@@HB9BLA Ahmet has Angel backers in the Ham community. They will be at the Ham cation in Florida. It's all very interesting and used in the VHF and above the potential seems amazing!
I was fixing to say that but you beat me to it. Rattle gram is awesome. I want to build a server on a R pi on my repeater. I like having a bulletin board like that. Awesome stuff friend.
I found it worked very well through my laptop speakers - though I could get 'decoding failed' by moving the phone further away than about 2m... but it always seemed to know the sender was HB9BLA - so I wonder if there is additional error correction for the sender id? though I'm not the first "Dear viewers, I wish you Merry Christmas :christmas_tree: :snowman: and a happy New Year" Congratulations to Ahmet on a successful implementation and coming up with a very catch name for it.
The preamble symbol in COFDMTV, that contains the call sign, is designed to be much more robust than the payload symbols, so we have a high probability to find out who is transmitting. Compliments are always welcome and motivating.
David Rowe developed the Fdmdv modem for use with his CODEC2 voice codec. That modem seems very similar to the one presented here. Unfortunately that modem is deeply embedded in the freedv application. I haven't seen it being used for non-voice data.
Very interesting and thank you. I was looking at using codec2 over lora a while ago but got distracted. This beautifully clear explanation of ofdm has inspired me. I think I'll revisit it.
Coincidentally, a few days ago I found a website showing how to send images captured by an ESP-32CAM through SSTV using these radios. SSTV transmission seems very interesting. Thank you for your videos and best wishes for 2023!
The equations for the DFT are for the continuous time domain, not the discrete time domain as would be used in an OFDM modulator/demodulator. Some carriers are also designated as pilots with fixed magnitude and phase for equalization and timing recovery, therefore not all carriers can be utilized for data.
Very interesting. I'd love to make a couple of dedicated devices using a pair of cheap BF888's and attached directly to a USB sound card just as done with use of Allstar nodes. We could take care of pressing ptt and reduce audible noise in that case. 73.
Forward (typo). At RF, COFDM is not a cure-all it does have the Peak-to-Average power issue requiring highly linear, inefficient, and complex RF amplifiers. Whereas, GSM uses GMSK and tolerates non-linear efficient simple Class-C amplifiers.
Downloaded from play store. Input my call. Entered message and transmitted. Very interesting. Collins radio used sync cohesrant ofdm in their kineplex system back in the 50's. Their adoption of coherent psk, qpsk dropped the necessary noise floor 10's of dB. Isn't it a great world we live in. Thanks so much for the presentations you do. I'm just now picking up the esp32 python hobby partially because of your wonderful videos..73. de Tom W5XTT
@@HB9BLA Very nice. I did teletype work as a young man; speed there about 10x Morse. Morse strictly by amateur radio. TTY machine was limited to 100 WPM if I remember this right.
Not a new concept, this is how vintage computers like Commodore 64 stored programs, in 80' there were even some transmissions of programs in public radio
Does anyone know if this method is similar or not to what the Trailblazer modems used back in the late 80s? I remember reading a description where it divided the bandwidth up into a hundred or so channels and did all the encoding/decoding in software.
@@jankkhvej I now read the story of Trailblazer PEP. Indeed, this was revolutionary back then. And they needed quite expensive chips for "just" a modem...
مضاعفة تقسيم التردد المتعامد (Orthogonal frequency-division multiplexing) وضع تعديل الإشارة في الاتصالات ، يعد تعدد الإرسال بتقسيم التردد المتعامد نوعًا من الإرسال الرقمي وطريقة لتشفير البيانات الرقمية على ترددات حاملات متعددة
That is extremely intertesting topic. I tried to do something similar actually.. Didn't finish it, but it seems like an awesome opportunity to start again :)
The implications of what this app can do has many important features. So.... if the internet, mobile phone network are down for any reason, but our smartphones can start up. I could communicate a serious text through UHF or VHF transceiver, say at a specific prearranged time and frequency, with another person ... and they can type an answer on their phone and send it back.
@@HB9BLA Rattlegram would have really been able to help in the recent wild fires in Maui Hawaï. I live in Belgium and am a newbie ham (ON3VCF). Ispent that night up listening to the only SDR on the island going up and down the 10, 11, 2m and 70cm bands, listening to sporadic desperate transmissions of people trying to find people.... Normal FM was also down. But on 1110Khz am KAOI was on emergency programming trying to help. They were the only station I could find... (using also an app called "Planet Radio" For Several days I would tune into KAOI to listen in to the real people sharing real stories. One day a firefighter was talking about how all repeaters were out and that they'd had big difficulties getting through to base, etc. He mentioned about a new super-simple app called "Rattlegram" could have helped everyone. I have seen a few RUclips reviews of the app, and I don't think they understand its special characteristics and features. Specifically "Parrot".
Encryption is not allowed on amature bands but could you use ultrasound as as long as you use of the accepted and published modulation types just shift the frequency to inauable?
@@HB9BLA prelookuptable or precalcul array could "help a lot to solve" compute problems with ram available on new µc remember what demomakers was beable to do with limited ressources 20 yeas ago !
I tried rattlegram with a cheap microcasette recorder. It didnt work, as expected. I get "Preamble failure" error message. But these kind of errors was expected. Even a trivial DTMF decoder cannot work with my microcasette recorder. I was hoping that the 50% forward error correction could decode at least a single character from the microcasette, but no, it couldnt. 10/10 👍
It is possible to analyze how exactly signal is corrupted by your hardware. And then select encoding (modulation) which is resistant to such corruption.
