Chapter 5 — CLOUDS AND VISIBILITY 



Figure 5-14. — Projector, transmissometer ML-47l/GMQ-10( ) front and side views. 



209.387 



photoelectric detector within the telescope, 

 which generates a pulse signal. At the same 

 time the receiver excludes most of the light 

 from the background. The pulse rate is pro- 

 portional to the amount of light falling on 

 the receiver. (See fig. 5-15.) 



The AMPLIFIER-POWER SUPPLY unitpro- 

 vides regulated voltage for the photoelectric 

 receiver and amplifies the pulse signal of the 

 receiver for transmission to the indicator. A 

 metering unit is also provided to facilitate 

 field adjustment. 



The INDICATOR is essentially a frequency 

 meter which converts the pulse signal to a direct 

 current which is proportional to the pulse rate 

 and hence to the transmission. 



The RECORDER provides upon a strip chart 

 a continuous record of the output of the indicator. 

 An auxiliary pen indicates the sensitivity range 

 on which the indicator is operating. 



In all models of Transmissometer AN/GMQ- 

 10( ), the Indicator and recorder are housed 

 in a single unit, which is known as the indicator- 

 recorder. 



The CABLE TERMINAL CHAMBERS, of 

 which there are two with each set, act as a 

 housing and a junction for all cabling used 

 in the set. One cable terminal chamber is 

 mounted on the projector stand, and the other 

 is mounted on the receiver stand. 





209.388 

 Figure 5-15. — Receiver, transmissometer 

 R-970/GMQ-10( ). 



A typical installation of the transmissometer, 

 showing the various component parts, is shown 

 in figure 5-16. 



Operation 



Since the initial starting of the transmis- 

 someter Involves several calibrations and ad- 

 justments not ordinarily performed by 

 Aerographer's Mates, the starting procedures 

 for the set are not given here. Once the set 

 Is in operation, no further on-off switching 

 is necessary. When the set is placed out of 

 operation or is not operating properly, 

 electronics personnel usually handle the shut- 

 down, repair, and restarting. Operational in- 

 structions given here cover only those 

 performed by Aerographer's Mates. 



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