Live video chat without reg

03-Mar-2015 04:47

RTTY is just normal RS232-style serial marks and spaces and stop bits etc., so why not let the hardware UART do the timing for me?It didn’t take long to write a small ‘C’ program that opened the serial port at 4800 baud, read enough GPS strings to find the longitude, latitude and altitude, then close the port and re-open at 300 baud (I found that switching baud rates without closing and opening wasn’t always reliable) to send out a formatted telemetry string.I settled on 432 x 240 pixels with 50% compression as a good compromise between quality and download speed.I measured the webcam current and it went from 50m A at idle to 250m A peak when taking a picture, hence the need to short out the USB fuse (140m A max).Telemetry from all receivers is sent to a central server that then drives a live map which can be viewed by anyone with an internet connection.The system works extremely well and has been used to track payloads at distances of 800km and more even though the transmitter is limited by UK law to 10m W ERP.

With the regulator dissipating up to 3 watts it needed and got a heatsink.The usual technique with the NTX2 is to send the ‘1’ and ‘0’ values in RTTY by waggling a general purpose I/O pin up and down at the correct rate. However the Pi runs a non-real-time operating system, so I could not rely on accurate timing especially if the operating system is busy taking a photo from the webcam.There are other options but I opted for the simplest one – connect the NTX2 to the serial port.In early May I received my first Raspberry Pi computer, and having flown several high altitude balloons before I thought about using one as a flight computer.In almost all of my previous flights I used Arduino Mini Pro boards, and these are ideal – tiny, weigh almost nothing, simple and need very little power.

With the regulator dissipating up to 3 watts it needed and got a heatsink.The usual technique with the NTX2 is to send the ‘1’ and ‘0’ values in RTTY by waggling a general purpose I/O pin up and down at the correct rate. However the Pi runs a non-real-time operating system, so I could not rely on accurate timing especially if the operating system is busy taking a photo from the webcam.There are other options but I opted for the simplest one – connect the NTX2 to the serial port.In early May I received my first Raspberry Pi computer, and having flown several high altitude balloons before I thought about using one as a flight computer.In almost all of my previous flights I used Arduino Mini Pro boards, and these are ideal – tiny, weigh almost nothing, simple and need very little power.“Near Space” is a fairly hostile environment – less than 1% atmosphere, temperatures down to -50C or so – and if anything goes wrong it’s likely to stay wrong.