@@HB9BLA I'm going to try this again. I was using a "GE 35375" microcasette recorder. I think it has something to do with this; en.wikipedia.org/wiki/Wow_(recording)
Hi !!! Greetings from Buenos Aires, Argentina. I bought two Baofeng Handies, the cheapest ones, the simplest ones, BF999S, how can I send data from DB9 to handy number 1, receive data on handy number 2, and decode it with arduino uno and RS232 module HW-044 ? , and show that data on a cheap OLED display like 1.3" (GND, VCC, SCL, SDA) Thanks so much !!!!!!!
i like the bit where you said "they" call a FT an "Inverse function of the IFT" :D not sure which "they" do that but i always just called the inverse of the inverse of a thing that thing :P joke aside great video though, learned a lot :)
Excellent video. Thanks! I'm assuming this would work between two Baofengs with K2 cables to thier respective phones. I'd expect this to improve reliability, yes?
@@HB9BLA Tried this and it worked. Here is the setup: HT setup (both HTs) HT model: Frequency: Wide (25 KHz) Power : Low (HTs at opposite end of 12' room) Vox: On, level 3/4 out of 7. (One level on each HT. 7 is most sensitive). Squelch: 1 (Zero is open squelch). Volume: 1/4 turn from off. Dual watch: off Receive power save: off.
Cable setup Baofeng standard cable (K1) and Baofeng APRS cable (K2).
Phone setup Phones: recent Motorola Androids. Volume: 3/4 or slightly less. Decoding does not work if transmitting phone's volume is too high.
Thanks Andreas for this interesting OFDM demonstration. Unfortunately, I could not decode your message, got always "From HB9BLA1 Decoding failed". Previously, I entered my call and experimented with different audio sources. Anyway, great idea and well explained! 73 Stephan
64QAM is actually really slow for WiFi and LTE/5G. WiFi 5 and LTE uses 256QAM (8bits) and WiFi 6 and 5G can go up to 1024QAM (10bits). And WiFi 7 will supposedly do 4096QAM (12bits). But obviously the FEC and ARQ at those rates are really high.
Weaker, but very low tech. Any form of radio, including cheap walkie talkies and a smartphone is all you need. Or any computer really. You can hack together a dedicated cable using a 4 pole audio jack from a cheapo earphone and a baofeng earpiece. That way the audio gets piped directly and doesn't suffer from background noise
I do believe in the case of FT8 you're confusing OFDM (orthogonal frequency-division multiplexing) with OFMDA (orthogonal frequency-division multiple access). Your full journey of modulation is a little sparse too, it should go a little something like: AM, SSB, FM, PM, FSK, MFSK, PSK, Angle Modulation, CDMA (FHSS/DSSS), QAM, and Chirp Spread Spectrum.
HB9BLA1-Received: Dear viewers, I wish you Merry Christmas…. but only after 3 decode failed, THEN it stabilized and never failed… does it have a “intelligent” error corrector ?
You can use the simple Btech interface leads from android to the radio. Using Skype as an additional source allows you to dial up another android or laptop anywhere to send a Rattlegram msg. The device at the far end can have audio connectivity to a radio on vox and retransmit the msg in another part of the country thereby using Rattlegram as a pager. This takes a bit of tweaking. Does anyone else have an idea on how to use Rattlegram as a pager?
Pretty interesting. If you were to send the sounds through a cable, could you use Rattlegram on HF? The mode does look very interesting. Greetings, Jeff
Thank you so much, very good explanation ; please, could provide us video that demonstrate ADSL modem ( internet for homes) that based on OFDM ! The OFDM processor is inside the ADSL modem? How it works? ... I'll so appreciative to you.
@@HB9BLA Thank you so much, please; could you do it this month? I'm extremely need to understand that for my academic report especially I'm still student without practical knowledge regarding this issue. I'll so apperciative to you.
Andreas, I had an idea last night and tested it out. I thought you might think it was useful or at least interesting haha. I used an open AI chatbot to create a sketch for an ESP32 dev board along with a BME280 pressure humidity sensor and an I2C OLED display. I also asked it to show me how to connect the wires. Below are the results. Maybe you could do a deep dive on this. I thought it was pretty cool although my wife thinks it's scary. Best, Jeff USA KG7ALC ruclips.net/video/ZdAZg85Z0UI/видео.html
Interesting experiemnt. I also use it from time to time and it is very useful! We will see what people will do with the technology and if we have to fear it.
Du hast recht. Diese App ist ähnlich. Sie ist auch schneller, hat aber nur rudimentäre Fehlererkennung CRC32 nach 250 Zeichen. Hast du sie mal ausprobiert?
Can any one spell 'acoustic coupler'... Oh the agony of trying to upload an assignment at 300bps desperately hoping no incoming call would insert call waiting tones and kill it...
Thank you so much for a good presentation video. I installed the Rattlegram and tested over Peanut VoIP radio for ham. BTW, please let me know how to delete sent text messages. de JR1FVK
Brilliant idea and implemented perfectly for the smart-phone era! I remember in the early 2000s I worked at a small internet company and stunned one of my colleagues (who was well versed in IT, but not radio). I installed an early piece of PSK31 software on both of our PCs (which were several meters away in a fairly noisy office environment, and had 90s style PC speakers and electret "stalk" microphones). I told him to go ahead and unplug the ethernet cable from his computer which he did. After a few warbling sounds from my PC, messages from me started appearing on his screen as I typed. He was dumbfounded at first and then quite impressed once he worked out what was happening :D I'm impressed that the RUclips MPEG audio compression didn't affect the reception of the Rattlegram whatsoever! Merry Christmas & a happy New Year to Andreas, Ahmet and all the viewers!
@@HB9BLA the reason why it didn’t work on DMR I suspect might be because the compression protocols there are optimised for voice readability and are much more aggressive than e.g. mpeg is even at lower bit rates. The goal of mpeg as used in YT et c. is to reconstruct as much as possible of the in-spectrum at the output without voice optimisation (I wouldn’t be surprised if other voice codecs would similarly destroy the message).
Some first generation computer modems had a cradle in which you placed your landline phone's handset -- so it was acoustic coupling between phone and modem.
