WARC NEWS BROADCAST FOR SEPTEMBER 1ST 2013.

Last week VK2RTZ went off the air unexpectedly and the Westlakes Club would like to thank WICEN for the use of their repeater to do our broadcast on. Peter VK2ZTV was notified and by the middle of the WIA news VK2RTZ was back on the air. I guess a little gremlin had crept into the system somewhere. At the club yesterday it was all antennas full steam ahead. Richard VK2FRKO was outside showing a few operators the Multiband Tilted Folded dipole. On hand to see how it performed was Norm VK2KNC, Dave VK2RD ( already knows how well this antenna performs ) along with a number of other members. Norm had his FT-817 and using the battery from my car we checked all the bands and VSWR and on every band the VSWR was less than 1:5 to 1 . The 80 meter Morse Beacon on 3.699khz was an S9 at 11:30 am. When we pulled the antenna down out came the measuring tape and all measurements were taken, checked and then photo copied. I'd say this antenna will be a club project very soon. Listen out on these broadcasts for further information on this up and coming project. In the library Morrie VK2CD gave an excellent talk on his screwdriver antenna and showed everyone how it went together. Morrie is no longer producing this antenna and was going to sell off his stock to anyone that wanted a screwdriver antenna. The talk went for an hour with about 26 people listening and asking questions. Thanks Morrie for the great lecture. The club is always looking for members or even non members to give lectures on various topics. Know someone? please contact a committee member or write to the club address with details. Last weeks meat tray winner Alan, was at the club to select this weeks lucky winner. Alan reached in and selected a home made ticket ( made by Greg VK2CW ) and the winner was Herb VK2ZVF ( another regular winner of the meat tray ). Enjoy Herb. A club SHOW and Tell Day at the club is in the planning and the show and tell topic and demonstrations will be SDR radios whether on the PC on a Flex Radio etc. The date has not been set yet so if you are using a SDR transmitter/receiver we would like to see you at the club. Once again listen here for the date of this event. Michael was once again cooking hamburgers in the kitchen as well as serving pies and sausage rolls. From Richard - absolutely delicious. Ice creams were once again selling pretty fast too. The Westlakes bikers were once again ( Greg VK2CW and Robert VK2MF ) at the club showing each other there fancy features etc. There was only one thing missing from the bikes and that was that they had no antennas on them. Is this going to be a future project for the club to design and produce efficient antenna for them? Two weeks tomorrow will be our clubs Field Day which will be held on the 15th September ( this is a Sunday ) and the club is looking for donations of equipment for the auction table. Remember no TVs, computer monitors, VCRs. Why not come and have your stall. If you are interested please contact Barrie VK2ABD to book your spot and remember to bring your own table for your goods. The famous Westlakes BBQ will be cooking steak and sausages and serving fresh salad for sandwiches. The guessing competition for the number of jelly beans in the jar will once again be there as a fund raising venture. Andrews Communications WILL NOT BE HERE THIS YEAR, THIS IS DUE TO OTHER COMMITTMENTS. Do we know of another vendor who would like to attend the club and sell there products? Please let a committee member know. kEN VK2KJ advisers that the store still has a quantity of power supplies/battery chargers,they are ex-government supply using quality transformers & rugged construction. They cover 0 - 16 volt & have been marked down from $15 to $10. These power supplies will be available on the day. WORLD NEWS: A Ham Radio AX.25 Open Source Soundcard Modem. Alejandro Santos LU4EXT is developing extmodem an open source APRS compatible AX.25 amateur radio packet modem. It is currently capable of both sending and receive packets. The main feature of the software is that it is currently running three different demodulators in parallel, increasing the quality of reception. The first modem is Thomas Sailer HB9JNX / AE4WA's multimon, the other two are described by Sivan Toledo 4X6IZ in an article in the July/August 2012 issue of QEX. Download extmodem for Windows from http://extradio.sourceforge.net/extmodem.html Electronic News. Wireless nodes take power from ambient TV broadcast signals 04 September: 13 Ambient Researchers at the University of Washington have communicated wirelessly using only ambient energy harvested from broadcast TV transmissions. The technology demonstrators communicated over around 50cm at 1kbit/s using a packet protocol. Communication is bi-directional and includes reception acknowledge as well as a simple anti-collision technique which allows point-to-point communication in an environment where multiple nodes operating. Like passive RFID, the nodes ‘transmit’ by changing the reflectance of their antenna – in this case by briefly shorting (making it reflect) the two