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Extron VTG 300

Extron's VTG 300 is a portable, battery/AC-operated combo video/audio test generator that is long overdue. I had been using Extron's original VTG 200

Extron VTG 300

Dec 1, 2003 12:00 PM,
By Peter Putman

Extron’s VTG 300 is a portable, battery/AC-operated combo video/audio test generator that is long overdue. I had been using Extron’s original VTG 200 for many years as my mainstay video/PC test signal generator, but the VTG 200’s design goes back to 1995 — an eternity in the world of display technology.

Although the 200 was a useful gadget and supported numerous PC standards, its days were clearly numbered. For one thing, the only video display rates it can generate are NTSC and PAL (plus variations) and 1,035i HDTV (only in the RGBHV format). To top it off, many of the PC and workstation standards it can serve up (such as DEC and PowerPC) no longer exist, having long passed into obscurity.

The VTG 300 fixes all that and then some. The available range of PC display formats has been standardized, featuring 16 PC rates from plain vanilla VGA all the way to UXGA and even 1,360/1,365 by 1,024 LCoS standards. In the composite video world, you’ll be able to choose from five standards — two NTSC, with one having black setup at 0 IRE, and three PAL rates (PAL-I, PAL-B,G,H, and PAL-N).

It also has seven SDTV/HDTV rates from 480p and 576p to 720p and 1,080i/30/25 Hz, as well as the more exotic 1,080p format with 50 Hz and 60 Hz refresh options. This list of formats is rounded out by four 16:9 rates common to LCD and plasma displays — 848 by 480, 852 by 480, 1,280 by 768, and 1,360 by 768.

You’ll be able to select any of these test rates in sync on green (YPbPr, RGsB), composite sync (RGBs), or component sync (RGBHV) modes. That’s useful when you are testing an older display that might be compatible with HDTV scan rates but only offers an RGB input, such as my old NEC MultiSync XM29 reference monitor.

Depending on the particular test signal you’ve chosen, you’ll have a bunch of test patterns at your fingertips. That includes crosshatch, split color bars, a fine text H pattern (great for testing auto sync circuits), 16-level split gray scale, alternating pixels, and a 100 percent white field. In NTSC/EBU mode, you’ll find color bars with pluge and a 4¼ MHz bandwidth multiburst pattern.

To round out the package, the VTG 300 also includes audio test signals such as pink noise, white noise, a sine wave at any frequency from 20 Hz to 20 kHz (selectable in ⅓-octave steps), selectable square wave output from 20 Hz to 5 kHz, a polarity test, and a swept sine wave that cycles between 20 Hz and 20 kHz.


Connections to the VTG 300 are made through a 15-pin VGA-style connector for all component video lash-ups, an S-video DIN jack, or a BNC jack for composite output. Audio connections are covered with an RCA jack, an ⅛-inch mini (mono on both channels), or an XLR jack with balanced mono audio on both channels.

Here’s the best part. Although the older VTG 200 was tethered to the nearest AC outlet, the smaller and lighter VTG 300 includes a battery compartment that accepts 4 AA-type cells (and ostensibly AA-size NiMH batteries). No word on how long they’ll last, but you should be able to get several hours out of a set of alkaline cells. A reversible rubber boot cover completes the package and protects the case from the usual dings and scratches.

To get the most out of the VTG 300, you’ll want to pick up a 15-pin to 5 BNC breakout cable so you can individually access any of the RGB/YPbPr channels as well as horizontal and vertical sync. These cables are pretty common, and Extron offers them in several lengths with male or female BNCs on one end.

I don’t do much testing or calibration of audio, so I put the VTG 300 to work on some projectors, relying heavily on the fine H pattern to check out the ability of each projector’s autopixel clock to correctly set up and center a variety of PC and DTV rates. This pattern is a killer because it contains lots of high- to low-luminance transitions, and thus it has plenty of high-frequency information that can and does fool projector autosync circuits.

