By Kiriakos Triantafillou ©2014 March 6 2014
Thanks to Miss Lily Cheung / sales manager of Twintex Electronics Co., Ltd, ITTSB is now able to present the first review of this TFG-3620E arbitrary function generator.
By getting in my hands this fresh GDS-2102A oscilloscope, I did gain access in the world of waveforms and fast pulses.
My PHILIPS PM5134 analog function generator despite it production date (old product) it did helped me allot to discover my new oscilloscope in the essence of functionality, response and capabilities.
Even so among the good stuff I did discover and the limitations of the analog design as for example the long warm-up times of 20 minutes and the difficulty to set your settings with precision.
The very modern digital function generators they do promise far more control.
Their keyboard aloud us dialing in numbers for setting or adjusting parameters, their in color TFT screen improves even further the over all experience of a fresh time user, and finally their fast warm-up time’s for acceptable stability it makes them an more attractive choice.
The Direct Digital Synthesizer technology have further advance in our times.
Among the new advantages is the ability to generate arbitrary waveforms, and even come with additional options as for example PC connectivity with serial or USB communication ports, and even come with options as for example USB stick data sharing or even with frequency counter.
An arbitrary waveform generator is a highly flexible signal source that generates any arbitrary waveform that has been constructed point-by-point in digital memory, and this provides unlimited flexibility to the user to create custom waveforms not available as presets on the instrument.
My plan about this review of TFG-3620E, is to discover and verify how well this product stands according my personal expectations by using simple descriptions and technical facts which will not scare away the lesser informed readers regarding function generators.
At this point I will make a statement so to pleasantly surprise even further my readers.
I was a RF guy for fifteen years in HF & VHF band, it started as hobby in 1986, later on I did engage in assembling FM band transmitters with PLL synthesizer, RF cable assemblies, RF filters, and even to repair VHF communication systems.
I did stepped back from this section mostly due it poor profitability.
The rapid expansion of Internet caused one sudden shrinking regarding demand for RF gear, at list in Greece.
Twintex Instrument Ltd was established in 1998 as a professional test & measurement
instruments manufacturer with its own brand of Twintex.
With honesty, innovation and continuation as the core of enterprise cultural, Twintex has been gradually developed into a professional test & measurement instruments manufacturer, products including oscilloscope, function generator, DC power supply, basic test & measurement instruments and other professional instruments.
Apart from providing instrumentation solutions to domestic industries and education institutions with good quality and excellent price, Twintex has also established professional logistics and business center – Twintex Electronics Co., Ltd in 2009 in Shenzhen China to explore global market of instrumentation. Backing up by strong R&D force in Taiwan and manufacturing advantage in Mainland China, Twintex has been entering the world market with Twintex brand.
Twintex has more than 10 reliable and top-quality cooperating factories in Mainland China.
Twintex has presences in more than 30 countries to provide its products and services.
My very personal note about Twintex would be that I did fail to find any customer complains over the Internet for their products.
And also my cooperation with Miss Lily Cheung regarding the arrangements of shipping and customs clearance (sample send to Greece) was spotless and highly professional, a true clock work.
Regarding Twintex and their sales network in Europe, recently there are ties in Germany.
Therefore there is availability in Euro zone.
TFG-3620E is a relatively fresh design of DDS AWG first shown around 2011.
Among it strong points by the first look:
1) Ergonomic design
2) Color TFT display
3) Two channels
6) Up to 20 MHz in sine wave.
TFG-3620E comes with 100 MSa/s in channel A and 12.5 MSa/s in channel B, and by a total of 1024 points of memory (1k).
List of supplied accessories:
BNC-double alligator clip
EU - Mains Power cable
Printed instructions manual
The first think that I liked to TFG-3620E is the mechanical power switch.
These five seconds as boot time is amazing too.
Regarding external construction TFG-3620E comes with is a full metal case that is very long and a bit heavy.
Rubber pads and protection bumpers at front and back gives further positive impressions.
I am even impressed by the clarity of the TFT screen, in which I was afraid in the beginning that it would be hard to see from a distance, but viewing angle it is excellent.
This wheel selector looks robust enough, but in comparison with the size of my hands this plastic knob looks as medium sized, and I would prefer it to be a bit larger.
All push buttons are made by stiff enough rubber and offer an excellent feeling, which translates to easy and accurate control when pressing them.
