Today's Message Index:
----------------------
1. 07:19 AM - Re: Minimum GPS Antenna Cable Length (Robert L. Nuckolls, III)
2. 07:44 AM - Re: Minimum GPS Antenna Cable Length (Kelly McMullen)
3. 07:55 AM - Re: Minimum GPS Antenna Cable Length (Tim Olson)
4. 08:01 AM - Re: Minimum GPS Antenna Cable Length (don van santen)
5. 08:06 AM - Re: Minimum GPS Antenna Cable Length (don van santen)
6. 08:30 AM - Re: Minimum GPS Antenna Cable Length (user9253)
7. 08:36 AM - Re: Minimum GPS Antenna Cable Length (Stein Bruch)
8. 09:00 AM - Re: Minimum GPS Antenna Cable Length (user9253)
9. 09:41 AM - Re: Re: Minimum GPS Antenna Cable Length (Charlie England)
10. 02:15 PM - Re: Minimum GPS Antenna Cable Length (user9253)
11. 06:34 PM - Thermocouple Wires (William Hunter)
12. 06:56 PM - Re: Thermocouple Wires (user9253)
Message 1
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Subject: | Re: Minimum GPS Antenna Cable Length |
At 06:01 AM 3/30/2017, you wrote:
>
>I am installing an Appareo Stratus ESG transponder with internal
>GPS. It did not come with antenna cables. I purchased a 19 inch
>RG400 GPS antenna cable before reading the installation directions
>which state, "All wiring should have a cable loss of minimum 2 dB .
>. . .Using RG400 the minimum cable length is 10 feet".
> Will the GPS work satisfactorily with the short cable? If not,
> what is a cheap and easy way to increase the dB loss? What is the
> theory behind the requirement for at least 2 dB cable loss?
I'm having trouble wrapping my head around this
requirement. GPS satellite signals are exceedingly
tiny . . . down in the atmospheric noise levels.
The only reason our tiny wrist-watch, hand-held,
and self-navigating drones work so well is because
the 'smarts' in GPS receiver software is looking for
specific patterns of data in the chaotic patternless
noise.
Routine variations in received GPS signals
is all over the magnitude map spanning perhaps
tens of db . . . a required 2 db 'addition of
attenuation' simply doesn't make sense.
The idea that a receiver's performance is
predicated on a minimum of 2db of loss in the
antenna system by making the cable longer is a
real puzzle . . . usually, the instructions will
say something like "limit cable losses to a MAXIMUM
of 2db where a 10' run of RG-400 is the practical
limit".
I'm wondering if this manual wasn't originally crafted
in Chinese and then translated by some academic instead
of a systems engineer.
One thing is for sure, if you install your system
using only the needed length of coax, you can certainly
ADD some later. I'm betting a dollar to a dozen doughnuts
that it will not be necessary.
Bob . . .
Message 2
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Subject: | Re: Minimum GPS Antenna Cable Length |
Garmin came out with the same requirement when the GNS-430W was
approved. I believe they later reduced the minimum length to perhaps 6
ft. I suspect it has more to do with matching the output of the antenna
pre-amplifier to the main receiver, and doesn't have a lot to do with
signal strength at all.
On 3/31/2017 7:16 AM, Robert L. Nuckolls, III wrote:
> At 06:01 AM 3/30/2017, you wrote:
>>
>> I am installing an Appareo Stratus ESG transponder with internal GPS.
>> It did not come with antenna cables. I purchased a 19 inch RG400 GPS
>> antenna cable before reading the installation directions which state,
>> "All wiring should have a cable loss of minimum 2 dB . . . .Using
>> RG400 the minimum cable length is 10 feet".
>> Will the GPS work satisfactorily with the short cable? If not, what
>> is a cheap and easy way to increase the dB loss? What is the theory
>> behind the requirement for at least 2 dB cable loss?
