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Test Equipment Review . . . Gratten GA4063 3GHz Spectrum & GA1484B 4GHz Signal Generat The GA4063 Spectrum Analyser features a large colour LCD and has a basic frequency range from 9kHz to 3GHz. If you’re in the market for a spectrum analyser or a signal generator capable of working at the frequencies used by mobile phones, cordless phones, WiFi networking and so on, don’t restrict your search to instruments from the USA or Europe. These two new units from Atten Instruments in China are most impressive in terms of performance, build quality and value for money. N OT LONG AGO, it was almost a foregone conclusion that if you wanted a top-quality test instrument, you had to go to one of the ‘big name’ design and manufacturing firms in the USA or Europe. And when you found what you were looking for, you’d end up paying the proverbial ‘arm and a leg’ to buy it and get it delivered to your benchtop. But things started to change when 84  Silicon Chip the big US and European firms began to get their instruments manufactured in China, to their own designs. Before long, the Chinese firms acquired a great deal of expertise from contract OEM manufacturing, allowing them to expand into designing and manufacturing their own instruments. Soon they emerged as full-scale global players in the test instrument market, with brand names competing directly with those long established in the US and Europe. As a result, we now have an expanded range of test equipment makers to choose from, together with the benefits of stronger competition in the market, including prices held in check. The two instruments being reviewed here are excellent examples of this. They are both from Shenzen Atten Electronics Co Ltd in Shenzen PRC, which has been producing test instrusiliconchip.com.au Analyser or Review by JIM ROWE ments for some years using the brand name “Atten Instruments” but is now using the name “Gratten Technology”. But enough preamble – let’s take a look at the two instruments. GA4063 Spectrum Analyser Physically, this is the smaller of the two, housed in a compact portable case measuring 400 x 210 x 136mm (W x H x D) and weighing 7kg. It’s only a little larger than many of the current portable DSOs, yet offers a surprising range of features. For example, there’s a colour LCD panel with a diagonal dimension of 212mm and a display resolution of 800 x 480 pixels. But that’s only the start. The basic frequency range of the GA4063 is from 9kHz all the way up to 3GHz, with a span which can be varied between 100Hz and 3GHz with a resolution of 1Hz, as well as 0Hz (zero span). The resolution bandwidth (RBW) can be varied between 1Hz and 3MHz in 1-310 steps, while the video bandwidth (VBW) can be varied over the same range and with the same steps (but not necessarily locked together). An interesting feature is that the GA4063 has triggered operation with zero-span mode. This means that it can be used like an RF oscilloscope and can capture pulse patterns in bursts such as in car key-fobs etc. In addition, for narrow-band sweeps, it can operate in FFT mode with a small resolution bandwidth. This means that intermittently occurring signals anywhere in the band are captured. The GA4063 has an input attenuator range of 0-50dB, adjustable in 10dB steps. The maximum safe input level siliconchip.com.au The rear panel of the GA4063 carries three ports (USB host, Ethernet LAN & RS-232C), any of which allow the unit to be operated remotely. Also on the rear panel are three BNC sockets providing a triggering input, a buffered output from an internal 10MHz reference and an input for an external 10MHz reference. is +30dBm (7.07V RMS) with the input attenuator set for -20dB, for frequencies between 2MHz and 3GHz. There’s also an input preamplifier, covering the range between 100kHz and 3GHz. The analyser’s reference level can be set to any level between -100dBm and +30dBm, in 1dB steps (setting resolution 0.01dB). Input VSWR (voltage standing wave ratio) is less than 1.5:1 between 10MHz and 3GHz, with 10dB or 20dB input attenuation – very good for such a wide frequency range. The displayed average noise level (DANL) for the frequency range 10MHz-2.5GHz is -130dBm with the input preamp off, dropping to -148dBm when the preamp is turned on. For the low end (100kHz-10MHz), the corresponding DANL levels are -120dBm with the preamp off and -130dBm with it turned on. Similarly, for the high end (2.5GHz-3.0GHz), the DANL figures are -120dBm with the preamp off and -140dBm with it turned on. Typical phase noise with 10kHz offset from a 500MHz carrier is quoted as less than -95dBc/Hz, falling to below -100dBc/Hz at an offset of 100kHz and to lower than -120dBc/Hz for an offset of 1MHz. All of this is pretty impressive and compares very well with similar instruments from US and European makers, costing much more. Other nice features include a very flexible graphical user interface with a choice of ‘hard’ function buttons, ‘soft’ button menus, with a keypad or a rotary control to adjust settings; the ability to set up to four measurement markers; the ability to save traces, settings or screen images to internal flash memory; a ‘file manager’ which allows any of these files to be copied to a flash drive plugged into the frontpanel USB port and the ability to operate the GA4063 remotely via any of three ports on the rear panel – a USB host port, an Ethernet LAN port or an RS-232C serial port. Also