![Ahmet Inan](/img/default-banner.jpg)
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Ahmet Inan
Registrace 28. 11. 2021
digital signal processing and forward error correction, mostly
Distortion vs Truncation
Shown is the amount of bytes used from the encoded file to decode. Original lossless encoded size is 318 KiB.
The lossless image compression project can found on GitHub:
github.com/xdsopl/dwt
The lossless image compression project can found on GitHub:
github.com/xdsopl/dwt
zhlédnutí: 92
Video
Testing chunked #Assempix transmission
zhlédnutí 195Před 6 měsíci
The encoded picture has a size of 62KiB and is divided into 12 blocks. There are 16 chunks in this video and any 12 of the chunks are enough to decode. This means you can skip 1/4 of the video and still recover the picture.
Testing #COFDMTV using [sic] 2.4 GHz toy walkie talkies
zhlédnutí 374Před 7 měsíci
Works astonishingly well with #QPSK, but #8PSK is too much
Another excuse to get a Hamburger, Cheeseburger, Big Mac, Whopper .. #Rattlegram testing!
zhlédnutí 474Před 9 měsíci
Get the #Rattlegram app for iOS on the Apple App Store: apps.apple.com/us/app/rattlegram/id1664526096 Get the #Rattlegram app for Android on the Google Play Store: play.google.com/store/apps/details?id=com.aicodix.rattlegram
So those INMP441 seem to work down to 8000 Hz
zhlédnutí 199Před rokem
So those INMP441 seem to work down to 8000 Hz
The #COFDMTV repeater for #Rattlegram in action
zhlédnutí 747Před 2 lety
The #COFDMTV repeater for #Rattlegram in action
Testing the #COFDMTV repeater for #Rattlegram
zhlédnutí 752Před 2 lety
Testing the #COFDMTV repeater for #Rattlegram
Receiving #COFDMTV encoded picture from a shortwave radio using AM modulation with #Assempix
zhlédnutí 1,5KPřed 2 lety
Receiving #COFDMTV encoded picture from a shortwave radio using AM modulation with #Assempix
Receiving #COFDMTV encoded picture from CB handheld radio using AM modulation with #Assempix
zhlédnutí 589Před 2 lety
Receiving #COFDMTV encoded picture from CB handheld radio using AM modulation with #Assempix
Receiving #COFDMTV encoded picture from CB handheld radio using FM modulation with #Assempix
zhlédnutí 484Před 2 lety
Receiving #COFDMTV encoded picture from CB handheld radio using FM modulation with #Assempix
Receiving #COFDMTV encoded picture from PMR handheld radio with #Assempix
zhlédnutí 2KPřed 2 lety
Receiving #COFDMTV encoded picture from PMR handheld radio with #Assempix
Sending #COFDMTV encoded picture over CB handheld radio with #Shredpix
zhlédnutí 492Před 2 lety
Sending #COFDMTV encoded picture over CB handheld radio with #Shredpix
Sending #COFDMTV encoded picture over PMR handheld radio with #Shredpix
zhlédnutí 755Před 2 lety
Sending #COFDMTV encoded picture over PMR handheld radio with #Shredpix
#COFDMTV Demonstration with #Assempix and #Shredpix
zhlédnutí 1,2KPřed 2 lety
#COFDMTV Demonstration with #Assempix and #Shredpix
Lol
Lol, if you guys are wondering what image it gave, it was an image of a cow with text saying "old mcdonald had a farm Had"
Out of curiosity, what air data rates are achievable using the aicodix cofdm modem in ideal conditions? This could be a viable replacement for 1200 baud AFSK particulsrly low bandwidth applications like aprs.
