Final updates

For the final Marco, Dorothy and I going to work on demodulating frequencies that use APCO Project 25. We’d like to see if we can decipher (1) whether communication is occurring and potentially (2) the information being transmitted. We’re not sure if communications might be encrypted but this itself might be useful information. If we have time we’d also like to build a tool that could send relevant information gleaned to affected parties.

The RTL-SDR tutorial I found before last class ended up being a pretty good one for pointing us in the right direction. We’re not using SDRSharp but we found this pretty detailed tutorial for how to use digital speech decoder (DSD) using GQRX. They also have a github. We were able to get as far as piping audio over UDP. After installing DSD, alsa-oss, and socat, you can display and set the port audio devices for dsd (we used 5 because this was our default; in the tutorial he used 11):

$ ./dsd -a

$ ./dsd -i pa:5 -o pa:5

Then we could get hex output, using this command:

$ socat stdout udp-listen:7355 | xxd

I think piping in audio through dsd is just a matter of changing the command to which the audio is getting piped, but when I tried this with a signal gqrx froze (example code below is saving output to a .wav file). I wonder if it will be a problem doing this in real time? Still, right now I think we are just trying to get enough P25 signal to play with. Another question I have is whether the mode we’re using to record/pipe audio will matter once we pass it through DSD?

$ socat stdout udp-listen:7355 | ./dsd -i – -w dsd_output.wav

We are using a linux laptop while we figure these pieces out. In an ideal deployment we also don’t want a human to have to listen constantly, so Dhruv pointed us to gqrx-scan to automate this piece, which will allow us to record and hopefully automate a response as much as possible when there is a signal. Assuming this all goes smoothly, we will create a prototype using Raspberry Pi that we could sell/deploy to various areas.

Frequencies for testing P25 decoding

NYC, National

Tap: Mushrooms

This week for our assignment on cut-ups, I decided to mash up the text of about 30 Magic the Gathering Artifact, Enchantment, and Instant cards and the recipes from Student’s Hand-book of Mushrooms of America, Edible and Poisonous by Thomas Taylor. I picked arguably the best cards from these categories from the Magic Card database, because of their language around spell-casting. I thought they would work well with recipes since both are essentially instructions.

I think I had spells on the mind because of the hexes witches have been placing on Trump, MTG because a friend recently gave away his entire collection, and I just loved all the sounds of all the mushroom names from this book while searching through Gutenberg and wanted to find a way to incorporate something about them. Even though I selected specific text to begin with by cutting and pasting, I struggled to cut down the text to what I wanted. I don’t think I’m quite there (mushroom language or structure-wise) but I was pleased by how couldron-y some of the products were.

Before cutting down lines and reducing length more intelligently I was getting a lot of text as output. There was something very nice about the repetition in a later version, but I refined this a bit more before settling on the final code. Right now I am picking out every other line I create, and there’s probably a better way to do this. My source text and final code are here. Each time it runs you get something a bit different. I thought this one was okay.

Limits to Growth Proposal: Algae Brewer


I met with NYU professor David Kanter last week and had a very helpful discussion. His work is focused on the nitrogen cycle, but nitrogen and phosphorus have a close relationship given their role as fertilizers. One important difference is nitrogen is renewable and phosphorus is not. He pointed me to the Planetary Boundaries update supplementary materials to learn more about how the boundaries are defined–but apparently for nitrogen they were set somewhat arbitrarily initially and have since been tested and adjusted.

He suggested a number of areas where change or improvement could reduce nutrient pollution and carbon emissions. I included these in my final presentation, but they are broadly split between consumer behavior changes and technological advances in farming. We discussed the benefits of individual changes versus focuses on larger systemic change, but really it comes down to: individual change (vegetarianism, for example) is important but not sufficient.

It was good for me to return back to the original idea of limits to growth (30-year update) to link the research I’d done about phosphorus back to the big picture–how we’re unsustainably exhausting many planetary boundaries.

I heard back from another expert and sent along some questions, but haven’t yet heard back. In the meantime, I’ve come across many other algae projects, articles, and companies [and their sustainability assessments]. I am meeting with Stefani Bardin this week to discuss ways I can experiment with algae to test out my project idea.

My article citations have also been updated.

