Oh.. What a weird and wonderful night. I was exited about assembling the walky-talky modules and went on imagining of scenarios I could use them in. An idea gloomed.. What if the module would work in FM domain? I’ve been making radio experiments with my raspi (see Hammeradio) and the itch to send wireless signals is an old one. The question led me on a frantic internet search stream and eventually I run into a website I visited years ago: Polimorphous Space by Tetsuo Kogawa. I learned about the site from Diego Cruz Martinez an activist/engineer who worked for/with Radio Oaxaca. I interviewed him when I was working for M2Hz and the interview in available Finnish: Ääni intiaanikylille (2009).
Kogawas site is fascinating. There are texts and interviews dealing with the work of Félix Guattari (whom Kogawa met in 1981), manifestos and poetry, bundled with technical notes and schematics. The radio art guides he offers are thorough and the radio transmitter builds seem very robust. Here is a quote from his Micro Radio Manifesto (2006).
Today, our microscopic space is under technologically control and surveillance. Our potentially diverse, multiple nad polymorphous space is almost homogenizee into a mass. Therefore we need permanent effort to deconstruct this situation. In order to do this, to use a very low-power transmitter is worth trying. Small transmitter can be easily made by your own hands. [SIC]
This is a direct call for action and aligned with the texts he offers, this sets a clear trajectory for critical radiophonic work! The looks of his builds are wonderful. He uses an adaptation of “Manhattan style” method in his circuit construction (some notes on the style on Parasit Studio blog). The name Manhattan style reflects the street grid and urban planning of Manhattan, New York and I guess it links to the era of the Manhattan project too.
I’m now dreaming of building an eurorack unit of “the standard model” transmitter in Manhattan style. Some components are rare (2SC2001 transistor) but he also offers plans with alternative components (BC337 transistor). I imagine that in a rack the transmission would cause a lot of noise and interference but the build is conceptually firm. I think that as a module it reflects and is a call for the “responsibility of speech”. I’ve come to believe we have a responsibility to make sound, to voice opinions so that we do not collide to each other. This idea is well drafted in a boating story I heard from Topi Äikäs. In short: “If everybody is silently looking for the truth, nobody is safe!”. I could etch this story on the PCB.
After an exiting couple of hours in the world of Kogawa, I realized that the module should also include a receiver: Whats would be the point in making noise if no-one can listen to it. After some search I found this Simple FM Radio build (credited to Charles Kitchin) which is simple and runs on the same voltage as the transmitter (the unit in the photo is also build in Manhattan style). This means both builds could be powered from the same supply! I’ll have to experiment if this will cause too much interference but the idea is clear. The module could have one input for transmitting and one for receiving. With two modules, two (or more) racks can be made to work in unison.
An additional bonus in the transmitter build is that I could use DIY mineral water capacitors (which I experimented with on the Simple EQ build) for setting the transmission frequency (it needs a variable capacitor between the values of 10 to 20pf). This is perfect because when working on the walky-talkies I felt horrible remorse for not continuing to develop/build modules I’m planning to use in upcoming mineral water performances. Suddenly a side quest to radio transmission domain proofs meaningful and everything makes sense for a while.
Maisie Williams in 2016.
[…] we should stop calling feminists ‘feminists’ and just start calling people who aren’t feminist ‘sexist’ – and then everyone else is just a human. You are either a normal person or a sexist
Notes to self: Hammeradio operates with scheduled scripts. Access schedules with
crontab -e, look for scripts in /home/pi/Desktop/. The entry
@reboot /home/pi/Desktop/startupfm.sh launches
sudo arecord -fS16_LE -r 22050 -Dplughw:1,0 -c 1 - | sudo /home/pi/PiFmRds/src/pi_fm_rds -audio - -rt Hammeradio & on startup. PiFmRds begins broadcasting at 107.9 MHz. The contab entry
0 */4 * * * /home/pi/Desktop/akustamatashutdown.sh waits for four hours before it runs the script (
sudo shutdown). With
top you can see active processes. PiFmRds shows ~24.5% CPU and arecord ~4.6%.
vcgencmd measure_temp shows a steady 49.4°C temperature.
Making the “Hammeradio” launch FM broadcast by scheduling tasks with cron.
@reboot /home/pi/Desktop/startupfm.sh works well. It launches
sudo arecord -fS16_LE -r 22050 -Dplughw:1,0 -c 1 - | sudo /home/pi/PiFmRds/src/pi_fm_rds -audio - -rt Hammeradio & I’ll also schedule a daily power off cycle for the device. I’ll set it to work during gallery open hours 14:00 to 18:00 (with a Lunch break in the middle). Found an old amplifier circuit I build (while learning to solder to make the WSG) and I’ll test it with the piezo mic I have handy (It would save the iRig pre-amp I bought).
I got PiFmRds to work on my RasPi3.
Note to self:
1. Use Etcher to flash Raspbian.
2. Enable ssh in RasPi using Terminal
3. Boot RasPi3, login via ssh
4. Set new password
5. Set locale
6. Install sndfile library
sudo apt-get install libsndfile1-dev
7. Install PiFmRds
git clone https://github.com/ChristopheJacquet/PiFmRds.git
8. Broadcast from usb audio in at 107.9FM in mono 22050
sudo arecord -fS16_LE -r 22050 -Dplughw:1,0 -c 1 - | sudo ./pi_fm_rds -audio - -rt Hammeradio
9. End broadcast
sudo pkill pi_fm_rds
Fiddled with PiFmRds settings (I want it to display Hammeradio as radiotext (RT) but I’m not sure if it’s working). I also want to run a .sh script on boot to launch pi_fm_rds broadcast (aka. step 8). Currently launching the pi_fm_rds from
/etc/rc.local. Tomorrow I’ll try to build a cron startup schedule so that I can spare the Hammeradio preamp from excess stress by powering the system down on gallery off hours (I have to use a preamp to connect a piezo mic to the RasPi). Other useful resources for future tightvnc manual.
Installed Sea Change: In the Scale of a Horse (2017) by Otto Karvonen feat Trans-Horse installation at Vuotalo. The installation consists of a performance documentation, a custom horse blanket with an embroidery with the text “Helsingin kaupunki – Kaupunkimittausyksikkö” and horse-gear used by Toivottu Poika during our HKI-TKU-HKI riding trip in 2014.
We met with the “In the Flow” reading circle last evening. Quotes to remember: “…Russian avant-garde art was not directed against the status quo, against the dominating political and economic power structures. The Russian avant-garde of the Soviet period was not critical but affirmative…” Groys on postrevolutionary art in Russia and “Only dull and impotent artists screen their work with sincerity. In art there is a need for truth, not sincerity.” by Kazimir Malevich.
I’ve wasted another day working on the Weird Sound Generator. Replaced every capacitor, added ribbon pins to the wires and resoldered them on board. Double checked the resistor values and pulled out some resistors for testing. Eventually replaced the CD40106 chip.. This returned the voice B Osc.2 but voice A Osc.2 is still missing. I had two chips to begin with and I might have damaged both. During the resoldering session I noticed that a capacitor had been missing a connection from the beginning (because the double sided circuit board I’ve etched is missing connections between sides) and I might have short circuited both chips at some point. I’ll acquire a new chip at some point but I’ll start working on the case now. Working on the board is addictive.
Contacted the Theatre Academy of Helsinki concerning our “Horse and Performance” course which is planned for next fall. They seem excited about our course and apparently students are eager to join register.
Idea: Attach a piezo mic (with a preamp) to hammer and broadcast the audio through the Raspberry Pi radio transmitter (on FM 99.0).