# What are the differences between a standing wave ratio meter and a frequency counter?

Im having a hard time understanding what the differences are, I see things on google saying they are both at once and I am really confused.

• Hi, when posing a question like this, please put a link as well as a direct quote from the source which contained the information in question. May 18 at 11:53

## 1 Answer

The frequency of an electromagnetic wave (or any other wave form) is the number of times that the wave reaches the maximum over a specific period of time. This is common when referring to radio communications as well as electrical (AC) power. It is a value which represents that aspect of the wave.

A standing wave ratio meter measures something completely different. In the cable television industry, for example, a fault in a coaxial transmission cable (trunk cable) will create an undesired reflection. This means that part of the energy in the wave does not make it to the destination and returns to the source.

In the process of so doing, it is reduced in power but interacts with the previously outgoing signal. The mixing of these waves creates a "stagnant" composite of a specific height/value.

The equipment will measure this ratio and present it on the device used to measure it. The equipment I used while in the cable television industry would send a test signal based on time (time domain reflectometry) and measure the duration required to receive the reflection. It would also measure the SWR (standing wave ratio) to ensure that the fault was properly located. Ordinary inline cable television equipment will create standing waves/reflections, but the level of the reflection is generally considered insignificant. Only those standing wave values representative of a fault were to be considered, primarily to locate the cut or damaged underground cable.

In amateur and citizens band radio, similar concepts apply. The transmitter generates a signal to be sent to the antenna. An ideal (imaginary) situation means all the power is sent to the antenna. Even an ordinary coaxial connector will generate a reflection/standing wave, but if properly constructed, will not affect the outgoing signal.

One uses such a meter to determine that the antenna is properly tuned for the desired frequency, as a mismatch between the transmitted frequency and the antenna's optimum frequency, if severe enough, can be problematic.

On the more powerful radio transmitters, the reflection can contain sufficient energy to damage the electronics on the transmitter. I believe the expression is similar to "fried the final," referring to releasing the magic smoke.

One device measures peak to peak duration (frequency counter), while the other measures unwanted return signals and compares amplitude.