Signal Hound USB-SA44B User manual

USB-SA44B Spectrum Analyzer
User Manual

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Signal Hound USB-SA44B User Manual
2016, Signal Hound, Inc.
35707 NE 86th Ave
La Center, WA 98629 USA
Phone [phone] • Fax [phone]
This information is being released into the public domain in accordance with the Export Administration
Regulations 15 CFR 734

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Contents
1 Preparing for Use .............................................................................................................................................................. 1
2 Getting Started .................................................................................................................................................................. 2
3 Theory of Operation .......................................................................................................................................................... 7
4 Troubleshooting ................................................................................................................................................................ 8
5 Calibration and Adjustment ............................................................................................................................................. 9
6 Specifications ..................................................................................................................................................................10

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7 Warranty and Disclaimer................................................................................................................................................13

Preparing for Use |Initial Inspection
1
1Preparing for Use
Unpacking your Signal Hound and Installing Software
The Signal Hound USB-SA44B is a USB-based 1 Hz to 4.4 GHz economy spectrum analyzer and
measuring receiver with an RF preamplifier. Using recent innovations in RF technology, the Signal Hound
has the sensitivity, accuracy and dynamic range you’d expect in a unit many times its cost. The Signal
Hound is powered from the USB cable, eliminating the need for a separate power supply. Measuring
less than 8 inches long and weighing only ten ounces, the Signal Hound can be used virtually anywhere!
1.1 INITIAL INSPECTION
Check your package for shipping damage before opening. Your box should contain a USB cable, a CD-
ROM, and a Signal Hound USB-SA44B.
1.2 SOFTWARE INSTALLATION
The Signal Hound is operated from a Windows®-based PC using our SpikeTM application software.
The Signal Hound software and drivers are compatible with 64 and 32-bit Windows®7/8/10 operating
systems. 64-bit Windows operating systems are recommended. You must have a computer with at least
500 MB of free disk space, 4 GB of RAM, and USB 2.0. An Intel®Core i3 or equivalent is recommended.
For serial numbers below 21000000, an internet connection is required the first time you launch

Getting Started |Front & Rear Panels
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the software. See the SpikeTM software manual for additional installation instructions and software
features.
Legacy software is available for 32-bit operating systems. Contact [e-mail] for further
information.
2Getting Started
Learn about the features of your USB-SA44B Signal Hound Spectrum Analyzer
2.1 FRONT & REAR PANELS
The front panel includes a 50Ω SMA RF input. Do
not exceed +20 dBm or damage may occur. A
READY / BUSY LED flashes orange each time a
command from the computer is processed.
The rear panel has three connectors:
1) 10 MHz Reference input, automatically detected
after each sweep completes. Use a clean 10 MHz
reference with >0 dBm level. +13 dBm is
recommended.
2) A USB type B connector. Connect to your PC
using the included USB cable.
3) A multi-purpose BNC connector. This may be
used as a Self Test Signal output, a Tracking
Generator Sync signal, or a TTL/CMOS trigger/sync
in some legacy modes. The Signal Hound software
controls the function of this BNC. It defaults to
unused / no output.

