Frequently Asked Questions

Receivers:

Why does my receiver pick up more than one of my collars at the same time? They're on different channels.
Extremely strong signals will get through even the most powerful filters in a receiver. If you have transmitters on adjacent channels transmitting right around you, you might hear a popping or thumping sound from them. This can be a distraction when you're trying to pick up a very weak signal from a lost animal.

The solution is to turn off the transmitters around you while you track a lost animal. If you're just turning up, switching the Range Switch to Near will help to remove the unwanted signals.

I lost the signal and tried to tune it in. I couldn't get it again.
If you loose the signal, don't panic and tune all over the dial. It's essential not to lose the correct tuning. The signal may have drifted, but not much. So if you really think the signal may have drifted, just turn the tuning knob very slightly and search for the signal by scanning the horizon 360‘. Count the clicks on the Fine Tune knob as you search. The small detents (or clicks) will help you remember where the original settingwas. If you don't find it, you're out of range. Turn the Tuning knob back where it was when you last heard the signal and go to higher location and try again.

I could only pick up a collar a half a mile away
This usually happens because the transmitter is putting out a weak signal. The range of transmitters varies tremendously, depending on where they are. A transmitter on the ground may go less than half a mile, especially if the antenna is pointing straight at you.

If the transmitter is putting out a good signal, the problem is almost always impropertuning of the receiver. It's possible to tune to a tone that sounds like your transmitter, but is actually at the wrong frequency (or even on the wrong channel!) It will sound fine when you're right next to the transmitter, but when you get in the field it becomes weak (this can happen on any receiver).

To avoid this, set your receiver on Near when you tune up - this removes all but the real, genuine signal you want to tune to. And stand a short distance away when you tune in.

Also, if you have the Filter Switch on Narrow, be sure to tune precisely to the loudesttone. This requires some practice and a steady hand. The Narrow Filter is the key to getting the best range. With it, your Marshall receiver will deliver range as good if not better than any other telemetry receiver on the market. But like any high performance piece of equipment, if you use it incorrectly, the performance can be degraded.

What is the single most important thing to do if I absolutely don't want to lose my dog?
Just remember this: if your animal has a working transmitter, you can almost always find it. It may take hiring a plane to fly over the area, but eventually you can find it if you're patient and there is a signal.

I'm not exactly certain what direction the transmitter is. Am I doing something wrong?
Getting the sharpest bearing to your transmitter saves a lot of searching (that’s why Marshall receivers use a full size, three element yagi antenna). But even a three or five element yagi has a fairly broad forward response (see the chart later on.)
The following, easy technique can help you get a more accurate bearing. Instead oftrying to find the strongest signal, try to find two points on either side of it. Scan to both sides of the maximum signal and notice the points on the horizon where the signal drops 1 unit on the S-Meter. Your best bet is that the transmitter is halfway between those two points. By the way, the wrong setting of the Range Switch could cause this problem, too. See the following question.

Why is the Range Switch necessary? My other receiver didn't have one.
It’s not that loud signals will hurt the receiver. It’s simply a matter of keeping your receiver optimally directional. Without this switch it would be difficult to track and get a direction of a strong signal up close. If the signal is very strong and you don’t switch down to Medium or Near, the receiver will not point out the right direction very precisely. This is because the signal is strong enough to bypass the antenna altogether and go straight into the receiver. The antenna, the only thing that gives you directionality, is effectively disabled. The strong signal also saturates the receiver,
making all signals sound equally loud. Marshall receivers use precisely machined, solid aluminum cases to shield out these unwanted signals, but the Range Switch is still needed. Your Marshall receiver employs a sophisticated active attenuator circuit, which other receivers don’t have, and that’s how it can take you to within a few feet of your transmitter! Marshall receivers have unequalled performance up close. You just have to flip the switch.

How can I tell how far away my transmitter is?
One of the biggest challenges in telemetry is determining distance. There is no scientifically sound way of getting the distance from a transmitter signal. You can easily be deceived by a loud signal from a transmitter very far away. However, there
are a couple of tricks to estimating it:

Distance Technique #1: Let’s assume you are receiving
a strong signal with the Range Switch on Far. Now
flip the switch from Far to Medium. If the signal remainsstrong, it means you are fairly close to the transmitter.
With a strong signal, here are typical ranges to a transmitter
near the ground:

      Near ............................. Less than 200 feet
      Far ............................... Over 200 feet

The above table is only an example; you won’t get the
same results. It depends on your transmitter, the terrain,
and many other factors. But over time you’ll get afeel for the distance these Range settings represent
with your transmitter and terrain.

Distance Technique #2: Just take a reading on the SMeter
and then proceed in the direction of the transmitter
until the meter reads twice as much. You will have
covered approximately half the distance to your target.
This only works with direct line-of-sight signals of the
same polarization and gives only an approximation.
Still, it could save you from driving miles out of yourway. Adjust the Volume Knob during the first reading
so the meter reads about a third of full scale (where it
is likely to be the most linear.)