The gray-scale patterns and white field are useful for testing white balance and setting color temperature, though an additional low-luminance gray field (about 20 IRE or 20-30 percent gray) would also be handy for adjusting red, green, and blue bias. The crosshatch patterns will show you any pixel misalignment or convergence errors with projectors that use three imaging panels, and the split color bars are helpful for setting color difference levels.


Two patterns missing from the VTG 300 (that were also absent from the VTG 200) that would be really handy are a straight pluge pattern on black and the ANSI brightness field. (There’s no ANSI checkerboard pattern, either.) Pluge helps you establish the low end of a gray scale for video or PC sources, and the ANSI bandage clearly shows what’s going on with the high end.

Between the two, you can set up a good-looking gray scale for any display in short order, and I hope Extron will add both of these patterns to future editions. (How about an HD multiburst pattern to check for system bandwidth with workstation and HD signals?)

The VTG 300 is a useful tool and a good deal at the listed price. If you are in the rental, staging, or systems integration business, keep one around. It lets you set up and troubleshoot many things in a display installation, and it won’t require much of your time to do so.


Company: Extron Electronics

Product: VTG 300

Pros: Good bang for the buck. Heavily updated display formats. Works on AC and battery power.

Cons: Lacks straight pluge pattern on black, ANSI brightness field, and HD multiburst pattern.

Applications: Testing signal generator for audio and video.

Price: $995



Dot Clock 108 MHz (max.)

Pixel Clock Accuracy 100 ppm

Horizontal Frequency 15-127 kHz

Vertical Frequency 30-85 Hz

Rise/Fall Time <4 ns


Number/Signal Type 1 RGBHV, RGBS, RGsB, component video, S-video, composite video

Connectors (1) 15-pin HD female (RGB/component); (1) 4-pin mini DIN female (S-video); (1) BNC female (composite video)

Nominal Level 1V p-p for Y of component video and S-video and for composite video and also R-Y and B-Y of component video (trilevel sync); 0.7V p-p for RGB and for R-Y and B-Y of component video (bilevel sync); 0.288V p-p (burst) for C of S-video

Minimum/Maximum Levels 0.0V to 1.0V p-p

Impedance 75ž

Resolutions Computer (VGA, UXGA), video (NTSC, PAL), HDTV, and 16:9 high resolutions


Output Type RGBHV, RGBS, RGsB (for RGB signals); trilevel on Y, R-Y, B-Y channels (component video 720p, 1,080i, 1,080p); bilevel on Y channel (for all other component video rates)

Standards NTSC 3.58, NTSC 4.43, PAL, SMPTE 170M, SMPTE 274M, SMPTE 293M, SMPTE 295M, SMPTE 296M


THD + Noise 0.5% @ 1 kHz at nominal level

Flatness ±1 dB

Accuracy ±0.7 dB


Number/Signal Type (1) mono, balanced; (2) mono, unbalanced

Connectors (1) 3.5 mm ministereo jack (unbalanced mono left and right, TRS); (1) female RCA jack (unbalanced, TR); (1) male 3-pin XLR (balanced)

Impedance 50ž unbalanced, 100ž balanced

Waveforms Pink noise, white noise, sine wave (fixed/swept), square wave, polarity test

Maximum Level (600ž) >+5.39 dBm, balanced or unbalanced at stated %THD+N; maximum level (Hi-Z) >+6 dBu, balanced or unbalanced at stated %THD+N


Power 4.8 VDC to 6 VDC supplied by four internal AA batteries (rechargeable or alkaline); 100 VAC to 240 VAC, 50/60 Hz, 12W, external, autoswitchable; to 12 VDC, 1A power supply. Product requires 1A.

Enclosure Type Metal

Dimensions (H × W × D) 8.3″ × 3.9″ × 2.1″ (21.0 cm × 9.9 cm × 5.4 cm)

Weight 1.2 lb. (0.5 kg)

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