Showing posts with label WiFi. Show all posts
Showing posts with label WiFi. Show all posts

Monday, December 7, 2020

Turning a doorbell switch into a home security camera...and still retain its original function

Today there is an off-the-shelf solution for practically every average-Joe-grade idea one may have. There is always the chance that when one thinks of something that could have a practical purpose and cover a specific need, that there is already a product in the market that will do that function.
Even though home automation may still be in its infancy, today we see a market practically flooded of solutions that one way or another aim to respond in terms of comfort, or to help improve the home experience, or even to enhance the safety and security of its occupants.

Saturday, April 4, 2020

Building a kiosk for Home Assistant from scrap parts

It is great to have automation in the house providing increments of comfort such as eliminating manual tasks like cleaning the floor, or to aid in managing the energy consumption by turning off lights and appliances which are not in use, or in the safety side, by providing intrusion detection or monitoring the presence of gas leaks or other hazards, and executing the adequate actions.

Wednesday, October 30, 2019

Waking up devices in (Home Assistant)

This is a quick post on a challenge I had to overcome while integrating my SmartTV (an LG TV 55UJ620V) with

I wanted to be able to turn on the TV (as such allowing automations to be built on top of it, or for example turning it on through a voice command via Google Assistant). As such I first resorted to using the Home Assistant Wake on LAN built in integration ( It kind of worked, but was not very reliable (perhaps 2 out of 5 times it would work).

I knew that by definition, the way that (Wake-up On LAN) WOL is implemented is inherently unreliable: essentially the target (dormant) device is expecting a frame with a specific pattern of bytes. If it receives that frame, it wakes up the host, otherwise nothing happens. The device will normally scan for that pattern of bytes in the frame regardless of the type of transport level protocol it may be on top of. In the case of WiFi in particular, there is the probability (high or low, depending on the network conditions) of that single frame not reaching the destination. This probability increases with the more hops we have in between.

With this implementation I was requiring the magic packet to be sent from a host (the Raspberry Pi where I keep running) that is in a separate router vlan, from where the TV is (these are connected via Ethernet and WiFi respectively):

Sunday, October 20, 2019

Consumer grade WiFi gear - when fixing the root cause is not at reach

Some time ago, I had to improve the performance and coverage of my home network, so as to be able to use the several devices around the house flawlessly, regardless of the location. Some of these devices have a certain demand for consistent bandwidth, as is the case of the SmartTV for watching IPTV and Netflix, and others such as the smartphones and tablets.

As always I tend to be frugal with spending money in hardware, trying to go with what performs well and is just about enough for the job.

This led me to aim for WiFi gear that would both be somewhat popular and low cost, while at the same time having some hope of being hackable and reflashed to OpenWRT in the future. This was the reasoning when I decided to buy a couple of TP-LINK TL-WR841N routers (with v9 hardware at the time).

At first I set these up and played with the stock firmware, configuring one to play the roles of  NAT, DHCP, DNS, firewall and so on, and the other to act solely as a WDS repeater, allowing WiFi coverage to be extended to the rest of the house.

Saturday, March 15, 2008

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:

Sunday, June 10, 2007

"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).