Wellington VHF Group, Inc: Online.

The unmodulated CW carrier on 506 MHz has been turned off, on the completion of coverage testing. Our thanks go to everyone who provided a reception report.

A prototype 2-way splitter, being one third of the 4-way drive splitter, has successfully passed all tests. A similar prototype, a 2-way combiner designed for higher power operation, is now under construction.

Transmission of the unmodulated CW carrier continues on 506 MHz, with horizontal polarisation. Reception reports are welcome.

Four power amplifier modules have been constructed and tested one-at-a-time with the digital exciter. Their gain and linearity match within half a dB. The four modules will operate in parallel to achieve the licensed power.

A 4-way drive splitter and 4-way output combiner have been designed and are under construction.

Transmission of the unmodulated CW carrier continues on 506 MHz, with horizontal polarisation. Reception reports are welcome.

Adjustment and testing of the digital modulator is complete.

The prototype power amplifier module has been constructed and is now undergoing quality testing. Once testing is complete another three modules will be constructed. The four modules will operate in parallel to achieve the licensed power.

Transmission of the unmodulated CW carrier continues on 506 MHz, with horizontal polarisation. The maximum EIRP is +20 dBW (100 Watts) towards the North East.

Calibrated coverage measurements, at more than twelve locations, confirm that the transmit antenna is performing as expected. Additional reception reports are welcome.

Work on the transmit antenna, and the installation of the transmitter, was completed last weekend, (9-10 February 2013).

At 9 am this morning, at the request of the users of the adjacent spectrum, the transmission was turned on at the maximum licensed power, while they tested for any effects on the operation of their repeaters, or degradation of mobile coverage along the road nearest the Belmont site.

No effects were noted and the station was cleared to continue transmitting.

Work has commenced on checking the coverage of the station. Reception reports are welcome.

Since update number 2, the quality of the prototype exciter and power amplifier, has been tested using professional test equipment.
These tests used both an unmodulated CW carrier, and a 7.6 MHz wide modulated spectrum, both centred on 506 MHz.
Both items performed better than expected and did not require any adjustment.

We are now working on getting the antenna system ready for the CW test transmissions.

Update number 1, as at 21st January, was published in January Q-Bit magazine, recently posted to members.

In summary, the update included a block diagram of the digital test system and discussed the various factors influencing the quality of the radiated transmission, such as the exciter quality, adjustment of the power amplifier, and the impedance matching of the output filter and antenna.

New Zealand Radio Spectrum Management (RSM) has granted the first Digital Amateur TV Licence to NZART Branch 74, The Wellington VHF Group, for use at its main station located on Mount Belmont, in Wellington.

The main features of Licence 236831 are:

The licence is valid for an initial period of 6 months, from 1st January 2013 to 30th June 2013.

© 2012 Dick Greenbank ZL2TGQ. First published in Q-Bit Journal July 2012.

I had been thinking for a while of trying out the sound card software AGW Packet Engine. I already had an Alinco Model DR1200T data radio, but had no accompanying interface to connect to the PC sound card. This article describes that part of the design which deals with the time-out function of the interface.

An acquaintance of mine published http://futureofutc.org/ on their Facebook page today.

This is interesting. An excerpt from their front page:

A conclusive proposal to fundamentally redefine UTC is scheduled for a vote by the Radiocommunication Assembly of the ITU-R in January, 2012. The proposal will halt the contribution of so-called leap seconds to UTC after 2017, and will also terminate the requirement that time services transmit the difference between UT1 and UTC. If approved, UTC would no longer be useful as a type of Universal Time for most technical applications.

Many software and hardware systems needing to know how the Earth is oriented with respect to the sky rely on UTC for this purpose. Should UTC be redefined, significant consequences may be anticipated for applications and infrastructures across various fields. Applications that do not apply so-called Earth Orientation Parameters and/or DUT1 corrections to UTC would be most affected.

Sessions will cover diverse topics of pragmatic timekeeping in a possibly changing world.

It's obvious to anyone working within the IT Sector alone that changes to the way UTC is handled will have far-reaching affects. This may be something that we all need to keep an eye on; all sorts of technology makes use of accurate timekeeping and the flow on effects of a change such as the one proposed may be significant.