What is kHz and a MHz?
These are measurements of frequency. Every transmitter has a unique frequency that makes it distinguishable from all others. Fortunately, a receiver can tune into a single frequency at a time and reject all the others. The basic measure of frequency is the hertz. It represents one cycle or vibration per second. A kilohertz (kHz) is a thousand
cycles per second, and a megahertz (mHz) is a million cycles per second. An AM broadcast station is fairly in low in frequency, perhaps .7 mHz, while an FM station is much higher, say at 105 mHz. Your telemetry operates at a still higher frequency, such
as 216.055 mHz. Thus, a single short pulse from your transmitter is made up of several hundred million electro-magnetic vibrations. The kilohertz unit is usually used in telemetry to measure the difference between frequencies. For example, if you had a second transmitter at 216.070, it would be 15 kHz higher than the one mentioned in the previous paragraph. Each of the channels on your Marshall receiver covers a range of 10 kHz.

My Marshall receiver doesn't tune in as "broadly" as the other receiver I'm used to. What's wrong?
Your Marshall receiver may tune “quicker” than some other receivers. If so, it’s probably because it covers more frequency spectrum on each channel, in order to give more coverage. It’s a feature, not a problem. Just turn the Tune Knob a little more slowly than you’re used to. If you tune across a signal slowly you’ll hear the pitch go from high to low until the sound is so low it disappears. If you keep turning the knob the sound will return, this time going from low to high. This is normal.

Is there an easier way to get the receiver in and out of the car?
It’s a lot easier if you push the sliding channel closed, partially collapsing the antenna. However, don’t forget to extend it when using the receiver in order to get maximum performance from the antenna.

How can I use my Marshall receiver with my car top antenna? It's got a different plug.
Marshall receivers use high reliability, lightweight, gold-plated SMB connectors. Call to order a short adapter that will fit the larger BNC connectors used on some other antennas.

Field Use:

I've noticed that when I rotate the receiver antenna from vertical to horizontal, the signal is many times stronger.
You know from using sunglasses that sunlight is somewhat polarized. Radio waves are strongly polarized. Polarization has to do with the alignment of the magnetic and electric fields that make up the wave. When the transmitter antenna is vertical we
say the waves are vertically polarized, and when it’s laying on its side they are horizontally polarized. The thing to remember is that your receiving antenna should
be oriented the same way as your transmitter antenna. This is important with weak signals. Your antenna will work poorly if it’s oriented the wrong way, as much as ten times worse. With a dog, the best orientation could be somewhere between vertical
and horizontal, maybe at 60º from horizontal.

Rule #1: When tracking a weak signal, always try both
orientations first! Stay with the orientation that gives the strongest signal. This cannot be emphasized strongly enough. It is easy to develop a preference for which way to hold your antenna, but in doing so you will miss the boat half the time. Try them both and remember that your animal can change positions at any time.

It may seem that polarization doesn’t matter once you have a
nice strong signal. Not quite so. The yagi antenna’s directionality is somewhat sharper if you hold it horizontally. Radiation from the end of the transmitter antenna (around the hole of the donut) has elements of both vertical and horizontal
polarization. And after a signal has been reflected it loses its polarization altogether (it actually becomes elliptically polarized, with equal elements of vertical and horizontal polarization). The same loss of polarization can occur after the wave
travels through obstacles.

Hint: Absence of polarization can be a clue. Suppose you’re
in a canyon and get a strong reading from a canyon wall. Either your transmitter’s up there, or it’s a reflection off the canyon wall from somewhere else. Before climbing, check the polarity of the signal. If it’s a reflection the strength won’t change much
as you rotate the yagi around its axis.

I've never used an OMNI antenna before. How important is it?.
OMNI antennas pick up equally well in all directions and can save a lot of time when chasing a signal from a vehicle. You should use one on top of your vehicle when moving to the next point where you’ll take a bearing. Hearing the signal from your bird or dog can tell you if you’re going in the right direction and warn you if you’re about to lose the signal.

Hint: If the signal starts getting weak you know to stop and take a bearing with your yagi. At least then you’ll know what point of the horizon your animal just disappeared behind, a vital piece of information. The omni-directional antenna is also useful when you lose the signal altogether. Hook it up and drive around in widening circles
around where you think the animal should be until you hear something.
The most common omni-directional antenna is probably a magnetically mounted whip (shown below). It should be in the center of the vehicle roof, as the roof forms a key component of the antenna. Whip antennas are usually 1/4 wavelength long. A 5/8 wavelength whip has more gain..

I hear a lot about signal bounce. How do I know when that's happening and why?
Radio waves reflect under many conditions and the result is always an illusion. You think the transmitter is behind the point of reflection, but it isn’t so. Suppose, for example, you pick up the signal coming from the side of a mountain. You spend hours climbing to the place only to find no transmitter there. It never was there. What you saw was the reflection of the transmitter’s signal from another valley. You’re comforted by the fact that without a reflection you would have gotten no signal at all.
Radio waves reflect off any surfaces that conduct electricity, including the following:

Metal is the ideal reflector. Reflections from your nearby
vehicle can easily give you a false reading and the steel
in a building can scatter your signal in every direction.
Put a few buildings together and you have a major problem.

