| Links to the latest
SeaSonde software below:
Current Radial Software available:
Current Combine Software available:
Note: CODAR Ocean Sensors, Ltd. no longer
Mac OS 9 software. OS X upgrades are free
all SeaSonde owners.
SMILE & PARTICIPATE
IN CODAR PHOTO CONTEST
Send us your favorite SeaSonde hardware
photo or data product image. If it makes it onto our
home page web site, then you'll receive
big kudos and a special gift!
Submit images electronically (as either
jpg, gif, tiff or pict) by 30 September
resolution is preferred. Send to,
using PHOTO CONTEST for subject title. Be sure
to include your name, e-mail and mailing
address within the body of the e-mail.
implies you are giving consent to CODAR
for use of this material.
IMPORTANT NOTE: After running Release4 installers,
please check/change the Archivalist preferences before running
the software. Default preferences will be installed the delete
all but 7 days worth of CSS files!!
Software can be downloaded from http://SeaSonde.com
using standard SeaSonde OS X login and password. Please call us if you have trouble
CODAR Ocean Sensors will be holding its semi-annual
training course this fall in sunny California. The course will
run from Tuesday 31 October at 9:30AM through Friday 3 November
at 3:00PM in the La Feliz Room of Long Marine Laboratory (UCSC).
Lodging is available at the Coast Hotel Santa Cruz (Link to hotel
info). A happy hour gathering on Monday Oct. 30 at 6PM will take
place at Olitas Cantina & Grill on the Santa Cruz Municipal
Tuition is USD $750 per person, and includes course materials,
4 lunches, two dinners. New SeaSonde owners should contact Company
for priority reservations.
available here for download (PDF 40K).
Software sessions will focus on SeaSonde10 - Release 5
(For Intel and PPC Macs).
||Long Marine Lab - Seymour
Coast Santa Cruz Hotel
175 West Cliff Drive, Santa Cruz, CA 95060 Phone: (831) 426-4330
Rooms have been reserved at the hotel, with check-in dates either Monday 30 October
and check-out on Friday 3 November.
Special Group Rate is USD $118 + tax per room per night.
For making hotel reservation, call the hotel Reservations Department at (831)
426-4330, or e-mail firstname.lastname@example.org,
and be sure to reference "CODAR" in the e-mail subject title for receiving
Reservations MUST be made directly with
hotel by 14 October 2006 to obtain discount
rates. Rooms will not be held beyond that date.
The hotel is situated on the beach next to the Santa Cruz Beach Boardwalk and
the Santa Cruz Municipal Wharf. Located just up the street is the Santa Cruz
lighthouse and some of the best surfing spots in the country. Visit the hotel
website for more information.
||The Coast Santa Cruz
HF radar technicians for the California Ocean
Current Monitoring Program (COCMP) attended an Advanced
HF Radar Training workshop August 23 - 24. The two-day workshop
first of its kind and was organized by Regan
Long of San Francisco State University. The specialized training
provided COCMP technicians
with advanced knowledge and skills to help
them better support California's new HF radar network. The trainers
CODAR staff members and researchers from COCMP
Topics included: Interference
diagnosis and solutions, techniques for measuring
and analyzing antenna patterns, transmit pattern
procedures, using "SHARE" (CODAR's
patented GPS synchronization method) and alternative
processing options. The sessions were
held at SFSU's Romberg Tiburon Center on San
State funding for a COCMP HF radar network was awarded in 2005 and provides for
a continuous network of 40+ SeaSondes along the California coast. Thirteen new
sites have been installed within the last year.
HF Radar Technicians with the California Coastal Ocean Currents
Program pose with CODAR's new Long Range "TopHat" transmit antenna
|What goes in should
-- A solution for high VSWR on some 12MHz SeaSondes --
|VSWR (voltage standing wave ratio) is a relative measure of forward power produced
by the transmitter to the amount of power that is reflected back by the antenna.
In an ideal world, we would like ALL of the power going into the transmit antenna
to be radiated out to the sea and not reflected back to the transmitter where
it will be lost in the process of generating unwanted heat. If you have one of
newer SeaSondes with a built-in wattmeter you can read the VSWR value directly
from the meter (see image to the right). With dual needle external meters, there
is a VSWR scale that can be read just below the point where the two needles intersect
VSWR is read
directly below the crossed needles on some
| How high is high?
