Brats FLC Technical Basics

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Bredhurst Receiving and Transmitting Society

Technical Basics Part 4

3c.2 Understand that frequency bands are allocated for particular use, e.g. broadcasting, aeronautical, maritime and amateur.

Frequency allocation table

Frequency allocation chart as is issued as part of the paper work in the examination For this part of the syllabus you have to be able to use the following chart to determine what is the "use" of the part of the radio spectrum asked in the question.
MHz and kHz

Do note that the frequencies given below are ALL in MHz - in the exam be careful to check that you are marking the box with MHz and not kHz.So there is nothing to learn - you just have to understand the chart and be able to apply it in the Foundation Licence examination.
The sort of question you might be asked is :-
What usage is allocated to 156.125MHz ? Answer from the table above is Maritime mobile.
So this is a look up table which you are provided with in the exam and thus will test your ability to understand information given in tabular form.

3c.3 Understand the relationship between frequency (f) and wavelength (). Use a graph to convert from one to the other.

Note: calculations are not required.

Frequency and wavelength conversion

animation of the use of the frequency to wavelength table which is issued in the examination

This is the chart that you will be given in the written assessment

Let's look at the side that is indicated Wavelength down the left hand side of the chart. You can see that the wavelength is measured in m for meters and co-incidentally this also give the name to the band eg 10MHz would be in the 30m band.

The Frequency along the bottom and marked in MhZ that is mega hertz.

Now if I asked you :-

What frequency does 2m equal in wavelength ? How would you go about finding out?

Think for a moment then put your mouse pointer on the chart for a demonstration of how to use the chart.

You are not needed to do calculations just to be able to understand how to use the simple chart and convert from wavelength to frequency or frequency to wavelength.

If the animation did not work with your brower then you have to draw a straight line from the given information on one axis to the diagonal line and then to the other axis ...see diagram below.

So not only can the chart tell you the Frequency to Wavelength conversion but also which band the frequency is in.

Comment on the chart.

Note on the chart that it shows wavelengths of less than 1m, 0.8 m is the same as 80cms, 0.6 is the same as 60cms.

So the chart covers wavelengths between 30cms and 300m which on the frequency range is 1MHz to 1000MHz even though the 1 is not identified on the chart.

the frequency to wavelength conversion chart showing how to do the conversion by crossing over line drawn from the wavelength axis to the diagonal and then drawn to the frequency axis from the intersection with the diagonal

You could get a question which asked which is the highest frequency and you have to select it from a list of amateur bands. You would use the chart above to convert from bands to frequency as the bands are given in in this type of question in meters.

Exam note

Students are getting in to a muddle with this chart and how to use it - so please pay special attention to all the ways it can be used :-

Convert Frequency to wavelength

Convert Wavelength to Frequency

Convert Frequency to Frequency Band

Convert Frequency Band to Frequency

Any of these combinations could be a possible question in the exam.