TFG-3620E metal case is a bit long and heavy, but there is benefits coming even from that:
a) You may plug the BNC connectors at the front panel by a single handed move, when other lightweight equipment requires both hands.
b) The large metal case does not require active cooling by a fan, therefore less background noise in your bench.
Even after 5 hours of operation TFG-3620E just becomes a bit warm (in the back side of it case).
c) Regarding placing other equipment at the top of TFG-3620E, this is no issue either, especially if you own similarly sized equipment and you also favor the rack able Feng-Shui ( your tower will become just higher by maintaining it stability).
Basic features set.
32 pre-stored waveforms plus 8 user-defined arbitrary waveforms.
The first obvious finding is that there is no AM modulation.
As mentioned and above Direct Digital Synthesizer technology is capable to generate any standard wave form, and an arbitrary generator can generate complex (advanced) wave form, but AM modulation is far challenging to digitally generate.
Twintex it does offer too this step-up class of DDS with the TFG3500A Series Arbitrary Function Generator but in a higher price range.
Pre-stored waveforms list
20=Sin (x) / x
22=Duty cycle 10%
23=Duty cycle 90%
32=Pluse? (Again looks like 01=Square)
33= Arb stored wave 1
34= Arb stored wave 2
37= Arb stored wave 3
38= Arb stored wave 4
40= Arb stored wave 5
By all those fundamental waveforms at hand and by the additional controls regarding parameters, I believe that is does offer a rich set of test signals.
Among the winning features of TFG3600E series is the feeling of control which offer back to their user, you may modify any parameter with precision by a simple key press or alternatively by rotating the wheel (selector).
TFG3600E series have next to their TFT display two rows of push buttons.
The horizontal line is used mostly for selecting units of parameters as volts and fundamental frequency, or recalling back a specific waveform by it number.
The vertical line is used for selecting the actual parameter that you are interested to adjust.
Due this clear TFT display, every attempt setting a value or parameter is easy as handling a toy.
In about three minutes after using it for first time, I did manage to get the feeling of 70% control over this equipment.
Product Selection & specifications
Twintex made a great job in their DDS Selection Guide document, every reader by examining the specifications with a bit of patience and caution, gets the message that TFG3600E series is actually an up to 1MHz generator in most cases, and the highest frequency is possible only with sine wave (20MHz).
As design limitation it can be considered the fact that when both channels are active by generating pulse signals, the channel B bandwidth is limited down to 100 KHz.
Another important specification is the actual voltage output (amplitude) that TFG3600E series is capable to deliver.
According the data sheet:
2mVpp~20Vpp, 1μHz~10MHz (high impedance)
2mVpp~15Vpp, 10MHz~15MHz (high impedance)
2mVpp~ 8Vpp, 15MHz~20MHz (high impedance)
Voltage accuracy specification:
± (1%+2mV RMS) (high impedance, RMS, frequency 1 kHz)
Sine wave total distortion ≤1% (20Hz~200kHz)
By been aware that arbitrary waveforms require far richer sampling as frequency gets higher, or else the sample waveform cannot accurately reproduced, plus the fact that most challenging waveform is the named as sin(x)/x, I did started my testing with confidence.
Among the list of my tests is also basic accuracy regarding voltage, frequency, stability.
Amplitude adjustments & output in volts & Frequency
By powering on TFG-3620E every one will be pleasantly surprised by this rich in digits resolution of main parameters, more specifically it display 6 digits for frequency and four digits for voltage, and it does pass monetarily in your head the idea that it resembles to a calibrator.
Therefore it does feed your expectations about getting back ultimate performance in the regard of accuracy up to the last count.
The enemy of those wild expectations is always the offered specification.
This 1% looks enormous when you talk about high quality multimeter, but in the world of oscilloscope such accuracy specification is very acceptable if it is true.
For these measurements my setup was my new GW Instek GDS-2102A Oscilloscope, and due the fact that I wanted as much counts resolution as possible and accuracy, the very latest 60,000 counts HIOKI DT4282 it got connected in series too.
What I was interested for is mV RMS accuracy at the 100Hz sine wave, the selection of this fundamental frequency was by choice, I am aware that the range of 100 up to 200Hz as fundamental frequency for sine wave it is suggested for calibration /adjustment of multimeter.