I have fond memories of programming games found in magazines into my first computer (the TI99) and saving and loading the programs using audio cassettes, so this seems like a modern evolution of that early 80’s tech... no doubt it was incredibly low bps, but it was surprisingly reliable despite the cheapness of the generic portable audio cassette recorder. I like how the error correction is built in, the same kind of thing was present on usenet for large files broken into multiple parts that would often have most but not always all the pieces, you were able to re-create a missing file or two from the other files as long as there was enough and this worked quite reliably to collect a bunch of cracked Dreamcast GD-ROM games from that old forgotten but not totally abandoned part of the early internet.
I also started with a TRS-80 and a cassette deck. But frankly, after the invention of the Floppy Disk, never looked back ;-) A lot of technology comes back in "new clothes" after years, I think. Like the electric cars ;-)
Not first, but message is "Dear viewers, I wish you Merry Christmas and a happy New Year". Took about a dozen tries to get volume levels and positioning correct. Very interested in a future series on GNU Radio! Merry Christmas to you as well!
At first I thought you were trolling us, because my first few attempts correctly decoded your callsign but gave "Decoding failed" as the message (as if that's what had been transmitted - the app could use some user interface improvements). Sticking the phone closer to my headphone cup finally got a successful decode, though! Very cool app, and I hope to see future improvements in this kind of easily accessible use of high-tech encoding. It's sad to me that there's seemingly a big divide in the amateur radio community where a majority of the hobby is "caught in the past" and unwilling or uninterested in combining the extremely capable modern encoding schemes and digital processing tools we have available with the very powerful and useful transmitters and frequency bands that hams have access to. There's all kinds of cool things you could do with encoding modes like this on HF for example, but every time I search for projects doing this kind of thing, I always end up at abortive or abandoned attempts that never really took off (with a few limited exceptions). Too many hams are satisfied with either their simple old SSB and FM audio modes, or happy to rely on weird proprietary clunky windows applications made 15 years ago that are awkward to interact with or don't run on many types of systems. This is not to say those modes don't have a place, but amateur radio was originally created to allow experimentation and development of this newfangled "radio" technology, and in many ways the community is reluctant to advance much past the 1950s. Modern open-source design methods seem like a perfect match for the sharing-friendly and experimental ethos of amateur radio, but somehow the two are rarely enthusiastically used together.
The preamble symbol in COFDMTV, that contains the call sign, is designed to be much more robust than the payload symbols, so we have a high probability to find out who is transmitting. Indeed, the UI needs improvement with the handling of errors. Thank you for the feedback.
In the board of the Swiss HAM Radio organization, I am responsible for modern technologies (all invented after 1980). After a short time, I decided not to care about the ones not interested. They love their hobby and are happy with it. I focus on the ones interested in this tech. This is part of the motivation to create this channel.
Lots of FT8 transmissions in the air means that there are enough interested people. Also WSJT-X is open source. This is enough for me to not be worried too much.
Hi. I have built something similar to Rattlegram and achieved 250 characters/sec speed on Aspera V-9. I have made some patch wires using off-the-shelf wires for headsets of WTs & phones to avoid the mixing of ambient noise or disturbance. Due this I was able to achieve a proper audio. However the audio frequency ranges of different WTs requires certain changes in the app's code and trial and error on volume of reception on listening side
.... "Dear viewers, I wish you Merry Christmas and happy New Year." This app is great, and since I am someone who was in 8 bit computing from 1980, girl now woman who loved to code on 6510, and Z80, and still love it, from machine language, assembler to high end languages, also woman who was playing a lot with HAM radio, took serious part in radio clubs ar that time, I know how beautiful was time when we were recording our data on the tapes. I can say that Era when AD and DA start becoming daily routine was magical time. Now we are mostly only D, D, D... but analogue can't disappear just like that
Very rare to read a comment from a woman on this channel with 99.5 male viewers! So we experienced similar things in the 1980. For me, still everything is analog in the end, but simplifying it with a digital model and throwing millions of cheap and small transistors on it gives great possibilities (as we see here). I feel I currently live in an electronics "land of milk and honey".
@@HB9BLA Dear, I don't think it is rare, only women are mostly pushed to the side, usually when they are young. There are many women scientist, electronics experts, and hackers. When you open up your male boxes and egos, you will see it is actually a lot.
@@TheAndjelika First: I would be extremely glad to see more women in our domain. All I saw were excellent. And I first thought that this was a Swiss problem. But my main (electronics) channel with 400'000 subscribers always had around 99% male viewers (according to RUclips statistics). So I thought it was a global fact. In which country do you live? BTW: My RUclips relationship manager told me that my channel has a higher male percentage than gaming channels (which are also bad in this respect).
@@HB9BLA Dear, they support girls, your daughters, granddaughters, don't buy them some dolls, get them tools, show them how to solder. I need to be honest with you, like year ago I was about to fully leave your channel because of a few sentences you've said... they were on edge of sexism, showing that only men are welcome here, and women should be somewhere else. One of the first steps is to develop sensibility and really invite all people to watch your channel, and to promote that in every moment you can. Happy holidays! Andjela
@@TheAndjelika jajajjaa 50/50 my ass, so funny to see you try to debunk the 99.5% statistics of male viewers found in RUclips studio for channel owners jajajajjaa feminism is gay
Thanks for the wishes! And my Rattlegram was listening while you sent your demo at 0:08 and I received "HB9BLA - The quick brown fox jumps over the lazy dog" and "HB9BLA - Decoding failed"... 😂😂😂 73!
If you use cell phones to transmit and pre-shared encryption keys for the data, it becomes extremely difficult to censor, something we need in this age. I had thought of using a central server so that a group of friends could send and receive secret messages over cell phones. No not Signal, that uses the internet. Talking about voice calls just like in the video, over cell calls, not ham radio.
