Converting to inches by multiplying wavelength
results to 39.3701
λ = 2.0675 x 39.3701 = 81.3990 inches
Hence:
λ = 81.4 inches = L
vf = 0.95
Solving for one-half wavelength:
Radiating Element = (λ*0.5)*vf = E
= (81.4 x 0.5) x 0.95 = 38.6645 inches
Divided by 2 elements for upper and lower
elements
= 38.6645/2 = 19.3 inches
Gap between Radiating Element = λ / 200 = 0.407 inch = G
L = 81.4“
E = 19.3”
G = 0.407”
Note: important Adjust
To the lowest Standing Wave Ratio (SWR)
Add 5% to radiating element -> = 20.265
inches
Check SWR, using SWR/Power Meter, tune to Operating Frequency
(e.g. 145.00MHz)
Connect cable. Antenna -> SWR/Power Meter -> Radio
Set to SWR / Power to test
Hence: if SWR = 1-1.2, Power = Radio Power Output Set, if you
set your radio power to 5 watts it should be 5 watts meter reading in the
SWR/Power meter.
If the measurements of the cut elements are correct for the
Operating Frequency, fixed and finalized antenna, else if the results reading
is/are not meet the ideal reading, cut both elements.
Cutting:
Operating Frequency = 145.000 MHz
If the SWR is high and Power is low
Adjust radio frequency to either higher or lower frequency to
read to the lowest SWR, take note the Frequency with the lowest SWR
Now, example the frequency with the lowest SWR is 146.000 MHz
New formula New Frequency divided by old Frequency multiple by
original radiating element results.
Bob Bruninga, a senior research engineer at the United States Naval Academy, implemented the earliest ancestor of APRS on an Apple II computer in 1982. This early version was used to map high frequency Navy position reports. The first use of APRS was in 1984, when Bruninga developed a more advanced version on a Commodore VIC-20 for reporting the position and status of horses in a 100-mile (160 km) endurance run.[3] [2]
During the next two years, Bruninga continued to develop the system, which he now called the Connectionless Emergency Traffic System (CETS). Following a series of Federal Emergency Management Agency (FEMA) exercises using CETS, the system was ported to the IBM Personal Computer. During the early 1990s, CETS (then known as the Automatic Position Reporting System) continued to evolve into its current form. [2]
As GPS technology became more widely available, “Position” was replaced with “Packet” to better describe the more generic capabilities of the system and to emphasize its uses beyond mere position reporting. [2]
OVERVIEW:
The Automatic Packet Reporting System was designed to support rapid, reliable exchange of information for local, tactical real-time information, events or nets. The concept, which dates back to the mid 1980’s, is that all relevant information is transmitted immediately to everyone in the net and every station captures that information for consistent and standard display to all participants. Information was refreshed redundantly but at a decaying rate so that old information was updated less frequently than new info. Since the primary objective is consistent exchange of information between everyone, APRS established standard formats not only for the transmission of POSITION, STATUS, MESSAGES, and QUERIES, it also establishes guidelines for display so that users of different systems will still see the same consistent information displayed in a consistent manner (independent of the particular display or maping system in use). See the original APRS.TXT. The two images below should give you an idea of the kinds of information available to the mobile operator on his APRS radio. On the left is the Kenwood D710 radio showing the station list, and on the right is the attached GPS with map display showing the location of other APRS stations. [1]
APRS is not a vehicle tracking system. It is a two-way tactical real-time digital communications system between all assets in a network sharing information about everything going on in the local area. On ham radio, this means if something is happening now, or there is information that could be valuable to you, then it should show up on your APRS radio in your mobile. See typical oversights and hear my talk on the 3 Oct 08 Rain Report See also some original APRSdos views and concepts overlooked in some new programs. [1]
APRS Internet System (APRS-IS): Like most other Ham radio systems, APRS has been fully integrated with the internet beginning with the efforts of Steve Dimse and the Sproul Brothers in 1997. Currently there are many web pages for live viewing of APRS activity such as APRS.FI, or FINDU.COM. [1]
APRS also supports global callsign-to-callsign messaging, bulletins, objects email and Voice because every local area is seen by the Internet System (APRS-IS)! APRS should enable local and global amateur radio operator contact at anytime-anywhere and using any device. See the APRS Messaging/Contact Initiative. [1]
APRS SPEC! . APRS continuously evolves. There have been several initiatives that have drastically improved APRS network performance and useability for users. The original APRS spec was updated in 2004 with the APRS1.1 addendum and since then with the APRS1.2 updates. [1]
There is NO known assigned frequency for APRS by the NTC in the Philippines.
