The Signal Hound series of spectrum analyzers are about as
small as three large-size Hershey chocolate bars stacked on top of each other.
The unit offered for review is the recently released model BB60C real time
analyzer, which can tune from 9 kHz to 6 GHz with a dynamic range of +10 to
approximately -158 dBm (DANL, which is dependent on resolution BW). It can
easily fit within a standard briefcase with room left over for a medium sized
laptop.
Figure 1 - The Signal Hound real time spectrum analyzer fits
easily into a standard briefcase.
So what does “real time” mean for a spectrum analyzer? In a
nutshell, it can display near instant frequency information in up to a 27 MHz
instantaneous bandwidth (IBW). The response is so quick, it can trap and
display intermittent signals with pulse width as narrow as 4 µs, with 1 µs
pulses only attenuated by 2-3 dB. The I/Q data stream is sent through the USB
3.0 port and data streams between 250 kHz to 27 MHz of amplitude-corrected
bandwidth may be viewed. The sweep speed is 24 GHz/sec with 1.2 million FFTs
per second Because much of the signal processing is performed within the PC,
you’ll need a pretty powerful computer. In fact the recommended setup would be
a PC running Windows 7 or 8, with an Intel i7 (3rd generation (Ivy Bridge) or
later with a quad core processor, 8 GB RAM, one USB 3.0 port and one adjacent
USB 2.0 or 3.0 port, and OpenGL 3.0 capable graphics processor. While my Mac is
a pretty fast machine and can display the GUI interface and waveform OK, some
of the display text is jumbled, making it tough to determine the frequency and
bandwidth parameters. So, I’ll borrow a Dell inspiron 17-inch laptop to
continue the review.
So, what’s in the box? The well-packed BB60C, of course, a
CD-ROM with the drivers and operating software and a special dual USB 3.0 cable
that connects and fully powers the unit. Be sure you have at least two USB 3.0
ports on the same side of your laptop, as this special cable has a Y-adapter
that won’t reach from one side to the other of most laptops. I had to purchase
a USB extension to try it out on my Macbook Pro. The user manual is
automatically downloaded to C:\Program Files\Signal Hound\BB60\manuals or it
may be downloaded from the Signal Hound web site.
Figure 2 - The analyzer, supplied CD-ROM and connecting
cable are included.
Architecture
The BB60C analyzer is based upon a two-stage superheterodyne
receiver. Two independent IF frequencies (1.26 and 2.42. GHz) are used based on
the tuned RF frequency. Distributed element notch filters are used to suppress
spurious responses. To reduce second-order intermodulation, push-pull
amplifiers are used to cancel even-order mixing. Direct conversion is used
below 10 MHz to avoid mixing products. The front end uses and preamp-attenuator
combination that has a spurious-free dynamic range better than 50 dB. The
14-bit ADC uses built-in dithering, which adds improved linearity as well as
decreased spurious IF responses. ADC spurs are typically less than 70 dB below
the carrier. From the ADC, the digitized IF data goes to an FPGA, where it’s
packetized and sent over a USB 3.0 port to the PC, where 80 million 14-bit ADC
samples per second are processes into a spectrum sweep or I/Q data stream.
Figure 3 - The system block diagram of the real time
analyzer. Courtesy Signal Hound.
Here are some primary specifications:
- Frequency range: 9 kHz to 6 GHz
- Streaming IF data: 250 kHz to 27 MHz real time analysis BW (amplitude corrected)
- Resolution bandwidth (RBW): 10 Hz to 10 MHz
- Internal timebase accuracy: +/- 1 ppm/year
- Sweep speed (RBW>10 kHz): 24 GHz/sec
- Amplitude range: +10 dBm to DANL
- Absolute amplitude accuracy: +/- 2.0 dB
- Displayed average noise level (DANL), (dBm/Hz, ref level -60 dBm, atten=0 dB):
- 9 kHz to 500 kHz: -140
- 500 kHz to 10 MHz: -155
- 10 MHz to 6 GHz: -159 + 1 dB/GHz
- LO leakage at RF input: -80 dBm
- Size: 8.63 x 3.19 x 1.19 inches
- Power: one USB 3.0 port and an adjacent USB 2.0 or 3.0 port.
Written by Kenneth Wyatt - July 08, 2014 Originally in EDN Network