We made QAM64 modes that transmit at almost 4Kbit/s with a 1/2-rate FEC code (8Kbit/s raw): github.com/aicodix/modem/tree/next
@@xdsopl that's really interesting - I've been playing with voice (highly compressed, codec2 at 450) and small scale data (telemetry, position reports, messages) over LoRa and GMSK on VHF & UHF - but if your modem can do that kind of speed with 50% FEC overhead I probably should start looking in that direction. One thing I did like about LoRa was its ability to work at levels well below the noise floor, but it has numerous cons too. Treating any voice as "near real time" has also been instrumental in getting things to work when relayed through, for example two other stations. Ultimately my plan is to have a mix of RF repeating (preferably on a second VFO) and internet routing, so the network may be degraded in speed but remains useful in a power out scenario. Authentication/message signing is something I'd also like to see at least for sensitive operations like telecommands to repeaters etc but that's a future desire, and I'm still in the "is there a better radio I can use" stage. 73 and great work on the modem and the sstv like and text like PoCs
@@manyshnooks LoRa (et al) struggle with multipath. For voice you could use a BCH code and OSD per OFDM symbol to lower the latency. Did some experimenting with Ed25519 for authentication: github.com/xdsopl/ed25519_blake2b
@@xdsopl hah I was going down the same route given the efficiency of EC. And yes, absolutely re LoRa, it is the wrong tool for the job.
@@manyshnooks LoRa works really well for ultra low power and is very easy to generate _and_ demodulate. But nowadays we have crazy amounts of transistors .. better to start using them.
You are a great person thanks bro❤❤
Hahaha! Cheers! 🍻
oop
Yup, tried to encapsulate as much as I could. Still need to make the main function smaller though.
Lol
Theres no way to select a picture in the app?
Assempix is for decoding only. If you want to send pictures, you need Shredpix for encoding: www.aicodix.de/cofdmtv/shredpix/
@xdsopl he means shredpix
@@pomni_tadc_real Either there is a problem with the picture file format or the concept of sharing a picture from the picture gallery is
@xdsopl fix it so an looking like select image no file chosen
@@pomni_tadc_real I can only fix problems I can reproduce. Please send me the problematic image.
😁 🐮🔥
Had😂
yes. yes he did
ooooo
oooooo hell yeah now we can big data
Dostum böyle devam et. Amatör camiaya böyle insanlar gerek
In rattlegram, what does "channel select" do?
If you have a device with two microphones, you can select which one to use. Sometimes just using Default will do some counterproductive extra audio processing, even though you have chosen Unprocessed in Audio Source. Then choosing either First or Second from the Channel Select menu will help you to improve the audio signal. There really is no way to figure these settings out in a programmatic way, so you have to play with those settings until you find the one that works best.
Would be awesome if you make rattlegram also capable of decoding ADS-B, Mode a,b and c and also AIS just by listening from a simple quansheng that's unlocked on the 1090mhz band, also a preinstalled low res map of the world to work completly offline would be awesome. Thanks for your amazing work 🙏
My pleasure. AFAIK ADS-B needs a much larger bandwidth (2 MHz) than voice (3 kHz). So using a higher bandwidth receiver like a RTL-SDR for example is necessary. Playing with ADS-B is on my bucket list.
@xdsopl I really don't know how this works, however..the quansheng UV-K5(8) radio that costs only $15 can be unlocked to receive on a frequency between 15khz to 1300mhz, again..not sure how it works but couldn't the signals received for AIS and ADS-B be decoded somehow only through audio?
@@ExploringWithJason I don't know if it can provide the 25kHz bandwidth necessary to receive AIS but ADS-B is out of the question with a voice receiver. You really need a higher bandwidth receiver with these signals. Just being able to tune to the right carrier is not enough, you also need the bandwidth at that frequency. RTL-SDR dongles are really cheap and there are smartphone apps that decode these signals via an OTG cable.
@@xdsopl oh, I know, I have an rtl-sdr V4 and I have SDRAngel and dump1090 installed on my android phone, but facinated about what those little quansgeng's can do 😅
Looks delicious!
Hi, is this a demo of a future feature? I tried decoding it with the existing 1.11 version, and it showed payload unknown. It would be great to send larger images.
I've just released Assempix v1.13 as open beta and it might take some time until you can install it from the Play Store. Shredpix does not have this feature yet and you need to use the command line modem and the CRS tool to create chunked transmissions.
is for what this port ?