There is no hard and fast rule for determining
what a high VSWR reading is. Some SeaSondes have been operating
with VSWR values > 3 for many years. The downside is that
their range is compromised. As a general rule, if your VSWR reading
is < 2.5 then you can disregard the solution below -- don't
worry about it. If your VSWR is 2.5 to > 3 then you should
consider a balun. For example, if VSWR is 3, then 75% of the
power down the line goes into the antenna to be radiated, and
25% comes back at you; that may be marginally tolerable to some.
If the VSWR rises to 5.8, then 50% gets radiated and 50% gets
reflected; that's no good in anybody's book! A perfect antenna
impedance match has a VSWR of 1; all power gets radiated and
none reflected. This is rarely attainable but is worth shooting
SeaSonde Transmit Monitor screen with VSWR Reading
|Why is high VSWR
more common on a
You may be surprised to hear that our 12MHz SeaSonde transmit antennas are not
optimally designed for the lowest VSWR. In theory, the two 8' horizontal whips
should be twice as long as they are to optimize the antenna for the frequencies
in that band. The physical limitations of two 16' horizontal side whips are obvious
(the whips would droop conspicuously). This led us to a compromise design which
works well in most cases and for most frequencies between 12-14MHz.
What is a balun?
You may have never heard the term balun, but I guarantee you've seen one. The
little adapter gadget that comes with every TV set to adapt a ribbon cable to
a coax is an impedance-matching balun. The term itself is a contraction of the
words BALanced/UNbalanced. It has two functions: (1) To match like a transformer
at terminals with two different impedances on either side, so that no reflections
(high VSWR) will occur and (2) to ensure that radiating currents do not flow
where they are not wanted, for example on the outside of a coaxial line that
feeds a dipole; the coax is an unbalanced line while the dipole is a balanced
device, and -- without a balun -- one will get the undesired current flowing
on the outside of the coaxial cable braid.
What does our balun look like? Balun's are
usually made with transformer components...
coils and the like. Our 12 MHz baluns consist
of an air coil (potted in resin) which
attaches to the base of the transmit head.
A length of RG-58 wire connects to the air
coil and then wraps around a stack of
ferrites (metal rings) sealed in a PVC container.
Tuning adjustments are made by changing the
number of wraps of RG-58 wire through
the stack of ferrites.
Sequence of balun installation
1) Disassemble transmit antenna to access the transmit feed
2) Thread the RG-58 cable segment through
the mast and attach the
potted air coil,
3) Attach the other end of the air coil to the antenna's transmit feed
4) Adjust the position of the ferrite stack on the cable
to fine tune (minimize)
your VSWR reading.
|How do I know when to use a balun?
First check to be sure your system's transmit cables and antenna are in good
condition. Then try adjusting the coil of RG-8 cable that the CODAR engineer attached
to the antenna mast at installation time. Small adjustments to the tightness
and orientation of the coil on the mast can have a significant effect on the
antenna impedance match and VSWR reading. In a sense this coil also functions
as a balun.
Where do I get one?
If you still can't get your VSWR below 2.5 then contact us for a consultation
at Once we have determined that your high reflected power is a result of a mismatch
for the frequency that you are using (and not antenna damage), we will be happy
to provide you with a balun for your 12MHz system along with instructions on
how to install it.
For additional information
please download PDF (204K): "Effects
|Care and Feeding of Your Loopstick Antenna Receive
Loopstick antennas are very robust and with the exception of lightening strikes
and hurricanes they will often run for years without service. However, we highly
recommend that you do a complete inspection of your receive antenna at least
once per year. The best time to do this is right after the rainy season and if
budget permits you should conduct an antenna pattern measurement as well. A sample
annual maintenance checklist is included at the end of this article.
| Water Damage: The Leading Cause of Loopstick Antenna Failure
The most common cause of loopstick antenna failure is leakage of water through
the lid gasket or o-ring seal on the monopole antenna connection on the lid.
High winds can work the monopole fitting loose over time but operator error
is the cause of leaks in the majority of cases.
Always use a second wrench when applying torque to unscrew the whip from the
monopole fitting on the receive box lid. If this fitting is accidentally loosened
it will also need to be tightened using two wrenches. The box lid will need to
be removed in order to do this. Check the condition of the o-ring and that the
fitting is tight whenever you have the opportunity (at least once a year).
ParkerOLube is a "silicone safe" lubricant for most types of o-rings
|Use a non-silicone based lubricant for both the lid gasket
and monopole o-ring. Silicone based lubricants will degrade the
box lid gasket material over time and prevent proper sealing.
Parker O-Lube is a good choice for this. Use Dow Corning DC-4
silicone grease for cable connectors, whip antennas and insulators.
