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Radio-tracking principles and appliccations.
Contents
1/ The company.
2/ Practical tips for the use of radio-tracking sets.
3/ Attachment of falcon transmitters.
4/ 216 MHz or 432 MHz (VHF or UHF). Pros and cons.
5/ New products.
6/ Coming developments.
7/ Satelite tracking. Pros and cons.
1/ The company
Ayama-Segutel, owned by Ignacio Amaya Dominguez
Ignacio Amaya was born in Córdoba, 1944. After a period of training in electronics, he worked in the telecomunication field for several years before founding AYAMA, a company devoted to the manufacture and trading of security microelectronic equipment, using the trade mark "seguTEL".
In 1993, through a long experience in electronic miniatures, Ayama-Segutel makes its first radio-tracking model for falconry. Then several models were progressively designed which make up an increasingly wide catalogue, ranging from security equipment to wildlife radio-tracking systems.
Ayama-Segutel is now engaged in the development of a range of microcomputer-controlled transmitters, endowed with a personal code to identify a particular animal, as well as other devices which will be dealt on further on in the present article.
2/ Practical tips for the use of radio-tracking sets.
I will first talk about batteries, the incorrect handling of which provokes some
unexpected malfunction in the
transmitter.
- Don't keep the batteries along with other metallic objects, because they will
short-circuit and eventually
loose life-time. - Don't preserve them with adhesive tape, because it can form an insulating coat that
prevents the current
from passing through them. - Instead, a soft plastic pipe must be used, which is included with the trasnmitter. The
batteries must placed
in it in order for their outer perimeter to be preserved from electrical crossings. If
just one battery is needed
it must as well thus preserved, for otherwise it could be activated even without the lid
having been screwed
up, because the battery could be in contact with the walls of the tube. In placing the two batteries within the nsulating pipe, care must be taken to prevent any possible electrical crossing between them. - The placement of the batteries in the transmitter is the same for all makes (except in
some rare cases) - the
negative pole of the first battery must be placed in contact with the centre of the
battery-holder, and its positive
one, that of the body, must be in contact with the negative pole of the second battery.
This is called
configuration in series, so that the voltages are summed up.
- The different kinds of batteries for the transmitters can be divided into four categories:
1º Silver oxide batteries
2º Litium batteries
3º Mercury batteries
4º Air-zinc batteries
- Silver oxide batteries (button-type, 1.5 V)
They are the most commonly used on account of the large range of models available, which means a great flexibility when deciding which one is most suitable for each transmitter. The batteries must always be those recommended by the maker, because there are basically two types, low-drain batteries (which are used in alarm- and light-less watches, but never in transmitters), and high-drain ones, the kind we must use. Since the dimensions of both types are identical, there can be some confusion. Let us take Maxell 357 battery as a reference, with a capacity of 165 mA/H, and then compare the four categories.
- Litium batteries (button-type, 3 V)
- Mercury batteries (button-type, 1.4 V)
- Air-zinc batteries (button-type 1.4 V)
They can be kept for up to three years with a minimal lifetime loss.
They are not as extensively used in falconry as silver-oxidum ones, because there is a shorter range of small diametres and they are more expensive than the latter. Their instant energy, especially as regards the button-type ones, is limited, so they are not suitable for high-power transmitters. Special, larger models exist, with a higher instant current, which are widely used in wildlife transmitters.
One instance of a litium batery for falconry is the 2L76 by UCAR, 165 mA/h, with quite the same performance as two 357 joined together - 3V 165 mA.
A litium battery can be kept for as long as 10 years with a minimal lifetime loss
Even if they have a higher capacity than the former, they are falling into desuse out of their pollutant efects to the environment, so the makers are relinquishing their production.
The capacity for the mercury battery 675 is 270 mA. They produce higher instant currents.