electrodes of a 258mm dipole tuned to a 50MHz band of UHF TV signals around 539MHz. Changing reflectance effectively amplitude-modulates the field around the dipole, radiating an AM signal. The dipole is busy as it is not only the transmit antenna, it is also the receive antenna and the source of power for the on-board microcontroller and receiver. UHF power it extracted straight from the dipole through a four-stage passive diode-capacitor charge pump, the result of a previous University of Washington research project that was done on conjunction with Intel. In the original case, connected to a TV-top log-periodic antenna, the circuit delivered 60µW of dc 4km from the TV transmitter. The receiver relies on the huge difference in modulation frequency between the ambient TV signal (6MHz) and the bit rates of the nodes (1kbit/s). It is simply a crystal set – a diode and capacitor connected across the antenna (see diagram) followed by a self-adjusting comparator (a TS881) acting as a detector. The resistors of the comparator act to load the demodulator capacitor, and the various time constants are set to reject any AM from the TV modulation while allowing through AM at the desired data rate. In practice the circuit can extract a signal that is invisibly buried in the TV signal. The squared comparator sends its output to a MSP430 microcontroller for preamble correlation, header decode, data decode, and packet cyclic redundancy checking (CRC). The modulation scheme chosen – at least one transition per bit and two transitions if the bit is a ’1' – gives a fairly even stream of 1s and 0s during transmission. The anti-collision scheme involves listening before transmission until the comparator output is largely 1s, or largely 0s, which means no nearby node is transmitting. This is not computationally intensive and needs little power. Sending the message involves transmitting a 10101010 sequence before the traditional pre-amble to give receivers a good chance of synchronising. Then the 64bit pre-amble, address, and 96bit data are sent. A range of 45cm was demonstrated indoors and 65cm outdoors, and at up to 10km from the TV transmitter. Power consumption of the comparator and microcontroller is under 1µW most of the time. The scheme is described in a paper: “Ambient backscatter: Wireless communication out of thin air“. The prototype nodes also include three touch pads and an LED (flashing only briefly) for interactivity, and were limited by the microcontrollers need for 1.8V. In a proposed smartcard application, the team suggest power would be shared: transmit modulator <1%, demodulator 1%, power management 8%, LEDs and touch sensors 26%. HackRF is a radio for all frequencies. Michael Ossmann, co-founder of Great Scott Gadgets, is developing HackRF, a software-defined radio (SDR) that lets you switch between radio frequencies on the fly. Most wireless gadgets, like the 3G antenna in a phone, operate using a fixed radio frequency band. But HackRF could potentially receive and transmit any radio frequency from 100 megahertz to 6 gigahertz – a range that includes broadcast and amateur radio, GSM, Bluetooth, Wi-Fi, and remote garage-door openers. Ossmann presented the device at ToorCon in San Diego, California, last weekend. There are other SDRs out there, but HackRF is intended to hit the sweet spot between versatility and cost – around the size of a USB hard drive and with a $300 price tag, the device could sit squarely in the consumer electronics bracket. Ossmann suggests SDR technology will bring about a revolution in the radio communications industry similar to the one that digital audio brought to the music industry. For now, HackRF remains a work-in-progress and isn’t yet being pitched at the mainstream market. “HackRF is designed to meet the needs of wireless communication security professionals, researchers and hobbyists,” says Ossmann. “It is for hackers, in the widest sense of the term.” Early applications range from identifying vulnerabilities in proprietary wireless control systems to listening in on police radio. Indeed, wireless security protocols that rely on obscure frequencies could be in danger. US military research instituation DARPA was interested enough to invest $200,000 in Ossmann’s use of HackRF for research into wireless communication security. But since the project is open source, hackers and researchers are free to take the device where they like. Ossmann thinks people will come up with uses he hasn’t yet thought of. Well that's all the news I have this week. Do you have a news items that you would like read out on a broadcast? Contact Richard VK2FRKO on email address vk2frko@tpg.com.au or give the item to Richard at the club. Now to wind up. Westlakes Amateur Radio Club Inc. is located in York Street, TERALBA - and is open on Saturday from around 11:00 am. Also on a Tuesday evening from around 6:00pm. To make contact at other times, try dialling (02) 49 581588 where an answering service operates. Visitors are alway welcome at the club. We have plenty of tea, coffee, long-life milk, a good Canteen and an interesting selection of biscuits.