Thread: Rca ant751
View Single Post
Old 6-Jun-2017, 2:29 AM   #78
rabbit73
Retired A/V Tech
 
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,747
The Sadelco DislayMax 800 signal level meter makes 43 measurements across the channel and diplays the average of all readings. If one of the 43 measurements is below -20 dBmV, the meter says "Ur" for under range and doesn't give a reading. The scan covers about 5.3 MHz of the 6 MHz channel.



If the meter is switched to the single frequency mode, it will measure down to -35 dBmV at the center of the channel, but the correction for a digital signal is not added; +6.8 dB IIRC.



The screen on the meter actually shows a dark gray image on a dark green background and doesn't have much contrast. The image looks pretty good on a computer screen, but makes a muddy image on a print.

analog channel:



digital channel:



To make an image that has more contrast and room for notes, I set my digital camera for a B&W image, and then edit in Photo Gallery to increase the contrast.



Photo Gallery will only allow me to increase the contrast one time, AFAIK, so I use Lunapic to increase the contrast 4x more:

Attached Images
File Type: jpg DisplayMax800_43meas.jpg (90.3 KB, 3427 views)
File Type: jpg DisplayMaxImg5.jpg (34.6 KB, 3304 views)
File Type: jpg DisplayMaxImg1.jpg (92.7 KB, 3405 views)
File Type: jpg DisplayMaxImg2_1.jpg (149.0 KB, 3377 views)
File Type: jpg IMG_1010 (4).jpg (68.2 KB, 3373 views)
__________________
If you can not measure it, you can not improve it.
Lord Kelvin, 1883
http://www.megalithia.com/elect/aeri...ttpoorman.html

Last edited by rabbit73; 6-Jun-2017 at 6:54 PM.
rabbit73 is offline   Reply With Quote