The Bridge - Issue 2, 2019 - 12

Feature

Electrical and Computer Engineering and Amateur Radio

Amateur Radio High-Altitude Ballooning
Amateur Radio High-Altitude Ballooning (ARHAB,
https://arhab.org) allows ECE students to design
functioning models of satellites and launch them into
a space-like environment at altitudes approaching
35 km (115 000 feet). The first launch of a weather
balloon carrying an amateur radio payload was
in 1987. An ARHAB flight consists of a balloon, a
recovery parachute, and a payload. One payload is
an amateur radio transmitter that permits tracking of
the flight to its landing for recovery. Other payload
components include a GPS receiver, sensors, data
loggers, digital cameras utilizing an amateur radio
Slow Scan Television (SSTV) transmitter and other
scientific experiments.
A typical ARHAB flight uses
a standard latex weather
balloon and is usually in
the air for up to 3 hours.
However, the California
Near Space Project flight in
2011 traveled 10,036 km
(6,236 mi) from San Jose
CA to a splashdown in
the Mediterranean Sea 57
hours later. Figure 3 shows
the ARHAB seal and motto.

Fig. 3: The seal and motto for
Amateur Radio HighAltitude Ballooning:
Knowledge from
under the sky.

Digital Data Networks
Amateur radio developed a practical wireless
digital data network beginning in 1978, using a
microprocessor-based Terminal Node Controller
(TNC). The TNC provided external support for the
8- or 16-bit, low clock frequency PC of the day. The
original technical contribution was the development
of the AX.25 packet radio data protocol over three
decades ago, which was adapted from the industrial
X.25 standard for amateur radio use. Amateur radio
operators thus had developed complex wireless data
communication systems with store and forward and
self-organization more than a decade before the
IEEE 802.11 standard.

THE BRIDGE

An Audio Frequency Shift Keying (AFSK) transmission
using APRS (www.aprs.org) on exclusive amateur
radio frequencies allows sending and receiving digital
messages as an alternative to vulnerable wired or
wireless public networks, especially during natural
disasters. TUARC operates an amateur radio APRS
digital data repeating (digipeating) station which
provides reliable communication throughout the
Philadelphia metropolitan area.
APRS though is limited by the available bandwidth
and FM transceivers on VHF and UHF to 9600
b/sec with AFSK. Although adequate for text
messaging, amateur radio has now developed a high
speed, self-configuring digital data network (www.
broadband-hamnet.org). An ECE capstone design
project used repurposed Linksys wireless routers on
2.4 GHz, which overlaps the upper portion of the
13 cm wavelength amateur radio band. Using an
amateur radio frequency of 2.402 GHz (channel
-1) allowed the use of RF power amplifiers and
gain antennas which are not permitted for WiFi. The
capstone design project developed an improved
Remote Machine Discovery Protocol as an original
contribution. The network used Raspberry Pi
microcomputers and the project report is posted
on the TUARC website. An example network is
illustrated in Figure 4.

Rover Vehicles
Semi-autonomous rover vehicles are a common
ECE capstone design project; examples are
shown in Figure 5. However, WiFi data and video
communication are limited in range because of the
low power and the UHF frequency required by FCC
regulation. Amateur radio projects do not have that
limitation and can implement a far roving vehicle.
The first-generation semi-autonomous rover vehicle
using amateur radio was developed as an ECE
capstone design project at Temple University with an
array of sensors in 2004.
http://www.aprs.org https://www.arhab.org http://www.broadband-hamnet.org http://www.broadband-hamnet.org https://hkn.ieee.org/ https://hkn.ieee.org/
The Bridge - Issue 2, 2019

Table of Contents for the Digital Edition of The Bridge - Issue 2, 2019
