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Old July 6th 03, 01:16 PM
Gjtatters
 
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Default Can Ham Radio interfere with a Biological Telemetry signal?

This may at first seem like a strange post to a Ham Radio newsgroup,
but I am hoping someone can help us out. We (Canadian Scientists) are
currently conducting research in Brazil near the city Rio Claro in Sao
Paolo state. We study lizard physiology and hibernation, and are
currently conducting a year long study using radio telemeters
implanted inside lizards. These telemeters allow us to monitor heart
rate, breathing rate and body temperature, and all of this information
is uploaded via radio frequencies and recorded to computer.

The telemeters themselves work in the high MHz range. Each animal (we
are currently looking at 4 animals) has a unique telemeter with a
unique transmission band. The 4 frequencies we are looking at a
182, 184, 206 and 208 Mhz. This radio frequency information is then
decoded with a demodulator, and the information stored as a voltage
signal on a standard computer acquisition system.

The problem we are finding is that typically, between 11am and 3pm
during the day, our telemeters are encountering massive interference
from some external source, and we cannot make any meaningful
recordings. Our signal strength goes to pot, and all we get is noise.
Strangely enough, during the evenings, the recordings seem fine.

To add to the story, all the telemeters can be turned on or off (they
have a battery that should last about 1 year) using a 1.8 Mhz burst
(we have a small battery powered wand-like antenna that we wave over
the lizards for this express purpose!). Once we started to encounter
our interference problem, we began to think that perhaps our
telemeters are being turned on and off intermittently by an external
source of 1.8 MHz. That was when we realized that Ham Radio operates
from about 1.8 to 30 Mhz.

What I wanted to ask the newsgroup was whether anyone thinks that the
signal strength from a local ham radio operator would be enough to
turn our telemeters on or off (I doubt you would know the answer to
this question, but thought I'd ask). Do Ham Radio operators typically
use 1.8 Mhz?

Otherwise, does anyone out there know what could possibly be
interfering at the higher frequencies (182-208 MHz)? There is a local
airstrip and flying club that flies overhead where we are conducting
this research, but I do not know if they typically transmit within out
frequency range!

But more importantly, if the Ham Radio signal could be the source of
our interference, we wanted to know if anyone could help us find out
if there is anyone in Rio Claro that is a Ham Radio operator?!! If
so, would they be willing to help us troubleshoot this problem!

Thanks for your time. Please reply directly to this email if you can.

Gjtatters

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Old July 6th 03, 03:21 PM
Doug Smith W9WI
 
Posts: n/a
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Gjtatters wrote:
What I wanted to ask the newsgroup was whether anyone thinks that the
signal strength from a local ham radio operator would be enough to
turn our telemeters on or off (I doubt you would know the answer to
this question, but thought I'd ask). Do Ham Radio operators typically
use 1.8 Mhz?


It's certainly possible ham signals would be strong enough to activate
your equipment. The 1.8MHz band is nowhere near the most popular ham
radio band, but it does see a fair amount of use, including in Brazil.

However, the 1.8MHz band is not good for work over any distance of more
than a few dozen km during the day. There is VERY little daylight
activity on this band - it is used almost entirely at night.

Otherwise, does anyone out there know what could possibly be
interfering at the higher frequencies (182-208 MHz)? There is a local
airstrip and flying club that flies overhead where we are conducting
this research, but I do not know if they typically transmit within out
frequency range!


The 182-208MHz frequencies are used by VHF TV channels 7-13:
182 & 184MHz fall in TV channel 8; 206 & 208MHz in channel 12. It is
concievable that TV stations outside the area you're working in are
"propagating" in via various atmospheric phenomona. (however, that kind
of thing tends to be more common right around sunrise and in the
evening, not in the middle of the day)

But more importantly, if the Ham Radio signal could be the source of
our interference, we wanted to know if anyone could help us find out
if there is anyone in Rio Claro that is a Ham Radio operator?!! If
so, would they be willing to help us troubleshoot this problem!


http://www.labre.org is the national organization for Brazilian hams.
If there is a ham in the area who might be able to help, they should be
able to find them. (and even if the problem doesn't have anything to do
with ham radio, hams are more likely to know what frequencies are used
by broadcast stations in your area - or what other localized sources of
interference are possible)

Two other things you might check...