What looks also interesting is the clicking sound of internal electrical relay, which helped me to find out how many circuits are assisting TFG-3620E so to offer a wide range of mV up to Volts.
1-5mV RMS (click)
6-59 mV (Click)
600mV - 7.071V
The results which I got from the measurements regarding accuracy in several settings they are very interesting.
1-5mV RMS tests: Set value = DMM measurement
1 mV = 0.98
2 mV = 1.93
3 mV = 2.88
4 mV = 3.85
5 mV = 4.85
6-500mV RMS tests: Set value = DMM measurement
6 mV = 5.91
7 mV = 6.90
8 mV = 7.83
9 mV = 8.84
10 mV = 9.80
20 mV = 19.600
40 mV = 39.423
50 mV = 49.539
100 mV = 97.63
200 mV = 195.38
500 mV = 493.64
600mV to 7V RMS tests: Set value = DMM measurement
600 mV = 613.1
1V = 1.016
2V = 2.033
3V = 3.048
4V = 4.090
5V = 5.139
6V = 6.195
7V = 7.234
In my attempt to interpret these results, I would say that definably there is no connection with the 1% specification at 4V and above.
And I did add in my calculations this 1% plus 2mV suggested by TFG-3620E specifications.
From the other hand this HIOKI DT-4282 at this voltage ranges comes with an accuracy of +/-0.3% reading with +/- 25 counts as offset, therefore my observations are correct due the fact that the multimeter is three times more accurate compared to TFG-3620E specifications.
But if you are dead serious regarding accuracy, TFG-3620E output it can manually adjusted with high resolution, which makes easy to manually compensate the output to any requested level, by trusting more the screen of an high quality multimeter with better accuracy in AC volts.
By testing the frequencies range of TFG-3620E I did feel that I am using a calibrator, and this finding filled me with lots of happiness.
Frequency is presented by six digits resolution, what amazed me other that all range is extremely accurate, is that any change in the last digit it is recorded on my external frequency counter too.
For gaining high display resolution I did use again as test setup, the 60,000 counts HIOKI DT4282, which helped me all the way from 2Hz up to 250 KHz, and then the Agilent U1273A helped confirming the output up to 1MHz, and my dedicated frequency counter by LEADER (Japan) with 150 MHz max range, helped me up to 20 MHz.
At this point I will say that Twintex Instrument Ltd. did a great job in the regard of accurate output in all frequencies range.
These great results drive me to perform even tests on my multimeter's at ridicules low frequencies as for example 300 & 500 mHz (that is half Hz).
Regarding the 1 uHz that is the slowest frequency, my multimeter's stopped measuring down to 300 mHz, but my oscilloscope it did continue following the DDS up to the point that the picture looked almost static (slow motion).
In the list of positive surprises offered by TFG-3620E to me, is the function of Duty Cycle.
The menu looks a bit as hidden (in the low right corner), and actually part of the secondary menus, in which you have to double press the button, so to show up.
As soon you get your way to it, TFG-3620E is capable to offer an amazing range of choices starting from 1% up to 99%, which is remarkable as finding.
Most budget DDS comes with out Duty Cycle function, or come with a limited range as 20% up to 80%.
Other than the full range of coverage in Duty Cycle, by using the wheel selector you gain back and the wonderful feeling of simplicity and speed, that only the good analog function generator are able to offer, due their dedicated potentiometer.
Naturally the strong point of modern DDS is about using their arithmetic keys as input, so to set the exact value that you need, therefore TFG-3620E is truly perfect by offering both combinations for setting it up, plus full range of Duty Cycle.
Overall the picture is so positive which I can almost ignore, the seven counts that TFG-3620E add by it self in the forth digit of duty cycle, for example 20.07% instead of 20.00% Duty Cycle (in all range).
Arbitrary waveforms / Mega samples / frequency limit.
As I did mentioned and above, the most challenging arbitrary wave form is the one named as sin(x)/x for any arbitrary DDS.
TFG-3620E has that stored in their menu as wave form Number 20.
In arbitrary mode TFG-3620E limits it bandwidth to 1MHz, my testing shown that even this limit is a bit optimistic.
According to my tests TFG-3620E started shown difficulty to accurately reproduce the wave form higher than 400 KHz.
