Let's say you had a conversation on our 147.000 Repeater and you're wondering just how far away it was.   If the band is open, ask the other station for their zip code, then let them know how well they're doing.

Enter your Zip Code: " size="5" maxlength="5">
<% fp_sQry="distance" fp_sDefault="Zip=" fp_sNoRecords="" fp_sDataConn="distance" fp_iMaxRecords=256 fp_iCommandType=4 fp_iPageSize=0 fp_fTableFormat=True fp_fMenuFormat=False fp_sMenuChoice="" fp_sMenuValue="" fp_iDisplayCols=4 fp_fCustomQuery=False BOTID=0 fp_iRegion=BOTID %>
Zip City ST Miles to the SFFMA 147.00 Repeater
No records returned.
<%=FP_FieldVal(fp_rs,"Zip")%> <%=FP_FieldVal(fp_rs,"City")%> <%=FP_FieldVal(fp_rs,"ST")%> <%=FP_FieldVal(fp_rs,"147")%>

For those interested, this program uses the center of zip code coordinates.    From this, it uses this equation to calculate the distance to the repeater.   

Exact distance in miles = 3963 * arccos[sin(lat1/57.2958) * sin(lat2/57.2958) + cos(lat1/57.2958) * cos(lat2/57.2958) * cos(lon2/57.2958 - lon1/57.2958)]   Source

If you assume that the other station has a height of 10', and the transmit antenna is 1500' (Above Sea Level) on the tower, the total line of sight distance is 59 miles.   Any more than that and you can pretty much expect we're enjoying some ducting.   By the way, the same data works for the 442.350 repeater since it is co-located with our 147.000.

VHF/UHF Line of Sight Calculator (Source)

 Antenna Height of 1st Station (ASL) 
 Antenna Height of 2nd Station (ASL) 
Feet Metres    
For the 1st station, the Radio Horizon is  away. 
For the 2nd station, the Radio Horizon is  away. 
The total line of sight distance is Miles Km.

07/15/2003 02:28:59 -0400

    © South Florida FM Association, 2003   
   

National Homeland Security Knowledgebase