Review: Magni WVM-710

User review article for the February issue of TV Technology magazine on the Magni WVM-710 scope. By Doug Hembruff of Impact Televideo Productions, London Ontario Canada. Revision C, Jan. 3/94 1049 words.

Recently I had an opportunity to use the Magni WVM-710 "Automated Video Signal Monitor" in our editing suite at Impact Televideo Productions. This full featured waveform/vectorscope/auto-measurement device is one rack unit high, displays on a standard monitor screen and simplifies signal measurement so users can concentrate on creative content.

Magni has incorporated so many features in this amazing little scope that I found it difficult to do justice within the length limitations of this article. True to form, Magni has managed to bring the WVM-710 in for a U.S. list price of $4500. which is substantially less than most other scopes with similar features.

The Magni WVM-710 should appeal to a wide range of users, but the biggest market seems to be editing suite operators who want to spend their time creatively and not with one eye always on the scope. To this end, the WVM-710 has several user-definable limit ranges. It offers on-screen pop up warnings over the video picture, or a full screen waveform that instantly shows red on any part of the signal that goes out of limit (see pictures 1 and 2). The only thing it doesn't do is reach out and slap you if you're not paying attention.

Remote scoping is another popular application. With a modem pair over telephone lines or RS232 cable and "Logbook" Event Manager software ($495. U.S. list), TV stations can spot check their antenna site. Editing suites with VTRs in another room can check the output without worries of signal loss over long cable runs.

The high resolution 10 bit rasterized video scope display has built in graticules for accuracy. The waveform and/or vectorscope display can be full or 1/4 screen (see pictures 2 and 3). All displays have a choice of black opaque background or semi-transparent over the video picture. Several out-of-specification "icons" (Picture Guard) can automatically pop up (keyed) over video (see picture 1) when there is a problem.

A stereo audio meter can be added to the screen. On full screen, you can superimpose the vectorscope over the waveform in a different user-definable color. The video screen outputs for the scope are composite or Y/C and are separate from the loop through outputs. Quality control of transfers from video tape to non-linear systems can be more easily maintained by non-techie persons when using any of the auto detect features.

There is a "Venetian Blind" split-screen type display which alternates the picture between channel "A" and external reference at 32 line intervals. These two signals will horizontally offset from each other if video signal timing doesn't match the reference signal. This allows quick and easy matching of timing, luma, chroma and hue to the reference signal without having to know how to read a scope.

There are also two sets of screens which measure 16 video parameters using numeric displays and a two colored bar graph showing whether they are in or out of acceptable range. A menu allows the user to adjust a minimum and maximum range of acceptability. These 16 measurements are: luma amplitude, chroma amplitude, chroma phase, setup, sync level, burst amplitude, peak video, horizontal reference timing, SC/H phase, color frame, luma noise level, chroma/luma/gain, chroma/luma delay, differential phase, differential gain and pulse/bar.

For these 16 video parameters as well as the waveform and vectorscope, it is possible to select which line to measure & whether it should be an even or odd field pair. There is also a VITC time code display with hours, minutes and seconds but not frames (see pictures 2 and 4). The VITC can be selected from lines 9 through 25. There are graticule marks that indicate proper horizontal blanking settings such as sync width/position, burst width/position and horizontal limits of the active picture (see picture 4).

The Magni WVM-710 works with NTSC or PAL and can select any two of the following inputs in loop-through mode (1 Component or RGB 15.75 kHz, 2 Composite and 1 Y/C 3.58). Computer graphic artists or character generator operators would find the WVM-710 a handy tool to keep within legal limits because of the automatic warnings. Computer graphic generated video has a much greater chance of exceeding legal chroma video limits because 25% of the RGB pallet choices are not legal.

The optional "Logbook" software allows unattended signal monitoring and logging at specified polling intervals as often as one minute apart. Time stamp, storage of the waveform, vector, auto-measurement screens & other parameters are also captured. Hard copies of the displays can be output from a printer via the "Logbook" software. The Magni WVM-710 can also store 6 scope readings for later recall and they can be sent directly to a printer without a computer because several standard printer drivers are built in.

The logging or hard copies could be a real labor saver for Broadcast stations who are federally required to keep regular records of video signal integrity. It can also be a great diagnostic tool for an engineer to track down intermittent problems or compare to previous readings. Other applications for this automatic logging are overnight transmissions and quality checks on tape duplication using vertical interval test signals (VITS).

Among the many valuable menu settings is one that changes the internal reference from CRYSTAL LOCK to VCR LOCK for better jitter free images when scoping an unstable source such as a VCR without timebase correction. Another buried menu lets a technician calibrate the scope using settings that Magni's customer support can supply. All memory & user preference settings on the WVM-710 are backed up by a lithium battery.

The Magni WVM-710 had some nifty features I didn't expect to find. There is a VITC time code readout, a stereo audio display that indicates levels and phasing, a luma signal to noise measurement usually only found on extremely expensive scopes and a safe action (5% off each border), safe title (10% off each border) outline generator.

This versatile Magni WVM-710 automated video signal monitoring system will be a "must have" scope for many production houses, TV stations and engineers. Magni maintains a 1 800 customer support line and a free BBS for software and bulletin updates. I also found Magni's instructional documentation to be much better than average.

Impact Televideo Productions is based in London, Ontario, Canada. Doug Hembruff is a corporate and broadcast video producer who also performs beta testing, product evaluation and technical writing. When this issue comes off the press, Doug will be doing field production in Israel. For more info contact Doug Hembruff.