Film-Tech Forum ARCHIVE: PC Based Oscilloscope & RTA Revisted

This is topic PC Based Oscilloscope & RTA Revisted in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Bhaskar Dhungana (Member # 1283) on 05-31-2006, 12:41 AM:

I know this topic has been discussed earlier, but I figured it would be nice to get an "updated" opinion from professionals as these kind of software based technologies change very quickly.

1. How many of us are using PC based Oscilloscope (e.g PICO) and/or RTA for alignment?

2. What are some of the technologies that you would recommend and/or not recommend.

Posted by Mark Gulbrandsen (Member # 72) on 05-31-2006, 06:12 AM:

RTA's

I don't have a problem with digitally based RTA's and actually prefer them but as far as using any simple PC software based setups you are seriously limited by the sound card in what ever computer you have. A very high end sound card and mics are needed and those would cost AT LEAST 2 to 3 times the cost of your computer brand new. So only the more expensive digitally based analyzers will do in this buisness. Consider the R-2, or the new D-2 analyzer and other similar types of computer based external analyzers.... These analyzers are the best there is for this type of work. Anyone that does any serious work in this buisness and doesn't have one is still living and working in the dark ages!

Scopes.....

Since only the more expensive digital scopes are capable of displaying some of the waveforms we look at very few if any theatre techs are using them. One of the main problems with digital scopes is the slow sampling and refresh rate they have.... you go through an adjustment and the slow refresh rate precludes you from seeing the changes you are making in real time. The more expensive digital scopes are definately more than capable though be prepared to spend upwards of 5K for a decent one. I woldn't waste my time even attempting to use any inexpensive PC based scope software yet.

I've been using a Tektronix 465B scope now for many years and for field work there are few if any analog scopes that can come close to its performance and reliability. I paid just $75.00 for it on E-Bay and got a great deal as it had spent its entire life in a rack mount in a lab.... so it was never abused. The 465B scope sold for just over $4,000.00 back in the late 80's... in todays dollars a new one would be nearly double that. Since I restore test gear as a hobby I then completely cleaned it up, and calibrated it myself. I previously used a Dolby recomended Leader 60 mhz dual trace portable scope but its reliability was not good and Leader equipment is a pain to get parts for. Used high end analog scopes are a dime a dozen these days on places like E-Bay and at Ham fests..... I can't imagine anyone wanting an inexpensive digital scope when these wonderful high end scopes some of which are the finest ever made cost so little today.

my 10 cents worth....
Mark

Posted by Steve Guttag (Member # 268) on 05-31-2006, 06:16 AM:

The D2 now sports an O'Scope display that is suitable for A-Chain work though it is not capable of Dolby Digital alignment (Tim is said to be working on that too).

An adavantage is to have on a single display with a single hook-up everything one needs in an A-chain alignment with less test equipment. It is one reason I like my ABACUS...it lets one do it all and it has the best ballistics of any RTA I've seen...plus I truely HATE LED based RTAs.