How to use Wolfbane Reception predictor

Type in your aerial height and full postcode. Click (GO).
Explanation:

• Local/Distant/DX. The distance from the transmitter. DX = usually impossible to receive.
• Transmitter: your nearest transmitter(s).
• UHF: The number of the UHF frequency used by the multiplex 1, 2, A, B, C or D.
• In this example, CP transmitter uses UHF 25, 22, 32, 28, 34, 29 and Bluebell Hill uses 59, 24, 27, 45, 42, 39.
• ERP: Effective Radiated Power of the multiplex.
• AOD: Transmitting Aerial height.
• Gp: The aerial "group" that you should buy. E.g. Group 'A' covers the lowest UHF band. Group W covers ALL the band.
• Pol: Mount your aerial with its elements H horizontal or V vertical.
• OS grid ref. Click on this to see a terrain map. Look for obstructions.
• OD m: Your house height above OS datum.
• Field: The predicted signal strength at your aerial position.
• Distance: Your distance from transmitter.
• Bearing: Point your aerial in this compass direction, relative to grid north. (Magnetic north is a few degrees further north).
• Antenna suggestion: The suggested type of aerial. ("Set top" refers to a coat-hanger type indoor aerial.)

Notes

• A log periodic aerial such as the V10-040 is suitable for about 85% of locations in the UK so it's a fairly safe bet, even if the suggestion says something else!
• The prediction assumes your aerial is OUTDOORS at the stated height with no obstructions (trees or buildings) between it and the direction of the transmitter. If it is in the loft, subtract 3 from the Field value. If it is in an upstairs room, subtract 6.
• If the Field value is at least 34, there should be sufficient signal to feed one TV. You'll need a masthead amplifier to feed additional TVs.
• If the Field value is at least 60, you should be able to feed additional TVs with a passive splitter.
• If the Field value is less than 30, you'll need a masthead amplifier and a high-gain aerial. A log-periodic aerial probably won't work well.
• If the field value is less than 26, you probably won't achieve reliable reception at all.

Analogue Interference

While analogue transmissions exist, they can interfere with digital reception. Read below...

For digital CP transmitter uses UHF 25, 22, 32, 28, 34, 29 (see digital chart above)

Compare these with the UHF channel numbers listed in this analogue chart. If any numbers matched up, that digital multiplex might not be receivable. In this example there are no matches. However, the analogue FIELD is a very high 86 which means that you must not use amplification, otherwise the analogue signal will "blind" the digital tuner.

This is a symplified explanation.

Now let's look at a real example.

Although the predicted field strength is a healthy 50 dBuV/m, clicking on the yellow link gets us the terrain map, below:

There are hills in the signal path and, although this map doesn't show it, the hills are tree-covered. Tree leaves and branches have unpredictable effects on UHF signals, especially when the leaves are wet. It's likely that various frequencies are attenuated at different times of year. The height and lateral position of the aerial is critical and it will be necessary to try several positions and measure the signal for every channel in order to find the optimum position for all conditions. You can't simply assume that "highest is best". This could be a long-term project!