Getting Started |Front & Rear Panels
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Getting Started |Measurement Capabilities
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2.2 MEASUREMENT CAPABILITIES
The Signal Hound is capable of making a wide range of measurements, with resolution bandwidths from
less than 1 Hz to 250 kHz. The internal I/Q demodulator captures up to 2 Megabytes of information each
second, with a hardware-limited bandwidth of 250 KHz. Sweeps with spans greater than this are actually
a combination of many smaller sweeps, mathematically combined to reject image and spurious
responses.
2.2.1 Image and Spur Rejection in Swept Mode
The USB-SA44B does not have hardware-based image rejection, instead relying on a software algorithm
to reject image responses. The algorithm mixes the incoming RF with two distinct local oscillator
frequencies, typically spaced by 21.4 MHz and up to 100 milliseconds, and rejects responses not present
in both. This algorithm has some limitations:
1. A signal must be present for both captures to be displayed. Pulsed or swept signals, which do
not stay at any given frequency for this duration, will be rejected as potential image or spurious
responses.
2. An analog modulation envelope may be clipped, since certain frequency components of the
modulation envelope may not be present at both times. Most digital modulation tends to spread
energy evenly across its bandwidth and is relatively immune from this effect.
3. Two RF input signals, spaced by 42.8 MHz, will generate a spurious response halfway between
the two RF input signals. This spurious response will not be present when a 200 kHz span is
selected. Broadband signals which exceed 42 MHz cannot be accurately measured with the USB-
SA44B because of this effect.
Disabling image rejection will allow pulsed and swept signals to be displayed, and will not clip
modulation, but image and spurious responses may be a major problem for some measurements. If
your application requires hardware-based image rejection, consider our BB60C.
Wide sweeps of strong signals, especially at frequencies above 1 GHz, may have noticeable fractional-N
spurs. To avoid these spurs, set your span to 200 kHz or less. In this narrowband mode, the incoming
signal is mixed using two distinct local oscillator frequencies with different frac-N modulus settings, to
two distinct intermediate frequencies, such that fractional-N spurs are completely masked out.
2.2.2 Real-Time Mode
The USB-SA44B can continuously stream up to 250 kHz of spectrum to the SpikeTM software running on
your PC or laptop. Real-time mode displays this stream of data in the frequency domain.
For modulated signals not exceeding 250 kHz bandwidth, real-time mode is recommended, as it will
capture and display the modulation envelope using overlapping FFTs, showing you an accurate
representation of the modulation envelope. All modulation types, including pulse and short digital RF

Getting Started |Limitations of the Signal Hound
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packets, will be displayed accurately in this mode. Other modes will work, but modulation details may be
masked out by the image rejection algorithm, and pulses and short packets may be missed entirely.
Image rejection is not available in this mode, therefore the image frequency, 21.4 MHz above the signal,
will not be suppressed, and spurious responses may be present.
2.2.3 Zero Span Mode
For modulated signals not exceeding 250 kHz bandwidth, time-domain amplitude, frequency, and phase
information, as well as several modulation measurements, are available in Zero Span mode. See the
SpikeTM manual for additional information. Image rejection is not available in this mode, therefore the
image frequency, 21.4 MHz above the signal, will not be suppressed, and spurious responses may be
present.
2.2.4 Attenuator, Preamplifier, Intermediate Frequency and
Gain, and ADC Clock Settings
The Signal Hound switches between two intermediate frequencies, four attenuator settings, two
preamplifier settings, two ADC clock frequencies, and three IF gain settings when measuring signals and
performing image suppression. Unless you explicitly disable the automatic settings, the best settings for
your reference level, center frequency, and span will be automatically selected. Simply select a reference
level that is a few dB above the input signal level.
2.3 LIMITATIONS OF THE SIGNAL HOUND
2.3.1 RBW Limitations
The maximum resolution bandwidth (RBW) of the SA44B is 250kHz, and the minimum is 0.1Hz. There
are additional restrictions on RBW depending on span and start frequency.
For spans between 201kHz and 99MHz with a start frequency above 16MHz, the RBW can be set
between 30Hz and 250kHz.
For spans larger than 99MHz or sweeps that start below 16MHz, the RBW can be set between 6.5 kHz
and 250kHz.
All RBWs are available for spans 200kHz or less.
Outside of these limitations, a 5MHz RBW is available through the use of an internal power detector. The
power detector can only be enabled with a start frequency and span above 200MHz.
To measure wider bandwidths, the channel power utility must be used. See the SpikeTM software manual
for additional information on channel power.