>
> I'm having trouble wrapping my head around this
> requirement. GPS satellite signals are exceedingly
> tiny . . . down in the atmospheric noise levels.
> The only reason our tiny wrist-watch, hand-held,
> and self-navigating drones work so well is because
> the 'smarts' in GPS receiver software is looking for
> specific patterns of data in the chaotic patternless
> noise.
>
> Routine variations in received GPS signals
> is all over the magnitude map spanning perhaps
> tens of db . . . a required 2 db 'addition of
> attenuation' simply doesn't make sense.
>
> The idea that a receiver's performance is
> predicated on a minimum of 2db of loss in the
> antenna system by making the cable longer is a
> real puzzle . . . usually, the instructions will
> say something like "limit cable losses to a MAXIMUM
> of 2db where a 10' run of RG-400 is the practical
> limit".
>
> I'm wondering if this manual wasn't originally crafted
> in Chinese and then translated by some academic instead
> of a systems engineer.
>
> One thing is for sure, if you install your system
> using only the needed length of coax, you can certainly
> ADD some later. I'm betting a dollar to a dozen doughnuts
> that it will not be necessary.
>
>
> Bob . . .
>
Message 3
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Subject: | Re: Minimum GPS Antenna Cable Length |
This is not that unusual. My Garman GNS480 had the same requirement.
Keep in mind that the antennas used are active antennas.
Tim
> On Mar 31, 2017, at 9:16 AM, Robert L. Nuckolls, III <nuckolls.bob@aeroele
ctric.com> wrote:
>
> At 06:01 AM 3/30/2017, you wrote:
>>
>> I am installing an Appareo Stratus ESG transponder with internal GPS. It
did not come with antenna cables. I purchased a 19 inch RG400 GPS antenna c
able before reading the installation directions which state, "All wiring sho
uld have a cable loss of minimum 2 dB . . . .Using RG400 the minimum cable l
ength is 10 feet".
>> Will the GPS work satisfactorily with the short cable? If not, what is
a cheap and easy way to increase the dB loss? What is the theory behind th
e requirement for at least 2 dB cable loss?
>
> I'm having trouble wrapping my head around this
> requirement. GPS satellite signals are exceedingly
> tiny . . . down in the atmospheric noise levels.
> The only reason our tiny wrist-watch, hand-held,
> and self-navigating drones work so well is because
> the 'smarts' in GPS receiver software is looking for
> specific patterns of data in the chaotic patternless
> noise.
>
> Routine variations in received GPS signals
> is all over the magnitude map spanning perhaps
> tens of db . . . a required 2 db 'addition of
> attenuation' simply doesn't make sense.
>
> The idea that a receiver's performance is
> predicated on a minimum of 2db of loss in the
> antenna system by making the cable longer is a
> real puzzle . . . usually, the instructions will
> say something like "limit cable losses to a MAXIMUM
> of 2db where a 10' run of RG-400 is the practical
> limit".
>
> I'm wondering if this manual wasn't originally crafted
> in Chinese and then translated by some academic instead
> of a systems engineer.
>
> One thing is for sure, if you install your system
> using only the needed length of coax, you can certainly
> ADD some later. I'm betting a dollar to a dozen doughnuts
> that it will not be necessary.
>
>
> Bob . . .
Message 4
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Subject: | Re: Minimum GPS Antenna Cable Length |
Bob,
The first Garmin 430 install manuals stated nothing about the GPS antenna
cable length. When the WAAS update was released Garmin stated that the GPS
antenna had to be at least 13 feet long. It also stated that it was alright
to "coil" the antenna. I know of two RV 10s with G 430s, o e with the 13
foot antenna cable and one with a 3 foot (roughly) anrenna cable. There is
no detectable difference in performance. I have not checked the current
G430 WAAS manual for cable length requirements.
