Homer Hot Measurement and Tuning System - S-TEAM Lab

containing 4 separate channels of precision programmable amplifiers (PGA) followed by A/D converters (ADC).
Solid-state switches preceding the detectors serve for capturing offsets of the DC circuitry (apparent signals in
absence of microwave power), which must be subtracted from the measured voltages V 1 to V 4 . The switches are
controlled by a digital input/output (DIO) portion of SD-2000. In a single-board computer (SBC), connected with
SD-2000 via PC/104 interface, the digitized voltages undergo a correction routine which eliminates nonlinearity and
temperature dependence of the detector transfer characteristics. The inner temperature is measured by a sensor with
serial output, connected to SD-2000 by means of I 2 C bus. The corrected voltages along with signal frequency and
stored SPR calibration data are used to compute the reflection coefficient and incident power P i .
Accurate knowledge of signal frequency is a precondition for accurate measurement. Since magnetrons used in
industrial applications are free-running sources with frequency depending on working conditions, frequency is not
known in advance but must be measured. A frequency counter is therefore integrated with the system. The counter
uses a separate directional coupler (Frequency Coupler) of basically the same design as the reference coupler. The
coupled signal frequency is divided in a microwave prescaler down to about 50 – 100 MHz, which is then measured
by a 150-MHz counter (CNT) implemented in SD-2000. Gating intervals down to 16 s plus the triggering built in
the SD-2000 software enable reasonable measurement even of pulsed signals with pulse duration down to about
100 s.
The system communicates with an external controller (e.g. a personal computer) via RS232 or CAN Bus interface,
the latter being implemented in SD-2000. Another function implemented in SD-2000 is a full control (MC in Figure
1) of three stepper motors for the purpose of automatic impedance matching.
Residing inside SBC is Homer firmware, which is a system of files that control its operation and behavior. The
firmware consists of an assembly of executable files (Servers), memory files (containing individual information, like
system identity and calibration data) and auxiliary configuration files, defining Homer startup behavior. One of the
Server program at a time runs in SBC, performing all tasks associated with acquiring data, computations of results,
receiving commands from PC and sending responses and measurement results. The results include real and
imaginary part of measured and load (deembedded) reflection coefficients, power incident on and reflected from
DUT, frequency, internal temperature and error byte. In case of Autotuner the data include tuning stub positions and
motors status. The configuration files, read by Server at its start, contain various Homer power-up settings.
While the configuration files can be transferred from one Homer to another to assure the same startup behavior, the
memory files are strictly individual. An attempt to transfer them to a non-native Homer results in raising Homer
Identity Error and refusal to perform except some basic operations like file transfers.
More about the firmware see in Homer Internal Files.
The Windows HomSoft application described in this document enables full Homer control, receiving of results,
converting them to a variety of formats, displaying and storing them, as well as long-term monitoring and data
logging.
Learn also about Homer Analyzer measurement accuracy.
Homer Versions
Many Homer Analyzer and Autotuner versions exist. They differ by the following main parameters:
Frequency range (ISM band)
- 900 MHz (subbands 896 MHz, 915 MHz, 922 MHz)
- 2.45 GHz
- 5.8 GHz
Transmission medium
- Waveguide
- Coaxial
Waveguide type
Coax dimensions
RS serial communication interface
- RS232
- RS422
Maximum input power (can be ordered by customer)
User's Handbook Homer Hot Measurement and Tuning System Introduction 5