SSB using a Raspberry Pi

Guido PE1NNZ has released code to enable the Raspberry Pi computer board to generate SSB on the 7 and 14 MHz bands.

“The following code can generate SSB modulation just by controlling a PLL carrier. I have applied this method on the RapsberryPi PLL, and made several contacts on 40m and 20m band with my RaspberryPi.” comments Guido

“The RaspberryPi receives the Microphone input via an external USB sound device. To improve the SSB quality, the signal is companded by a A-law compression technique. Three parallel BS170 MOSFETs where directly driven by RaspberryPi GPIO4 output to create about 1Watt of RF.”

“On 40m I could made several SSB contacts through Europe using this setup, receiving stations back by using a nearby online WebSDR receiver.”

Direct SSB generation by frequency modulating a PLL - http://pe1nnz.nl.eu.org/2013/05/direct-ssb-generation-on-pll.html

Warwick University students fly CubeSat

On Saturday 6 April 2013 students from the University of Warwick sent a CubeSat 30km into the stratosphere  

Starting from near Welshpool, the CubeSat travelled high into the stratosphere, to over 30km above the Earth's surface, where the balloon popped and a parachute safely carried the CubeSat back to Earth. The prototype was successfully recovered from near Banbury following the 2 hour flight.

The CubeSat carried three cameras and a radio communications link to transmit data and images. The transceiver used was a XBee-PRO 868 operating in the licence exempt 868 MHz band (the UK amateur radio licence prohibits aeronautical operation).

“The successful test launch - and recovery - is said to pave the way towards a longer-term plan to put a small satellite, built almost entirely by undergraduate students in the School of Engineering, into low-earth orbit at around 2,000 km”,

“The eight students have been working for the past year on the Warwick University Satellite (WUSAT) Project, which has been building a 10cm CubeSat capable of carrying equipment including cameras and sensors.”

Read the article in The Engineer - http://www.theengineer.co.uk/channels/skills-and-careers/news/balloon-launch-for-students-prototype-satellite/1016026.article

WUSAT Warwick University Satellite Project - http://www.warwick.ac.uk/cubesat

WUSAT Winter 2013 Newsletter - http://www2.warwick.ac.uk/fac/sci/eng/meng/wusat/media/wusat_newsletter_2013_winter.pdf

UK 434 MHz balloons head for Poland

Two balloons were launched from Cambridge on Saturday 13 April 2013, one transmitting video images from a Raspberry Pi. On Saturday evening the M0UPU-11 APRS signal indicated they were over Germany.

The first balloon is flying a Raspberry Pi which transmitted live Slow Scan Digital Video (SSDV) images back to the ground by a pair of transmitters to double the bandwidth. The data was RTTY 300 baud 8N2.

The frequencies used were 434.070 and 434.074 MHz. The balloon call sign was $$PIE.

The second balloon flew a 70cms tracker on 434.450 MHz 50 baud 7N2. Additionally once it entered air space where the airborne use of APRS is permitted a second APRS transmitter was enabled, presumably on the APRS frequency of 144.800 MHz, with the callsign M0UPU-11.

Live video of the launch was streamed by the British Amateur TV Club (BATC) - http://www.batc.tv/

Tracks of both balloons - http://www.spacenear.us/tracker

Direct link to M0UPU-11 APRS track - http://aprs.fi/#!call=a%2FM0UPU-11&timerange=86400&tail=86400

Images from the PIE5 Raspberry Pi balloon transmitted using SSDV - http://ssdv.habhub.org/

Beginners Guide to Tracking using dl-fldigi - http://ukhas.org.uk/guides:tracking_guide