Some useful & some abandoned sketches

Waste systems 

While my project proposal went in a different direction, I’ve generally been very curious about how we might better capture and recycle waste. I came across a project where someone went to great lengths to install a waste recycling system in their home: by adding many small red worms to a biosolids tank they were able to produce soil. I wonder if something like this could be more easily installed in homes with septic tanks? There were also several projects out of Maker Faire Africa a few years ago that focused on human waste repurposing.

One contact that Kanter suggsted was Will Brownlie at the Center for Ecology and Hydrology in England. I haven’t yet contacted him but his thesis work was on “Assessing the role of domestic phosphorus emissions in the human phosphorus footprint” so he would likely be a useful expert if I continue to work in this direction.

I also learned that NYC has a biosolids management program.

Proposal & Ad


This week I learned about the green revolution, which increased world-wide food production and fed masses of people, but resulted in inefficiencies to the extent that more energy is being used to produce food than its output. I also learned about the haber-bosch process–its use in industry is responsible for massive amounts of ‘nitrogen fixation.’

I couldn’t shake this interest in the massive amounts of algae being produced by over-fertilization. I found there’s a distinction between toxic & non-toxic algal blooms (this is a very cool project focused on the toxic algal blooms in Lake Erie). New York State has a website with information about, and contacting information for reporting HABS (harmful algae blooms). But, there are thousands of species of algae. I didn’t realize how much work was being put into innovative uses of algae. I found this industry site that catalogs innovations, research, and news. Algae is being used as biofertilizer and biofuel, to the extent that it’s already displacing some other agriculture.

I wanted to know what algae looked like at the micro level because I hadn’t seen it yet and wondered if it was a possible way to form my project.

After the analogy exercise we did in class I kept thinking about algae death and hypoxia–how in a way the algae are suffocated the life in the waters where they bloom, and how in the end they are also displacing the nutrients, water, and oxygen that other living things, including humans, need. I found this algaculture project while learning about algae farming, which struck me partially because of the uncomfortable-looking design which reminded me of the asphyxiation I began to associate with algae blooms. It’s also an imaginative extrapolation into what humans and our food source might become.

How fragile is our food system? If we run out of fertilizer how will we eat? Do we want to live in a future where the answer is algae?

I was able to send along some questions to one professor, and will meet with another at NYU this week. I hope to address some broad questions about how phosphorus depletion and over-fertilization relate to other planetary systems and boundaries, and more specific questions about the potential for recycling and re-use, including potentially the cultivation of algae.


What if we could manage nutrient flows and algae growth in such a way that we could usefully re-purpose the algae grown? The potential for algae re-use is interesting because it intersects with a number of other planetary boundaries we’re approaching: fresh water use, land use, the nitrogen cycle, the phosphorus cycle, and climate change. It could perhaps also address biodiversity loss if the toxic algal blooms are related to species die off at a significant rate (this is real but I am unsure of the magnitude), and definitely relates to social limits: most directly, food security.

At first I imagined taking a critical approach, where giving people a way to envision the pills and soylent-like concoctions of our likely future would be incentive to avoid such a fate. But after doing more research I am very curious about the viability. I also wonder whether people will be disgusted regardless of whether the product is purposefully unappetizing, or if edible algae could be made desirable.


In the future we may use the runoff from farms or cities to grow algae that among other uses like biofuel, could be used for food. Products that may result include algae spread, algae pills, and algae alcohol. By purposefully engineering the runoff with these non-toxic algae, these blooms will not only be controlled, but be useful, nutritious, and maybe trendy.

SDR, digital voice & P25

This week we used our SDRs and gqrx to listen to different frequencies. There’s some playing around required with squelch and gain before you can actually listen to something. I looked at radio reference to find radio frequencies used for communications in NYC. These communications happen on narrow FM. If you type in the frequency and then move the red receiver bar around, you can listen in on some usually mundane but sometimes funny or interesting stuff. I wondered whether the “hardware freq,” which shows up under “receiver options” and changes when you match the red receiver bar up with where you see information on the waterfall, was supposed to match up with the publicly available frequency? Are these just separate channels?

I found a number of organizations’ communications frequencies are publicly available, but often the “mode” they use is P25 “a digital voice specification used by first responders worldwide” according to this person on youtube. Tuning in to the frequencies posted publicly, it was clear the transmissions I was hearing sounded like those demonstrated in the youtube video, which made me hopeful that I had at least identified them correctly.

