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File updated in [email protected]
Hello, This email message is a notification to let you know that the following files have been updated in the Files area of the [email protected] group. /Tiny Spectrum Analyzer/Build instructions for the Tiny Spectrum Analyzer.pdf Uploaded By: erik@... Description: A document describing how to build and use the tiny spectrum analyzer. Latest update includes the wiring of the ILI9341 Cheers, The Groups.io Team
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New file uploaded to [email protected]
Hello, This email message is a notification to let you know that the following files have been uploaded to the Files area of the [email protected] group. /Tiny Spectrum Analyzer/ESP32/tinySA_touch02.zip Uploaded By: m0wid <david.wilde@...> Description: A few small changes and fixes. Added a menu item (under config) to set agc or fixed preamp gain. Removed DFU mode if ESP32. Time between setting frequency and taking a reading varies with RBW. Cheers, The Groups.io Team
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When you make the BPF and measure it using your nanoVNA you hope the BPF will perform as measured, but are you sure it does? Now it is possible to use a buildin function of the tinySA to measure the performance of the BPF after it is integrated You have to set the Sweep to "First IF" instead of "Regular" and set the first IF 10MHz lower then its normal value. When sweeping with these settings the RX SI4432 will track the LO SI4432 so together they act as a scalar network analyzer. This is possible as the mixer is not perfect so sufficient signal will leak from the LO port to the RF port. As we can not sweep negative frequencies we have to offset the first IF to a lower frequency to make sure we sweep the whole passband and the outside the passband. The result is a bit disappointing. The passband of the BPF is correctly centered at 10MHz because we set the first IF 10Mhz lower. The width is also correct, about 1MHz. The first problem is the very high leakage between the LO SI4432 and the RX SI4432 that create a -50dBm background obscuring the out of band rejection below -50dBm. During normal measurement this is not a problem as normally the RX stays fixed on the first IF frequency. Any form of shielding will also reduce this but it shows how easily signals at 433MHz are leaking. The coupling is caused by the capacitor between the last SAW filter and the SMA connector together acting as a antenna for the signal radiating from the LO SI4432. Completely disconnecting the BPF drops the leakage to -55dBm. Removing the SMA female-female connector from the RX SI4432 drops the leakage to -70dBm. The second problem is the bumpy passband.This will generate changes in sensitivity when doing spur rejection. Some more tuning to do. -- HBTE Files section: /g/HBTE/files Erik, PD0EK
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Measuring SSB modulation poses some problems for the tinySA. First the modulation bandwidth is typically 2.7kHz which is very close to the minimum BW of the tinySA. Next the phase noise of the SI4432 will have a significant impact measuring with such low BW. So I decided to give it a try. The test setup is HDSDR for the I/Q encoding and a Softrock ensemble II RXTX as transmitter. At first I set the LO and the TX frequencies both to 7.1MHz to simulate what you will get when you use traditional transmitter using a side band suppression filter. The test tone used was 2.5kHz to have almost the maximum distance between the LSB and USB signals. Setting the I/Q balance way of just shows the unwanted upper sideband as a right shoulder about 15dB below the main signal. Tuning the I/Q balance in the HDSDR calibration panel is easy and quickly the shoulder representing the upper side band disappears in the noise With only 30dB measurement range available due to the phase noise floor it is impossible to see of the I/Q balance side band suppression can be tuned to 40dB or better. In HDSDR you are free to choose the TX frequency versus the LO frequency as long as the delta between TX and LO is within the bandwidth of the audio channel. So I set the TX 10kHz lower to avoid the phase noise. Without tuning you get this (different vertical scale!) and after some tuning the left peak disappears in the noise and it must be at least 40dB below the wanted sideband. In conclusion the tinySA is just capable to visualize this SSB modulation and can support tuning. -- HBTE Files section: /g/HBTE/files Erik, PD0EK
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I've posted a document on GitHub that describes a couple of different approaches I have used to neatly apply labels to various homebrew projects, resulting in a nearly professional look. Enjoy! -- John P. WA2FZW
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TinySA Members, I got my TinySA working in the first model that I'm working on - the Arduino Nano version (same as Gary is working on). I'm using a pair of 1.6 MHz Qualcomm bandpass filters at 433.92 MHz but can clearly see I need to use 700kHz filters that I also have on hand to clean up some of the images I'm seeing. My setup is still on a breadboard for ease of reconfiguring (and I'm about to set it up for the Protoneer board that Erik is using with the ILI9431 touchscreen display next). Pics of my setup follow, also, I'm planning to spin a PWB for the 'Stand Alone' version and will do that once the breadboard proof is done. More as I have it - please do stay tuned... 73 de Marty, KN0CK