They have the highest capacity. They are widely used in deaf aids. There is an abundant
range of sizes, similar to that of silver-oxide batteries. Taking as a reference the size
357
(silver-oxide) we have the ZA675, with 520 mA., which means two times the life-time
of the mercury battery and three times that of the silver-oxide ones. Unfortunately, these
batteries usually have an adhesive label stopping one or two holes of the flat face of the
battery, which prevents the air from passing through it. If the holes are stopped by
attaching
two batteries, they will not yield the maximum current capacity. Eventhough the maker
advises to remove the label just a few minutes before using the battery, we have verified
it is better to do so at least one day before. If we wonder why the label is placed, we
can
say that it is in order to preserve it, because in a way it is as though removing the
label
would be the last phase of the making of the battery. If we want to get the maximum
performance of the battery, we should always have a set of batteries in reserve ready at
hand, without fastening them together, their labels removed.
When they are due to be used, it would be highly recommendable, in order for the batteries
to have air, to have thin metallic washers of a good conductive material, 0.1 mm thick,
the diametre slighty smaller than that of the battery, with a cutting so as to better let
the
air pass through. One washer should be placed for each battery, and the plastic pipe
designed to fasten two batteries together and insulate them from the alluminium tube must
be cut in such a way so as to let the air in both of the batteries independently. It seems
very complicated, but if done with precision, a lifetime of up to 24 days can be achieved
for our 50-km-range transmitters, instead of the 8 days with two batteries 357.
- The battery checkers for conventional batteries don't help much as regards our
confidence
after having checked the batteries of a transmitter. The reason is that the conventional
checkers
don't show the percentage of the battery power. When a battery that is due to be used in a
watch
is checked the checking is valid, because the consumption is so low that the watck can
still work
when the battery is at 10% of its capacity. Unfortunately, transmitters (excepting some
used in
wildlife) consume much current, because the question is to get the maximum range for few
days
of lifetime. This leads us to the conclusion that we may be using batteries that have
satisfactorily
passed the checking and within just a few hours stop working. As a rule, the batteries should be replaced at half the lifetime indicated by the maker.
Even if there are much more sophisticated cheking systems, more often than not they
are not
available because they are either very expensive or very hard to manage. If in spite of
everything
a conventional checking system have to be used, the battery must be connected as little
time
as possible, because there is a partial discharge while connected. On the other hand, if a
set of
batteries is used, each of them must be checked individually.
3/ Attaching the transmitter to the falcon
The two basic systems are:
- Tail attachment.
The tail attachment is done with two main parts: The transmitter has a steel wire named
'tail clip', which is inserted into the 'tail support'. The latter is made of brass plate,
with two
tabs which must be fastened to the central tail, with the possible reinforcement of the
attachment by some waterproof instant glue. The clip easily catches on the support, an
then
the bent tips of the steel wire of the clip prevent it from accidental unfastening. In
order to
unfasten the transmitter, the tips of the clip must be pressed together.
- Leg attachment (a new leg attachment).
- With the conventional method, that is, on the tail, the transmitter is hit every time
the bird alights, not
to speak of its being dragged when the bird is walking. This can seriously damage the
electronic circuit
of the transmitter, especially the quartz crystal that determines the emitting frequency.
In this case,
experience has demonstrated that the falconer thinks that the transmitter is working
correctly, while
in fact he has lost many kilometres of the original range, due to a partial damage.
Besides, some time the
transmitter may change its frequency. In any of these cases, don't take risks and send us it for a check.
We have a 48-hour repair service.
- With the conventional tail attachment, whenever the animal is on the ground the radiation of the transmitter highly limited because the antenna is touching the ground. This is especially relevant when the ground is wet.
- The new attachment method, consisting of a steel clip which rounds tube of the transmitter and is fastened to the leg with a leather strip, avoids these shortcomings. When the bird is walking on the ground, the transmitter antenna must be placed at an angle of 45º.
4/ 216 MHz or 432 MHz (VHF or UHF). pros and cons.
216 MHz Advantages.
- The receiver is cheaper than the 432 MHz one.
- Proportionally the transmitters work with higher lifetime and power.
- The penetration in vegetation is higher than the with the 432 MHz reveiver.
- The range is theoretically higher than that of the 430 MHz receiver (but it is usually lower because of the electrical noise, much higher than that of the 430 MHz receiver).
- The difraction is higher.
