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Digital Television tests - Bulletin No 10

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.

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Digital Television Tests – Bulletin No 9

The 502 to 510 MHz Digital TV Transmitter is being prepared for the final series of spectrum compatibility tests, to be witnessed by users of the adjacent spectrum.

Ever mindful of the cost of these tests to the users of the adjacent spectrum, we want to ensure the tests are successful at the first attempt. Accordingly, we have performed an extensive series of field tests and laboratory simulations to determine the performance margins of the transmitter system.

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Digital Television Tests – Bulletin No.8

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.

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Digital Television Tests – Bulletin No.7

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.

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Digital Television Tests – Bulletin No.6

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.

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Digital Television Tests – Bulletin No.5

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.

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Digital Television Tests – Bulletin No 4

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.

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Digital Television Tests – Bulletin No 3

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.

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Digital Television Tests – Bulletin No 2

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.

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DIGITAL TELEVISION BULLETIN No 1 - RSM grants the first Digital Amateur TV (DATV) Licence.

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:

  • Digital TV Channel 25 (DTV25)
  • 502 MHz to 510 MHz
  • DVB-T format
  • 7.7 MHz emission bandwidth
  • 100 W mean effective isotropic radiated power (eirp)
  • Horizontal polarisation
  • The licence is valid for an initial period of 6 months, from 1st January 2013 to 30th June 2013.

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