( Free42 ) Decibel Addition and Subtraction
06-01-2020, 12:50 PM (This post was last modified: 06-03-2020 01:48 AM by Gamo.)
Post: #1
 Gamo Senior Member Posts: 750 Joined: Dec 2016
( Free42 ) Decibel Addition and Subtraction

HP-41C Heating, Ventilation and Air Conditioning Page 65

Assign [dB-] and [dB+] to Soft Menu

Example 1:

A noise level of 72 dB is measured in a room.
The air conditioning is turned on and
the noise level increases to 74 dB
What is the noise level of the air conditioning system.

[FIX] 02

74 [ENTER] 72 [dB-] display 69.67 dB

Example 2:

A compressor is known to have a sound pressure level of 90 dB.
The background noise is 85 dB. What is the total?

90 [ENTER] 85 [dB+] display 91.19 dB
-----------------------------------------------------------------------
Program:
Code:
 00 { 51-Byte Prgm } 01 LBL "dB+" 02 XEQ 00 03 + 04 GTO 01 ---------------------- Add Decibels. 05 LBL "dB-" 06 XEQ 00 07 - 08 ABS ---------------------- Subtract Decibels. 09 LBL 01 10 LOG 11 10 12 x 13 CLA 14 ARCL  ST X 15 ⊢"dB" 16 AVIEW 17 RTN --------------------- Display Result. 18 LBL 00 19 10 20 STO÷ ST Z 21 ÷ 22 X<>Y 23 10↑X 24 X<>Y 25 10↑X --------------------- Convert for Add or Subtract.
Remark:
When Subtracting dB(1) < dB(2), the program will exchange values.

Gamo 6/1/2020
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