Transmission1's guide to scanning

General scanning discussion forum. Talk about anything to do with scanners, equipment, VHF/UHF reception and the art of catching those illusive signals!
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5thElement
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Transmission1's guide to scanning

Postby 5thElement » 25 Mar 2008, 22:09

Welcome to the Transmission 1 guide to scanners

If you're a complete beginner/novice to scanning, I hope this guide will give you some useful advice and point you in the right direction to get you started.

This guide will be updated time to time to add new subjects and teach you more about your scanner and various scanning activities.

First off, I'll start with the basics of what a scanner is and does in its simplest form.

The Basics

1: What is a scanner?

A scanner is a radio that covers a far wider frequency range than your average radio at home. Most radios you find in everyday use have a single purpose, i.e. the radio in your car/home is designed to only receive commercial radio stations. Scanners on the other hand, can receive signals transmitted on a wide range of frequencies, allowing the user to listen in to a huge range of different communications including air traffic control, emergency services (ambulance and fire), hobbyists (Citizens Band, Amateur radio), security guards, taxi's and a lot more.

2: What does a scanner do?

A scanner has two main modes of operation; these are commonly known as 'search' and 'scan'

In 'search' mode, you are searching for any transmissions within a certain frequency range specified by the user, i.e. 400-470 MHz. The scanner will quickly scan through the frequencies and if it detects a transmission it will stop immediately and let you listen to what it has found. At this point you can hold the scanner on this frequency and continue to listen or you can let it continue scanning for other transmissions. You can also store the frequency it stopped on into a memory channel for future reference. That brings me to the next mode on your scanner, 'scan'

Once you start filling up your memory channels with frequencies of interest to you, you can set the scanner to scan through only the channels you've saved. This mode on most scanners is extremely quick so you never miss any action.

3: Types of scanners?

Scanners come in two types, handheld and base/mobile. Deciding which to buy is simply a case of knowing where you will use the radio most. If you only plan to use it at home, a home base unit would be a better option. If you plan to take your scanner out and about, a handheld unit will be the best option. Purchasing a handheld is probably the best option for beginners as you can use this at home and also outdoors so you get the best of both worlds.

Getting technical

Now that we've got what a scanner basically does, we'll move onto some of the more technical aspects of scanning.

A lot of beginners seem to falter at this stage, they've bought a scanner, played around with it and can't find anything to listen to and are disappointed and blame the scanner, when 90% of the time, it's a user error, or just a lack of knowledge in regards to knowing where to scan and what to look for.

I'll start with some of the other basic functions on a scanner, I'll stick to the basics that every scanner will have, most scanners will have a lot more features but these will all be model specific.

1: Squelch

You need to set your squelch control properly for the scanner to search/scan. This is easy to do. To start off, turn the squelch right down so you get the constant hissing/white noise coming through the speaker, then slowly turn it back up, you want to set it just above the point where the hissing/white noise stops and that's it, your squelch is set.

2: Modes

Nearly all scanners will have at least 2 modes, those being AM and FM. For the best part, you'll be sticking to FM. There are some exceptions though, Air Band (108-136 Mhz) for example uses AM, so when searching through the air band range, make sure you're using AM.

Some scanners will list FM as NFM and WFM, NFM stands for narrow fm and WFM stands for wide fm. You only need WFM for listening to commercial radio stations, for everything else stick to NFM.

There is also USB and LSB, upper and lower sideband, these modes are used mainly on the HF bands (3-30 MHz) by radio amateurs, ships, aircraft etc. You will only find these modes on more advanced scanners.

3: Step size

You're scanner will usually have various step sizes for you to choose from (on cheaper/older scanners you may find these are locked and you have no choice) these will typically range from 5/6.25/8.33/10/12.5/25/50khz steps. Choosing the correct step size is essential for searching efficiently and making sure you don't miss any transmissions, and also to make sure that when the scanner stops, it's accurately tuned to the frequency.

A general guide is to stick to 12.5 kHz steps for VHF, and 6.25 kHz steps for UHF.

4: Scan delay

Most scanners will have an option for you to choose how long the scanner will stop on a frequency after the transmission ends, before it starts scanning or searching again. The times will vary from scanner to scanner, usually 2-30 seconds and it's entirely up to you which you choose. This is a handy feature as the other radio user may take a few seconds to respond to the first person, so without this feature, the scanner would just immediately move on without waiting for the response.

5: Lock out

Again, this is a feature most scanners have. This enables you to lock out certain frequencies you want to skip past/ignore. In "search" this is useful as you will occasionally come across a transmission which is constantly there making the scanner stop, so instead of having to manually make the scanner continue, with the lock out feature the scanner will simply ignore it and continue scanning. In 'scan' mode, you might not want to listen to some of your stored channels while scanning through them, so if you lock them out, the scanner will ignore any activity found on them. Any channels locked out, can be unlocked at any time as well, refer to your manual on how to unlock the channels (usually just the same way you locked them to start with)

6: Hold

Most scanners have a 'hold' button, pressing this will indefinitely hold the scanner on the current channel/frequency until you press it again which is handy for monitoring one channel if something interesting is happening, this will ensure you miss nothing.


Using your scanner

Now that you have a basic understanding of what your scanner can do, and what the basic functions do, it's time to put it to use.

You will need to refer to your scanners manual to find out how to get it into search mode (to find frequencies in your area) or scan mode (to scan frequencies you've stored)

Here is a rough guide of where to search and what you may find using your scanner.

31.000 - 32.000 MHz FM - Cordless phones
70.500 - 71.500 MHz AM - Fire Brigade
85.000 - 88.000 MHz - PMR (Private Mobile Radio)
117.975 - 136.000 MHz AM - Civil Air band.
144.000 - 146.000 MHz FM - Amateur Radio 2m Band
156.000 - 163.000 MHz FM - Marine band
163.000 - 185.000 MHz FM - PMR (security,taxis,ambulance etc)
200.000 - 399.000 MHz AM - Military airband
430.000 - 440.000 MHz FM - Amateur Radio 70cm band
440.000 - 446.000 MHz FM - PMR
446.000 - 446.500 MHz FM - PMR (including licence free pmr)
446.500 - 470.000 MHz FM - PMR (security etc)

It's now simply a case of searching through the various ranges over and over and finding transmissions within range, listening to them and trying to identify them.

Have patience when you're searching and don't get frustrated if you pick up nothing the first few times you scan through, just keep on searching and you will come across transmissions eventually! Once you do, you can start adding them to your memory channels and building up your own database of frequencies in your area.
2E0XGA

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