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A tinySA, packed in like sardines
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My tinySA is starting to work, built ugly/manhatten style on a 2.25"x4.0" (55mm x 100mm) copper clad board, sized to be the lid of a Seasons brand sardine tin. https://www.amazon.com/Season-Skinless-Boneless-Sardines-4-375-Ounce/dp/B01FR2EPHE Photo here, will be removed in a few weeks once it becomes outdated: /g/HBTE/files/KE7ER/DSC_6884.JPG The DB9 connector at the top of the photo and the SMA connector down and to the right are the only connections out of the tinySA. SMA will eventually go through the board, once I'm sure placement is final. I'll probably want to add the attenuator chip. A big 3.3v LT1585 regulator rides on top of the DB9 (will be LM1117's), converting from 5v. SPI signals from the DB9 go though a 200 ohm resistor, then a 0.001uF cap to ground, hoping that might keep processor hash out of the tinySA. This stuff around the DB9 will have to change when I add shielding. RX Si4432 is on the left, going down from there are two B3790 SAW filters (different pinout that most, quite narrow with a very deep stopband) and an ADE-1 mixer at the bottom. Room is left near the ADE-1 for possibly adding attenuators and an MMIC. The 250mhz LPF is to the right of the ADE-1. A wire with 10mhz from the TX SI4432 GPIO2 goes to the SMA for initial testing. The wire used is 30 gauge (10 mil diameter, a 5 mil thick coating of PVC insulation). Should be close to 50 ohms if the wire is taped flat to the copper plane: https://www.eeweb.com/tools/wire-microstrip-impedance Final version will likely use miniature 50 ohm coax to reduce interference. Board is laid out for shielding. The ideal would be to have it all in one long row, unfortunately I had to turn a corner before implementing the 250mhz LPF and the SMA. Shielding can be 0.25" high (6.36mm) strips of PCB board material. One strip down the middle from the DB9 to below the mixer, another along the left side, then three short strips between them placed at the obvious gaps plus two more for the top and bottom ends. Note that one of those strips will divide the two SAW filters. The 250mhz LPF would have to be treated separately with this layout, and can also have a shielding strip between the two halves of the filter. Note that adjacent 250mhz LPF inductors are at right angles (but awfully close). Will then solder some copper braid across the top of all the shields, and bolt a copper clad FR4 board across the top for a cover. If you look closely at the TX Si4432, you can see that I am tapped into the bottom of the "LC" inductor that feeds power to the Si4432 final amplifier. I have removed the tiny "C0" cap just below it to remove connection to the output LPF and harmonic trap and RX/TX switch on the Si4432 module. Much easier than removing all those LPF filter components. That tap must have a series cap to prevent power from the "LC" inductor from burning out our mixer, I have a 0.001uF cap placed near the mixer. I have also removed the "CO" cap from my RX Si4432 module, as this module is only used to receive and I don't plan to have it transmit for signal generator mode. Don't want to risk having 20dBm of RF going out into my 5dBm absolute max SAW filters. The Si4432 schematic shown on page 2 of Erik's build instructions does not quite agree with my Electrodragon Si4432 module. Mine has 3 inductors in the 434mhz LPF, where as that schematic shows two at "LM" and "L0". Board standoffs were made using a sheet metal punch on CEM board material as per K7QO's suggestion here: /g/qrp-tech/message/13590 I'm using the 3/32" punch from this Neiko set: https://www.amazon.com/Neiko-02612A-Multi-Purpose-Power-Punch/dp/B0002T87CW It takes a really hot iron to solder something like that SMA to a ground plane, would be very frustrating with the wrong iron. The SAW filters also took an awful lot of heat, the ground pins are directly connected to the top cover. Since I have that SAW filter sitting directly on the ground plane, the ground pins lose a lot of heat when trying to solder to them. Just got my first more-or-less successful scan of the the 10mhz reference last night, using the Nano (converted to 3.3v) shown in the photo and Arduino's Serial plotter. Serial plotter left a lot to be desired, definitely ready to move to pyplot on the RPi. Am using my tinySArpi.c code, will need some work before I'm ready to post it. Code drives the ADE-1 at 8dBm (not 20dBm), has AGC off. Not keen to find a MSWindows machine to run tinySA.exe on. Will park this for awhile, need to spend time on other stuff. Jerry, KE7ER
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Measuring the LPF before the mixer can be done also with the tinySA itself by using the Calibration output. Switch the calibration output to 3MHz and measure without LPF between 0 and 500MHz. You will see something like this. The harmonics extend well till the first IF frequency and beyond. Now insert the LPF and do the same measurement. My LPF start to roll off above 250MHZ and not much is left above 350MHz. You will notice the harmonics come back above 420MHz. These are probably not aliases or leakage through the LPF but direct leakage from the unshielded wire connecting GPIO2 of the LO SI4332 with the output SMA connector because even when I disconnect the input from the calibration output they are still there -- HBTE Files section: /g/HBTE/files Erik, PD0EK