After doing some research I found that there’s and open source software project, OP25, that can demodulate these communications.

Going to try and get OP25 working in VirtualBox so we can play with OP25 even on a Windoze system. Here’s the general plan:

1. Install Ubuntu on Virtual Box
2. Install GNU Radio
3. Install OP25
4. Plug in my RTL SDR dongle, configure OP25 accordingly and see if it works.

From the radio reference forum.

I tried downloading OP25 using their installation instructions, but I couldn’t launch gnuradio by typing gnuradio into terminal which had be stumped for a while. I tried downloading gnuradio from their site, which was perhaps unnecessary, before coming to the understanding that gnuradio doesn’t have a gui interface–to open something resembling the gui interface I had seen the videos/tutorials I actually had to enter: $ gnuradio-companion. This seems like a non-trivial point! It’s important to know what a thing is, not just that you “need” it:

It’s extremely useful. However, there are ways to use GNU Radio without being able to code. First, there’s the GNU Radio Companion, a graphical user interface similar to Simulink. It allows you to create signal processing applications by drag-and-drop. Also, GNU Radio comes with a set of ready-to-use tools and utility programs. These serve to manage the most basic operations, such as recording RF signals and performing spectrum analysis. If this has sparked your interest, perhaps have a look at the beginner’s guide how to use GNU Radio.

If you want to extend GNU Radio (i.e., add new functionality), however, then you must write code. For creating applications that are too complex for the GNU Radio Companion, Python is the easiest way to go. For performance-critical code, you should write C++ code.

From the GNU Radio wiki 

Once opened, I realized I had to write a “flow”/program and got stuck. There are tutorials so perhaps I will be able to write a functional program soon.

After all of this and ubuntu yelling at me because I only had 200mb of memory left on my virtual box, I realized also has a tutorial on decoding digital voice, which was very helpful in understanding more broadly what P25 effectively is, and the different ways of listening to any “unencrypted digital radio voice conversations.” The tools they suggest are: RTL-SDR software defined radio combined with SDRSharp and a program called “digital speech decoder” (DSD). They also note “The most common digital speech codec is APCO P25, which DSD is able to decode,” and, regarding encryption: “most users of digital radio do not bother to encrypt their systems as it can introduce lag, monetary expense and extra battery drain in portable radios.”

I’m not sure if this second method is a better solution?

Rare earths in things

This week I spent some time learning about rare earths, which have very obscure element names but are ubiquitous. All their names end with the same few letters which seemed like it might lend itself nicely to computational manipulation.

I wanted to play with the scientific taxonomy and naming conventions of these strange elements, the weirdness of their rarity, and their displacement. Like my last poem, I wanted to use space on the page/screen as a way to see this. Playing with spaces and elemental numbers didn’t work as well as I’d liked this time.

The source text is all 17 of the earth metals plus 17 products made of these elements I assembled from the internet.

My final poem and code.

Telescope lenetium
Nuclear control rodsetium
Aircraft enginesetium
Automotive Lutexhaust systemsetium
Pulsed lasersetium
Camera lenetium
Surgical suppliesetium
Optical glasetium
Computer disksetium
Fluorescent lampsetium


Project sketches

Reading “contaminated soil” described as Mel Chin’s “sculpture medium” in To Life! Eco Art in Pursuit of a Sustainable Planet made something click. Of course soil is central to the problem of exponentially increasing phosphorus use, but I hadn’t thought of as a ‘medium’ in itself. I was immediately reminded of the image included in Liu, Tang, & Li’s paper studying plant roots experiencing phosphorus deficiency.

Some ideas

  • Micro-materials flow analysis: change the scale to make it personal
  • More personal: collecting your own phosphorus. Would Jasmine-fertilizer be sufficient to grow my own food? The Bradford-Hartke et al. article noted issues with ecotoxicity and salinization with the use of untreated urine.
  • Designing larger scale interventions: create an easier way to capture and re-use phosphorus from urban waste streams, or from farm run-off. These processes are currently energy-intensive, and struvite (made from recovered phosphate) is still more expensive that mining for phosphate (Roy). Roy also explains, “several researchers have explored the potential for havesting P in the biomass of macrophytes and algae in ecological wastewater treatment systems.” I wonder if this kind of exponential algal growth and subsequent re-capture could be demonstrated?
  • What is a P-focused soil sculpture? What does healthy soil look like? What do healthy roots look like? Could I create a planter that shows their growth under different conditions somehow?

