Receiving ATV pictures

Overview

One of the easiest ways to try ATV is by setting up a receive system. The VK3RTV ATV repeater currently has its output on 445.500 MHz using DVB-T2 HD, which can be received on some (but not all) digital set top boxes. All that is necessary is for the signal to be amplified — it is much weaker than a normal broadcast TV signal — or an unobstructed RF view to the transmitter site.

This can be achieved with a small preamp or masthead amplifier and a high gain antenna. If you are in direct line of sight you may get a picture with your normal UHF TV antenna. The receive antenna polarity should match the transmitter — VK3RTV is vertically polarised.

23cm reception involves more equipment. FM ATV (most common on 23cm) uses an analogue satellite receiver. As satellite receivers are inherently deaf, a preamp is needed between the antenna and the receiver. Digital reception uses DVB-S or DVB-S2 with a digital satellite receiver.

VK3RTV has a two-channel multiplexed output. The 1253 MHz input feeds VK3RTV2, and the 1245 MHz input feeds VK3RTV1. The system still accepts DVB-S signals to ensure no station is disadvantaged if not transmitting HD.

Antennas

The output power from the ATV repeater is not very strong (200W ERP) compared to broadcast stations. At UHF frequencies, small antennas can have significant gain. The yagi antenna is most common for ATV in Melbourne. Remember to use the same polarity as the transmitter — VK3RTV is vertically polarised.

Receivers and preamps

To receive the VK3RTV repeater a TV or set top box capable of receiving DVB-T2 HD on 445.500 MHz is required, along with a good UHF antenna and — unless you have a good line-of-sight view — a preamp. Not all set top boxes will tune DVB-T2 on 445.500 MHz, and none will find it automatically; you need to tune manually via the menus.

See the Equipment & Software page for a list of set top boxes known to work. Let us know at vk3rtv@hotmail.com if you have a working receiver not on the list.

Antenna location

The best location for an ATV receive antenna is where there is a clear, unobstructed view of the transmitter. At UHF frequencies signals are attenuated by trees, buildings and hills. If you can see (RF-wise) Mount View, Victoria Police Academy, Glen Waverley, you have an excellent chance of receiving the repeater.

In general: the higher and more "in the clear" the antenna, the better the results. Outside antennas are the only way to go — antennas inside the roof rarely work unless you are very close to the transmitter. Remember the antenna must be vertically polarised.

Installation and alignment

Most preamps and antennas mount to a standard TV antenna mast using common U-bolts and mast clamps. Note: VK3RTV output is vertically polarised (antenna elements perpendicular to the ground).

The coax from antenna to preamp should be kept as short as possible (6 feet or less) and of a large-diameter low-loss variety. Coax out of the preamp should be low-loss foil-shielded RG-59 or RG-6 — the better shielding reduces the chance of nearby strong signals leaking into your ATV receive system.

Alignment is critical, especially for larger antennas. Point your antenna at the Victoria Police Academy in Glen Waverley. It is handy to be able to monitor signal quality while adjusting. Ask on 147.400 MHz FM Simplex (or the backup frequency is 439.375 MHz FM Repeater) for someone to put up a picture, or contact us at vk3rtv@hotmail.com.