TELEMETRY SYSTEMS RADIO FREQUENCY (RF) HANDBOOK

PREFACE
This document was prepared by the Range Commanders Council, Telemetry Group
(RCC-TG), RF Systems Committee. It represents the initial release of the Telemetry Systems
RF Handbook and is published as a “work in progress.” The RF Systems Committee
objective is to develop this handbook as a useful document that will be beneficial to engineers
and technicians working in the field of telemetry RF systems.

The Committee requests the assistance of those who use this handbook in identifying
subject areas that have been overlooked or not covered in sufficient detail. In addition,
comments regarding the content and the presentation of the material are solicited and
encouraged. Please forward any material you feel may be helpful in preparing updates to this
document.

INTRODUCTION
The Radio Frequency (RF) Systems Committee of the Range Commanders Council -
Telemetry Group (RCC-TG) has prepared this document to assist in the development of
improved RF telemetry transmitting and receiving systems in use on RCC-member ranges.
The RCC-TG expects that improved system design, operation, and maintenance will result
from a better understanding of the factors that affect RF systems performance and,
consequently, overall system effectiveness. Additional information can be found in RCC
Document 119-88, Telemetry Applications Handbook.1

This document is not intended to be a tutorial or textbook on the theory of RF systems
design. It is intended to be a living document used to convey ideas, suggestions, lessons
learned and other items of importance to the new telemetry systems engineer or technician
working in the field of RF telemetry. This document is arranged into three sections according
to the basic telemetry RF system model below.

Radio Frequency Basics
Radio frequencies are electromagnetic waves that are propagated through space and
are the basis for many different systems of communication. Because of their varying
characteristics, radio waves of different frequencies are used not only in radio broadcasting
but also in wireless devices, telephone transmission, television, radar, navigational systems,
and other types of communication such as telemetry systems.

Radio waves are usually identified by their frequency. The shortest waves have the
highest frequency, or numbers of cycles per second, while the longest waves have the lowest
frequency, or fewest cycles per second. In honor of the German radio pioneer Heinrich Hertz,
his name is used to refer to the cycle per second (hertz, Hz); one kilohertz (kHz) is 1000
cycles per second (cps), one megahertz (MHz) is one million cps, and one gigahertz (GHz) is
one billion cps. The electromagnetic energy that is useful for communication purposes ranges
between roughly 10 kHz and 100 GHz. In vacuum, all electromagnetic waves travel at a
uniform speed of about 300,000 kilometers per second (about 186,000 miles per second).
Because electromagnetic waves in a uniform atmosphere travel in straight lines, and
because the earth’s surface is spherical, long distance radio communication is made possible
by the reflection of radio waves from the ionosphere. Radio waves shorter than about 10 m
(about 33 ft.) in wavelength ? designated as very high (VHF), ultrahigh (UHF), and super
high (SHF) frequencies ? are usually not reflected by the ionosphere; thus, in normal
practice, such very short waves are received only within line-of-sight distances. Wavelengths
shorter than a few centimeters are absorbed by water droplets or clouds; those shorter than 1.5
cm (0.6 in.) may be absorbed selectively by the water vapor present in a clear atmosphere. In
the atmosphere, the physical characteristics of the air cause slight variations in velocity, which
are sources of error in such radio-communications systems as radar. Also, storms or electrical
disturbances produce anomalous phenomena in the propagation of radio waves.

A typical radio communication system ha