Getting Started |Limitations of the Signal Hound
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A traditional 1-3-10 RBW sequence is used by default in Spike, but any RBW up to 250 kHz may be
selected.
2.3.2 IF Feed-Through
Intermediate frequencies of 2.9 MHz and 10.7 MHz are used for all frequencies. An RF input signal near
these frequencies may generate spurious responses and degrade the performance of the image
rejection algorithm.
2.3.3 LO Leakage
A Local Oscillator signal may be observed at the RF input port, often found 10.7 MHz above the RF
frequency being scanned. Typically, this level will not interfere with your measurements. If you are
connecting to an antenna, set your reference level to -30 dBm to activate the preamplifier to minimize
LO leakage.
2.3.4 Sweep Time
Sweep Time may only be set in zero span mode. In all other modes, the minimum sweep time which
satisfies your RBW, VBW and span settings will be used.
2.3.5 Using an External Timebase
An external 10 MHz timebase my be used to improve the accuracy of frequency measurements. The
level of the external timebase must be > 0 dBm. +13 dBm is recommended to achieve optimal phase
noise performance. To use, simply connect the timebase to the Ext Ref In after connecting the USB,
then select external reference in the SpikeTM software.
2.3.6 Using Sync Out / Trigger In
A 3.3V CMOS output may be used to synchronize the USB-SA44B to the TG44A or TG124A tracking
generator. Legacy software allowed some additional triggering options available for a very limited range
of applications, but these have been removed to enhance the stability of our new platform. Consult the
appropriate manual for additional details.
2.3.7 Measuring Low Level Signals
To measure low-level signals, simply set your reference level to -40 dBm or lower. This internally selects
the highest sensitivity settings. Video averaging may be required for a stable amplitude reading.
2.3.8 Measurements near DANL
The amplitude displayed is the sum of all energy present in the IF. This includes the signal as well as
noise and residual responses. Measurements of signals less than 10 dB above the noise floor will have a
measurable amplitude error due to the addition of noise. To compensate for this, subtract the

Theory of Operation |Limitations of the Signal Hound
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amplitude with no signal present (the noise), in linear power units, from the amplitude with signal
present, to calculate the signal level. Please note that the measurement uncertainty will increase from
this process.
3Theory of Operation
Learn about the internal blocks that make up the Signal Hound
The Signal Hound is built around a narrow-band IF-to-bits receiver with a maximum bandwidth of 250
KHz. It receives up to 2 Megabytes of I/Q data each second, which it processes into a trace. To bring you
a low cost, compact spectrum analyzer, we used high-level RF integrated circuits. The block diagram,
below, illustrates the major elements of the design. Image rejection is accomplished by mixing high side
and low side (sometimes with separate IF frequencies), then masking together the results.
Figure 5: Simplified Block Diagram
3.1.1 Operating Modes
I/Q streaming: This is used for real-time mode (frequency domain) and zero span mode
(time domain). In this mode, the USB-SA44B continuously mixes a fixed LO frequency with
the RF input and streams the data to the PC or laptop for processing.
Narrowband Sweep: This mode is used for spans of 200 kHz or less. In this mode, a fixed,
predetermined amount of I/Q data is captured at two distinct combinations of LO and IF
frequencies, then combined into a single trace for display. There are minimal restrictions
on RBW.
Midrange Sweep: For spans of 201 kHz to 99 MHz with a start frequency above 16 MHz, the
firmware captures between 256 and 65,536 I/Q samples at each 200 kHz step, allowing
RBW / VBW settings of 30 Hz to 250 kHz.
Wide Sweep: For all other spans, the firmware captures 256 I/Q samples at each 200 kHz
step, meaning RBW and VBW must be 6.5 kHz or higher.
Broadband Sweep: 5 MHz RBW, only available above 200 MHz start frequency. Rapidly
sweeps across the spectrum, to find a strong signal quickly. Certain RF frequencies may
produce spurious responses in this mode, and amplitude accuracy is reduced.