on the rear panel are three BNC connectors which provide a triggering input for the GA4063, a buffered output from the internal 10MHz frequency reference and an input for an external 10MHz reference. The GA4063 is also available with an optional Tracking Generator, with its output made available at a second N-type socket on the front panel. The Tracking Generator has a frequency range from below 2MHz to 3GHz, with an output level which can be varied between 0dBm and -25dBm in 1dB steps. The output impedance is 50Ω, the same as the input impedance of the analyser itself. Power consumption of the GA4063 is typically 24W from any 100-240V AC mains supply (50-60Hz). The GA4063 comes with a User Manual, a Programming Manual, a power cable and a small plastic tool box containing a range of useful accesNovember 2013  85 The GA1484 Signal Generator features a large LCD panel to display the operating parameters. Its RF output can be adjusted anywhere from 250kHz to 4.0GHz with a resolution of 0.1Hz and is set using the keypad or varied using the rotary control at top right. sories: a number of N-type to BNC and SMA adaptors, an SMA-SMA coupler, three signal cables with SMA connectors on each end, a signal cable with BNC connectors on each end, a LAN jumper cable, a small whip antenna with SMA connector, two mains fuse cartridges and an 80mm CD-ROM with its labelling in Chinese – so I can’t be sure of the contents. It may provide a driver for interfacing the GA4063 with a PC. GA1484 Signal Generator The signal generator is somewhat larger than the analyser, measuring around 425 x 450 x 145mm (W x D x H) and weighing around 10kg. Clearly, it’s intended to be located on a benchtop, rather than lugged around for mobile testing. But like the GA4063, it offers a very impressive range of features along with performance of a high order. For a start, there’s a TFT-LCD panel measuring 178mm (seven inches) diagonally and used to display many of the operating parameters, along with the legends for the ‘soft’ function buttons just to the right of the display. There’s a keypad and a rotary control to input frequency, output amplitude and other parameters, plus eight ‘hard’ function buttons which are used to select RF output frequency, output level, modulation mode and level and so on. 86  Silicon Chip A further three buttons on the left select local/remote control, call up a preset configuration or ask for help (via the GUI). Three more buttons on the right control the RF Output (on/ off), modulation (on/off) and the LF output (on/off). The main RF output is via a standard N-type female connector at lower right, while the internal LF modulation oscillator’s output is also made available at upper right via a BNC connector. Before we leave the externals, there are no fewer than eight BNC sockets on the rear panel of the GA1484, with functions as follows: 10MHz internal timebase output, 10MHz external timebase input, external trigger input, sweep signal output, external pulse modulation input, internal pulse modulation output, external analog modulation input and internal trigger signal output. Also on the rear panel are the mains power input, a USB type B host connector, an Ethernet LAN connector and a GPIB connector. The last three are for remotely controlling and programming the GA1484 from a PC or other network controller. It’s in terms of performance that the GA1484 is particularly impressive. Its RF output can be set to any figure from 250kHz right up to 4.0GHz, with a resolution of 0.1Hz and a stability of better than ±1ppm for the ‘A’ version, or ±0.1ppm for the ‘B’ version. The frequency can be set directly using the keypad or varied from the current setting using the rotary control. The RF output level can be set to any figure between -127dBm (100nV) and +13dBm (1.0V), with a resolution of 0.01dB and an accuracy of better than ±1dB. The RF output is via an Ntype socket on the front panel, with an output impedance of 50Ω and a rated VSWR of below 1.8:1. The output level can be set in a range of units: dBm, dBµV, mV, µV, mVemf or µVemf. The rated SSB phase noise level at 20kHz offset from a 1GHz carrier is less than -105dBc/Hz for the ‘A’ model, and less than -115dBc/Hz for the ‘B’ model. The residual FM with zero modulation (CW) is less than 30Hz peak for the ‘A’ model and less than 10Hz peak for the ‘B’ model; this is for a 1GHz carrier and a bandwidth from 300Hz to 3kHz. There are four basic modulation modes: AM, FM, phase modulation and pulse modulation. In each of these modes, the modulating signal can be sourced from either an internal LF generator or an external source via one of the rear panel connectors. When the internal LF generator is used for AM modulation, the modulation depth can be adjusted to any level between 0% and 100%, with a siliconchip.com.au resolution of 0.1%. The modulation frequency can be adjusted to any value between 20Hz and 20kHz, with a rated distortion of less than 2% when modulating a carrier of 0dBm to a modulation depth of 80% at 1kHz. For frequency modulation, the frequency deviation range can be adjusted between 20Hz and 100kHz, while the modulation frequency can be adjusted between 20Hz and 80kHz. Rated distortion with a modulation rate of 1kHz and a deviation of 50kHz is less than 1%. For phase modulation, the modulation frequency can be varied between 300Hz and 20kHz. The phase offset range can be set between 0 and 10 radians with a modulation rate of below 10kHz, or