What I actually witnessed was a perfect behaviour from lower frequencies’ up to 400 KHz, above that mark the wave form starts to degrade and as soon you get up to 1 MHz it is obvious that most low in amplitude parts of the waveform looked as flattened in the screen of my Oscilloscope.
I did try to increase the amplitude (volts) so to see if this move will improve things, but it did not.
At 400 KHz my 100 MHz oscilloscope works with full 2GSa/s sampling, therefore all detail coming from the TFG-3620E it is perfectly visualised.
From the other hand, my most demanding application which uses an arbitrary wave form will be the simulation of one wave form of AC that is the usual output of inverters.
And more specifically the wave form which causes issues to average measuring multimeter, therefore my range is between 50Hz up to 400Hz and TFG-3620E is totally capable for that.
Over all Noise & Distortion
In this regard I do not have any equipment so to perform in-depth testing, but by one in-depth reading of the User’s manual of Twintex, it becomes obvious that this AWG it does it best at 1Hz~200kHz.
Jitter & stability
I never forget that I am just inquisitive industrial Maintenance Electrician, and not some specialized engineer trained in evaluation of such complex instruments.
But I am good at finding answers and also good at working by observing even the finest detail.
One text of Teledyne Lecroy regarding Jitter it did pointed me in the right direction of what to look as sign of Jitter.
Also another educational text of B&K Precision Corp, regarding waveform frequency VS sample size, it did helped me too in understanding that the generation of high quality waveforms it is very hard to be achieved in high frequencies.
By combining all these information’s I did manage to confirm too the information offered by B&K that one 100 Mega samples equipment it can do it best regarding complex waveforms up to 30 kHz.
I did test both channels of TFG-3620E by using square wave and by carefully observing the screen of my Oscilloscope I did discovered the limits.
Channel A: at 100 Mega Samples were almost rock stable up to 30kHz and soft instability was starting above 35 kHz.
Channel B: at 12.5 Mega Samples were also rock stable but up to 3 kHz.
Regarding basic sine wave I did some comparisons from 5 MHz up to 20 MHz by my analog function generator & the TFG-3620E, and in that testing I did made an incredible finding that my scope supports alternative trigger function (trigger works in both channels at the same time) and I did start a small party with beers about it.
Regarding ultimate performance TFG-3620E displayed good stability up to 10MHz.
Above that 10 MHz mark TFG-3620E started shown the first signs of phase and amplitude instability and above 18MHz is not stable, when my analogue FG showed solid performance up to 20.4 MHz that is their top limit.
In summary from all my tests I did come down to some interesting conclusions regarding how TFG-3620E measure up? And even took plenty screen shots so to be evaluated by my readers eye’s too, by having use my oscilloscope's persistence display mode, so to record Jitter or instability.
And also at the end of my review there is even FFT measurements at 1 kHz & 10MHz too.
Below is on quick chart of frequency VS amount of displayed digits ( resolution)
100 MHz to 200 MHz = 6D (100,000 MHz)
100 kHz - 100MHz = 6D
10 KHz to 99.999 Hz =5D
1.000 Hz to 9.999 Hz = 4D (1,000 KHz)
100 Hz = 3D
10 Hz =2D
1Hz = 1D
My first comment would be that I would expect full resolution to all ranges.
But far more important seems my observation, that Display update rate very is slow, sampling looks almost between 1,5 ~ 2 times per second.
There is a trigger indicator (flashing icon) on the GUI (bottom left corner) which looks as out of sync above the 10ms and especially at 100ms / 250ms/ 500ms and up to 1 Second.
My impression of the frequency counter option is that is nothing remarkable to it.
Mostly because it can not compete in measurement update speed with a dedicated frequency counter, for example when it comes down to fine tune a FM PLL synthesizer your expectations are the counter to be ahead of your hand in speed, in order to adjust with accuracy even up to the less significant digit.
From the other hand, if you are not repairing demanding RF circuits and you do need an accurate frequency counter for basic verification, those 6 digits of resolution from 100 kHz up to 200MHz it would be nice to have.
Remote Control: standard RS232 interface
To be honest I did read the user manual regarding this remote control ability due command line but I did not move forward in testing it.
Mostly because the documented how-to, is not well explained for a first time user.
I did show as brave for a moment and started windows Hyper Terminal and try as experiment to establish an AT command communication, but it did not worked.