- How selective is your equipment? (how close does a signal have to be
to 1.8MHz to cause problems? Might 1.5MHz or 1.6MHz be close enough?
In which case it might be an AM broadcast station that's involved?)

- The timing is suspicious. I'm having a hard time thinking of any
radio service that transmits only between 11am and 3pm. Hams typically
operate erratic schedules and more likely at night. Broadcast stations
operate all day long.

I wonder if your equipment is sensitive to heat and drifts off frequency
or otherwise malfunctions in the heat of the day, then returns to normal
operation as the sun goes down and it cools off?

Or, some other transmitter (most likely an AM broadcast transmitter that
operates all day) is drifting with the heat and causing your problem?
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

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Old July 6th 03, 04:17 PM
Green Freddie
 
Posts: n/a
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This may at first seem like a strange post to a Ham Radio newsgroup,
but I am hoping someone can help us out. We (Canadian Scientists) are
currently conducting research in Brazil near the city Rio Claro in Sao
Paolo state. We study lizard physiology and hibernation, and are
currently conducting a year long study using radio telemeters
implanted inside lizards. These telemeters allow us to monitor heart
rate, breathing rate and body temperature, and all of this information
is uploaded via radio frequencies and recorded to computer.


Dear Mr. Scientist-persecutor: we do not like having these things
inside us. Why don't you stick them up YOUR ass?

You should be aware that the boys and I are considering legal action.


The telemeters themselves work in the high MHz range. Each animal (we
are currently looking at 4 animals) has a unique telemeter with a
unique transmission band. The 4 frequencies we are looking at a
182, 184, 206 and 208 Mhz. This radio frequency information is then
decoded with a demodulator, and the information stored as a voltage
signal on a standard computer acquisition system.


It hurts like hell and produces a ringing in the ears.


The problem we are finding is that typically, between 11am and 3pm
during the day, our telemeters are encountering massive interference
from some external source, and we cannot make any meaningful
recordings. Our signal strength goes to pot, and all we get is noise.
Strangely enough, during the evenings, the recordings seem fine.


At the hottest part of the day, we all congregate at Renaldo's Jungle
Bar. You can find us by the large crack in the wall where the air
conditioning leaks out. It's right under the huge neon signs.


To add to the story, all the telemeters can be turned on or off (they
have a battery that should last about 1 year) using a 1.8 Mhz burst
(we have a small battery powered wand-like antenna that we wave over
the lizards for this express purpose!).


We all hate that zap, Dr. Mengele. George gets it worst, though. It
makes him pee and **** himself.

Once we started to encounter
our interference problem, we began to think that perhaps our
telemeters are being turned on and off intermittently by an external
source of 1.8 MHz. That was when we realized that Ham Radio operates
from about 1.8 to 30 Mhz.


Glad to see you Einsteins put a lot of thought into this before coming
down here to torture us. Why not go to Komodo and pick on the big
lizards, tuff guy?


What I wanted to ask the newsgroup was whether anyone thinks that the
signal strength from a local ham radio operator would be enough to
turn our telemeters on or off (I doubt you would know the answer to
this question, but thought I'd ask). Do Ham Radio operators typically
use 1.8 Mhz?

Otherwise, does anyone out there know what could possibly be
interfering at the higher frequencies (182-208 MHz)? There is a local
airstrip and flying club that flies overhead where we are conducting
this research, but I do not know if they typically transmit within out
frequency range!


Nothing like a well-thought out plan. You got grant money to radiate
our bowels but not for a frequency guide?

But more importantly, if the Ham Radio signal could be the source of
our interference, we wanted to know if anyone could help us find out
if there is anyone in Rio Claro that is a Ham Radio operator?!! If
so, would they be willing to help us troubleshoot this problem!


The boys and I wish someone would "troubleshoot" the cause of the
problem.


Thanks for your time. Please reply directly to this email if you can.

Gjtatters


You'll be hearing from Greenpeace, PETA and our lawyers, chump!

The lizards -- Freddie, George, Pedro, and Maurice

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Old July 6th 03, 05:48 PM
*Watt
 
Posts: n/a
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Graters,

Sorry to hear about your problems.