Use household silicone caulk to seal the gap
Grooved O-ring with monopole fitting
(Note the groove in the new style o-ring)
(Use a second wrench with opposing force to prevent monopole fitting from unscrewing)
Apply only enough silicone caulk to fill the
crack, then wipe the excess off with a damp
paper towel before it dries
Wipe off the excess caulk
|When re-installing the lid after an inspection, tighten the
four corner screws a little bit at a time as
you would when tightening the lug nuts on your wheel after a
tire change. Then inspect
the gap clearance around the perimeter of the
lid to be sure it has been tightened evenly. As an added measure
you can apply a small bead of silicone bathtub
caulk to the gap. Use just enough to seal the crack and then
use a damp finger
tip or damp paper towel to wipe off the excess
before it dries. You don't want to force the caulk into the gasket
seal but just
seal the crack.
|Note: we have recently switched
to a "grooved" O-ring
for the monopole fitting which has better sealing
properties and is somewhat resistant to degradation by silicone
If you are planning to visit and service an
older loopstick antenna and would like to replace the o-ring
with the new style, please
Another common problem that can put you out of commission in a hurry is a damaged
Helicoil® on one or more of the ground plane whips. A Helicoil® is
a stainless steel insert that prevents electrolysis from occurring between
dissimilar metals. It also protects against damage to threaded holes in soft
metals such as aluminum. The SeaSonde receive antenna box has an aluminum ground
plate attached to a non-metallic box. The corners of the plate are tapped with
a 25/64' bit and a 3/8'-24 thread stainless steel Helicoil® is threaded
into the hole with a special tool.
Damage to the Helicoil® can occur when the ground plane whips
into the Helicoil® or the leading edge of the Helicoil® is
of the tapped hole. If this occurs, the damaged Helicoil® can be removed
with a small pair of needle-nose pliers and the hole can be cleaned out with
a 25/64" tap. A new Helicoil® can then be inserted IF you
have the "special
tool". The tool can be purchased for about $40 (www.toolsource.com, part
#HEL5528-6) and is highly recommended as an addition to your field toolkit.
Helicoil Thread Insert and Tool
| Annual Receive Antenna Checklist:
- At the back of the receiver check loop 1,
loop 2 and monopole RG-58 cables for proper
resistance. The loop resistances between center pin and coax
shield should be ~ 1550
ohms (+/- 75 ohms) and the monopole should
be open (OL) or an extremely high resistance. Re-check these
values at the connectors
on the base of the receive box after it is
removed and the cables are disconnected.
- Check the "black arrow" bearing of the receive box
and note it in your desktop computer log before
taking the antenna down.
- Check the aluminum mast for signs of metal
fatigue or electrolysis damage. Replace any
- Take down the receive antenna mast. Mark
the orientation of the receive box bracket on the mast and remove
the antenna box (whips can be left in place
if you like).
- If your whips have ferrules (joints) check
to see that the fiberglass is secure in the
metal fittings and that you have continuity between the base
of each whip and the
metal ferrule piece holding the tip section
of the whip.
- Remove the box lid and inspect for leakage
around the seals or moisture on the top of
the loopstick's printed circuit board.
- Note the orientation of loop 1 on the loopstick
board in the box. Use a black felt pen make
index marks on the board and box if necessary.
- Carefully remove the board and inspect for
water or water damage at the base of the box.
Clean, repair or replace connectors as needed.
- Re-assemble the receive box and inspect carefully.
- Re-check the cables with the loopstick disconnected.
Check for shorts between the center conductor
and shielding on all three cables. Then short the center conductor
to the shielding
and measure the resistance through the center
conductor and back along the shielding. This should be a very
low resistance value.
- Re-assemble the receive antenna with the
black arrow pointing in the direction that it was for your original
antenna pattern measurement. Secure the mast
screws at the plastic
coupler with a couple of wraps of electrical
tape over them. (if the screws fall out, the antenna can rotate
and your bearing
will be incorrect). If you plan re-do your
antenna pattern you can reset the loop 1 bearing in the RadialSiteSetup
use ideal radials until your new pattern file
- At the receiver, re-check the settings for
your loop 1 bearing (black arrow magnetic bearing
converted to loop 1 True). Wait for at least one full CSS file
to see that the noise floor and S/N values
are within normal limits.
Take precautions now! "This
could happen to you!!"
Click here to downlaod the QuickTime movie - "Receive_box_trouble.mov"
If you have any questions,
please email us
1914 Plymouth Street
Mountain View, CA 94043 USA
Phone: +1 (408) 773-8240
Fax: +1 (408) 773-0514