Glynn Chamberlain, ZS6GLN, Deputy Regional Director, HAMNET Gauteng South, tells us that Hamnet exhibited at the Southern African Emergency Services Institute (SAESI) expo at Nasrec Expo Centre in the south of Johannesburg from Wednesday the 1st of November till Friday the 3rd November inclusive.
Hamnet Gauteng South had their forward control centre on show together with other equipment used in community events and disaster situations.
This is the first of hopefully many expos that Hamnet will be participating in to spread the word of emergency communications in disaster and community events.
For more info on SAESI, visit https://www.saesi.com/. Thanks, Glynn.
Continuing my references to space and radio signals, consider the case of the two Voyager spacecraft, which have left the solar system and are currently in interstellar space. Voyager one and two are about 20 Billion Kilometres and 16 Billion Kilometres away from us respectively, and a round trip to send and receive the results of a command to and from either of them takes about 39 hours. They were launched in 1977, completed their solar system tasks in the 1980’s, and have been travelling outwards ever since.
The fact that their signals can still be received is a tribute to the antennas they carry and transmit to, and those are the figures I’d like to bring to your attention today.
The signal path loss for Voyager one, using one of its comms frequencies of 2.3 GHz, has been calculated at 306.6dB. Voyager’s 3.7m parabolic dish antenna has a gain of 57 dB, but the strength of its transmitted signal is only 23 watts. However, at the receiving end, NASA’s Deep Space Network has three sites, at Goldstone, Canberra and Madrid, each of which has three or more large dish antennas, the biggest of which is 70 metres in diameter, giving it 82 dB of gain.
No matter how strong the signal, it is the quality of the antenna which guarantees the reception of the signal. And the greater the gain, the narrower the beamwidth, so the antennas need to be pointed exactly at each other to hear each other. The obvious conclusion to be drawn is that the success of any radio system lies with the antennas. In the case of the Voyagers, there’s nothing to be done about the speed of travel of the message, at the speed of light, so those astronomers need to be patient and wait the 39 hours!
Thank you to Microwaves & RF for the details in this insert.
Now, here’s something for the scientists amongst you. In the ARRL letter for November the 2nd, HamSCI – the Amateur Radio citizen science initiative – has announced a 2-day workshop February 23-24, 2018, at New Jersey Institute of Technology (NJIT) in Newark. HamSCI’s Nathaniel Frissell, W2NAF, has posted a survey to gauge interest and potential attendance.
“We are inviting all hams and scientists interested in ham radio science,” Frissell said. “The aim of this workshop is to foster collaborations between the ham radio and the space science and space weather research communities through presentations, discussions, and demonstrations. This year’s meeting will focus on solar eclipse analysis, ham radio data sources and databases, and the development of a ‘personal space weather station.'”
Frissell, an NJIT assistant research professor, invited presentations from within the Amateur Radio community. “We will also accept submissions of abstracts and demonstrations of other topics that are of interest to ham radio and ionospheric science,” he said. “The solar eclipse topic is a follow-up to this summer’s total solar eclipse and the Solar Eclipse QSO Party (SEQP). We hope to have presentations from both ham radio operators and professional scientists showing the data that they have collected and what they think it means.”
The tentative schedule calls for oral presentations on “Ham Radio Data Sources, Databases Analysis” and “Solar Eclipse Effects on the Ionosphere, including results from the Solar Eclipse QSO Party.” Phil Erickson, W1PJE, of MIT’s Haystack Observatory is scheduled to be the Friday evening banquet speaker. Tutorials on Saturday will include “Ham Radio for Space Scientists,” with Frank Donovan, W3LPL, and “Space Science for Ham Radio Operators” (speaker pending).
Frissell said HamSCI would like to encourage development of the “Personal Space Weather Station” concept. “This is analogous to a personal weather station that people install at their homes to measure temperature, wind speed, rainfall, and humidity, and report this data to groups like the NWS, NOAA, and Weather Underground,” Frissell said. “We want to create a similar package for space weather and have that data go to a single repository.”
|“An ideal personal space weather station would likely include instruments able to detect things such as traveling ionospheric disturbances, radio blackouts, propagation changes, lightning, and magnetospheric activity, Frissell said. It would probably include, at a minimum, a wideband software-defined radio, a magnetometer, a timing source, and a computer — all currently available, but not as an integrated package, he pointed out.|
At the February workshop, HamSCI wants to better define the capabilities of a personal space weather station as well as how to implement the concept. “HamSCI will be teaming up with TAPR to do this,” Frissell said. “Scientists will talk about what science topics the device should be able to measure, and TAPR will discuss how to actually design and implement the device.”
So there’s a nice challenge for you!
A quick dam report for the Western Cape. The dam levels have subsided with 0.1percentage point, which is a relief, and other good news is that the water quality compliance is 99.59%, above the 98% target, so whatever comes out of the taps is drinkable! We squirm uneasily in our chairs as we watch the sky for clouds!
This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.AMNET