Troubleshooting |Limitations of the Signal Hound
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3.1.2 Reducing Spurious and Residual Responses
Certain RF frequencies may produce small spurious and/or residual responses. To verify a displayed
signal, center it and step the span from 1 MHz down to 100 KHz. If it is not present in both spans, it was
likely a spurious mixing artifact or a harmonic from a system clock. To avoid known residual responses
at multiples of the primary system clocks, a secondary clock frequency is selected for some frequencies
when span is 200 KHz or less.
The mixers can typically operate with up to +0 dBm input, but keeping the input level –25 dBm or lower
will greatly improve linearity, reducing harmonic and spurious mixing products. You can accomplish this
in software by setting your reference level 15-20 dB above your actual input level.
3.1.3 IF-to-Bits Receiver
The IF-to-bits receiver has three gain ranges. The gain range will be automatically selected based on
attenuator settings and reference level to avoid IF ADC compression, which will greatly distort the data.
The software should warn you if compression is occurring. If this happens, increase your reference level.
3.1.4 IF and RBW Selection
The I/Q data comes in over USB and is processed using an FFT with a custom Flat Top window based on
the selected RBW. Software and firmware limitations only allow certain very low or very high RBWs for
certain spans, to keep sweep speed and trace size reasonable. For example, an RBW of less than 30 Hz is
only allowed for spans of 200 kHz or less, and the minimum RBW for spans of 100 MHz or more is 6.5
kHz. See the SpikeTM manual for additional information. The available RBWs are a function of the span,
since very large RBWs with a small span would result in a trace with only a few data points and a blocky
appearance, and very small RBWs with a large span would result in a large data set that would be
difficult to manage and process.
4Troubleshooting
If you experience a problem with your Signal Hound, please try these troubleshooting techniques before
contacting us:
1) Your Signal Hound Is Not Sweeping Properly
Try this first: Close the SpikeTM software. Unplug the USB cable and any external 10 MHz
or trigger cables from the Signal Hound and wait 5 seconds. Plug the USB cable back in.
Check that both ends of the USB cable are firmly seated and the Signal Hound LED is green.
Launch the SpikeTM Software. Try your sweep again.
Still not working? Contact technical support at http://www.signalhound.com
2) Your Signal Hound LED is off

Calibration and Adjustment |Limitations of the Signal Hound
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Make sure the USB cable is connected at both ends, your PC is on and the USB drivers are
installed properly.
Is your PC or laptop configured in low power mode? The Signal Hound is a high-powered
USB device and may be shut down in some power-saving configurations. To remedy
this, open your computer’s Control Panel, and change your Power Options setting to High
Performance.
3) Your Signal Hound doesn’t find a signal
Is it a swept or transient signal, a pulse or a rapidly modulated signal? If so, and you know
the frequency of the signal, set up for a 200 KHz span or less, then turn “spur reject” off.
This disables the image rejection algorithm which will reject data if it has moved or
disappeared when the image is checked (it also allows the image frequency through, which
is 21.4 MHz above the CENTER FREQ). You may also try MAX HOLD to capture transient
signals.
4) Your phase noise seems too high
You may consider using a low phase noise external reference or contacting us about lower phase
noise options. Be aware that the Signal Hound phase noise is noticably higher than a YIG-based
spectrum analyzer, especially at higher frequencies.
5) You receive a specific error code
Error 1: Your Signal hound was not found on a USB port. Plug in your Signal Hound if it isn’t already.
If it is already plugged in, unplug it, reboot, re-install the USB driver, and/or try a different USB port.
Error 2-6: A USB communications error occurred. If multiple errors occur, close out of the software,
unplug the Signal Hound, wait 5 seconds, plug it back in and try again. If you get a recurring error,
please make a note of the error number, and e-mail or call tech support.
6) General Advice to avoid problems
Use a DC block and limiter to protect your Signal Hound from DC voltages, ESD, and excess
RF power. This is especially important when connecting to antrennas or unknown signals.
Do not overpower the Signal Hound.
5Calibration and Adjustment
Contact Test Equipment Plus for more information regarding calibration services, or our free calibration
software and required equipment.

