:45 PM, <erik@...> wrote:
The purple line is when I started and after tightening the SMA connectors I got the blue line
Nice, awesome example details to get the general idea.??
Thinking torque wrench will be a good idea to invest in, adding that to the list for next month (I guess I can use a scale to a wrench).
I just installed the SDR Spectrum Analyzer, tried plugging in my SDRPlay RSP1a and having a driver issue that I need to work on next.?
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K9HZ
jafinch78 .