patibilicy writh most existing instruments. At present., use is * 
mainly made of transformer type encoders which have from 8 to 
11 bits in a single unit. To cover the full range of linear 
displacement, separate units of the encoder are coupled to each 
other via an intermediate reducing gear. The encoder for preci 
sion stereocomparator CKA contains two stages: the first with 
11 bits and the second with 7 bits (3)* Code masks use. the 
Barker code. Another encoder, part of universal coordinate re 
corder APKV, can be used together with different photogrammet- 
ric instruments (4). It is provided with three identical sta 
ges having code masks in the form of a 8 -bit Gray code. The use 
of tne cyclic code allows for smaller size and increased reli 
ability of the encoder. As stated above, the accuracy of en 
coding linear displacement in analog-to-code encoders is mainly 
determined by manufacturing tolerances encountered in'a-screw- 
nut pair. Test results show that at a discrete value of 1 um 
the accuracy of coordinate measurement amounts for different 
instruments, to 2 .S -4 um. 
The above discussion indicates that the selection oji spe 
cific type of an encoder depends on technical requirements to 
a given photogramiaetric instrument and on resources available. 
Since nowadays several types of coordinate recording systems 
photogrammetric instruments exist, their future development 
must involve standardization of their units along with attempts 
to increase reliability and cut down cost. 
References: 
1. Зотов Г.А, "Система автоматического отсчета координат 
к стереокомпаратору СКВ-I". - Труды ПДИИГАиК, вып.190, М., 
"Недра", 1971. 
2. Мироненко А.В. "Фотоэлектрические измерительные 
системы". М., "Энергия”, 1967. 
3. Д е р в и з В.Д., Филимонов В.В. "Высокоточные ав 
томатизированные стереокомпараторы СКВ-18 и СКВ-I" (симпо 
зиум по фотограмметрии). М., ОНТИ ЦШИГАиК, 1968. 
4. Богданов И.А. и др. авт. свид. 399894 МК 08с/9/00. 
Преобразователь "Угол-код". Опубл. 3.X.I973. Выл. № 39.