I re watched your video as I start on a new project. Ham radio applications for OFDM include the VARA and some versions of ARDOP as used by Winlink. VARA in particular is robust in very difficult conditions, but it is proprietary system..
DRM (Digital Radio Mondiale) uses OFDM with QAM modulation of the sub carriers. There is an amateur radio version of DRM using open source software on a PC
@@HB9BLA Lingua-technis, also known as Techna-Lingua, is the official language of the Adeptus Mechanicus and its tech-priests. It is actually a form of binary machine code that is comprised of bursts of non-random static emitted through the cybernetic implants present in most tech-priests of the Mechanicus which cannot be understood by unaugmented Humans. This digital language has been optimised for the rapid transmission of technical data to other tech-priests and to provide commands to servitors and other servant machines of the Mechanicus. Look for warhammer 40k ;)
Thank you for your kind words. I started with a course in modern communication. As said in the video, this topic is not easy for me. I did this kind of math 40 years ago.
I have a couple of questions if I may. I presume this will work if you use a k plug repeater connecting from the mobile phones 3.55mm jack? Also will this work where dcs is set on a channel? Thank you.
But this is just the audio signal, right? The RF signal is still FM (The RF carrier being frequency modulated by the OFDM audio? Or am i missing something about the radios in the demo? Is the radio doing something different than FM?
A nice intro into the world of OFDM which is also used for our dvb-t & dvb-t2 standard & high-definition terrestrial TV broadcasts.
Indeed, Ahmet did also SSTV applications. So far I never looked into it.
@@HB9BLA I believe the Vesa HF digital mode for Winlink is also OFDM, but I could be wrong there.
@@HB9BLA Ahmet has Angel backers in the Ham community. They will be at the Ham cation in Florida. It's all very interesting and used in the VHF and above the potential seems amazing!
Message is "Dear viewers, I wish you Merry Christmas🎄⛄ and a happy New Year" 🙂
Yes!
I was fixing to say that but you beat me to it. Rattle gram is awesome. I want to build a server on a R pi on my repeater. I like having a bulletin board like that. Awesome stuff friend.
I found it worked very well through my laptop speakers - though I could get 'decoding failed' by moving the phone further away than about 2m... but it always seemed to know the sender was HB9BLA - so I wonder if there is additional error correction for the sender id?
though I'm not the first "Dear viewers, I wish you Merry Christmas :christmas_tree: :snowman: and a happy New Year"
Congratulations to Ahmet on a successful implementation and coming up with a very catch name for it.
The preamble symbol in COFDMTV, that contains the call sign, is designed to be much more robust than the payload symbols, so we have a high probability to find out who is transmitting. Compliments are always welcome and motivating.
David Rowe developed the Fdmdv modem for use with his CODEC2 voice codec. That modem seems very similar to the one presented here. Unfortunately that modem is deeply embedded in the freedv application. I haven't seen it being used for non-voice data.
Thank you! Interesting links. I will have a look at these projects.
Very interesting and thank you. I was looking at using codec2 over lora a while ago but got distracted. This beautifully clear explanation of ofdm has inspired me. I think I'll revisit it.
I am interested in your results, too!
Coincidentally, a few days ago I found a website showing how to send images captured by an ESP-32CAM through SSTV using these radios. SSTV transmission seems very interesting.
Thank you for your videos and best wishes for 2023!
Ahmet dis some SSTV before this project, too.. Happy 2023 to you, too.
Can you share a link?
1:24 "Decoding failed" 😅🔊
Have a great sunday, Andreas ;) Thanks for your content!
It seems you need to enter your Callsign first.
The equations for the DFT are for the continuous time domain, not the discrete time domain as would be used in an OFDM modulator/demodulator. Some carriers are also designated as pilots with fixed magnitude and phase for equalization and timing recovery, therefore not all carriers can be utilized for data.
You are right.
Mt63 is OFDM mode which is widely used in e.g. prepping community for years. And yes, cable is not required for this mode too.
Thank you for the link. I did not know this protocol.
@@HB9BLA Q15X25 by the same author is also quite interesting.
Very interesting. I'd love to make a couple of dedicated devices using a pair of cheap BF888's and attached directly to a USB sound card just as done with use of Allstar nodes. We could take care of pressing ptt and reduce audible noise in that case. 73.
Should be possible. It seems you can add noise befor the transmission to trigger the VOX
Decoding worked fine with normal PC speakers. I wish you a happy new year as well!
Thank you!
Dear viewers, I wish you Merry Christmas🎄⛄ and a happy New Year
Correct!
@@HB9BLA wish you merry Christmas and happy new year also. Stay well. DE VU3EZX.
@@ArindamGhoshal Thank you!
Merci Andreas pour cette découverte, Joyeuses fêtes de fin d'année... Frohe Festtage, 73's, HB9DVD, Marc
Vielen Dank! Dir und deiner Familie ebenfalls Frohe Weihnachten und einen guten Rutsch ins neue Jahr.
Merry Christmas and a happy new year to you also.
Thank you!
Forward (typo). At RF, COFDM is not a cure-all it does have the Peak-to-Average power issue requiring highly linear, inefficient, and complex RF amplifiers. Whereas, GSM uses GMSK and tolerates non-linear efficient simple Class-C amplifiers.
You are right. This is why it is not used in low power applications.
Downloaded from play store. Input my call. Entered message and transmitted. Very interesting. Collins radio used sync cohesrant ofdm in their kineplex system back in the 50's. Their adoption of coherent psk, qpsk dropped the necessary noise floor 10's of dB. Isn't it a great world we live in. Thanks so much for the presentations you do. I'm just now picking up the esp32 python hobby partially because of your wonderful videos..73. de Tom W5XTT
Interesting that OFDM was already used in the analog tube times!
We've had digital modes since the invention of radio. In fact, it was the first mode.
