Erik, I just swept my 433MHz BPF with results below. I used the stock values for matching.

Approx +-0.75dB? ripple.? Pretty close to the data sheet actually.? The 2 filters are mounted on my tinSA pcb shown in another thread. Note; I followed the recommended PCB layout for the grounding, shown in the data sheet also.

Glenn
vk3pe

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_touch05.zip

Uploaded By: m0wid <david.wilde@...>

Description:
Work in progress. Very much faster display updates (problem turned out to be some delay() instructions in the TFT_eSPI touch library!), some bug fixes, basic WiFi just to see if it interferes with the SI4432. In my set up it appears to have no effect. To use WiFi you need to edit the SSID and password defines in TinySA.h. In addition you will need to load some libraries into the Arduino environment. Websockets by Markus Sattler can be found in the standard Arduino library management tool. This is not really used yet but should allow data to be pushed to the browser each sweep, if I can work out how it works. Also used is ESPAsyncWebServer. Google it for the installation files. You also need to use the ESP32 filesystem uploader to upload the contents of the Data folder to the ESP23 SPIFFS filesystem. This contains some basic webpages. When you start the ESP32 and it successfully connects the IP address is printed out via the serial port. I will add this to the splash screen for the next release. Point your browser to this and you should see a simple page showing if the websocket connected or not. You can get the RSSI data for the sweep either as XML or JSON, by follwing the ipaddress with /getScan for XML and getSweep for JSON format. I hope to work out how to use this with CanvasJS to display the sweep. This is new territory for me so if anyone can help please do! Some clean up done, I got fed up with all the #ifDef compiler options, so no going back to a Nano for this one, sorry. Not yet included the many comments John P has provided, or the latest mods by Erik for Serial parsing or measurement of filters. Good luck! Dave M0WID

Cheers,
The Groups.io Team

开云体育

Not true if you are doing all the processing on board with the touch display!
73,
Gary
WB6OGD

Marty, from a visible performance perspective you're not going to see much improvement regardless of the processor. The limiting factors are the SPI bus speeds and the built-in delays in the scanning process.?
--
John P.
WA2FZW

开云体育

Glenn,

Looks great and I have to admit that the mezz for the microcontroller is a really great idea, too. While I have a prototype coming, I'm planning to check out the performance of my ESP32 on a breadboard and then do a similar design with the exchangeable mezz meant for an ESP32, but convertible to any other microcontroller with an adapter board.

73 de Marty, KN0CK

Proto pcb panel received today.? Pity I don't yet have all the parts.

The pictures show the method of construction though. Most likely a central shield plate will be fitted between the two PCB's if needed.


glenn vk3pe

Kind of newbie question and might be a firmware hack I'm envisioning that isn't feasible and a sampling rate limiting
factor, though was looking at the latest and greatest pricing of the GPS chips and modules and decide to review
specs again since I've learned more and didn't even know there were 9th generation chips on the market.?

I see the sensitivity for the 8th gen is amazingly low (~140 to 170dBm) and?if the GNSS engine can be hacked
somehow to access the spectral input signal data, does that make the GPS chip/modules useful as a lower noise
floor detector for a power meter or signal/spectrum analyzer?? Seems the power or signal strength alone is all
required.

Mixing into the GNSS range for the modules seems easy... though other than the sampling rate... the sensitivity
getting closer to a lock-in amplifier noise floor seems like might be useful.? Seems like will be very slow though of
a sweep rate if I'm interpreting correct the Digital Engine on the receiver side is the limiting factor (update rate).?

I haven't looked into the GPS code to decode the outputs and am thinking will earmark as a project alone for an
interesting study of just reading the GPS signals with the Arduino IDE.?

Any thoughts or references?? Thinking will be super slow... though if shielded well... might be really sensitive for low
baud rate com or detecting weak signals.?

The tinySA is a double conversion spectrum analyzer. First the input signal is upconverted to the high IF at 434MHz where it is filtered using the SAW BPF. Then the SI4432 does a conversion to a low IF at 937kHz. This low IF is read by a I/Q ADC and the image is removed in the digital domain. Then a resolution filters are applied also in the digital domain.
For a spectrum analyzer the requirements for the filter to be bell shaped and smoothly going down flanks is not for the first IF filter but for the resolution filter. The first IF filter is there to suppress images caused by the limitations of the I/Q image suppression.
And for the resolution filter the requirement only holds when doing an analog VCO LO sweep.
The tinySA does a stepped LO sweep where the steps are half the RBW.?

The SAW filter should be selected based on the datasheet.?
As an example the insertion loss curve (S21) of two different SAW filters,?



and


Both have their passband around 434Mhz and both have a somewhat flat passband and steep flanks.?
But very narrow SAW filters often have unwanted responses close to the passband with limited insertion loss.
For the tinySA these unwanted responses should be at least 3MHz away from 434MHz as the SI4432 is capable to suppress anything outside the selected BW plus low IF at 937kHz times two.
The flatness of the passband is determined by the impedance matching and as demonstrated rather sensitive to small mismatches of some pF

To summarize.
The high IF SAW BPF should optimally be 1MHz wide, have steep flanks and a flat top.
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK

Erik,
As far as I know this filter must have a transfer curve like a bell without being flat and the flanks go down smoothly. I don't know the explanation for GDT, but these SAW filters are just for tight selectivity. Is it a problem or can it be canceled? with a long sweeping time? From my experience in analogue television, the SAW filters all the time have given great variable phase delay. From the discussions I know that many hobbyists like?me?who want to build SA do not know the implication of an IF filter. You can make for us a little light in a few words ?

