AT1200 Selective Audio Frequency Level Meter

AT1200 is a selective audio frequency level meter, which measures the energy of the signal at specific selected frequencies with very high accuracy. This product is designed for use in harsh environments and specifically designed for railroad engineering.

To better understand AT1200, let’s describe the “Audio Frequency System”.

It’s a type of AC track circuit in which audio frequency signals are used instead of varying amplitude AC signals or DC level signals. Most track safety related signals are generated in this form of audio frequency signals. The frequencies are selected with odd numbers, which can be generated as harmonics of each other, a very simple way of using the maximum number of signals in a limited bandwidth of 20Hz to 25KHz. An Audio Frequency Track Circuit (AFTC) is an example of these signals, it shows that there is no train on the track. Signaling in the train industry is using these basic frequencies in every fault or situation needed, such as indicating if a switch is closed or a rail is switched from one track to another track, and many more.

Rycom-60 had been one of the important brands of this equipment – Audio Frequency Systems- in this industry for many years. The producer company, which was an old one, stopped its production in the mid-nineties, and this device was not available after that. The devices have been under maintenance for many years. After a while, the maintenance was not practical anymore and parts became obsolete one by one.