The frequencies you are using for telemetry aren't in the ham bands, they
are in the TV broadcast bands. It would be unlikely for hams to be causing
interference in those frequencies.

I am not familiar with the atmospheric background noise levels in Brazil,
but many of the VHF bands get noise like this during the day. Perhaps at the
equator it is worse than what you may have found with your testing in
Canada.

Can you tell us what the power output is on your lizards, and what the
distance is you are listening from ?

You may be able to improve your signal to noise ratios by using a
directional antenna such as a Yagi aimed toward the lizards, or adding notch
filters tuned to the correct frequencies.

The interference seems to cover a very large bandwidth....suggesting this
may not be a ham or aviation transmitter on your frequencies. Hams would
transmit on a discrete frequency, such as 146.940 mHz. A TV station could
cover 2 of the frequencies at a time though.

Could the problem be in the selectivity of your receiver ? Perhaps there is
an FM radio transmission at 91 - 104mHz that is swamping your receiver. Do
you have another radio (such as a scanner) capable of listening to the
frequencies involved to see what you are hearing....is interference really
there at those frequencies, and if so what does it sound like. If the
equipment has a signal level indicator you might get an idea of the
interference pattern.

The 1.8mHz signal burst is unlikely to be your problem. Do all 4 lizards
turn on and off ? It would be an unusual station that transmits once to turn
off your lizards at 11am , and once again at 3pm to turn them back on. If
there was such interference, I would expect the lizards to be turning off
and on continuously from 11am to 3 pm. It sounds more like a signal/noise
problem, and you are getting swamped with noise.

If there are any hams out there near your experiment site, they would
probably be interested in helping you find out the problem, even if they
aren't the ones causing it.

And be sure to mention them in the credits if you get your research
published,

Good luck,

*Watt



"Gjtatters" wrote in message
om...
This may at first seem like a strange post to a Ham Radio newsgroup,
but I am hoping someone can help us out. We (Canadian Scientists) are
currently conducting research in Brazil near the city Rio Claro in Sao
Paolo state. We study lizard physiology and hibernation, and are
currently conducting a year long study using radio telemeters
implanted inside lizards. These telemeters allow us to monitor heart
rate, breathing rate and body temperature, and all of this information
is uploaded via radio frequencies and recorded to computer.

The telemeters themselves work in the high MHz range. Each animal (we
are currently looking at 4 animals) has a unique telemeter with a
unique transmission band. The 4 frequencies we are looking at a
182, 184, 206 and 208 Mhz. This radio frequency information is then
decoded with a demodulator, and the information stored as a voltage
signal on a standard computer acquisition system.

The problem we are finding is that typically, between 11am and 3pm
during the day, our telemeters are encountering massive interference
from some external source, and we cannot make any meaningful
recordings. Our signal strength goes to pot, and all we get is noise.
Strangely enough, during the evenings, the recordings seem fine.

To add to the story, all the telemeters can be turned on or off (they
have a battery that should last about 1 year) using a 1.8 Mhz burst
(we have a small battery powered wand-like antenna that we wave over
the lizards for this express purpose!). Once we started to encounter
our interference problem, we began to think that perhaps our
telemeters are being turned on and off intermittently by an external
source of 1.8 MHz. That was when we realized that Ham Radio operates
from about 1.8 to 30 Mhz.

What I wanted to ask the newsgroup was whether anyone thinks that the
signal strength from a local ham radio operator would be enough to
turn our telemeters on or off (I doubt you would know the answer to
this question, but thought I'd ask). Do Ham Radio operators typically
use 1.8 Mhz?

Otherwise, does anyone out there know what could possibly be
interfering at the higher frequencies (182-208 MHz)? There is a local
airstrip and flying club that flies overhead where we are conducting
this research, but I do not know if they typically transmit within out
frequency range!

But more importantly, if the Ham Radio signal could be the source of
our interference, we wanted to know if anyone could help us find out
if there is anyone in Rio Claro that is a Ham Radio operator?!! If
so, would they be willing to help us troubleshoot this problem!

Thanks for your time. Please reply directly to this email if you can.

Gjtatters





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