I wanted to know what recovering phosphorus from algae looked like

Maybe these ideas could be merged actually–if the food were edible witnessing this process could be different?

I wonder about the potential of using time lapse imagery or measurements?

P recycling research & references

[updated 5/7/2017]


Roy, E. D. (2017). Phosphorus recovery and recycling with ecological engineering: a review. Ecological Engineering, 98, 213-227. doi: 10.1016/j.ecoleng.2016.10.076

Bradford-Hartke, Z., Lane, J., Lant, P., & Leslie, G. (2015). Environmental benefits and burdens of phosphorus recovery from municipal wastewater. Environmental Science & Technology, 49(14), 8611-8622. doi: 10.1021/es505102v  

“Overall, mineral depletion and eutrophication are well-documented arguments for phosphorus recovery; however, phosphorus recovery does not necessarily present a net environmental benefit.”

Kalmykova, Y., Harder, R., Borgestedt, H. and Svanäng, I. (2012), Pathways and Management of Phosphorus in Urban Areas. Journal of Industrial Ecology, 16: 928–939. doi: 10.1111/j.1530-9290.2012.00541.x

Liu H, Tang C, Li C. 2016. The effects of nitrogen form on root morphological and physiological adaptations of maize, white lupin and faba bean under phosphorus deficiency. AoB PLANTS 8: plw058; doi: 10.1093/aobpla/plw058

“Low phosphorus (P) availability in the soil is one of the most limiting factors for crop production (Schachtman et al. 1998 ; Lynch 2007). Plants have evolved different mechanisms in roots in order to increase P acquisition under P-limiting conditions.”

Steffen, W., Richardson, K., Rockström, J., Cornell, S., Fetzer, I., Bennet, E., Biggs, R., Carpenter, S., Vries, W.,  De Wit, C., Folke, C., Gerten, D., Heinke, J., Mace, G., Persson, L., Ramanathan, V., Reyers, B., & Sörlin, S. (2015). Planetary boundaries: Guiding human development on a changing planet. Science, 347(6223). doi: 10.1126/science.1259855

Brownlie, W., May, L., Mcdonald, C., Roaf, S., & Spears, B.M. (2014). Assessment of a novel development policy for the control of phosphorus losses from private sewage systems to the Loch Leven catchment, Scotland, UK. Environmental Science & Policy, 38, 207-216. doi: 10.1016/j.envsci.2013.12.006

Kanter, D. (2014). Returning to the planetary boundary for nitrogen: Science, economics and policy (Doctoral dissertation, Princeton University). Retrieved from

Tuantet, K., Janssen, M., Temmink, H., Zeeman, G., Wijffels, R. H., & Buisman, C. J. (2013). Microalgae growth on concentrated human urine. Journal of Applied Phycology, 26(1), 287-297. doi: 10.1007/s10811-013-0108-2

Jaatinen, S., Lakaniemi, A., Rintala, J. (2015) Use of diluted urine for cultivation of Chlorella vulgaris. Environmental Technology, 37(9), 1159-1170. doi: 10.1080/09593330.2015.1105300

Fernandes, T. V., Shrestha, R., Sui, Y., Papini, G., Zeeman, G., Vet, L. E., . . . Lamers, P. (2015). Closing Domestic Nutrient Cycles Using Microalgae. Environmental Science & Technology49(20), 12450-12456. doi: 10.1021/acs.est.5b02858

Nguyen, T. D., Frappart, M., Jaouen, P., Pruvost, J., & Bourseau, P. (2014). Harvesting Chlorella vulgaris by natural increase in pH: effect of medium composition. Environmental Technology, 35(11), 1378-1388. doi: 10.1080/09593330.2013.868531 


Richmond, A., & Hu, Q. (2013). Handbook of microalgal culture applied phycology and biotechnology. Oxford: Wiley-Blackwell.

Hackett, S. C. (1960). Environmental and Natural Resource Economics (4th ed.). Armonk, NY: M.E. Sharpe, Inc.

Weintraub, L. (2012). To Life! Eco Art in Pursuit of a Sustainable Planet. Berkeley and Los Angeles, CA: University of California Press.

