# A question about frequency range

1. Feb 12, 2008

### sulymani

Hey guys

How can I know the range of frequency whether it's long or short ??? I have hard time knowin the range of for exmple ( 80 t0 120) MHz, 27 KHz .... or small value like 10 Hz .. strugglin with unit of Hz ??? please guys convert those values into feet unit or in meter .. that would be great ..

2. Feb 12, 2008

### ranger

Wavelength is related to frequency by the following:

$$\lambda = \frac{v_w}{f}$$

Where $v_w$ the velocity of the wave and $f$ is frequency. You can then use the definition of shortwave and longwave to help you along.

3. Feb 12, 2008

### waht

The higher the frequency the shorter the wavelength.

4. Feb 12, 2008

### sulymani

well .. i know all these stuffs .. my questio How can i know how far the frequecies above go ?? please i am sick of rules and math .. i need just written language.

5. Feb 12, 2008

### ranger

Elaborate on what you mean by this.

6. Feb 13, 2008

### sulymani

ranger ... i am tryin to build a transmitter that is compatible with the legal limits here in the USA. Further do u know how can i fix the frequency for both the transmitter and the receiver ??

7. Feb 13, 2008

### NoTime

8. Feb 13, 2008

### edmondng

what has this got to do with the original question? Legal limit as in within the legal operational laws? Try FCC

9. Feb 13, 2008

### ranger

Since this seems to be a digression from the OP, I suggest you open a new thread or request that a mentor split this thread into a new one (use the Report button).

Its a good thing that you mentioned your intentions. The airwaves are regulated by the FCC and you must exhibit caution in these regards. Berkeman, one of our mentors, has already cautioned several posters on this matter. You can view some of his comments here. Keep in mind that if you have a specific question for berkeman, it may have to wait until a week or so as he is currently busy with other obligations and may be inactive during that time period.

10. Feb 13, 2008

### sulymani

you know guys ... I have been thinkin of buildin a transmitter and a receiver that use an FM modulation. However, all plans have changed because of some obstacles came ahead. What I'm ganna do is to build the same transmitter and receiver, but using a short range signal modulator such as Wi Fi. Then I will have a fixed frequency that my transmitter will deal and the receiver, and for the regards of legal limits of FCC. Guys, I am new to the mechanism that's called Wi Fi. A friend of mine just told about it and how useful it would be compared with other mechanisms.

11. Feb 14, 2008

### edmondng

12. Feb 14, 2008

### waht

You are better off finding already built transmitter and receiver modules. Building a transmitter from scratch in that frequency range is difficult and requires access to specialized test equipment.