Going after radiosondes with a Portapack H2 / HackRF

For those who know me, it is nothing new that among other things I am somewhat of a radio technologies enthusiast as well.

In the current state of affairs, it is an even more interesting field, considering how much it can be done without a significant financial investment. Radio technologies have evolved tremendously in a short time span. Some of that evolution can be directly attributed to the large demand caused by the mobile communications industry, but also by the computer and digital broadcast industry. All of these called for the development of highly integrated semiconductors capable of many functions, from the analog frontend and digital processing, to applications.

Reverse engineering the ZMAi-90 DIN rail meter/switch and integrating with Hass.io using Tasmota - Part 2

I finished the first post with  a tone of optimism, in spite of not being quite there yet. But this time I'm bringing the complete story, with something which hopefully can be a useful takeaway for most users.

Initial analysis of the MCU communication

After figuring out what kind of communication was going on between the ESP8266 and the Vangotech V9821 chip (the specialized MCU which does all the metering functions - and a bit more which I will go in detail afterwards), I got a bit puzzled with the output and its consistency. I first connected a known AC current source through the shunt mounted in the relay's output rail, and in the middle of a stream of garbage, some values seemed consistent with the current I was putting and  being shown in the device's display.

I still cracked my mind at trying to figure out a pattern (I felt as if I was trying to incarnate John Nash while looking for patterns in seemingly chaotic data), and trying to prove assumptions such as the last byte being a checksum. But nothing fruitful came out of that first iteration.

Attempting to reverse engineer a home automation oriented smart-meter - Part 1

In my quest to make my house smarter, but still looking forward to keep having control over it, I have been doing some additions which I plan to further document here, in the short term.

In the meantime I thought it would be more relevant to share my findings in regard to a device a bit more "exhotic" than the Sonoff boxes we are all used to. This device is a sort of a miniature smartmeter that fits in a DIN rail next to the circuit breakers.

Just like the Sonoff modules, it also pairs with your WLAN, and connects to a cloud service. Instead of the eWeLink cloud to which Sonoff devices connect to, in this case it connects to another relatively popular cloud service called Tuya.

Building a kick-ass home automation by reflashing the Sonoff devices with Tasmota and getting it all working with hass.io

For some time I have been gradually bringing more devices to my house, which are either designed or having features allowing these to be integrated to a home automation system.

In spite of all the concerns that can arise from bringing smart/connected devices to the place where you expect personal privacy to exist, the convenience of having these ends up speaking louder overall..

It all started with having a set of unrelated devices in the house, each featuring connectivity and some cloud-based features provided by the vendor. This is the case for the Xiaomi Rockrobo vacuum cleaner, the Sonoff switches, the multimedia devices such as the TV set (an LG smartTV), and also the Google Chromecast and Assistant devices.

4-wheel adventures ranging from customer relationship to automotive hacking

1. Context

Since more than a decade ago, automotive technology have captured my interest to some extent. Not so much in the mechanical domain, for which the industry have in most part been over the years conservative and slow in pushing inovation, but mostly in respect to the digital framework that integrates the vehicles. This overlay of digital technology plays a fundamental role in modern cars, ranging from safety, fuel economy, controlling the production cost (by reducing the number of individual parts), emissions control, comfort and entertainment.

Repurposing an old Android Phone

I had an old Samsung Galaxy Y (GT-S5360) which the previous user didn't particularly enjoy for its performance and replaced with a fancier, newer model. With no obvious use to give to the device, I decided to repurpose it for building some kind of a remote monitoring/observation station, and try to find out how it stands out against the harsh outside environment.

While not attempting to simply put the device outside, directly exposed to the sun, rain and extremes of temperature, I made several customizations to better prepare the smartphone turned into a monitoring station.

The first thing I wanted was to have it entirely self-sustainable. As such I bought a 10 watt photovoltaic panel to harvest the energy required by the device:

Receiving weather satellite images with cheap hardware

Before the Internet, anyone willing to independently obtain satellite imagery from the source would need to buy expensive equipment capable of decoding the analog slow scan video images transmitted by weather satellites  such as the NOAA APT ones. Today there are four of these NOAA satellites still operational, the NOAA-18, 17, 15 and 19. All of these are sun-synchronous satellites, which means these orbit the earth at around 800 Km of altitude and cross every latitude at approximately the same mean local solar time for each pass. This kind of orbit is useful because of the consistent illumination (by the sun) of the target upon each pass.

The meanders of OBD-II protocols

As we travel through the history of automotive technology back and forth, we realize that at the heart of the machines that enable us to go from point A to point B faster than our legs, are a number of components that essentially haven't changed too much: engines still burn fossil fuels and the vast majority are based on pistons that transform the explosive energy of the fuel combustion into movement.

Long-haul WiFi - new developments

Returning to the WiFi topic, here is the new antenna development that I had promissed in the early post, once the dual "cantenna" design was finished.

The dual cantenna is quite efficient, as I realized by connecting it to reasonably distant access points (in excess of 200 meters, with many obstacles between, including houses). By verifying the antenna efficiency was the expected, I assumed that in better conditions the range could be far greater, by establishing a link between two antennas of this type or other type of optimal configurations.

However, I knew I could push it a little further, so I decided to buy a 12 euro 45 cm dish from a regular satellite TV system, and the materials to build a biquad feed. I installed the dish on top of the tripod used for the cantennas, and attached the biquad feed (built according to these instructions) to it:

"Long-Haul" point-to-point WiFi links

I start this blog with a great, not so new idea that I decided to reimplement and see working with my own eyes. The principles behind it are not new at all and go back to the early days of RADAR technology (1930's), in a time where microwave radio research was taking place to improve the accuracy of this type of equipment. The need for guiding radio waves through a low loss medium and to be able to selectively pickup signals coming from a particular direction (in this case echoes from the emitted pulses) led to the design of different types of microwave antennas. These antennas had to be both compact (in order to fit into small airplane compartments) and efficient (output most of the signal from the transmitter in a particular direction and receive with exceptional gain the signal returning from that same direction).