Don
On Mar 31, 2017 7:26 AM, "Robert L. Nuckolls, III" <
nuckolls.bob@aeroelectric.com> wrote:
> At 06:01 AM 3/30/2017, you wrote:
>
>
> I am installing an Appareo Stratus ESG transponder with internal GPS. It
> did not come with antenna cables. I purchased a 19 inch RG400 GPS antenna
> cable before reading the installation directions which state, "All wiring
> should have a cable loss of minimum 2 dB . . . .Using RG400 the minimum
> cable length is 10 feet".
> Will the GPS work satisfactorily with the short cable? If not, what is
> a cheap and easy way to increase the dB loss? What is the theory behind
> the requirement for at least 2 dB cable loss?
>
>
> I'm having trouble wrapping my head around this
> requirement. GPS satellite signals are exceedingly
> tiny . . . down in the atmospheric noise levels.
> The only reason our tiny wrist-watch, hand-held,
> and self-navigating drones work so well is because
> the 'smarts' in GPS receiver software is looking for
> specific patterns of data in the chaotic patternless
> noise.
>
> Routine variations in received GPS signals
> is all over the magnitude map spanning perhaps
> tens of db . . . a required 2 db 'addition of
> attenuation' simply doesn't make sense.
>
> The idea that a receiver's performance is
> predicated on a minimum of 2db of loss in the
> antenna system by making the cable longer is a
> real puzzle . . . usually, the instructions will
> say something like "limit cable losses to a MAXIMUM
> of 2db where a 10' run of RG-400 is the practical
> limit".
>
> I'm wondering if this manual wasn't originally crafted
> in Chinese and then translated by some academic instead
> of a systems engineer.
>
> One thing is for sure, if you install your system
> using only the needed length of coax, you can certainly
> ADD some later. I'm betting a dollar to a dozen doughnuts
> that it will not be necessary.
>
>
> Bob . . .
>
Message 5
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Subject: | Re: Minimum GPS Antenna Cable Length |
My UPSAT 480 manual did mot list a cable length requirement. I used a 3
foot rg 400 csble and never had any issues with reception.
On Mar 31, 2017 08:00, "Tim Olson" <Tim@myrv10.com> wrote:
> This is not that unusual. My Garman GNS480 had the same requirement.
> Keep in mind that the antennas used are active antennas.
> Tim
>
> On Mar 31, 2017, at 9:16 AM, Robert L. Nuckolls, III <
> nuckolls.bob@aeroelectric.com> wrote:
>
> At 06:01 AM 3/30/2017, you wrote:
>
>
> I am installing an Appareo Stratus ESG transponder with internal GPS. It
> did not come with antenna cables. I purchased a 19 inch RG400 GPS antenna
> cable before reading the installation directions which state, "All wiring
> should have a cable loss of minimum 2 dB . . . .Using RG400 the minimum
> cable length is 10 feet".
> Will the GPS work satisfactorily with the short cable? If not, what is
> a cheap and easy way to increase the dB loss? What is the theory behind
> the requirement for at least 2 dB cable loss?
>
>
> I'm having trouble wrapping my head around this
> requirement. GPS satellite signals are exceedingly
> tiny . . . down in the atmospheric noise levels.
> The only reason our tiny wrist-watch, hand-held,
> and self-navigating drones work so well is because
> the 'smarts' in GPS receiver software is looking for
> specific patterns of data in the chaotic patternless
> noise.
>
> Routine variations in received GPS signals
> is all over the magnitude map spanning perhaps
> tens of db . . . a required 2 db 'addition of
> attenuation' simply doesn't make sense.
>
> The idea that a receiver's performance is
> predicated on a minimum of 2db of loss in the
> antenna system by making the cable longer is a
> real puzzle . . . usually, the instructions will
> say something like "limit cable losses to a MAXIMUM
> of 2db where a 10' run of RG-400 is the practical
> limit".
>
> I'm wondering if this manual wasn't originally crafted
> in Chinese and then translated by some academic instead
> of a systems engineer.
