Modular construction, both of sensors and of consoles, has been 
particularly specified in these instruments and instrument systems. 
This has been done primarily to facilitate field maintenance and repair; 
however, it also allows for the different lengths of time that may be 
required to develop any given sensor. Additional factors, which have 
prompted specification of this mode of construction, are: 
l. Higher resolutions and accuracies are more economically attained 
with a yroup of modular sensors, each interchangeable and covering a 
different sensing range; 
2. A greater demand may be generated for a particular sensor than 
the overall demand indicated in these descriptions for the total in- 
strument or systems3 
3. Standardization will afford the widest possible sensor application 
and market, inasmuch as many of these sensors are to be utilized in more 
than one of the described instruments and instrument systems; 
4. Interchangeable, modular sensors will permit many companies, who 
may have neither the interest nor the capability to contract for an en- 
tire svstem, to devote their specialized talents to development of a 
particular sensor. This is expected to be especially true of companies 
having a specialized chemical analysis capability. 
In conjunction with this policy of modular construction, vehicles or 
Capsules proposed as components of the described instruments or instrument 
systems must be capable of accommodating the standardized sensors and 
their associated recording or transmitting units in the groupings stipulated 
in the accompanying instrument descriptions. 
Althoush projected estimates of the numbers which may be utilized have 
been presented for each instrument or system, in order to acquaint in- 
dustry with the possible extent of the market, these numbers are obviously 
a function of: (1) the unit cost of production models, (2) opportune 
breakthroughs in the state-of-the-art, (3) budgetary considerations of the 
various agencies that may comprise the market, and (4) the individual re- 
quirements of segments of the national oceanographic community other than 
those concerned principally with survey operations. 
The following are additional general requirements which inherently 
apply to all oceanographic instruments or instrument systems: 
1. Provision must be included for rapid, accurate, shipboard calibra- 
tion. 
2. Wherever electronic components are utilized, long electronic life 
must be a basic factor in their design. In this reyard, military specifi- 
cations, especially those written for existing specialized projects, are 
iat 