I agree. I do not know your capability, but my morse speed never got higher than a bit over 2 characters per second...
@@HB9BLA About 12 WPM or 1 character per second peak for me. A good bit lower now.
When I was young I worked as a professional radio operator…
@@HB9BLA Very nice. I did teletype work as a young man; speed there about 10x Morse. Morse strictly by amateur radio. TTY machine was limited to 100 WPM if I remember this right.
This is amazing ! My head is hot after taking so much info but technology is worth of it.
Indeed, it is not easy ;-)
And a Merry Christmas and a
Happy New Year to you, too!
Thank you!
It would be possible to transfer small files by sound. Incredible.
Even larger sound files could move across, depending on the compression of the files. :)
Not a new concept, this is how vintage computers like Commodore 64 stored programs, in 80' there were even some transmissions of programs in public radio
As DV writes, we stored our programs on cassette decks. But did not use these modern high speed protocols.
It's time to recall 20 years old dial-up modems with speeds up to 56kbps
Does anyone know if this method is similar or not to what the Trailblazer modems used back in the late 80s? I remember reading a description where it divided the bandwidth up into a hundred or so channels and did all the encoding/decoding in software.
AFAIK OFDM was not used back then. The chips were not capable...
@@HB9BLA Trailblaizer's PEP was based on OFDM, those modems was a revelation for uucp. Never forget their line signals, it's a music for my ears.
@@jankkhvej I now read the story of Trailblazer PEP. Indeed, this was revolutionary back then. And they needed quite expensive chips for "just" a modem...
مضاعفة تقسيم التردد المتعامد
(Orthogonal frequency-division multiplexing)
وضع تعديل الإشارة
في الاتصالات ، يعد تعدد الإرسال بتقسيم التردد المتعامد نوعًا من الإرسال الرقمي وطريقة لتشفير البيانات الرقمية على ترددات حاملات متعددة
على وجه التحديد
That is extremely intertesting topic. I tried to do something similar actually.. Didn't finish it, but it seems like an awesome opportunity to start again :)
Indeed, a good chance!
Nice thing about such project that it can be perfected indefinitely.
Many thanks for that Andreas.
You are welcome!
Message: Dear viewers, I wish you Merry Christmas and happy New Year.
Great idea!
Correct!
The implications of what this app can do has many important features.
So.... if the internet, mobile phone network are down for any reason, but our smartphones can start up. I could communicate a serious text through UHF or VHF transceiver, say at a specific prearranged time and frequency, with another person ... and they can type an answer on their phone and send it back.
I agree.
@@HB9BLA Rattlegram would have really been able to help in the recent wild fires in Maui Hawaï. I live in Belgium and am a newbie ham (ON3VCF). Ispent that night up listening to the only SDR on the island going up and down the 10, 11, 2m and 70cm bands, listening to sporadic desperate transmissions of people trying to find people....
Normal FM was also down. But on 1110Khz am KAOI was on emergency programming trying to help. They were the only station I could find... (using also an app called "Planet Radio"
For Several days I would tune into KAOI to listen in to the real people sharing real stories. One day a firefighter was talking about how all repeaters were out and that they'd had big difficulties getting through to base, etc. He mentioned about a new super-simple app called "Rattlegram" could have helped everyone.
I have seen a few RUclips reviews of the app, and I don't think they understand its special characteristics and features. Specifically "Parrot".
Encryption is not allowed on amature bands but could you use ultrasound as as long as you use of the accepted and published modulation types just shift the frequency to inauable?
As long as you do not encrypt, you are safe.
Could encoding and/or decoding of Rattlegram be implemented on a microcontroller of some sort?
It needs quite a lot of power. Maybe Ahmet will try an ESP32-A1S
@@HB9BLA prelookuptable or precalcul array could "help a lot to solve" compute problems with ram available on new µc remember what demomakers was beable to do with limited ressources 20 yeas ago !
I tried rattlegram with a cheap microcasette recorder. It didnt work, as expected.
I get "Preamble failure" error message.
But these kind of errors was expected. Even a trivial DTMF decoder cannot work with my microcasette recorder.
I was hoping that the 50% forward error correction could decode at least a single character from the microcasette, but no, it couldnt.
10/10 👍
Strange. A cassette recorder should be able to replay the frequency range. Maybe it is a problem of different speeds?
It is possible to analyze how exactly signal is corrupted by your hardware.
And then select encoding (modulation) which is resistant to such corruption.
@@HB9BLA I'm going to try this again. I was using a "GE 35375" microcasette recorder. I think it has something to do with this; en.wikipedia.org/wiki/Wow_(recording)
It sounds like this when I'm playing back the audio
ruclips.net/video/kCwRdrFtJuE/видео.html
Hi !!! Greetings from Buenos Aires, Argentina. I bought two Baofeng Handies, the cheapest ones, the simplest ones, BF999S, how can I send data from DB9 to handy number 1, receive data on handy number 2, and decode it with arduino uno and RS232 module HW-044 ? , and show that data on a cheap OLED display like 1.3" (GND, VCC, SCL, SDA) Thanks so much !!!!!!!
There doesn't seem to be an iPhone version of Rattlegram, at least not in the German app store.
Not yet
Pointu, efficace, super travail merci
De rien!
Is Vara an OFDM protocol?
I think so. But I did not look into it. And it seems to be proprietary.
i like the bit where you said "they" call a FT an "Inverse function of the IFT" :D
not sure which "they" do that but i always just called the inverse of the inverse of a thing that thing :P
joke aside great video though, learned a lot :)
They are the guys to understand it ;-)
Yup, I'm in. Well in as far as I can be with the very limited free time I've got. :-)
It will be spread over time...
At what distance can you maintain 2800bps throughput?
I do not think that distance matters.