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Panadapter
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#tinysa
An offshoot of this project could possibly be a simple Panadapter. With a TFT display and modified sketch to sweep either side of a defined frequency (ie the IF of the associated Transceiver) plus a band pass input filter, might be worth pursuing ?? Glenn vk3pe
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My TinySA is taking form. I haven't yet removed the filters from the Si4432 modules because I wanted to see how they fit on the board. I will combine Erik's TinySA software with this https://www.changpuak.ch/electronics/Arduino-Project-VISIONARY.php to have a standalone SA. I'm not sure I will implement the PC-communication, time will show. /Niels
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A caution about an ebay vendor
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This vendor: vesny89735-6 told me that "hackers got his account" and he wasn't able to ship my order. It's pretty stupid, because he's into me for about USD$2.50. That's right, two and a half bucks. I'm going to work it for full recompensation, but it's almost beyond comprehension how a hacker could steal three bucks or some offshore ebay spooger could try to rip me off for three bucks. I plan to ensure that his pain point ends at about USD$5000. Have a nice evening, all. 73 Jim N6OTQ
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There has been some debate on having attenuators around the mixer, it is even suggested it may reduce spurs. So I did test. First picture is a scan of the 15MHz power calibration signal with 6dB attenuators between LO and mixer and mixer and BPF Second picture without any attenuator Signal improved with a bit more then 6dB and noise a bit less so the attenuators are NOT improving the noise level. The spurs reduced both in absolute level and even more compared to the 15MHz signal (keep in mind the levels indicated are relative to the strongest peak, in this case 15MHz) My guess is the spurs I'm seeing are caused by harmonics of the power calibration signal directly getting into the signal path after the mixer. -- HBTE Files section: /g/HBTE/files Erik, PD0EK
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Hi, I hacked the standalone mode by adding another trace showing the combined gain of the LNA and PGA during a sweep. If the AGC is enabled then the gain can be read in Register 0x69 bits 4-0 The vertical scale for the gain is 5dB/division. The yellow trace is the 0-255 RSSI value from the SI4432, I was too lazy to change the scale at the side for the quick hack. This is how the gain varies with agc enabled (x69 = x60). The dBm value at the peak includes the correction for the filter/mixer loss, and yes I know it should say dBm not dB - fixed after the photos were taken. Interesting how the gain drops early, and the spike at each change of gain. Also interesting how the gain starts increasing before we get to the main signal spike. Presumably the gain algorithm is working on the signal strength before the FIR filter? Fixing the gain at the value the ALC chose, 37dB we get this: go up to 43dB and we see some spurious signals and the peak RSSI drops - ADC overload?: Drop down to 25dB and the peak RSSI stays at -13dBm but the minimum detectable signal level increases: So it looks like the AGC does a great job of setting the best gain level, the RSSI value is compensated for the gain change, but there are unwelcome spikes at the changes in gain. Perhaps some sort of on-demand "Optimise gain" button is needed where the gain at the peak (or perhaps the minimum through the sweep) is recorded and then used to keep a fixed gain throughout the sweep. I tried detecting a change in gain then delaying and retaking the reading, but that did not offer an improvement. Perhaps there is some instability and the gain is swapping between different levels? 73 M0WID
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*PLEASE DISREGARD THIS ORIGINAL MESSAGE AND SEE THE MESSAGE POSTED ON 2/18 FOR MORE INFO.* TinySA Team, Today, I took a programmed Arduino Nano (with TinySA for the Nano) and performed the 'surgery' to the schematic to make the Nano a 3.3VDC compliant device by replacing the regulator to a 3.3V type (from 5V) and a few cuts and jumps (I improvised on the cuts and took out a diode where it was clearly not being used). I am here to tell you that while all that is possible and all the measurements I took and the checkout of the I/Os looked good...It WON'T communicate to Erik's TinySA Windows PC program. The PC 'sees' the modified board as a 'COM4' device (sometimes this can also be a 'COM11' device) but no matter what, the TinySA PC program DOES NOT see the 'COM4' device when powered and running and it cannot even start it because it never makes the list - - the list just shows 'Mockup. It may work for other applications, but not for TinySA, and it also becomes more problematic to upload a sketch to the device even when powered in-situ in the setup, too - multiple bad read and write errors. In closing, I would NOT advise doing this for the Arduino Nano for the TinySA application. I have become a believer that Level Shifting is necessary to make this work for the TinySA and a standard 5V programmed Arduino Nano - that's how I'm going to try mine next. 73 de Marty, KN0CK
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Does TinySA write to a file..?