>
> One thing is for sure, if you install your system
> using only the needed length of coax, you can certainly
> ADD some later. I'm betting a dollar to a dozen doughnuts
> that it will not be necessary.
>
>
> Bob . . .
>
>
Message 6
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Subject: | Re: Minimum GPS Antenna Cable Length |
It seems that the minimum cable length is a requirement of the GPS receiver and
not of the antenna. I agree with you Bob. I always thought that shorter cable
length is better.
I ordered 2 of 90 degree TNC adapters to increase the dB loss. eBay item number:
232142074744
Below is a quote from a separate unrelated company. Notice that they contradict
themselves in the last sentence.
http://utahscientific.com/support/protected/fb_contemp/GPS%20Installation%20V1_6.pdf
> In the world of GPS; too much signal gain can be just as detrimental as too little,
and RF noise, even if it is out of band, can severely disrupt the performance
of your GPS application.
> The Courtyard GPS receiver has a minimum input gain of 20dB and a maximum of
30dB.
> The recommended antenna has a 26dB gain.
> Recommended cable is RG58 and TNC connectors having a loss of 0.85dB per metre.
> (RG174 has a loss of 1.2dB per meter.)
> Maximum cable length is: (26dB-20dB)/0.85dBpermetre = 7.06 metres
> Minimum cable length is: (30dB -26dB)/0.85dBpermetre = 4.70 meters
> As a general rule, keep RF cable lengths as short as possible and use a good
quality GPS antenna with the correct gain.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=467869#467869
Message 7
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Subject: | Minimum GPS Antenna Cable Length |
That is a fairly accurate statement correct. For others who have 'used' or
'seen' shorter cables work, indeed sometimes they do...but I lost count of
the number of phone calls we've had from customers about antenna or GPS
issues, only to find out they had a short little cable. Once extending the
cable to the proper length most issues disappeared. Our recommendation is
to keep it on the longer side - sometimes shorter than 10' will be ok, but
something as short as 18" will almost certainly cause issues.
Cheers,
Stein
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Kelly
McMullen
Sent: Friday, March 31, 2017 9:38 AM
Subject: Re: AeroElectric-List: Minimum GPS Antenna Cable Length
--> <kellym@aviating.com>
Garmin came out with the same requirement when the GNS-430W was approved. I
believe they later reduced the minimum length to perhaps 6 ft. I suspect it
has more to do with matching the output of the antenna pre-amplifier to the
main receiver, and doesn't have a lot to do with signal strength at all.
On 3/31/2017 7:16 AM, Robert L. Nuckolls, III wrote:
> At 06:01 AM 3/30/2017, you wrote:
>> --> <fransew@gmail.com>
>>
>> I am installing an Appareo Stratus ESG transponder with internal GPS.
>> It did not come with antenna cables. I purchased a 19 inch RG400 GPS
>> antenna cable before reading the installation directions which state,
>> "All wiring should have a cable loss of minimum 2 dB . . . .Using
>> RG400 the minimum cable length is 10 feet".
>> Will the GPS work satisfactorily with the short cable? If not,
>> what is a cheap and easy way to increase the dB loss? What is the
>> theory behind the requirement for at least 2 dB cable loss?
>
> I'm having trouble wrapping my head around this
> requirement. GPS satellite signals are exceedingly
> tiny . . . down in the atmospheric noise levels.
> The only reason our tiny wrist-watch, hand-held,
> and self-navigating drones work so well is because
> the 'smarts' in GPS receiver software is looking for
> specific patterns of data in the chaotic patternless
> noise.
>
> Routine variations in received GPS signals
> is all over the magnitude map spanning perhaps
> tens of db . . . a required 2 db 'addition of
> attenuation' simply doesn't make sense.
>
> The idea that a receiver's performance is
> predicated on a minimum of 2db of loss in the
> antenna system by making the cable longer is a
> real puzzle . . . usually, the instructions will
> say something like "limit cable losses to a MAXIMUM
> of 2db where a 10' run of RG-400 is the practical
> limit".