between 0 and 5 radians for modulation rates between 10kHz and 20kHz. Rated distortion with a modulation rate of 1kHz and an offset of 5 radians is less than 1.5%. For pulse modulation, the pulse width can be adjusted between 400ns and 2s, while the pulse period can be varied between 1μs and 2s. The modulation rise and fall times are rated as less than 60ns, while the carrier on/ off ratio is greater than 60dB. As well as these standard functions, the GA1484 offers another very useful facility: frequency sweeping. Here too it’s very flexible, giving you the ability to set the start and stop frequencies, the output power/amplitude at both the start and end of the sweep (separately), the number of ‘dwell’ points between the two (2 - 100+), and the dwell time at each point (minimum 1ms). The spacing can be set to be either linear or logarithmic. It’s also possible to sweep through a list of designated frequencies, instead of a series of regularly-spaced points. The GA1484 is supplied with a User Manual, a Programming Manual and a power cable. Fig.1: this screen grab from the Gratten GA4063 Spectrum Analyser shows the “raw” output spectrum from the 125MHz crystal oscillator in the ‘LF-HF UpConverter For SDRs, as published in June 2013. Note the harmonics up to 1GHz. Fig.2: the same signal after filtering, before it is fed into the mixer chip. Note that all harmonics have been attenuated below the -60dBm level. Trying them out Thanks to Gratten Technology’s Australian representatives, Trio Test & Measurement, we were able to check out both instruments at the same time. As a result, we were able to use the GA4063 to check the performance of the GA1484, at least for frequencies below 3GHz, as well as using GA4063 to look at a variety of other signals – eg, from WiFi routers, 2.45GHz cordless phones and other devices. We could also use it to check the harmonics of the 125MHz crystal siliconchip.com.au Fig.3: here the GA4063 Spectrum Analyser is showing the output from the GA1484 Signal Generator, with the latter set to 920MHz and an output level of -127dBm (= 100nV). November 2013  87 The rear panel of GA1484 Signal Generator carries eight BNC sockets: 10MHz internal timebase output, 10MHz external timebase input, external trigger input, sweep signal output, external pulse modulation input, internal pulse modulation output, external analog modulation input and internal trigger signal output. Also on the rear panel are a USB-type B host connector, an Ethernet LAN connector and a GPIB connector, any of which can be used for remotely controlling and programming the GA1484 from a PC or other network controller. oscillator in our LF-HF Up-Converter for SDRs (SILICON CHIP, June 2013) and also the performance of the LC filter we used to ‘clean up’ the oscillator output to get better cross-modulation performance from the balanced mixer. We were also able to use the GA4063 with its inbuilt tracking generator to measure the performance of various cables over the frequency range 9kHz3GHz, as well as that of the UHF input amplifier stage in one of the prototypes of the SILICON CHIP 12-Digit Frequency Counter (December 2012-January 2013). In short, we gave both instru- ments a fairly thorough work out. Our basic conclusion is that both instruments stack up very favourably against broadly comparable instruments from the hitherto ‘big name’ manufacturers, in terms of both performance and build quality; especially when you consider their significantly lower cost. The only minor criticisms we could make with regard to both instruments is the degree of clarity in their User Manuals, which does leave a bit to be desired. A few more chapters in each manual walking you through various Fig.4: a sweep over the GA4063’s full frequency range, up to 3.0GHz, with the Tracking Generator output connected directly to the Spectrum Analyser’s input via a 1-metre length of RG213 cable, with SMA connectors at each end attached to N-type/SMA adaptors. Some of the loss at the top end is attributable to the cable and its connectors. 88  Silicon Chip common measurement set-ups would certainly not go amiss. Overall, both instruments are pretty good in terms of the English clarity of their GUIs and menu systems. I noticed only one small transgression with regard to the GA4063 Analyser, when the File Manager is used to copy screen image files saved in its internal flash memory to a USB memory stick plugged into the front-panel socket. During the ‘paste’ operation, a dialog flashes on the display with all text displayed in Chinese – just slightly baffling to those of us not fluent in it. After a while you get used to it, of course. Similarly, I did notice that when you are sweeping with the GA1484, the main frequency display at upper left on the screen remains fixed at the last frequency the generator was set to before sweeping. The start and stop frequencies are displayed in small print over on the right next to their soft buttons. It would be less confusing if the main frequency display changed to either the start or stop frequencies as well. My only other criticism is that whereas the GA4063 comes complete with a little tool box with some handy cables and adaptors etc, the GA1484 doesn’t even come with a single output cable. A bit minimalist . . . You’ll find further information on either of these instruments at the Trio Test & Measurement web site, www. triotest.com.au Or contact them by SC phone at 1300 853 407. siliconchip.com.au