Hello Hal -
I spent a lot of my RF engineering career in related areas, including radar,
EW, and spread spectrum timing
systems. Since the distance is short and the cost is an issue you may wish to
consider an analog
system solution.
Specifically your master station transmits a RF signal that is FM modulated
with a high frequency tone.
The remote unit is a transponder. It receives the tone and re-transmits back on
another frequency. Almost no parts required.
At the master station the phases of the outgoing and returning tones are
compared. The distance is directly
proportional to the phase shift between the outgoing and incoming tones. For
instance if the tone is 10 MHz
the 360 degrees of phase is 100 nS which is about 100 ft round trip.
The phase may be measured either analog and A/D converted or digitally and in
either case is then easily converted to range by your processor.
By adjusting the tone frequency you can set the full scale range. To increase
resolution higher frequency tones may be used. To overcome ambiguity when the
range goes beyond 360 degrees of phase, add a lower frequency tone to resolve
the ambiguity.
This scheme has been used in surveying instruments (the Teleurometer) and even
an ill fated German bombing system in WWI. The latter proved delightfully easy
to jam since the Brits had a spare TV
transmitter in the correct band.
Look up something like tone ranging.
-john c roos k6iql
-Original Message-
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Sent: Fri, Feb 1, 2013 4:24 am
Subject: time-nuts Digest, Vol 103, Issue 2
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Today's Topics:
1. Re: Loran again (Stan, W1LE)
2. question for expert time guys (Rick Harold)
3. Re: Low noise power supplies? (gary)
4. Re: Low noise power supplies? (John Miles)
5. Re: question for expert time guys (Hal Murray)
6. Re: question for expert time guys (Azelio Boriani)
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Message: 1
Date: Fri, 01 Feb 2013 00:30:40 -0500
From: Stan, W1LE stanw...@verizon.net
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Loran again
Message-ID: 510b5300.8000...@verizon.net
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Fired up the SRS FS700 and auto found the GRI 89700 microsecond stations
in Dana Il (master)
and Seneca NY, (slave) both with equal signal strength of 63 db. Other
slaves were not to be found.
Noise margin of 32 dB and Rx gain of 72dB. So the Rx is all locked up.
Tomorrow I will have more data comparing the 10 MHz from the T'Bolt.
Right now they are comparing to within 10EE10.
Stan, W1LE Cape Cod
On 1/31/2013 10:44 PM, Stan, W1LE wrote:
What GRI should we be listening for ?
Stan, W1LECape Cod FN41sr
On 1/31/2013 9:56 PM, paul swed wrote:
Rich indeed its on the air. Warming up the FS700 to see if it will lock.
Have a pattern ram thats getting flakey and takes about 30 minutes to
warm
up along with the oven.
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Message: 2
Date: Thu, 31 Jan 2013 22:37:00 -0600
From: Rick Harold rickhar...@gmail.com
To: time-nuts@febo.com
Subject: [time-nuts] question for expert time guys
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CAODR2TDuMSpOr8JYvjMm-QRnRhM8sxYGkY=vrn6yttk5t3t...@mail.gmail.com
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To time experts/EE's.
I would like to triangulate a position of a device which moves using 3
fixed positions devices of known location.
The idea is to have these operate on 915mhz or 434mhz or 2.4ghz or
appropriate frequency.
These two type of devices (fixed and mobile) are all under my control and
thus customized as needed.
The mobile device (not a phone, custom device) would be the least expensive
item. I'd like a range of 150 feet or better and accuracy of 3 feet or
better.
When manufactured these items they can be calibrated in order to adjust for
any variation in IC's, discrete components etc...
We can assume for now the temperature is constant 70 degree temperature.
Cost is the key design factor.
The general flow is:
1. base station 1 indicates we are determining position of device A.
2. Each base station 1, 2, 3 take turns pinging the device to determine
distance.