Specifications |Frequency
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6Specifications
Unless otherwise stated, specifications are valid for an ambient temperature range of 0 to 70°C (or -40 to
+85°C for option 1), image rejection on, amplitude of signal applied less than the reference level, and a
supplied USB voltage to the device above 4.39V.
6.1 FREQUENCY
Frequency Range
1 Hz to 4.4 GHz, Standard
100 kHz to 4.4 GHz AC-coupled, Option 3
Span Modes
(Center Frequency + Span) or (Start + Stop Frequencies)
Maximum Span
4.4 GHz
Minimum Span
10 Hz or Zero Span
Internal Frequency Reference
Accuracy
1 ppm
Note: For greater frequency accuracy connect to external 10 MHz
timebase (0 to +20 dBm)
Frequency Readout Accuracy
reference error 1 sample (1)
Marker Accuracy
reference error 1 sample
Resolution Bandwidth
0.1Hz to 250KHz and 5MHz(2)
Spectral Purity
Residual FM, 3KHz Audio LPF, 15 KHz IF BW: [0.1 Hz + 4 Hz / GHz]
typical RMS FM (e.g. 2 GHz RF would have 8.1 Hz RMS FM).
Increasing IF BW increases residual FM.
Note 1: 1 sample represents approximately 40% of the selected
RBW
Note 2: 5 MHz RBW accuracy not specified, and is available only in
legacy software.
6.2 AMPLITUDE (RBW ≤100KHZ)
Range
1dB Gain Compression to Displayed Average Noise Level (DANL)
1dB Gain Compression
(attenuator set to 15dB, preamp off)
+16dBm Typical, 1Hz to 150MHz (100 kHz to 150 MHz, Option 3)
+19dBm Typical, 150MHz to 4.4GHz
Displayed Average Noise Level
0dB input attenuation, 1Hz RBW

Specifications |Sweep
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Frequency
RF Preamp Off
RF Preamp On
10Hz
-124 dBm(1)
NA
100Hz to 10KHz
-130 dBm(1)
NA
10KHz to 500KHz
-142 dBm(1)
NA
500KHz to 10MHz
-142 dBm
-153 dBm
10MHz to 100MHz
-148 dBm
-161 dBm
100MHz to 1GHz
-144 dBm
-158 dBm
1GHz to 2.6GHz
-139 dBm
-151 dBm
2.6GHz to 3.3GHz
-135 dBm
-151 dBm
3.3GHz to 4.4GHz
-128 dBm
-134 dBm
Note 1: Option 3 is unspecified below 100 kHz
Absolute Accuracy (Reference
level ≤0 dBm)
1.5dB
Absolute Accuracy (0 dBm <
Reference level ≤ 10 dBm)
2.0dB
Relative Accuracy (Reference
level ≤0 dBm)
0.25 dB
Maximum Safe Input Level
(preamp off, 15 dB atten)
+20dBm
DC Volts
< 0.2V absolute maximum (16VDC, option 3)
Residual Responses (Input
terminated, ≤100 KHz span, 0 dB
atten, preamp on)
<-80 dBm 1
Note 1: Known residual responses at multiples of 10 MHz
Spurious Responses (≤100 KHz
span, CW tone input)
< -80 dBm typical
Typical Maximum LO Feedthrough (preamp on, attenuator
set to 15 dB)
1Hz to 500KHz*
-70 dBm
500KHz to 1GHz
-57 dBm
1GHz to 2.3GHz
-47dBm
2.3GHz to 2.6GHz
-40 dBm
2.6GHz to 3.0GHz
-27 dBm
3.0GHz to 4.4GHz
-35 dBm
*RF Preamp Off and Internal input Attenuator on any setting
6.3 SWEEP
Zero Span Sweep Time 0.1 ms to
10 sec
0.1%
All other sweeps times are estimates reported after sweep

