Just How Did You Know That ?

There really isn't any trick involved with scanners, a little know how can go a long ways.

The most powerful feature available on a scanner is the ' SEARCH ' function.

This button can find freqs that you never thought existed!
But I've seen a few scanners with the same Fire Dept programmed in 4 times...all using 3 diff freqs!

Those are called IMAGE freqs, one sure way to know if you have a listed Freq ( or good Freq ) is by doing some simple math.

Lets use Tower 8A Of the OPP this example

Lets say you used your search button and came up with this

142.365

A good way to know if this Freq is the right on is to figure out its " INPUT " Freq.

Now lets do some basic math.

We have the Freq of 142.365, how do we determine the input ?

We will either ADD or SUBTRACT 4.022

This formula works on all VHF freqs.


142.365
- 4.022
----------
= 138.343

Now 138.343 isn't possible, so we would round off the last digits.( to the closest 5 Khz )

Making our INPUT FREQ:138.345

Notice that 138.345 is the mobile freq that is for Tower 8A ( Isnt Math Fun )

So there is the INPUT Freq, now program this new Freq in your scanner, if you hear any transmissions that are fire ( mostly will be 1 way ) you have found the input Freq , but also have CONFIRMED the 142.365 beyond a doubt!


With the band plan below, if the input say fell into the AIRCRAFT Band , then perform the math by SUBTRACTION ( Minus ) or By Adding ( Addition ) the 4.022 . The standard method always used is Subtract first.


Always keep on mind if its VHF your looking for you must add or subtract 4.022

UHF is also the same only ADD or SUBTRACT 5.00

This method prevents duplicates in your scanner, and can confirm a new Freq !

But how do you know who is where?


I used a simple BAND PLAN for many years.

This layout is very crude, but works for me.

( all in MHz )
30 - 42 ( Fast Food , Low Power Units )

42 - 49 ( Cordless Phones, Baby Monitors )

50 - 53 ( 6 meter Ham Band )

108 - 135 ( Aircraft Band )

136 -143 ( Police inputs, police VHF outputs , MTO , Snow Plows)

144 - 147 ( 2 Meter Ham Band )

148 - 154 ( Pagers , Ambulances , Fire Dept )

156 - 157 ( Marine Band )

158 - 173 ( Tow Trucks, Commercial 2 Way Radio, About Everything Here )

200 - 300 ( Military , Satellites , Aircraft ( MIL )

400 - 440 ( Ambulance , 70 cm Ham Band )

450 - 500 ( RCMP , Television Audio )


After 500 MHz , things change far to much.

I hope this little guide and math formula works for you in helping to identify some freqs you may have.