APRS in the Philippines
AFAIK, there is not too much APRS activity in the Philippines. Most of the stations are DMR and Echolink beacons through APRS-IS.
Here is an image capture from APRS.FI website.[3]
APRS stations in the Visayas Regions [3] APRS stations in Luzon Regions [3] APRS stations in Mindanao Regions [3]
RF-to-RF and RF-to-IS: There is an active APRS SatGate and Igate in District 6 by DU6DKL. Experimental APRS Stations are currently made, as of writing, in Cebu.
DV7HAA spearheaded the APRS System development in Cebu as his amateur project for 2020. Together with the DX7CBU-Ham Radio Cebu, Inc. members, slowly the APRS system in Cebu is making progress, with the specific motivation to aid Disaster Resiliency in Communications.
The project has a facebook group APRS-PH. As of the moment the APRS frequency is at 145.825MHz, same as to ARISS.
References:
[1]Automatic Packet Reporting System, Bob Bruninga, WB4APR , http://www.aprs.org/
Get
familiar with the etiquette of two-way radio communication. Learn walkie
talkie lingo. To make radio communication go more smoothly, over the years
certain rules, or etiquette, have been established. Below we have outlined the
basic etiquette a radio user should understand. It will help improve your
overall experience when using your radio!
Basic Radio
Etiquette Rules
The
international radio language is English, except in cases where you
are licensed to speak in some other language.
When using a
two-way radio you cannot speak and listen at the same time, as
you can with a phone.
Don’t
interrupt if
you hear other people talking. Wait until their conversation is
finished unless it is an emergency. If it is an emergency, inform the
other parties that you have an urgent emergency message (see
“Emergency Calls” below).
Do not respond
if you aren’t sure the call is for you. Wait until
you hear your call sign to respond.
Never
transmit sensitive, confidential, financial or military
information. Unless you are certain your conversations
are secured with the proper level of encryption for the level of
sensitivity, assume your conversations can be heard by others.
Perform
radio checks to ensure your radio is in good working condition.
Ensure
the battery is charged and the power is on.
Keep
the volume high enough to be able to hear calls.
Regularly
make radio checks to make sure everything is working and that you are
still in range to receive signals.
Memorize
call signs and locations of persons and radio stations you communicate
with regularly.
In
radio communication, you are not called by your name. Everybody has their
own unique call sign.
Think before
you speak.
Decide
what you are going say and to whom it is meant for.
Make
your conversations as concise, precise, and clear as possible.
Avoid
long and complicated sentences. If your message is long, divide it into
separate shorter messages.
Do
not use abbreviations unless they are well understood by your group.
4 Golden Rules of Radio Communication
1.
Clarity:
Your voice
should be clear. Speak a little slower than normal. Speak in a normal tone,
do not shout.
2.
Simplicity:
Keep your
message simple enough for intended listeners to understand.
3.
Brevity:
Be precise and
to the point.
4.
Security:
Do not transmit
confidential information unless you know the proper security technology is in
place. Remember, frequencies are shared, you do not have exclusive use of the
frequency.
Speaking the Language
General Terms
Meaning
Radio/Signal
Check
What is my
signal strength? Can you hear me?
