Tuesday, February 23, 2021
Wednesday, December 2, 2020
Well it has been a while since I did an update post for the TinySA or anything else. It has been a combination of some computer problems that I had to correct along with the associated data recovery. I also made a mistake and bought a FireStick for my TV. With all the streaing channels available it is WAY TOO EASY to spend a lot of time watching some of the older movies and TV shows. I have also been doing a little bit of another type of Home Brewing. Just finished up the 2nd. generation batch of UJSSM, and starting on the 3rd. generation.
So, lets get back to the TinySA. There has been quite a bit of information by way of groups.io, and several YouTube channels with coverage of the unit. Because of these the developer has released several updates to the firmware. These have corrected some of the problems fund in the early versions, and some added features. Because of these updates, I have been more impressed with the TinySA.
The one thing it is missing is a tracking generator. But, since I have a NanoVNA it was not an immediate issue. I finally decided I would build a very simple from available eBay or other outlet modules. The most basic tracking generator is just a RF source at the first IF of the SA and a mixer. The RF from this source is mixed with the LO of the SA to give you a signal that tracks the sweep frequency of the SA. I looked around at some of the PLL modules, and planned on doing something with an Arduino. Then I found several versions of ADF4351 modules that were complete RF generators. There were 3 versions that differed mainly in the type of display and controls. I went for one that has a full graphics display touch-screen controls, instead of the ones with text only display and push-buttons.
This is a self contained unit only needing 5 volts supplied through a USB connector. Along with fixed frequency output, it also has a sweep function. There is also a connector that brings out the 25 MHz reference used by the PLL. With a frequency range of 35 MHz. to 4.4 GHz. it is quite a impressive for the $35-$50 they sell for depending on the supplier. The other versions are available for around $20 to $30.
I had previously ordered a RF test board to use with the NanoVNA. The filters included on this fixture should work well for checking the tracking generator. Since this also comes with SMA connectors on the test cables everything should be realy easy to test.
Now the hard part of the whole project was waiting for the parts to come in. With the whole Covid mess parts delivery times for anything from the Far-East have been greatly increased. Most of these have gone from 1 to 2 weeks to 5 or 6. Although I had ordered these parts over a 2 week period they all came in with 2 days of each other.
After powering the RF generator from a 5 volt USB power pack, I connected it to the Low input cnnector and set it for 100 MHz. output. There is a slider control for setting the output level, so I set that for around 50%.Looking at the signal it was on frequency, with what looks like some phase-noise. This would not be unusual for a PLL generated signal. Amplitude level is very usable, with this at 50% output, there should be plenty of drive for the ixer.
Sunday, August 16, 2020
I have received several questions about the TinySA. So, just a little history and overview of the hardware of the TinySA before I get into the settings and actual use.
|TinySA Main Menu|
After I joined Home Brew Test Equipment in Groups.io, I became interested in a series of posts by Erik Kaashoek detailing a SpectrumAnayzer he was building using mostly small modules that are available on E-Bay.
These are basically a complete SDR transceiver in an about 1 cm. square IC, and cover a frequency range of 240 to 960 Mhz. They are designed for digital data transmission in applications such as remote time pressure monitors, therefore very inexpensive. There are several different modules, with support circuitry available for well under $5. The other thing that simplifies the design, is using a 433 MHz. 1st. IF, where Erik could use readily available 433 MHz SAW filters to obtain required selectivity. I had attempted to copy portions of the design, but without much experience or equipment suitable for use above the HF range, I ran into several problems. I decided to just wait and see what others finally came up with. And, I am really glad that I did. When I saw the unit was prduced by Hugen, I jumped at the first production run. Hugen has done a fantastic job with his several versions of the NanoVNA, and I am very satisfied with the units I have from him.
Tuesday, August 4, 2020
Saturday, July 25, 2020
Over a year ago I found some information on a very small VNA for around $60. Since this NanoVNA was less than 1/10 the price of any other VNA with a built in display, I jumped at it. It gave me an instrument that had the frequency response I would need to work on a SA.
There was an IO group formed to support the little VNA.
Following that group I found another group about Home Brew Test Equipment. One of the ongoing projects in that group was a Tiny SA. Several different versions of that were being developed and it looked very promising. Around the first of the year a TinySA group was started for several people who were testing a future commercial version of the TinySA. Some of the info on this group looked very interesting, especially a short video on the nearly finished product.
Just the other day I saw a post on the TinySA group, that the product was available for order. The TinySa is being produced by the same person who originally produced the NanoVNA. With that as a recommendation I quickly placed my order, since I understand there is only an initial production run of 300 being made.
The availability of a less than $100 SA with a range of 100kHz to 350MHz (240- 950 MHz. without bandpass filter )will make the life of the home-builder a lot more fun if not easier.
Now all I have to do is wait #@*& !
Monday, June 15, 2020
The board layout has provisions for a up to 7 pushbutton switches that can be read by a single analog input pin.
I chose to use a double row header so I could add individual switches as desired or a switch array connected through a single ribbon cable. I also brought out the connections, 3.3v, and ground for use by a rotary encoder with switch..
The connector for the SI5351 module is mounted on the bottom, so the boards can be stacked. Also, a female header strip can be mounted on the bottom for a 1.8" TFT display which then can also be stacked. I have provision for an optional 5 volt regulator so you can power the assembly form 7-12 volts if desired, instead of directly with 5 volts
One thing I like about the Wemos module is that I only have to make connections to the inside rows of header pins. If I need additional control pins, I can put header pins in the outside rows of connections and just plug onto them. This means I do not have to worry about those pins in the PCB layout.
After playing around with the options this gives me,I decided to modify the layout to make the small corections in layout positions I found.
I am also going to bring out some of the pins I had not originally used , and add a couple connectors for additional connections to the I2C and SPI signals. This will allow me to use the same board as display-controller for several other projects I have been slowly working on. Now just need to send this off to a board house in China, then wait.
Tuesday, May 19, 2020
I downloaded the software, and got it to compile without any problem. After looking at the code, I can see where having two 240 Mhz. cores doing the processing is nearly a necesity for something like this. And also still has plenty of room and power to addd other features. I quickly built a simple board to see how it looks, and works .
After getting the basic software running for the display, I did some modifications to add a couple things I want to have on the display. a LSB/USB indicator and I will probably add a T/R indiator light of some type. The response of the display is really nice, except for some small jumping around that is coming from the really cheap rotary encoder I used. I have a couple better ones that I will use after I get a board designed, now I will see if I can correct with some filtering capacitors.
I plan on using one of the Adafruit SI5351 modules I have, so will have to see what if any changes I have to make to use them with 3.3 volt logic instead of 5 volt. I have not looked at the 5351 library used with the original software, so do not know if I will keep it or use the same library I have used before.
Trying to think about what I want to include on the board design. All the pins required are on the inside set of pins on the Wemos module. That means I can just add some header pins to the top of the Wemos module instead of having to route them on the board. This should allow for fairly easy expansion.
I like the single analog pin method for monitoring multiple push buttons. I will probably add the resistor chain and some header pins on the board to make it easy to add several push button controls. Also thinking of having provision to add a retoary encoder directly on the board, or a connector for adding an external encoder.
I will get started on the board layout, then decide if I want to order some from one of the board houses. They all offer DHL shipping, so should not have to wait too long to get them.
I tried to make a video of the board working, but couldn't find a way to keep the camera steady while operating the encoder.
So here is a link to the original YouTubevideo I watched.