216 MHz disadvantages.
- In order to get the maximum range, the transmitter antenna must be 35 centimetres long,
which
corresponds to 1/4th of the wavelength, even though 23-cm-long antennae (compensated) are
made, but
with a loss of 50% of the range if compared with the 35-cm-long one. With the 430 MHz band the transmitter antenna is 17 cm long, without loss of range because that is the suitable size for the frequency.
This is very important, in order to prevent the bird from getting electrocuted.
- Interference from industrial machinery, high-tension cables, etc. may prevent the
reception of weak
signals. This can be to a certain extent avoided by using a 432 MHz receiver instead.
- The receiver antenna is somewhat cumbersome for the 216 MHz model. Instead, our 432 MHz
model
has a compact two-element folding antenna, as well as a comfortable handle, which is
extraordinarily
easy to use, proving very agile in the tracking, since it is as well possible to use it from inside the car.
- Lower reflection than the 432 MHz model.
- Higher difraction with trees, whick provokes errors in the tracking, especially in vertical polarization.
Comments
I should like to be as objective as possible in giving my advice, while my condition of being a maker makes it hard. That is why I am going to refer to some comparisons (216 MHz vs. 432 MHz) by other experts.
- Mr.Tony Crosswell, a renowned falconer from the UK has, after extensive tests, come to the conclusion that, according to the shortcomings of each case, the 430 MHz version is more effective. This article was published in the British Falconers' Newsletter, March, 1998.
- A renowned Belgian falconer living in the province of Cádiz, who works for a well-known chain of aquariums, tells me he has tried both versions and he as well prefers the 432 MHz one.
- A friend of mine, Benedicto, a well-known falconer who has worked in Germany with one of the best German breeders, also prefers the 432 MHz version.
Personally, I think that as for flat ground, the best choice by far is 432 MHz, and as
regards
mountainous terrain it can also be the best choice, provided it is used dexterously.
5/ New products
- Several transmitter 216 MHz and 432 Mhz models, just 2.8 gr of weight,
batteries inclusive
which makes them ideal for small birds such as sparrowhawks and the like, or even
as a 2nd transmitter.
- Several transmitter 216 MHz models. Aluminium-tube formats with weights of 9 and 13 gr batteries inclusive, for hacking or as a 2nd transmitter with lifetimes of 1 month (9 gr) and 2 months (13 gr) and arange of 20 km in optimal conditions (with an extra lid you have the two models in one), besides the 50-km range for 216 KMz and 430 MHz.
432 Falconry Transmitters
216 MHz Falconry Transmitters
- A new 432 MHz, 10-channel, miniature receiver, very easy to use, with folding handle and
antenna, which
is delivered along with a case similar to the video-camera ones. Its compact size enables
you to track from within
your car.
- A new signal processing system for the receivers, which is delivered as an option, when
a new
receiver is bought. The system, called PT-3, produces distinct, loud, long sounds even if
the received
signal is noisy, because it creates a new signal from it. It also includes an optional lighting system for night tracking, by which the light winks at the rate of the received signal. It can be delivered with any frequency band.
6/ Coming Developtments
The progress of microelectronics enables us to develop devices which are closer and closer to the ideal, which we endeavour in all aspects, to wit:
- Transmitters that emit a simple identity code in order for us to make sure that the
animal is ours.
Experience has demonstrated that we may lose a precious piece of time tracking somebody else's transmitter.
- Transmitters that emit just the hours and the days of the week we want. This is
specially interesting in
wildlife tracking, because it both proportionally increases the battery lifetime and the
range, with the same
weight.
- Transmitters that besides performing the above-mentioned functions, control the heart
pulses of the animal,
the body temperature, the activity, the height, etc. and send us these data via radio for
our knowledge and
consideration.
7/ Satellite tracking. Pros and cons.
Pros:
- The situation can be determined at a distance of thousands of kilometres.
- The daily course of the transmitter can be known, along with the time and position.
Cons
- 10-20 times as expensive as a conventional transmitter.
- Expensive daily fee - aprox. 15 euros per day (Argos)
- Much more heavy than the conventional systems, a minimum 35 gr.
- A continuous access to the situation is not possible, because on technical grounds it only emits every two minutes.
- It must generally be used along with a conventional transmitter in order to have access
to it.