>
> I'm wondering if this manual wasn't originally crafted
> in Chinese and then translated by some academic instead
> of a systems engineer.
>
> One thing is for sure, if you install your system
> using only the needed length of coax, you can certainly
> ADD some later. I'm betting a dollar to a dozen doughnuts
> that it will not be necessary.
>
>
> Bob . . .
>
Message 8
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Subject: | Re: Minimum GPS Antenna Cable Length |
Below is a quote from Garmin:
http://www.vansairforce.com/community/showpost.php?p=824265&postcount=3
> Once the antenna mounting position has been prepared, route the coax cable from
the antenna to the 400W Series unit. Proper selection of coax cable and assembly
of connectors is critical to GPS signal performance. The cable loss from
the GPS antenna shall be between 1.5 dB and 6.5 dB in order to aintain proper
rejection to interference signals.
> The coaxial connectors and adapters, such as TNC to BNC, add additional loss
to the cable and should be considered when computing the cable loss. A typical
loss of 0.2 dB can be used for each connection.
> NOTE: If RG-142B or RG-400 is used, 1.5 dB equates to a length of approximately
6.5 feet of cable with a connector on each end. RG-142B or RG-400 cable can
be used as long as the length is less than 35 feet.
Another website says, "Be kind to the 0.000 000 000 000 000 1 watt GPS signal at
the Antenna !!"
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=467874#467874
Message 9
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Subject: | Re: Minimum GPS Antenna Cable Length |
I think we may be losing sight of what signal we're actually talking about.
It's extremely unlikely that the GPS antenna puck is sending raw,
unamplified 1/5 GHZ RF to the receiver.
Most GPS pucks send either decoded digital data (serial or USB), or
amplified 1.5GHZ RF, or amplified and downconverted IF (intermediate
frequency) to the receiver. If it's either of the 2nd two options, then
the next stage (in the receiver) can be overdriven by a very strong
signal from the puck.
On 3/31/2017 10:57 AM, user9253 wrote:
>
> Below is a quote from Garmin:
> http://www.vansairforce.com/community/showpost.php?p=824265&postcount=3
>
>> Once the antenna mounting position has been prepared, route the coax cable from
the antenna to the 400W Series unit. Proper selection of coax cable and assembly
of connectors is critical to GPS signal performance. The cable loss from
the GPS antenna shall be between 1.5 dB and 6.5 dB in order to aintain proper
rejection to interference signals.
>> The coaxial connectors and adapters, such as TNC to BNC, add additional loss
to the cable and should be considered when computing the cable loss. A typical
loss of 0.2 dB can be used for each connection.
>> NOTE: If RG-142B or RG-400 is used, 1.5 dB equates to a length of approximately
6.5 feet of cable with a connector on each end. RG-142B or RG-400 cable can
be used as long as the length is less than 35 feet.
> Another website says, "Be kind to the 0.000 000 000 000 000 1 watt GPS signal
at the Antenna !!"
>
> --------
> Joe Gores
>
Message 10
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Subject: | Re: Minimum GPS Antenna Cable Length |
I will follow Stein's (and the Mfg's) recommendation and will use a 10 foot cable.
They are the experts. It will be a lot easier to do it right the first time.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=467885#467885
Message 11
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Subject: | Thermocouple Wires |
Hi all ,
Are thermocouple units polarized? In other words does it matter when
connecting up a thermocouple to a dynon EMS unit what wire goes in what pin?
THANKS!!!
Message 12
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Subject: | Re: Thermocouple Wires |
>From the SkyView Installation Manual:
> Polarity is important, so
> ensure that you are routing the positive side (yellow for K-type; white for J-type)
of the thermocouple to pin 27 or pin 36 on the 37-pin harness, and the
negative side to pin 28 or pin 37
Note that the red wire from type J thermocouples is NOT positive, but is negative.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=467898#467898
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