TinySA Team, Quick question...I have things running now on my modified Arduino Nano and the Windows TinySA application spectrum display came up REALLY nice at the beginning, but I went to change frequency settings and may have caused something else to happen because now all my spectrum analyzer wants to do is measure things at +37dBm (I think)...And then I did something really dumb thinking that Normalizing things would recover the spectrum I had that looked normal. Does the TinySA Windows app write a file somewhere that contains things like it's last run and settings? I cleared the registry settings, but somehow it still goes to the frequency I set last. Please let me know - But I DO have things running and really need to focus on building the filter assembly now - - I just wanted to make sure the transmitter and receiver were working - looks like they are. 73 de Marty, KN0CK
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I'm thinking to make a PCB for the tinySA but don't have the PE4302 attenuator module yet. I have most all the other parts but need some dimensions of the Attenuator from eBay to speed things up. I have made a drawing based on scaling a picture of the board. Could somebody who has this module kindly see if my dimensions are accurate. All are in mm. Glenn <vk3pe>
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I have attached my version of the schematic diagram . To get to the PCB stage I have to have the correct connections with the controller. Is anyone kind enough to tell me which pins connect LO and RX to HW-267 (STM32F103C8T6 STM32 Development Boards (Blue Pill)? I want to clarify the following about my schematic : RLC values are generic. System ground does not reflect the appropriate situation in the future PCB. It's just the electrical connections. For example, on the SAW Epcos B3555 filter the ground connections for the housing are top and the signal ground connections must be to the bottom PCB plane to avoid the "ground-loop" . Level Shifter is optional. I have no connection to the attenuator because I don't know what data pins are connected at STM board. Any suggestions on removing / adding components or changing the controller are welcome. Daniel Ungureanu YO8SAK
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Well...Since I am having no luck getting the Windows drivers working with my 'Blue Pill' board, I switched over to the Nano and attempted to compile and upload the tinySA.ino sketch into my Nano (prior to doing the hardware fix for 3.3V). Compiles fine when I installed the Adafruit_1306 libraries and the header file (Adafruit_1306.h) into the project. Compiles clean, but it won't upload to my Nano because it says the following: *Arduino: 1.8.10 (Windows 10), Board: "Arduino Nano, ATmega328P"* *Sketch uses 31462 bytes (102%) of program storage space. Maximum is 30720 bytes.* *Global variables use 1974 bytes (96%) of dynamic memory, leaving 74 bytes for local variables. Maximum is 2048 bytes.* *Sketch too big; see http://www.arduino.cc/en/Guide/Troubleshooting#size for tips on reducing it.* *Error compiling for board Arduino Nano.* *This report would have more information with* *"Show verbose output during compilation"* *option enabled in File -> Preferences. *...And I have tried other Nano variants of the board support package (ATMega328P (Old Bootloader)) with similar results - can't upload. So I tried commenting out the display in the following line: // #define USE_DISPLAY 1 ...and it gives me a compiler error later in the compile that I don't think I should have to fix. Is there a way to get this compiled so it'll make the upload happy? Is there a variant to the code that everyone else is using with their Nanos that will compile better than what I thought? Until I can get the 'Blue Pill' issue fixed, I would like to get the Nano going around the hardware and then use the PC Windows program to play with the tinySA just to get 'stick time'...But so far the stick is beating me to a pulp with getting either the Nano or the 'Blue Pill' going... :=/ Any help with this will be GREATLY appreciated - let me know where I'm going wrong... 73 de Marty, KN0CK
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New file uploaded to [email protected]
2
Hello, This email message is a notification to let you know that the following files have been uploaded to the Files area of the [email protected] group. /VA3NOI/Eagle/SAW_Filter_QCC8C.zip Uploaded By: Ion Petroianu, VA3NOI <ion.petroianu@...> Description: Schematic, PCB, Gerbers for a 10 PCBs Panel Cheers, The Groups.io Team
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Sat 8:39am
Sat 8:39am