Go Ahead
You are ready
to receive the transmission.
Stand-by
You acknowledge
the other party, but I am unable to respond immediately.
Roger or QSL
Message
received and understood.
Negative
Same as
“No”.
Affirmative
Same as
“Yes”. Avoid “yup” or “nope” as they are difficult
to hear.
Say Again
Re-transmit
your message
Over
Your message is
finished.
Out
All
conversation is finished, the channel is clear for others to use.
Break, Break,
Break
You are
interrupting in the middle of communication because you have an emergency.
Read you
loud & clear
Response to
“Radio Check”. Means your transmission signal is good. Also,
use “Read you 5-by-5“.
Come in
You are asking
the other party to acknowledge they hear you.
Copy
You understand
what was said.
Wilco
Means “I will
comply”.
Repeat
Used before you
repeat something. ex: “I require 9-5, repeat 9-5,
gallons of diesel fuel. Over”
Marine &
Aviation
Sécurité
Safety call.
Alert to some safety warning. Repeat 3 times. Has priority over routine
calls.
Pan-Pan
Urgent call.
Help needed. Repeat 3 times. Has priority over safety calls.
MayDay
Distress call.
Repeat 3 times, and again following each transmission. Has priority over all
other calls.
These
terms can be combined such as “Roger Wilco” means “I understand
and will comply”, or “Over and Out” means “I’ve finished
talking and I’m signing off”.
Making a Call
Follow
these easy steps to make a call.
First,
listen to ensure the channel is clear for you.
Press the
PTT (Push-To-Talk)
button.
After 2
seconds:
Say “recipient’s
call sign” twice
Followed
by “THIS IS” and “your
call sign“.
Once the
person replies, convey your message.
Here’s a typical radio conversation:
You:
“4 Foxtrot
7 Mike Hotel Zulu(4F7MHZ), 4 Foxtrot 7 Mike Hotel Zulu(4F7MHZ), This is Delta
Whiskey 7 November Charlie Mike(DW7NCM), Come in, Over” (4F7MHZ
is their call sign, DW7NCM is your call sign)
Recipient:
” Delta
Whiskey 7 November Charlie Mike, This is 4 Foxtrot 7 Mike Hotel Zulu, Go
Ahead, Over”
You:
Say your
message and then say:
“Over”
Recipient:
“Roger
Wilco, Over”
You:
“This is Delta
Whiskey 7 November Charlie Mike, Over and Out”
Did you notice how at the beginning
and end of the transmission you pronounce your call sign?
Because there can sometimes be many people listening on the frequency,
pronouncing your call sign, and the call sign of the party you are calling,
lets everyone know who the transmission is for. Communicating this way might
feel a little odd at first, but you’ll soon get used to it. With practice, it
will start to feel natural.
Emergency Calls
If
you have an emergency message and need to interrupt others’ conversations:
Wait and
listen until you hear “Over”.
Press PTT
and say “BREAK, BREAK, BREAK, your call sign, I have an
emergency message for (recipient’s call sign), Do you copy,
Over”.
Memorize the
Phonetic Alphabet
It is almost
certain you will have to use it in your conversations.
You will often
be required to spell a certain word or name in your radio conversations to
make sure you are understood.
Using the
phonetic equivalents instead of letters will make sure letters such as ‘F’
are not misinterpreted as ‘S’, ‘T’ as ‘C, or ‘M’ as ‘N’.
Following is a list showing the international
phonetics used for the alphabet:
It’s been a year since I become member of HRC, and I would
say that it gives more meaning to my life as a volunteer, to feel high when
there are in need for emergency or in any other volunteer works to be done.
Hope for the years to come that HRC will be a stronger and better
one with purpose, even though the ups and downs we experienced, old and new
members will be as one for the betterment of the group to help others in needs
especially in times of disaster.
“Volunteer for me is very difficult meaning to fathom it’s an
infinite as long as I live.”