We developed the #Rattlegram app on Android first and after many requests, we ported it to iOS too. #Rattlegram can now be found on both app stores.
Bro, your mode is getting popular! Tomorrow, a stratospheric balloon will be transmitting COFDMTV in Poland as part of the New Year's celebration. Today, 36 pictures have been transmitted in this mode by our fellow SP4UBW to test the system. Great work, hope you continue to develop your skills! All the best and happy new year!
Cool, that explains the recent uptick in download numbers. Very happy to hear about it. Have fun with the apps!
how did you do this? is this similar to how distant satellites in space send images back to earth? im really intrigued and interested
That's the spirit! Satellites usually use much simpler signals, as they don't have to deal with multipath (or echo) but rather with the Doppler effect if they are non-stationary and with distortion caused by non-linear but efficient RF amplifiers. You can either contact me directly or watch some of the videos about #OFDM (Orthogonal Frequency Division Multiplexing) and #FEC (Forward Error Correction) if you are interested in this subject.
Ey yo dayum
Is this the new iPhone version of Robot36?
I don't know how easy it is to get another SSTV app on the Apple App Store, while there is one already. I was thinking to maybe try that if I get motivated enough to rewrite Robot36 and make it multi-platform, as Renderscript has been deprecated ..
@@xdsopl I don't use Apple, so I'm not familiar with their app store offerings. Last you and I had talked, you were moving development of Ribbit/Rattlegram from Android to Apple. This is the second video I've seen of a better looking SSTV decoder app though, and I'm curious what it is.
@@coreymckay4433 It's Assempix, available on the Google Play Store. You can use Shredpix to send pictures digitally over audio, which can be decoded by Assempix. Unfortunately they have not taken off as much as Rattlegram has, so I've decided to focus my efforts into the next multi-platform app, which does file transmission.
@@xdsopl I completely forgot about those, I'll experiment with those. Those use OFDM as well, correct?
@@coreymckay4433 Yes, same procedure as every year 🥰
Are you one of the creators of shredpix, assempix and rattlegram?
Yeah, that's me
Rattlegram is great. I wish more people knew about it. I've even used it over a zello handheld because it's much faster than typing messages using the handheld's keyboard.
I agree that messaging these days leaves much to be desired when it comes to something a simple as writing to a small group as fast and hassle free as possible
will you make a desktop GUI? or webUI?
Eventually. Right now I would like to focus on the next app. Have you seen the port of Rattlegram to Rust/WASM by @bastibl yet?
@@xdsopl no I have not
very cool
Ok i have NO FUCKING IDEA WHAT THAT IS but it looks cool🤔👍🎐🛬🏙
Yeah, I made this as a meme. It is totally impractical to send a #QAM256 modulated signal over the air. I just barely managed to send data over a loudspeaker and a microphone where both are so close that they are almost touching. If you want to try this kind of technology yourself, search for Rattlegram on either the Apple App Store or Google Play Store. It is free!
im in gimmie
The code for the new #QAM16 modes can be found here: github.com/aicodix/modem/tree/next
Made three new meme #QAM256 modes, just for you @ArclampSDR ! This way you can send up to 680 bytes in a second, if the channel allows it: github.com/aicodix/modem/tree/silly
I think I am gonna add a couple of comb type pilots to make it more practical
@@xdsopl hell yeah
@@ArclampSDR Cool, adding comb type pilot tracking proved to be useful indeed. I've also rebased your silly branch, so have fun!
Here is a clever Spanish man demonstrating Rattlegram using a cable from the hand mike/speaker port directly into the "hands free" port of the SIM card-less smartphone. He also is using "Parrot" mode and VOX. czcams.com/video/1VtkNj0ii1A/video.htmlsi=S52KEnTAtFjFC2ZJ This is is clever, because essentially it is user-friendly simple, and most anyone can do it
I don't know why your comment is not shown and I had to search in CZcams Studio for it .. anyway, thanks!