TWINTEX offer also complete remote control software with graphical interface which makes the remote control as far easier and inexpensive too, when compared to other far complex product solutions which require buying a software license.
Waveform builder software
I did passionately explore this piece of software, mostly because I think that this software package measure up allot even for real and even for educational applications.
My personal need was to use this arbitrary generator as source of modified sine wave, a simulator of bad quality sine wave that is generated usually by inverters with passive Power Factor Correction which is not that great.
All ACV average measuring multimeter, fail to measure this correctly and only True-RMS meters does the job.
Therefore I wanted more than anything to load such arbitrary waveform in this generator so to add further value to it as tool in my bench.
I did succeed and now I have a smile in my face, but it was not easy.
The supplied software comes with a poorly documented internal help file.
This Ultrawave.exe is a single executable which is unable to store any settings regarding serial communication ports.
Only the 70% of it features as wave builder editor work, and the 30% of it functionality is greyed out.
The work space is limited at 720 x 650 pixels.
While it does work for creating and uploading your waveform, the journey at doing that looks more like walking in a thin rope.
You need to follow specific sequence of actions, and some are not even documented.
a) By starting the software: You need to change the language to English by pressing the EN button at the task bar of it.
b) Select new file, so to get the pop up screen with parameters for voltage range and frequency range, by entering your parameters in it, then you are ready to start creating your waveform.
c) The software is limited to just one undo step, therefore be careful and save manually any successful step.
d) How-to Waveform upload, Sequence:
1) Tools -> Instrument selection -> MFG6000CH-> OK
2) Tools -> Communication ->
Serial address:88 ( do not change that this is also default preset at TFG-3620E)
Baud rate 19200 (do not change that, this is also default preset at TFG-3620E)
COM Port: My laptop is rather modern and does not come with serial port, and I did use an USB to serial adapter (which came with a BRYMEN data logging kit).
Because this software uses COM1 as default port, in order to avoid setting its and every time port settings, I did set this USB to serial adapter as default COM 1 port within windows operating system.
After doing so all that I would have to manually adjust is the setting called as download.
This setting is responsible for the destination of the waveform file.
TFG-3620E non-write protected presets, Wave number 33 up to 40 are available as destinations, therefore you select the destination and you press OK again.
3) Now press the communication settings icon in the software, if your COM port settings and parameters are correct, you will receive a pop-up window saying success, and TFG-3620E actual control panel gets locked because now works in remote control mode.
Now you may upload your own waveform on the TFG-3620E, but be aware to manually turn off the output of all channels prior setting the TFG-3620E in slave mode, in my tests some times the software crashed because of that by giving an error message and it was not responding normally after that.
It did not crash my computer, but it was need to be closed and restarted so to work back again.
One last tip that I have to offer is when you do freehand drawing is to lower down the DPI of your mouse pointer.
The files which are generated by this software are exclusively in *.txt format.
Their internal structure is rather simple but not simple enough for been edited by hand when they are 1024 positions of points.
When you do add parameters when you starting a new waveform sheet which will host the shape of your waveform, when the file it will uploaded on the generator these parameters are not maintained in the TFG-3620E.
Therefore if for example I create one sine wave at 3 kHz with 20Vpp, the stored preset at TFG-3620E will not include by default these settings when I recall the specific waveform, and I would have to manually adjust frequency and amplitude.
I did mentioned my discoveries to Twintex and their response were that currently there is no planning this software to further improve, their description as economy product it does tough and the very basic features offered by this software.
My comment would be that yes it works as is, but is not as user friendly as some one will expect.
The learning curve is about two hours, and if you have all your serial communication settings correct, by following it’s and every time the correct sequence of steps, you will manage to create and upload your own waveforms to it.
More updated versions of this Ultrawave software are used by RIGOL and Teledyne Lecroy, but are not backward compatible with TFG-3620E due the fact that the other versions are specially modified to support specific AWG equipment and other selections of saved waveform files format.
Even OWON uses software listed as Ultrawave which is something really different internally as software engine, it actual name is OWON control software 2.1.2.
I did download and test even Wavepatt from PICOTEST ltd., their software engine comes also close to Ultrawave.
What I did skip from download and test is the Agilent software because of the need for special additional file libraries which I do not wish to install in my PC.