Cohen, T. (2012). Telemorphosis: Theory in the Era of Climate Change, Vol. 1. Open Humanities Press.

Morton, T. (2012). The ecological thought. Cambridge, MA: Harvard University Press.


EPA Nutrient Policy: nitrogen and phosphorus data access tool 

Scope Newsletter

Blog/article: how the phosphorus shortage could leave us all hungry

New ideas/vocabulary [wikipedia]

Industrial Ecology: The study of the human-influenced stocks and flows of resources and energy, from the perspective of resources and the environment

EutrophicationCultural eutrophication is a form of water pollution. Cultural eutrophication also occurs when excessive fertilizers run into lakes and rivers. This encourages the growth of algae (algal bloom) and other aquatic plants. Following this, overcrowding occurs and plants compete for sunlight, space and oxygen. Eutrophication arises from the oversupply of nutrients, which leads to over growth of plants and algae. After such organisms die, the bacterial degradation of their biomass consumes the oxygen in the water, thereby creating the state of hypoxia.

Material flows analysis: an analytical method to quantify flows and stocks of materials or substances in a well-defined system. MFA can also be applied to a single industrial installation, for example, for tracking nutrient flows through a waste water treatment plant. When combined with an assessment of the costs associated with material flows this business-oriented application of MFA is called Material Flow Cost Accounting. MFA is an important tool to study the circular economy and to devise material flow management.

Art/Design inspiration

Experts [updated 5/7/2017]

I reached out to an David Kanter, an NYU professor who studies the nitrogen cycle and fertilizer, a UVM professor who studies phosphorus and has an ecological design lab, and a professor of industrial environmental management and solid waste at Yale School of Forestry and Environmental Studies (FES).

Interviews with David Kanter at NYU’s Environmental Studies department, who spoke with me at length about nutrient pollution, and Lauren Jabusch at UC Davis’ Department of Ecological and Environmental Engineering, who gave invaluable guidance and insight regarding algae, made my project this semester possible.

Built to Last: ch.3-4 response

I used to think I didn’t understand the motivation of for-profit companies, but now I think I understand it even less. If part of what makes a company ‘visionary’ is its pursuit of varied goals and a ideals, then what’s the point of being for-profit? I understand that making money is important for the continued existence of a company, for it to invest in its development, guiding, and for it to pursue its main purpose while maintaining its foundational principles, but don’t non-profits also do this? And aren’t non-profits even better positioned to re-invest any profit rather than having to give it away? If the point is to get initial investment funds, wouldn’t the leaders of a company want to buy out the shareholders whose sole interest is continued interest? I didn’t study business and have always viewed money and simply a means to an end, so I’m probably missing something. But then Packard said “Profit is not the proper end and aim of managements–it is what makes all of the proper ends and aim possible” so maybe I’m not.  I realize there are probably a number of accounting/practical differences between the two so I wonder what goes into the calculation of being either. Anyway, if a for-profit structure was imposed upon me I think I’d try to keep shareholder influence to a minimum at most.

I liked this formula, where core values are “a sound set of [authentic] beliefs on which it premises all its policies and actions”, and purpose is “the set of fundamental reasons for a company’s existence beyond just making money”:

Core Ideology = Core Values + Purpose

Chapter 4 expanded on the book’s core thesis, that visionary companies “preserve the core” while they simultaneously “stimulate progress.” They explain “A visionary company protects its core ideology, yet all the specific manifestations of its core ideology must be open for change and evolution.” I couldn’t help but think these qualities could define a person as easily as an organization, and so this made a lot of intuitive sense.


This week we made a device a client of the Towers of Power VPN–I used the virtual box we set up last week. Downloading openvpn and running the ssh server were pretty straightforward. The ps command allows you to see a snapshot of current processes.

After creating the client.conf file and leaving my cert and key lines blank, I thought I’d need to generate these using easy-rsa. I downloaded this, since it didn’t come with the version of OpenVPN I installed, and spent a lot of time trying to figure out how to generate keys this way. Luckily Sharif saved me from my descent down this path–it seems like the cert and key information was just our netid’s! Then we could SSH into the server using the instructions on the Towers of Power github.

Then, you can log in from the client machine and scp the appropriate files from the server to the client. I also confirmed tun0 was open using the ifconfig command.