Page 39 - EngineerIT November 2021

RADIO COMMUNICATION

The Next-Gen, Software Defined

Radio (SDR) transceiver delivers big

advances in frequency hopping (FH)

By Mizhou (Michelle) Tan, RF product applications engineer

This article provides an in-depth discussion of the high-level concept of
frequency hopping (FH), the design principles of FH enabled through
the flexible phase locked loop (PLL) architecture of the ADRV9002 SDR
transceiver, and its four major FH features. These features empower
users with the FH capabilities to handle applications such as Link 16 and
fast, real-time carrier frequency loading in both single and dual channel
operation modes. Furthermore, the combination of FH with multichip
synchronisation (MCS) and digital predistortion (DPD) makes this SDR
transceiver an attractive solution for achieving advanced requirements
in today’s complex communication systems.

Introduction frequency sub bands, the advantages of FH become more prominent,
In contrast to conventional radio communications, frequency hopping which makes it an attractive solution for many different applications.
(FH) defines a method of transmitting radio signals by rapidly changing
its carrier frequency and was first mentioned by Nikola Tesla in his The Next Generation SDR transceiver
1
1903 U.S. patent “Method of Signaling.” Later, in 1942, actress Hedy The ADRV9002 is a dual narrow-band and wide-band SDR transceiver
Lamarr and composer George Antheil further solidified the concept which provides state-of-the-art RF performance as well as advanced
by using a piano roll to change among 88 frequencies to prevent system features such as DPD and FH. ADRV9002 operates from 30 MHz
interference to the radio control of torpedoes. Over the past hundred to 6 GHz and covers the ultra-high frequency (UHF) bands, very high
years, from the non-real-time, slow speed communication between frequency (VHF) bands, industrial, scientific and medical (ISM) bands
fixed command points in World War I to the real-time, high speed and cellular frequency bands in narrow-band (kHz) and wide-band
multimedia communication between aircrafts, ships and land-based operation up to 40 MHz.
systems, FH has arrived at a new era in military applications. In addition
to that, FH has been widely adopted in many wireless personal
communication networks such as Bluetooth® personal area network
(PAN), as well as in consumer and hobby radio areas, such as walkie-
talkies, model cars and drones.

What is frequency hopping?
The high-level concept of FH is described in Figure 1. The entire
frequency band and time duration are divided into two-dimensional
grids. At any given time slot, a different frequency sub band is
utilised for communication. This brings the benefit of high resistance
to narrow-band interference and strong capability in combating
malicious interception and jamming, since the randomness of the
hopping pattern equivalently adds another layer of security that is
only decodable between the transmitter and receiver. In addition,
FH signals can easily share the bandwidth with other conventional
communications due to the minimal mutual interference, resulting in
high spectrum efficiency. With an increased hop rate and a larger set of Figure 1: High-level concept of frequency hopping.

EngineerIT | November 2021 | 37