In summary all similar to Ultrawave software offered by RIGOL, Teledyne Lecroy, PICOTEST, are more improved than the basic version of Twintex.
OWON gets the last position in this comparison.
Their AWG software solution looks tremendously poor due their very few options regarding editing tools, compared to that, the Ultrawave of Twintex looks as to be Adobe student version of Photoshop in small dimensions (far more complete).
The journey of exploring TFG-3620E loaded me with fresh and valuable experiences.
Among them is the answer in the question of why TFG-3620E is marketed as economic one.
The results of my tests are very interesting, especially my attempt to detect jitter.
When I did compare in my Oscilloscope identical sine wave waveforms at 100 kHz coming from the TFG-3620E and from my own analog PHILIPS PM5134 by using this persistence display mode, the results were identical.
The screen shots below are clearly demonstrating that the weak spot of arbitrary generators is mostly the arbitrary waveforms, square wave is somewhat easy to reproduce and sin(x)/x are an example of the complex ones to reproduce.
By my opinion TFG-3620E showed satisfactory behaviour, in the ranges of 50Hz up to 400Hz which I consider as electrical engineering bandwidth, and even up to 30 kHz which I consider as electronics engineering bandwidth for audio applications.
By my observations the far complex arbitrary waveforms starting to gradually suffer above 500 kHz, therefore I got the impression that sampling rate was not enough for maintaining all detail up to 1 MHz that is the end of the road for arbitrary waveforms in the specific AWG.
Regarding sine wave the same thing happened at about 8 MHz and above.
Somewhere at 12 MHz TFG-3620E started shown us unstable and at 18 MHz and higher it was clearly jumping around.
I have the feeling that the offered specifications as max are a bit optimistic regarding what this equipment are actually capable to deliver.
The specific AWG design by it OEM name as MFG6000CH it is marketed from three brand names up to date, it is well build and tested by many specialized engineers before it receive approval for distribution.
Therefore all that I wanted to find out is how acceptable and appealing is the set of the offered features.
Among the strong points:
1) Easy to use.
2) Clear TFT display (digital cameras have issues to capture it quality).
3) Great exterior design, high quality metal case, high quality buttons and rotary wheel.
4) Fast warm-up time so to stabilize, which looked as less than two minutes.
5) Even after seven hours of use the case become just a bit warm at the back (transformer side).
6) Acceptable stability and low Jitter in most frequently used bandwidth.
7) Great range in Duty cycle.
8) Well written in English users manual.
Among the weak points:
a) Accuracy of the output in volts (amplitude) especially above 4V up to 7V RMS
1) Waveform builder software with a minimum of 1024 x 768 working area.
2) Among the standard accessories one USB to serial adapter.
3) Frequency counter option not that great performer.
3) A soft bag with the Twintex logo, for storing all accessories/cables/
I am aware that currently there is a pricing battle in the market of AWG’s.
There is a large availability in 2014 of products capable even for 12 bit sampling, or with higher Mega samples and memory, or higher bandwidth and lower distortion.
But personally I thought that far important for some one like me that does not use GPIB Interface or LAN and do not work with high bandwidth, are far important the AWG to be easy to use and also the large display which present both channel settings, this combination it did gain my preference above anything else.
This AWG it does come with a nice package of features and accessories, and for electrical engineering and basic testing is very worthy.
TFG-3620E seems reasonably priced too and even if TWINTEX follow my suggestions, I believe that pricing will not change that much.
By my opinion AM modulation looks as dead horse in the regard of a usable feature today.
And also saved waveforms from an Oscilloscope which they can uploaded and reproduced by AWG is something more valuable, but this solution implying that you will be forced using equipment of an very specific vendor.
In conclusion TFG-3620E it is a very appealing AWG, ready to serve for professional and educational applications’ and it does gain the recommendation of ITTSB too.
I like to thanks again Miss Lily Cheung / sales manager of Twintex Electronics Co., Ltd, for their positive response in my invitation, and also for their help and quick response in every one of my emails, and also for their patience regarding receiving my review.
I could not predict either that my own preparation time that it would be that long, but even so, today I do feel that this presentation is close to high standards, and over all an interesting product review.
Test setup and first measurements.
GDS-2102A at persistence display mode
GDS-2102A at FFT display mode
TWINTEX Remote control software
First tests of making my very own Arbitrary waveform, and the happy end !!
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