Excellent video. Thanks! I'm assuming this would work between two Baofengs with K2 cables to thier respective phones. I'd expect this to improve reliability, yes?
I think so, but did not try
@@HB9BLA Tried this and it worked. Here is the setup:
HT setup (both HTs)
HT model:
Frequency: Wide (25 KHz)
Power : Low (HTs at opposite end of 12' room)
Vox: On, level 3/4 out of 7. (One level on each HT. 7 is most sensitive).
Squelch: 1 (Zero is open squelch).
Volume: 1/4 turn from off.
Dual watch: off
Receive power save: off.
Cable setup
Baofeng standard cable (K1) and Baofeng APRS cable (K2).
Phone setup
Phones: recent Motorola Androids.
Volume: 3/4 or slightly less. Decoding does not work if transmitting phone's volume is too high.
Thanks Andreas for this interesting OFDM demonstration. Unfortunately, I could not decode your message, got always "From HB9BLA1 Decoding failed". Previously, I entered my call and experimented with different audio sources.
Anyway, great idea and well explained!
73 Stephan
You are welcome! Others were successful. So I do not know why it did not work with your setup.
64QAM is actually really slow for WiFi and LTE/5G. WiFi 5 and LTE uses 256QAM (8bits) and WiFi 6 and 5G can go up to 1024QAM (10bits). And WiFi 7 will supposedly do 4096QAM (12bits). But obviously the FEC and ARQ at those rates are really high.
You are right. The available bandwidths and S/N ratios allow higher speeds.
How many characters per message on Rattlegram?
I do not remember :-(
is it more powerful than meshstastic?
Weaker, but very low tech. Any form of radio, including cheap walkie talkies and a smartphone is all you need. Or any computer really.
You can hack together a dedicated cable using a 4 pole audio jack from a cheapo earphone and a baofeng earpiece. That way the audio gets piped directly and doesn't suffer from background noise
Do we finally have minimodem for Android? :O
AFAIK there are others like the APRSdroid. But not for OFDM.
I do believe in the case of FT8 you're confusing OFDM (orthogonal frequency-division multiplexing) with OFMDA (orthogonal frequency-division multiple access).
Your full journey of modulation is a little sparse too, it should go a little something like:
AM, SSB, FM, PM, FSK, MFSK, PSK, Angle Modulation, CDMA (FHSS/DSSS), QAM, and Chirp Spread Spectrum.
I did not want to say that FT8 is OFDM. I just mentioned that it also has many parallel narrow channels in one SSB channel.
Very interesting.
Glad you think so!
1:36 from HB9BLA1: Dear viewers, I wish you Merry Christmas🎄⛄ and a happy New Year
You got it right!
HB9BLA1-Received: Dear viewers, I wish you Merry Christmas…. but only after 3 decode failed, THEN it stabilized and never failed… does it have a “intelligent” error corrector ?
I do not think so. Maybe you found good positions for the loudspeakers and microphones.
a great video, thanks
Glad you enjoyed it
Nice! Could you please make a tutorial about using Rattlegram ?
I showed all what is needed ;-)
so what is the message?
Good question!
range distance?
As far as your transceiver reaches.
You can use the simple Btech interface leads from android to the radio. Using Skype as an additional source allows you to dial up another android or laptop anywhere to send a Rattlegram msg. The device at the far end can have audio connectivity to a radio on vox and retransmit the msg in another part of the country thereby using Rattlegram as a pager. This takes a bit of tweaking. Does anyone else have an idea on how to use Rattlegram as a pager?
It seems that you can add noise before the transmission to open a VOX.
Pretty interesting. If you were to send the sounds through a cable, could you use Rattlegram on HF? The mode does look very interesting.
Greetings,
Jeff
It should also work through HF. But it is not optimized for fading, etc.
Wish you Merry Christmas and a happy New Year too! 73 de Daniel, OE2DHH
Thank you!
SDR solves so many hardware problems with hardware, just throw billions of transistors at it. ;-P
Indeed, they use a ton of transistors. But they are extremely cheap these days. And easy to use.
Thanks!
Thank you for your support!
super nice video :)
Thanks for the visit!
The message reads: Dear viewers, I wish you Merry Christmas🎄⛄ and a happy New Year
Yes!
If only there was a better way to do this
Which way do you think of?
Thank you so much, very good explanation ; please, could provide us video that demonstrate ADSL modem ( internet for homes) that based on OFDM !
The OFDM processor is inside the ADSL modem?
How it works?
...
I'll so appreciative to you.
Maybe I will cover it on our journey…
@@HB9BLA Thank you so much, please; could you do it this month?
I'm extremely need to understand that for my academic report especially I'm still student without practical knowledge regarding this issue.
I'll so apperciative to you.
@@bstanis1237 There will be no additional video this year 😞
Very interesting :-)
Glad you think so!
"Dear viewers, I wish you Merry Christmas 🎄☃ and a happy New Year"
Correct!
That's badass 😱
:-)
Diese Android App heißt audio modem und ist schon ewig alt
Nein.
Fax is death, long live Fax🤣🏆
:-))
Andreas, I had an idea last night and tested it out. I thought you might think it was useful or at least interesting haha. I used an open AI chatbot to create a sketch for an ESP32 dev board along with a BME280 pressure humidity sensor and an I2C OLED display. I also asked it to show me how to connect the wires. Below are the results. Maybe you could do a deep dive on this. I thought it was pretty cool although my wife thinks it's scary. Best, Jeff USA KG7ALC
ruclips.net/video/ZdAZg85Z0UI/видео.html
Interesting experiemnt. I also use it from time to time and it is very useful! We will see what people will do with the technology and if we have to fear it.
Diese App gibt es doch schon ewig und ist sogar noch schneller
Du hast recht. Diese App ist ähnlich. Sie ist auch schneller, hat aber nur rudimentäre Fehlererkennung CRC32 nach 250 Zeichen. Hast du sie mal ausprobiert?
