Projects of the Wellington VHF Group
Radio Spectrum Management has granted a short-term licence, number 256129, for additional tests of Digital Amateur Television transmissions from our Mt Belmont site.
The first transmissions will consist of an un-modulated carrier on 506 MHz during testing of the modified transmitting antenna. The dates and times of these tests will be notified on this website.
A further series of mobile field strength test runs along Stratton Street has been performed, and a report is being prepared for consideration by the interested parties.
An inspection of the BQ32 sheet of the Topo50 map series shows that some receive locations on Stratton Street are line-of-sight from Belmont and are heavily obstructed from transmitters using the adjacent 494 to 502 MHz and 510 to 518 MHz bands, potentially resulting in reception in these bands having an unfavourable signal-to-noise ratio, caused by any out-of-band radiation of the DATV transmitter.
Since the DMR system was set up at Colonial Knob, a number of enhancements and extensions have occurred. The code plugs determine the radio front panel channel setup, and changes have been made to make the radio easier to use when moving around the Wellington region, to support new DMR repeaters, and allow for the upcoming frequency changes. Support for the analogue channels has been made within the local zone, and plenty of channels added to make the radios usable in a number of situations.
Using the Spark free WiFi zones for Internet access
Need a digital radio hotspot for an AREC operation, a demonstration at a branch meeting, or something like the recent VHF Convention?
Telecom, now Spark, operate a network of more than 1,000 WiFi access points conveniently located on many public telephone call boxes around the country. The commercial terms of the service are essentially free WiFi for Spark on-account mobile customers subject to a 1GB limit per day for up to five devices per account.
Members of the DATV Project Team recently met with representatives of several Government agencies to
discuss the final series of adjacent-channel spectrum compatibility tests.
Following the extensive series of field tests that have been carried out, and laboratory simulations using an output filter
consisting of a 6-pole cross-coupled bandpass filter plus a 6-notch filter, we expect a successful
outcome from the tests.
We are grateful to one of our corporate sponsors for the bandpass filter, and also to our member Steve ZL2ASF,
for the notch filter.
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.