Specifications |Measuring Receiver
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completes.
Maximum sample rate
486K/sec
Sweep Trigger
free run, single, video, external
External Trigger
3.3V CMOS/TTL input
6.4 MEASURING RECEIVER
FM Accuracy
1% typical
AM Accuracy
1% typical
Synchronous Level Detector (15
KHz IF BW, timebases locked)
100 KHz to 1 GHz +0 dBm to –125 dBm after 10 min warmup
0.25dB
1 GHz to 4.4 GHz +0 dBm to –115 dBm after 10 min warmup
0.25dB
Average Level Detector, 15 KHz
IF BW
100 KHz to 4.4 GHz +0 dBm to –70 dBm after 10 min warmup,
0.25dB
Maximum IF Bandwidth
240 KHz
Audio Filters
Low Pass: Digital Windowed Sinc, selectable cutoff
Band Pass: Available in version 2.xx legacy software only
Maximum sample rate
486K/sec
6.5 INPUTS AND OUTPUTS
BNC External Timebase
(10 MHz input)
BNC Shared
Self Test Output
SYNC Out
Sweep Trigger In (legacy software only)
SMA RF Input
6.6 ENVIRONMENT
Operating Temperature
0 to +70 °C (std), -40 to +85°C (option 1)
6.7 CALIBRATION
Test with factory calibration software to verify that USB-SA44B is operating within tolerance.
Recommended calibration interval is 1 year at 20°C to 25°C.

Warranty and Disclaimer |Adjustments
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6.8 ADJUSTMENTS
Factory adjustment software shall be used to generate new calibration constants when USB-SA44B will
not pass calibration. Temperature correction data is generated only at time of manufacture.
6.9 OPTIONAL ACCESSORIES
1. 20dB Fixed Attenuator, Mini Circuits Part # VAT-20+
2. DC Block, Mini Circuits Part # BLK-89+
3. SMA(m) to BNC(f) Adapter, Mini Circuits part# SM-BF50+
4. 3GHz RF Probe, p/n P-20A (made by Auburn Technology,
(www.auburntec.com)
6.10 FCC COMPLIANCE
This device is exempt from FCC Certification under 47 CFR Part 15.103(c).
6.11 CE COMPLIANCE
This device complies with the Class B limits of CISPR 11 and all relevant requirements of EN 61326-1:
2006.
7Warranty and Disclaimer
© 2015 Signal Hound. All rights reserved.
Reproduction, adaptation, or translation without prior written permission is prohibited, except as
allowed under the copyright laws.
7.1 WARRANTY
The information contained in this manual is subject to change without notice. Test Equipment Plus
makes no warranty of any kind with regard to this material, including, but not limited to, the implied
warranties or merchantability and fitness for a particular purpose.
Test Equipment Plus shall not be liable for errors contained herein or for incidental or consequential
damages in connection with the furnishing, performance, or use of this material. This Test Equipment
Plus product has a warranty against defects in material and workmanship for a period of one year from
date of shipment. During the warranty period, Test Equipment Plus will, at its option, either repair or
replace products that prove to be defective.

Warranty and Disclaimer |Warranty Service
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7.2 WARRANTY SERVICE
For warranty service or repair, this product must be returned to Test Equipment Plus. The Buyer shall
pay shipping charges to Test Equipment Plus and Test Equipment Plus shall pay UPS Ground, or
equivalent, shipping charges to return the product to the Buyer. However, the Buyer shall pay all
shipping charges, duties, and taxes, to and from Test Equipment Plus, for products returned from
another country.
7.2.1 Limitation of Warranty
The foregoing warranty shall not apply to defects resulting from improper use by the Buyer, Buyer-
supplied software or interfacing, unauthorized modification or misuse, operation outside of the
environmental specifications for the product. No other warranty is expressed or implied. Test
Equipment Plus specifically disclaims the implied warranties or merchantability and fitness for a
particular purpose.
7.2.2 Exclusive Remedies
The remedies provided herein are the Buyer’s sole and exclusive remedies. Test Equipment Plus shall
not be liable for any direct, indirect, special, incidental, or consequential damages, whether based on
contract, tort, or any other legal theory.
7.2.3 Certification
Test Equipment Plus certifies that, at the time of shipment, this product conformed to its published
specifications.
7.2.4 Credit Notice
Windows® and Excel® are registered trademarks of Microsoft Corporation in the United States
and other countries.