Never trust a guy with small hands...
:-(
This approach is ass backwards. It would make more sense to develop a radio that can send text messages, duh.
Just do it! (Nike slogan)
Can any one spell 'acoustic coupler'... Oh the agony of trying to upload an assignment at 300bps desperately hoping no incoming call would insert call waiting tones and kill it...
Indeed, this tech would have helped back then.
hello, can you please share your discord server link
I have no particular discord server for this channel. Only for the other channel.
Merry Christmas Andreas.
Thank you! Same to you.
Thank you so much for a good presentation video. I installed the Rattlegram and tested over Peanut VoIP radio for ham.
BTW, please let me know how to delete sent text messages. de JR1FVK
Ahmet wrote in an other comment that they decided to not include this function to keep the UI lean.
Tnx for your amazing project
'73 de Ol52hh
You are welcome!
Brilliant idea and implemented perfectly for the smart-phone era!
I remember in the early 2000s I worked at a small internet company and stunned one of my colleagues (who was well versed in IT, but not radio). I installed an early piece of PSK31 software on both of our PCs (which were several meters away in a fairly noisy office environment, and had 90s style PC speakers and electret "stalk" microphones). I told him to go ahead and unplug the ethernet cable from his computer which he did. After a few warbling sounds from my PC, messages from me started appearing on his screen as I typed. He was dumbfounded at first and then quite impressed once he worked out what was happening :D
I'm impressed that the RUclips MPEG audio compression didn't affect the reception of the Rattlegram whatsoever! Merry Christmas & a happy New Year to Andreas, Ahmet and all the viewers!
Nice story!
Indeed, I was also impressed that it worked on RUclips. We did tests with DMR and there it did not work at all.
@@HB9BLA the reason why it didn’t work on DMR I suspect might be because the compression protocols there are optimised for voice readability and are much more aggressive than e.g. mpeg is even at lower bit rates. The goal of mpeg as used in YT et c. is to reconstruct as much as possible of the in-spectrum at the output without voice optimisation (I wouldn’t be surprised if other voice codecs would similarly destroy the message).
Dear viewers, I wish you Merry Christmas🎄⛄ and a happy New Year
Great stuff
Thank you!
Some first generation computer modems had a cradle in which you placed your landline phone's handset -- so it was acoustic coupling between phone and modem.
I remember them, too. But they used simple modulations.
hmmmmmmmmm back in the 80s we would send zx spectrum and other computers. setup one of taxi data so that other drivers couldn't eavesdrop on client
Indeed, computers back then used acoustics a lot (cassette decks for programs, or first modems).
Received: Dear viewers, I wish you Merry Christmas and a happy New Year
Yes!
I have fond memories of programming games found in magazines into my first computer (the TI99) and saving and loading the programs using audio cassettes, so this seems like a modern evolution of that early 80’s tech... no doubt it was incredibly low bps, but it was surprisingly reliable despite the cheapness of the generic portable audio cassette recorder. I like how the error correction is built in, the same kind of thing was present on usenet for large files broken into multiple parts that would often have most but not always all the pieces, you were able to re-create a missing file or two from the other files as long as there was enough and this worked quite reliably to collect a bunch of cracked Dreamcast GD-ROM games from that old forgotten but not totally abandoned part of the early internet.
I also started with a TRS-80 and a cassette deck. But frankly, after the invention of the Floppy Disk, never looked back ;-)
A lot of technology comes back in "new clothes" after years, I think. Like the electric cars ;-)
Not first, but message is "Dear viewers, I wish you Merry Christmas and a happy New Year". Took about a dozen tries to get volume levels and positioning correct. Very interested in a future series on GNU Radio! Merry Christmas to you as well!
Correct!
At first I thought you were trolling us, because my first few attempts correctly decoded your callsign but gave "Decoding failed" as the message (as if that's what had been transmitted - the app could use some user interface improvements). Sticking the phone closer to my headphone cup finally got a successful decode, though! Very cool app, and I hope to see future improvements in this kind of easily accessible use of high-tech encoding.
It's sad to me that there's seemingly a big divide in the amateur radio community where a majority of the hobby is "caught in the past" and unwilling or uninterested in combining the extremely capable modern encoding schemes and digital processing tools we have available with the very powerful and useful transmitters and frequency bands that hams have access to. There's all kinds of cool things you could do with encoding modes like this on HF for example, but every time I search for projects doing this kind of thing, I always end up at abortive or abandoned attempts that never really took off (with a few limited exceptions).
Too many hams are satisfied with either their simple old SSB and FM audio modes, or happy to rely on weird proprietary clunky windows applications made 15 years ago that are awkward to interact with or don't run on many types of systems. This is not to say those modes don't have a place, but amateur radio was originally created to allow experimentation and development of this newfangled "radio" technology, and in many ways the community is reluctant to advance much past the 1950s. Modern open-source design methods seem like a perfect match for the sharing-friendly and experimental ethos of amateur radio, but somehow the two are rarely enthusiastically used together.
The preamble symbol in COFDMTV, that contains the call sign, is designed to be much more robust than the payload symbols, so we have a high probability to find out who is transmitting. Indeed, the UI needs improvement with the handling of errors. Thank you for the feedback.
In the board of the Swiss HAM Radio organization, I am responsible for modern technologies (all invented after 1980).
After a short time, I decided not to care about the ones not interested. They love their hobby and are happy with it. I focus on the ones interested in this tech. This is part of the motivation to create this channel.
Lots of FT8 transmissions in the air means that there are enough interested people.
Also WSJT-X is open source. This is enough for me to not be worried too much.
