Dave Akerman Daves World. This was a fun flight to provide a remote serial terminal on a Pi, between ground and a high altitude balloon, using a bi directional radio link. Lo. Ra Possibilities. Most high altitude balloon flights use a simple unidirectional data stream from the balloon to the ground, sending the telemetry balloon position and sensor data and sometimes images too, from balloon to the ground. I tried the example but it no longer works. Im using RPI3B. I even modified the sample code for the serial test to ttyS0 and lowered the baud to 9600. Readline Be carefully when using readline. Do specify a timeout when opening the serial port otherwise it could block forever if no newline character is received. In this tutorial we will see how to use the serial port on Raspberry Pi. We will use the serial port available on Raspberry with a RS232TTL 35,5V adapter and a. A curated list of awesome Go frameworks, libraries and software. Inspired by awesomepython. Contributing. Please take a quick gander at the contribution guidelines. Users guide for the Pololu Micro Maestro 6channel USB Servo Controller and the Pololu Mini Maestro 12 18 and 24Channel USB Servo Controllers. PuC4.png' alt='Python Serial Read Timeout Example' title='Python Serial Read Timeout Example' />Most often this is RTTY or in the USA APRS but there are alternatives such as Lo. Ra which more easily provides a means of reliably transmitting data to the balloon as well as from it. This greatly expands the range of things we can do during a balloon flight, for example A ground station can request re sends down to the ground of missing data image data or anything else see http www. A balloon can repeat data from other balloons, which might be flying or have landed see http www. Uplink to request cutdowns. Uplink to provide a guided parachute or parafoil with a new target landing position. You are in a maze of twisty little passages. H.jpg' alt='Python Serial Read Timeout Example' title='Python Serial Read Timeout Example' />I am helping a friend to finish a final year project in which he has this circuit that we want to switch on and off using a C program. I initially thought it would. Another possibility is to run a terminal session between ground client and balloon host, allowing programs to be run on the balloon tracker as requested by a ground station This could even be used to change the tracker program, or have that program use new configuration parameters. Here though Im going to use an idea provided by Philip Heron run an old text adventure game. And to make this a group experience, I added a web dashboard that displays the terminal window in real ish time. The following diagram shows how this is achieved in software The Lo. Ra gateway is the standard release with modifications added to provide a server socket on a specified port, to which any network terminal program e. In this case I have written a simple terminal program, in Delphi, that screen scrapes the terminal window and sends the contents to a Python script, which then updates a web dashboard so that anyone with the URL can see what I see in my terminal program. Separately and not shown on this diagram another Python script updates the same dashboard with the current telemetry, using data from the habitat system. Each time that a key is pressed in the terminal window, the key character is sent to the gateway that stores it ready for radio upload to the balloon tracker. Normally with balloon trackers, they transmit all the time, but instead this tracker sits listening for an uplink, to which it replies immediately. So the gateway program reads the keys sent to it from the terminal program, adds them to a custom message, and sends the result to the tracker. Assuming the messages arrives intact, the tracker replies with an ACK any other reply or no reply at all results in the message being re sent. At the tracker, these messages result in those key codes being sent to the telnetd program telnet daemon which is an installable program on Raspbian. That program provides a regular command interface same as a login on a Pi using a keyboard and monitor and any responses to those key codes are sent back from telnetd to the tracker program, where they are included in messages sent back to the ground. Periodically, when the tracker receives an uplink it will reply with a telemetry string so that the gateway can upload the balloon position to habitat as usual. The string is standard except for the addition of some status information about the uplink. Theres also a timeout so that if no uplink is received for a while, telemetry is sent anyway useful for tracking after landing. Houston, We Have Another Idea. As the Apollo missions of the 1. Apollo mission control console. So I grabbed a suitable photograph from the web, edited it fairly heavily, and incorporated in a new web server program that populates the screen with balloon telemetry and the terminal session. I wrote this in Delphi, with some Python to grab the telemetry from Habitat. I opted for a green screen monitor though I later noticed the Apollo screens had white screens. I think green looks better Radio Waterfall. This is what it looks like in action, minus the web dashboard Lo. Ra packets are up to 2. That window is screen scraped every 1 second, and the results are pushed to the web dashboard at that rate or slower depending on the time needed to post to the server. Iggy Pop Discography Completa Download Music on this page. The following video shows the terminal window and dashboard, for a short session that includes logging in to the tracker, running a couple of basic Linux commands, and then starting the Colossal Caves adventure game. Choice Of Frequency. We have a range of frequencies available to us for balloon flights, with different restrictions according to power and duty cycle. For this flight the duty cycle proportion of time spent transmitting is between 5. I had to choose  frequency in the band that allows that. Its also important to choose a frequency that doesnt have a lot of use from other devices. For those receiving on the ground, they may be near ISM Industrial Scientific and Medical devices such as oil level senders, weather stations etc, that can be bothersome if transmitting near the receiver. For the flight though, it can potentially hear transmitters over 1. I did a test flight to scan the spectrum and report on the signal levels as received by the balloon. The results of that test showed that some frequencies are 1. B better which is a lot better than others The quietest area does not allow 1. I chose a frequency centred on the quietest area that does namely 4. MHz. Payload. Normally I would use a PITS tracker, but as I didnt need RTTY I decided to use a custom GPSLo. Ra board, atop a Raspberry Pi model A. Power came from an AA emergency phone charger with 4 Energizer Ultimate Lithium cells. The lid of this was firmly taped down with duct tape, and the cells held in place with double sided pads, but even so the Pi rebooted when it landed. Not an issue but a reminder that soldered cells are bestAs usual, the lot went into a Hobbycraft polystyrene box, with GPS aerial on the top and a 14 wave aerial on the bottom, made from an SMA bulkhead plug and 5 pieces of guitar wire. The Launch. The conditions were favourable, without too much ground wind makes it difficult to launch or high level winds can take the flight a long way away I wanted the flight to stay fairly close to give the uplink the best chance of working throughout the flight. First step was to get all the ground station software started Lo. Ra gateway, Telnet terminal client, web server for Apollo dashboard and Python scripts for updating the two dashboards Apollo and thedash. I intended to use a gateway up on my Clark mast, for the best range, but that position is beyond the reach of my house wifi signal, and the TP Link repeater I bought the day before completely failed to extend the signal far enough. Soon Ill have my shed next to the mast wired to the house network, and that problem will go away. Meanwhile though, I had to go with the Lo. Ra gateway in the house, using a short colinear aerial in the loft. With the software all set up, I started the tracker, checked that the 2 way communications was all working as expected, and then filled the balloon. I chose a 3. 50g Hwoyee, a 2. Sphereachute, and a gas fill to have the flight land south of Monmouth. I needed to launch by about midday as after the the flight would land further east, increasing the risk of a tree landing. The launch itself was easy, with little wind.