Difference between revisions of "RF Engineering"

Revision as of 02:31, 7 April 2010

Before getting started you may want to study or refresh your knowledge of Ohm's Law.

Electricity Supply

Alternating Current (Mains)

UPS & Battery Backup

How to calculate what size battery system is needed for emergency backup
1. Find the current drain in Amps during transmit, receive and stand-by operation for each piece of equpment you will be attaching to the battery backup system.

This usually can be found in owners manual specs page or on the internet.

2. Determine the equipment's Duty Cycle. Duty Cycle is expressed as a series of three percentages:

Transmit | Receive | Stand-By | Device
.00 | .80 | .20  for a Scanner (low)
.50 | .50 | .90  For a Transceiver (Medium)
1.0 | .00 | .00  For a Transmitter TV broadcast (High)

3. Use the following formula to calculate the average current required per device.

Where i is the DC current in Amperes required during transmit (TX), receive (RX), and stand-by (SB)
Where %Duty is the duty cycle represented as .xx ie. .50 is 50%

Average Current in Amps = (I_TX)(%Duty)+(I_RX)(%Duty)+(I_SB)(%Duty)

4. To determine the battery size required, multiply the average current in Amps by the number of hours of backup power required.

Battery/UPS Size = (Average Current in Amps)x(Number of hours backup power required)

Direct Current (Battery)

Grounding

Coax Grounding

Manuals

General Electric Lynchburg Book of Instructions (LBI) Term for GE Manuals
All LBI manuals are in Adobe PDF format and under 5Mb

Motorola R56 Standards and Guidelines for Communications Sites

Motorola Part Number 68-81089E50 Printed version
Motorola Part Number 98-80384V83 CD-ROM version

Tools

Gives the current carrying ability for wires and wire bundles based on their AWG and Metric.

External Links

Repeater-Builder's Radio Site Standards

@@ Line 7: / Line 7: @@
 ====UPS & Battery Backup====
-'''How to calculate what size battery system is needed for emergency backup'''
+'''How to calculate what size battery system is needed for emergency backup'''<br/>
-#Determine the average current drawn by '''''all''''' equipment to be provided with ''emergency'' backup power.
+. Find the current drain in Amps during transmit, receive and stand-by operation for each piece of equpment you will be attaching to the battery backup system.
-#*Find the DC current drain during transmit, receive and stand-by operation.
+ This usually can be found in owners manual specs page or on the internet.
-#**Determine the equipment's [http://en.wikipedia.org/wiki/Duty_cycle Duty Cycle].
+. Determine the equipment's [http://en.wikipedia.org/wiki/Duty_cycle Duty Cycle].
-#***Duty Cycle is expressed as a series of three percentages:
+Duty Cycle is expressed as a series of three percentages:<br/>
-#***'''Transmit'''
+ '''Transmit''' | '''Receive''' | '''Stand-By''' | '''Device'''
-#***'''Receive'''
+ .00 | .80 | .20  for a Scanner (low)
-#***'''Stand-By'''
+ .50 | .50 | .90  For a Transceiver (Medium)
+.0 | .00 | .00  For a Transmitter TV broadcast (High)
-Use the following formula to calculate the average DC current required.
+. Use the following formula to calculate the average current required '''per device'''.
-: IA.VE=(I_TX)(.5)+(I_RX)(.5)+(I_SB)(.90)
+*Where '''i''' is the DC current in Amperes required during transmit (TX), receive (RX), and stand-by (SB)
+*Where '''%Duty''' is the duty cycle represented as .xx ie. .50 is 50%
+ Average Current in Amps = (I_TX)(%Duty)+(I_RX)(%Duty)+(I_SB)(%Duty)
+. To determine the battery size required, multiply the average current in Amps by the number of hours of backup power required.
+ Battery/UPS Size = (Average Current in Amps)x(Number of hours backup power required)
-Where '''i''' is the DC current required during transmit (TX), receive (RX), and stand-b (SB) operation the above is for a 50%, 50%, 90% duty cycle.
-If a different duty cycle is required change the percentages in the equation.
-To determine the battery size required multiply the average current by the number of hours of backup power required.
-Battery Size = (IA.VE)*(Hours of backup power required)
 ===[http://en.wikipedia.org/wiki/Direct_current Direct Current (Battery)]===