Comments (11)
It seems like this is caused by the cpufreq
kernel module, which changes the frequency in order to save power. The ondemand
governor is enabled by default.
from rpitx.
Hello! How did you see these diagrams? Thanks.
from rpitx.
Using this: https://signalhound.com/products/usb-sa44b/
However you can catch the signals also with RTL-SDR or SDRPlay(better) too..
from rpitx.
Ok, thank you!
from rpitx.
Perhaps I'm reading the graphic incorrectly, but both images show Mkr1 and Mkr2 having the same frequency.
It appears that the only difference between the two images is the center frequency.
Image 1 has a center freq of 25MHz and Image 2 has a center freq of 14MHz.
Am I correct in reading this?
from rpitx.
No, you are mistaken the fact that the Mkr1 is the intended transmission (14 MHz) Mkr2 showing the randomly shifter carrier (16.8 MHz)
The reason for two screenshot is the different span
from rpitx.
Maybe this video gives a better understanding of this phenomena:
https://www.dropbox.com/s/xxihgxrakkejlji/14MHz_and_random_16M8_shifting_RPi3_gpio18.png.MP4?dl=0
from rpitx.
My friend András, @ha7ilm noticed that this shift issue possibly caused by the dynamic CPU frequency change algorithm in RPi 3. I've tested it and looks like a workaround for the problem:
" sudo -s
echo powersave > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor "
from rpitx.
force_turbo=1 in /boot/config.txt shoud solve the issue
from rpitx.
The problem is frequency of PLLC (used by rpitx), which drifts with overclock.
from rpitx.
Should be fixed with feb6f4c : PLL_D is used which is very stable compare to PLL_C (variable)
from rpitx.
Related Issues (20)
- PL tone on nfm transmission? HOT 1
- Do we support the Pico? HOT 3
- Car hacking HOT 1
- Where is SendOOK.sh? HOT 2
- Installation fatal error: librpitx/librpitx.h HOT 1
- Pager message sent 4 times on some frequencies HOT 3
- O/S Question HOT 1
- Wont install on latest Debian Bookworm HOT 1
- Pi4 POCSAG transmission failure
- More dead projects? HOT 2
- Transmission not working on Raspberry Pi 3B+ HOT 7
- On/off codes? (Feature or doc request)
- Compile fails at ./install.sh: missing semicolons at code HOT 1
- librpitx
- Raspbery Pi Bookworm lbcm_host and semicolons missing HOT 2
- Will you continue work on this project HOT 1
- dvb/dvbsenco8.s:2: Error: junk at end of line, first unrecognized character is `@' HOT 7
- POCSAG message sent 4 times and text is an alphanumeric string
- Continuous wave during NFM .wav file tx HOT 4
- Amplitude modulation HOT 4
Recommend Projects
-
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
-
Vue.js
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
-
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
-
TensorFlow
An Open Source Machine Learning Framework for Everyone
-
Django
The Web framework for perfectionists with deadlines.
-
Laravel
A PHP framework for web artisans
-
D3
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
-
Recommend Topics
-
javascript
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
-
web
Some thing interesting about web. New door for the world.
-
server
A server is a program made to process requests and deliver data to clients.
-
Machine learning
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
-
Visualization
Some thing interesting about visualization, use data art
-
Game
Some thing interesting about game, make everyone happy.
Recommend Org
-
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
-
Microsoft
Open source projects and samples from Microsoft.
-
Google
Google ❤️ Open Source for everyone.
-
Alibaba
Alibaba Open Source for everyone
-
D3
Data-Driven Documents codes.
-
Tencent
China tencent open source team.
from rpitx.