Hi. I have built something similar to Rattlegram and achieved 250 characters/sec speed on Aspera V-9. I have made some patch wires using off-the-shelf wires for headsets of WTs & phones to avoid the mixing of ambient noise or disturbance. Due this I was able to achieve a proper audio. However the audio frequency ranges of different WTs requires certain changes in the app's code and trial and error on volume of reception on listening side
Ahmet Limited the number of channels because he also experienced bandwidth differences. Your speed is quite impressive.
.... "Dear viewers, I wish you Merry Christmas and happy New Year."
This app is great, and since I am someone who was in 8 bit computing from 1980, girl now woman who loved to code on 6510, and Z80, and still love it, from machine language, assembler to high end languages, also woman who was playing a lot with HAM radio, took serious part in radio clubs ar that time, I know how beautiful was time when we were recording our data on the tapes. I can say that Era when AD and DA start becoming daily routine was magical time. Now we are mostly only D, D, D... but analogue can't disappear just like that
Very rare to read a comment from a woman on this channel with 99.5 male viewers! So we experienced similar things in the 1980. For me, still everything is analog in the end, but simplifying it with a digital model and throwing millions of cheap and small transistors on it gives great possibilities (as we see here). I feel I currently live in an electronics "land of milk and honey".
@@HB9BLA Dear, I don't think it is rare, only women are mostly pushed to the side, usually when they are young. There are many women scientist, electronics experts, and hackers. When you open up your male boxes and egos, you will see it is actually a lot.
@@TheAndjelika First: I would be extremely glad to see more women in our domain. All I saw were excellent. And I first thought that this was a Swiss problem. But my main (electronics) channel with 400'000 subscribers always had around 99% male viewers (according to RUclips statistics). So I thought it was a global fact. In which country do you live?
BTW: My RUclips relationship manager told me that my channel has a higher male percentage than gaming channels (which are also bad in this respect).
@@HB9BLA Dear, they support girls, your daughters, granddaughters, don't buy them some dolls, get them tools, show them how to solder. I need to be honest with you, like year ago I was about to fully leave your channel because of a few sentences you've said... they were on edge of sexism, showing that only men are welcome here, and women should be somewhere else. One of the first steps is to develop sensibility and really invite all people to watch your channel, and to promote that in every moment you can.
Happy holidays! Andjela
@@TheAndjelika jajajjaa 50/50 my ass, so funny to see you try to debunk the 99.5% statistics of male viewers found in RUclips studio for channel owners jajajajjaa feminism is gay
Thanks for the wishes!
And my Rattlegram was listening while you sent your demo at 0:08 and I received "HB9BLA - The quick brown fox jumps over the lazy dog" and "HB9BLA - Decoding failed"... 😂😂😂
73!
Very good!
If you use cell phones to transmit and pre-shared encryption keys for the data, it becomes extremely difficult to censor, something we need in this age. I had thought of using a central server so that a group of friends could send and receive secret messages over cell phones. No not Signal, that uses the internet. Talking about voice calls just like in the video, over cell calls, not ham radio.
So there's this app called Signal...
@@pete3897 Signal relies on the internet. I'm talking about making voice calls, just like in the video. I'll update my comment.
In HAM radio, encryption is not allowed.
@@HB9BLA correct. Hence the need for cell phone calls.
as an added bonus you're adding random noise to the NSA database where they record all of our phone calls. won't compress very well either 😂
I re watched your video as I start on a new project. Ham radio applications for OFDM include the VARA and some versions of ARDOP as used by Winlink. VARA in particular is robust in very difficult conditions, but it is proprietary system..
DRM (Digital Radio Mondiale) uses OFDM with QAM modulation of the sub carriers. There is an amateur radio version of DRM using open source software on a PC
I had a quick look at DRM. An interesting project combining old AM technology with newer Smartphones!
They just speak in binaric base language of Adeptus Mechanicus.
Who?
@@HB9BLA Lingua-technis, also known as Techna-Lingua, is the official language of the Adeptus Mechanicus and its tech-priests.
It is actually a form of binary machine code that is comprised of bursts of non-random static emitted through the cybernetic implants present in most tech-priests of the Mechanicus which cannot be understood by unaugmented Humans.
This digital language has been optimised for the rapid transmission of technical data to other tech-priests and to provide commands to servitors and other servant machines of the Mechanicus. Look for warhammer 40k ;)
Hey, I would love to build multi-digital radio based on CM4 pi supporting m17 digital mode too. It would be good if you covered that mode too.
Thank you!
Dear viewers, I wish you Merry Christmas and a happy New Year
Yes!
Dang. No iOS app (yet). :-)
He is working on it...
a beautiful initiative so much more beautiful if I can do it,
Once again an excellent video. You should look at VARA and VARA FM
Unfortunately, these modems are not open source :-(
Great fun, _and_ educational! Before I finished watching I had loaded the app (Android Pixel6) and decoded your message (first try).
Cool. I wonder how many downloads he had today...
A semester's worth of comms-101-theory explained in 13 easy-to-digest minutes. Bravo :)
Thank you for your kind words. I started with a course in modern communication. As said in the video, this topic is not easy for me. I did this kind of math 40 years ago.
I have a couple of questions if I may.
I presume this will work if you use a k plug repeater connecting from the mobile phones 3.55mm jack? Also will this work where dcs is set on a channel?
Thank you.
The audio just has to be able to travel from the Smartphone to the transceiver.
But this is just the audio signal, right? The RF signal is still FM (The RF carrier being frequency modulated by the OFDM audio? Or am i missing something about the radios in the demo? Is the radio doing something different than FM?
In my case, the radios do. FM. But it does not matter. As you say, it is just an audio sound. Very versatile.
"Dear viewers, I wish you a Merry Christmas🎄☃ and a happy New Year"
Worked first time decoding :)
Correct!
-Deer viewers.... -merry cris....dam it even takes emojis!!!
Yes!
The Rattlegram app would be great if it didn't have the huge drawback, which is that it doesn't work with the lock screen.
I agree.