The performance of the passband of the BPF of my tinySA was not as it should be. Too much ripple



but after reducing two capacitors with only 1pF things improved


The stop band is a bit worse in the last measurement? due to removal of shielding.

So when creating a PCB be aware the parasitic capacitance of you PCB can have a big impact on the filter performance and some very careful tuning may be needed

--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK

From:?/g/HBTE/message/1247

After watching the?, I started thinking again about studying most lossless clean switching method if wanting to have say two SAW filters to switch between and how will change and possibly improve performance.? Was also wondering about switching for the LPF.?

When I read into last... I didn't read into the specs and only looked into the methods, i.e. diode, transistor and relay.?

Any insight into best practices for switching RF and in regards to frequency range?

?

References for RF Switches (I think I answered my question):

Looks like there are a many more from the various supply stores.?

Wow... I was hoping for a simple answer and if there is a neat way you know... feel free to share. :-|)? Thanks

On Thu, Mar 12, 2020 at 07:23 AM, Dan Reynolds wrote:

I was more looking for the nano attached to the PC version - just as a convenience to get me going.

Looks like three have got the PC software version moving forward with various forms of the Nano:

Marty KN0CK (later in the message thread):?/g/HBTE/message/1051?
... though looks like wound up getting to work:?/g/HBTE/message/1081
/g/HBTE/message/1119

Jerry KE7ER:?/g/HBTE/message/927 (not tried yet reads like)

Gary?WB6OGD:??/g/HBTE/message/1032
/g/HBTE/message/1059

Looks like another UHF Spectrum Analyzer design using a Nano and the Si4432 is in the works too:

DuWayne? KV4QB:?/g/HBTE/message/1242

In regards to the UHF Spectrum Analyzer, I was wondering what code optimization can be performed if there are any similarities to improve performance as Erik last left off demonstrating his fastest experimental way.?

After watching the , I started thinking again about studying most lossless clean switching method if wanting to have say two SAW filters to switch between and how will change and possibly improve performance.? Was also wondering about switching for the LPF.?

When I read into last... I didn't read into the specs and only looked into the methods, i.e. diode, transistor and relay.?

Any insight into best practices for switching RF and in regards to frequency range?

I was thinking to reduce the risk of magic smoke, starting with the Nano iterations.?

Thanks in advance for your time and support!

I have been following the TinySa since it started, and have been working on a version using an ESP32 board.?Still waiting on some SAW filters for that project.?
The UHF SA I mentioned does not cover the HF bands, only 240-940 MHz.? It only uses a single si4432 module and controller.? This will give me a chance to play with some software whiule I am waiting on some other parts.
--
DuWayne,? KV4QB

Marty, yes I was more looking for the nano attached to the PC version - just as a convenience to get me going.
Building is not new territory for me - but this project definitely is brand new territory for me.--
Dan Reynolds - KB9JLO

DuWayne,

Erik (on this forum) has a version for stand-alone version using the Protoneer Board (Arduino Zero compatible) and several of us started with the Nano on the PC. This TinySA works incredibly well but I would advise you to look through the threads because a lot of what you're doing has already been realized - but if you have a different spin of it, please share that here, too.

73 de Marty, KN0CK

On Sun, Mar 8, 2020 at 11:48 PM, jafinch78 . wrote:

the 0603 size pads are a little small on my printout... maybe going back to make into 0805 would better fit what they sent me as "0603."

Here's the latest 0805 version of the 16th Order Chebyshev LPF to create a little more space between the pads:

Feel free to critique, question, comment, suggest, modify, etc.? Not supposed to be ugly, though figured is marker (sharpie) acceptable and close enough.??

Now, to figure out the easiest and cost effective way to duplicate (thinking using InkScape) the design so can print out more on one sheet of paper.?

Duplication process in a video for posterity (and when I forget if I need to perform again) since I noted in a previous post (looks like I don't need InkScape unless for maybe the laser cutter/engraver resist removal method of the inverse of the image with some mods).

Just saw this on instructables.com.? A tiny spectrum analyzer using? just a a si4432 and a small controller.? Looking at everything, it looks liike it willl be easy to just us a nano.
Tried the software and it compiles on a nano? after getting the correct version of the RF22 library.? The PC program that goes with it appears to work.? Going to wire one up tomorrow and see if it works.? \If everything looks OK I will see about adding a display? and some controls to make it stand alone.
https://www.instructables.com/id/UHF-Spectrum-Analyzer/
--
DuWayne,? KV4QB

On Sat, Feb 29, 2020 at 09:15 AM, John P wrote:

I still have a few of the older PCBs without the preamp if anyone is still interested.

PCBs are all spoken for!
?
--
John P.
WA2FZW