Water is another good conductor. Radio waves will
bounce off the surface of a lake like light off a reflecting
pool.

Hills and mountains reflect, but their properties will depend
on the nature of the material in them, particularly
the moisture they hold; wetter structures reflect better.
Most natural structures will give significant reflections.

Live trees reflect radio waves, but dry wood does not. A
forest can scatter the signal in many directions. Any
green plant more than a meter in size can do it.
Stealth Tracking Receiver

Radio reflections occur just like with a mirror, in that the angle the wave comes out is the same as the angle going in. A flat surface will reflect the signal in only one direction (the concept behind the flat, angular surfaces of Stealth aircraft), while a
rounded surface will reflect in many directions, and most natural surfaces behave like that. Multiple reflections are possible and a signal may funnel a long distance down a canyon through successive reflections.

What's the effect of wire fences or powerlines on a signal?
A power line or fence wire can really mix things up. The fence picks up your transmitter’s signal, like an antenna, and the signal races down the wire and re-radiates. Your receiver picks up false signals which will most likely be horizontally polarized. The effect is worst when your animal is right next to the wire.

Why is it that I can have a good signal, and then step two or three feet to one side, and it's suddenly very weak?
When you are near the animal you may experience checkerboard patterns (technically known as interference patterns.) If you plotted the strength of the signal near your transmitter, it would look something like a round checkerboard. One spot is
strong, while a few feet away you get little signal. Checkerboard patterns occur when the signal reaches your receiver over two different paths, one being line-of-sight and the other usually a reflection off the ground. When the two signals combine they compliment each other in certain spots, nullifying each other in others. When the transmitter is close: The checkerboard effect is most pronounced when your animal is off the ground in a tree, especially when the transmitter antenna is pointing at you. Checkerboard patterns can weaken the signal in the direction of the animal while it remains strong in some other false direction. It can throw you off by exactly ninety
degrees!

Don’t rely on signal strength alone to find the animal, especially up close, because you could have just moved into one of the low signal pockets. Instead, rely on the directionality provided by your antenna. Don’t get too close. Circle where you think the animal is. Use vertical polarization, since ground doesn’t reflect vertical waves well. When the transmitter is distant: The checkerboard effect simply makes the signal stronger in some spots. Therefore, when you’re trying to pick up a very weak signal,
always move around and try to get the signal at several spots within a 15 foot radius.

I train and hunt in the midwest where it's totally flat. How far should the signal go with no obstructions?
The biggest obstacle to radio waves is the earth itself. The range of a telemetry system is limited first and foremost by the horizon. The curvature of the earth creates a circular area around the transmitter where you can pick up the signal, the so-called line-of-sight radius. The actual radius depends on the elevation of both the transmitter and the receiver.

If your transmitter is on flat ground and you are standing on the ground, the range can be just a few miles. Irregularities like hills reduce the line-of-sight to even less than what it would be if the earth were smooth. Every kind of terrain produces “radio shadows”. As you move around you can go in and out of shadows, even picking up a signal much further away from a spot where you picked up no signal.

The key to getting the best range from your receiver is altitude. High spots are least
likely to be in a shadow. If you’re not getting a good signal, the first thing to do is get higher. Driving to the top of a hill or climbing a water tower can dramatically increase
your transmitter’s range.

Is there a simple way to figure out how close the signal really is other than volume?
After you take your first bearing, the natural tendency is to go straight in that direction toward the transmitter. And if you have a pretty good idea where the transmitter is that’s not a bad idea. However, usually you will end up taking a lot of extra measurements that way because you lack information about the transmitter’s distance. If the signal is weak it doesn’t always mean the transmitter is far away.

Another approach is triangulation. Instead of moving directly toward where you think the transmitter is, you move closer and sideways. By taking only two bearings you can theoretically pinpoint the exact location of the transmitter: at the intersection of the two lines. You probably can’t follow the line to the transmitter directly anyway because of roads and obstacles or the need to stay on high ground, so take advantage of that fact.

For triangulation to work, you have to remember the line of the previous bearing. You can do that mentally by noting two landmarks on that line as you take the bearing. Note a landmark behind the transmitter and another behind you. When you take the next bearing you’ll know that the transmitter should be somewhere on the line connecting the two landmarks. Proceed toward the point of intersection, but again offset to a third point. You’ll end up rapidly closing in on the transmitter in a spiral.

What's the best thing to immediately do if I lose the signal?
Go to high ground that looks down on where you expect the transmitter to be. If that doesn’t help try high ground on the other side of where you expect the transmitter to be or that looks over the horizon in the direction the bird was headed.
If you have no clue where the bird is, drive in widening concentric circles around where you last saw it, as closely as roads will permit. If you have an omni-directional antenna put it on and keep your receiver on.

When you are on a hilltop, the best location for getting a weak signal is usually slightly in front of the peak, though you can get a better 360°radius from the top.
The ultimate way to get up high is to hire an airplane and circle the area, using a yagi antenna mounted on the wing struts, pointing at an angle downward. Be sure to use good headphones in a plane. You’ll need a long piece of antenna coax with the right connectors on each end.

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