Very narrow channel spacing

This paper describes the approach that has been made in the U.K. toward narrower channel spacing for VHF mobile radio. Equipment of the type in current use for 25 kc/s channel spacing was modified for field trials with 12½ kc/s channel spacing, and successful field trials were conducted. The same equipment was then supplied to the British Post Office who conducted their own successful field trials and have since announced their decision to make 12½ kc/s spacing compulsory for new schemes after April 1967.