A spectrum analyzer is a measuring instrument used to measure the relationship between the amplitude and frequency of a RF signal, and is typically used for frequency domain measurements. The instrument commonly used for time domain measurements is an oscilloscope. The spectrum analyzer can be used to measure frequency, power amplitude, harmonics, bandwidth, and other RF signal related parameters.
One of the most important test items I have conducted frequently at ARRL Labs is the testing of out-of-band radiation indicators for transmitters or amplifiers. During the testing of this indicator, the difference in level of all harmonics and spurs relative to the fundamental (carrier) signal of the transmitted signal is measured. Typically we test with a metered Agilent/HP 8563E spectrum analyzer with a frequency range from 9 kHz to 26.5 GHz. The HP 8563E is a very accurate, laboratory-grade professional instrument, but its price will be daunting for most ham and electronics enthusiasts. Even a lab-scale spectrum analyzer, such as the second-hand HP 8563E, usually costs tens of thousands of dollars, and fans are often unable to afford the price range.
Figure 2 In the lab, we use 1~2 high-power attenuators and 1 step attenuator to attenuate the signal power of the transmitter under test to a safe power level that the test instrument can accept (usually adjusted to 1mW) Left and right). The DSA815-TG is used to test the fundamental and harmonic signals transmitted by a 2m hand station.
in conclusion:RIGOL's DSA815-TG is a lightweight spectrum analyzer that is affordable to experienced electronics enthusiasts and field service engineers. It can also be used in radio activities for radio enthusiasts.
RIGOL (Beijing Puyuan Jingdian Technology Co., Ltd.) is a Chinese company that has emerged in the field of test and measurement in recent years. Its products have been widely sold worldwide. RIGOL recently introduced a spectrum analyzer model DSA815 with frequency coverage from 9 kHz to 1.5 GHz and pricing in the US starting at $1,295. The spectrum analyzer was advertised in QST magazine and was also shown at several ham festivals. Many members of ARRL consulted us about this instrument and they felt that this spectrum analyzer was "unbelievably good." As a test engineer, I am also curious as to whether this is true or not, so our product review editor ordered a DSA815-TG with a factory pre-installed tracking source for $1,495 (excluding tax) ).
OverviewRIGOL's DSA815 is a very compact instrument with a handle on the top of the main unit and weighs approximately 9.4 pounds (about 4.25 kg). It is suitable for both laboratory and portable mobile use. The instrument's 8-inch color LCD screen occupies the main area on the front panel with a resolution of 800 & TImes; 480 pixels. The vast majority of the control buttons of this spectrum analyzer are similar to other higher-priced instruments of the same type, so anyone familiar with the spectrum analyzer can easily understand the use of the underlying functions.
You don't need to pass the common GPIB interface on most old-fashioned professional spectrum analyzers. Using the USB master-slave interface on the DSA815 and the dedicated PRINT button on the control panel, you can easily get the spectrum curve and related information of the screen display. Instrument setup data. (GPIB - General Purpose Interface Bus - also known as IEEE488 bus. RIGOL provides a USB to GPIB converter option.) I really like its reversible front support foot design, which makes the instrument support The operation on the table is more ergonomic. The side of the instrument has venting holes and the fan of choice is also quiet.
There are two 50Ω characteristic impedance N-type connectors on the front panel for RF input (PUT) and tracking source output (GEN OUTPUT). In addition to the AC power socket on the rear panel, there are USB and LAN interfaces, as well as three BNC connectors for input, output and trigger signal input of the 10MHz reference signal. From the outside, the whole machine design is very sophisticated and modern. I don't know what the internal functions and performance are.
Although I have not been able to disassemble and analyze this instrument (which will affect the calibration accuracy), according to the manufacturer's explanation of RIGOL, "DSA815 uses all-digital intermediate frequency technology (using DSP technology for digital signal processing), making the spectrum analyzer The background average noise level is reduced while achieving a smaller resolution bandwidth setting. The instrument's minimum resolution filter bandwidth is 100 Hz. The use of all-digital IF technology can greatly reduce the complexity of the hardware circuit, and this is one of the reasons why the structure of the whole machine is very compact. The instrument's frequency range is from 9 kHz to 1.5 GHz and is suitable for testing most amateur radio equipment. RIGOL also offers other series of spectrum analyzers (DSA1000A series) that can cover frequencies up to 3 GHz with higher sensitivity and narrower resolution bandwidth.
In the ARRL laboratory, our RF shielding rooms and associated test equipment are primarily used to test common amateur radio equipment and do not have the conditions to test other laboratory equipment. To verify that the DSA815 instrument performance metrics meet the manufacturer's stated specifications, I sent the instrument to the Essco Metrology Laboratory in Chelmsford, Massachusetts, which provides annual metering services for test instruments in our laboratory. . Essco checked all the performance specifications of the instrument and quickly posted the metering label and sent it back to the ARRL lab. Table 1 lists the key performance indicators of RIGOL DSA815-TG. After testing, Essco also confirmed that its test results meet the “nominal†index.
Silicon Transistor are solid-state semiconductor devices with functions such as detection, rectification, amplification, switching, voltage regulation, and signal modulation. The transistor acts as a variable current switch and can control the output current based on the input voltage. Unlike ordinary mechanical switches (such as Relay and switch), transistors use electrical signals to control their opening and closing, and the switching speed can be very fast. The switching speed in the lab can reach more than 100GHz.
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