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.
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