RDL-SDR Scanner

[kd6soj]

I want to build the SDR shown in "Freq Show: Raspberry Pi RDL-SDR Scanner."
My questions are: Can I easily use a Raspberry Pi 3? Does it take any hardware changes?
Can I use a 7" display instead of the 3 1/2 "? Which one is best for that application?
Does it take a modifications beyond the ones mentioned for the 2.8" display?

[adafruit_support_rick]

You an use a Pi 3. The software is designed to use the 3.5" TFT. You can probably modify it to use a 7". Not sure what's involved with that. At a minimum, you'd have to change the frame buffer from fb1 to fb0 in freqshow.py to use an HDMI monitor.

[JIMHAM65]

Okay, the FreqShow software is working with the help of a person familiar with Linux and AdaFruit products. The problem was in the config file. It specified the data rate much higher than the touchscreen can handle. It works fine set to 16 MHz. The software works fine if the bandwidth is set to values between .91 MHz and 3.2 MHz. I tried decreasing the bandwidth to 50 KHz and I get an error message "invalid sample rate: 500000 Hz" followed by some Traceback lines. How can the bandwidth be set to values below .90 MHz?

[mvolt3]

I have a 7" screen attached to a Pi 3b and it works perfectly in the workbench & terminal areas. When FreqShow is started the splash screen comes up the correct size and after a few seconds the FreqShow starts normally showing everything shown in the install guide. I touch the screen and everything disappears but the signal with no response from keyboard, mouse or touch screen. Could someone please explain whats going on or what to look for?

I've tried 4 reinstalling each time with the FreqShow installation page doing everything it said to do -each time it does the same thing. normal until the screen is touched

Thank You in advance!

[adafruit2]

freqshow is written for the pitft, so not surprising it may not work with a larger screen!

[Banjopkr]

I have been able to get FreqShow working via the HDMI, the 7" screen and the 2.8" PiTFT. To get it to work on the larger displays, you need to get into the freqshow.py and modify some of the settings. Though I didn't necessarily know Python, it seemed pretty intuitive. For the 2.8" display, I modified the text size in every reference to 18 and the number size to 20. I had to also look through the other .py files for any references as well.

Concerning the bandwidth settings, that is limited by the RTL device, there are two different ranges and anything outside of those will result in a crash of the program. The valid sample rates for the RTL2832U chip are .225001 - .300000 MHz and .900001 - 3.200000 MHz. So I wrote that protection in an If-then-else statement into the python code. Now if you enter an invalid sample rate, the code just won't change it, instead of crashing the program as before.

It is possible to get less of a frequency range to display on the screen, but that required writing a zoom function into the code. I can now go all the way down to 10 kHz on the screen, but that's using a sample rate of .24. In order to do that required some math and some more complicated code to increase the total number of "samples" taken, and then only transfer the center 320 samples to the screen in the pygame drawing code in views.py.

In my version of this program I ended up adding lots more functionality including up and down buttons to step the frequency up and down right from the main screen, and of course I also added a setting to control the tuning rate step.

To address the minimum gain value dropping out to a - couple hundred db, I just fixed the minimum gain at -10 and that solves the issue. That's all relative any way. I also added a background grid and and a line that follows the zero db level across the screen as a reference.

FreqShow is a great starter for learning Python programming, and I have learned a lot in the last three weeks playing around with this. I intend on using the RPi 3 b with the 2.8" PiiTFT as a dedicated Panadapter for an older ICOM HF tranciever as a pan adapter monitoring the 1st IF. So now onto building a buffer amp and tapping that 1st IF!

[Banjopkr]

I have two new "very enhanced" versions of FreqShow. One is for 7" screens or larger and the other is for the smaller PiTFT screens. I am specifically using this on a 2.8 inch PiTFT, it would work fine on the 3.5" as well. The additional features are many. Additional features include: Full resolution zooming, I and Q Swap, 9 different pre FFT windowing functions to choose from. Center frequency offset or shift. PPM correction for the RTL2832. FFT averaging or FFT peaking. Easy frequency up and down from main screen. Easy Scale adjustment from main screen. I also built desktop shortcuts to both versions as well, included in the folders. I have two files FreqShow_Large.tar.gz and FreqShow_Small.tar.gz if you are interested. Do you have an address to upload these to?

Dan
Banjopkr

[Hulken]

Dear Banjopkr,

Could you please upload those FreqShow versions to by a post here, github or send them to me by email? Thanks in advance.

[Banjopkr]

I have just signed up for a github account. When I figure out how to upload the tar.gz files I’ll post another reply. One thing to note is that the enhancements I have made to FreqShow will require the Python-Scipy Library to be installed in addition to what FreqShow already required. I will be including a pdf document that covers all of the enhancements as well as how to save your own defaults and what to do if you run into trouble. The folders also include a desktop.launcher file to copy to the desktop so it’s easy to start the enhanced FreqShow.

Dan,
Banjopkr

[Banjopkr]

OK I think I have the files now available on git hub.

You can try this to "git" them!

git clone https://github.com/Banjopkr/WQ7Tpanadapter.git

Make sure you read the read-me and the PDF manual as it covers how to save your own defaults to the program

Let me know what you think.
Dan
Banjopkr

[Banjopkr]

Here is a you tube video of two Raspberry Pi 3 B's with the enhanced versions of FreqShow
I still need to add sub titles and its a bit fuzzy, but you'll get the idea

https://youtu.be/BX3iLQBBAmM

Dan
Banjopkr

[davelawrence]

Hi Banjopkr,

Will your updated Freqshow work with a HackRF?

Currently I get an error on startup:

Code: Select all

IOError: Error code -1 when opening SDR (device index = 0)

Thanks,